Internet radio - classical music, etc
 

In article , Jim Lesurf
scribeth thus
In article , David Looser
wrote:
"tony sayer" wrote in message
...

You went involved in the MP2 codec tests for the development of DAB?..


No, voice codecs only, but the principle is the same. More to the point
I know just how hard it is, and the lengths we had to go to, to
eliminate bias from listening tests.

FWIW I've now had a chance to record some mp3 streams 'broadcast' by some
of the net stations. This meant I could write the results onto a CDRW and
listen to them on some players. Have examples at 128/192/256kbps. What I've
found interesting is that the results *didn't* show that the 'higher the
bitrate the better the sound'. This was a totally uncontrolled test, so is
suspect, but it does strengthen my bias towards feeling that the way the
specific encoder is used (and the details of the sound patterns to be
encoded) can matter more that the output bitrate chosen.


And where it came from in the first place;)...
Slainte,

Jim


--
Tony Sayer

Internet radio - classical music, etc
 

In article , Dave Plowman (News)
scribeth thus
In article ,
tony sayer wrote:
Perhaps that's the difference between us. I'm only interested in the
sound I hear in my room. I don't really care how it is unacceptably
degraded.


That I find a really odd attitude from someone who works as a sound
recordist;?..

No, IMHO, the correct one. It's the end result that matters - not what
equipment is used.


So you don't seem to mind that your work can be degraded?..
--
Tony Sayer

Internet radio - classical music, etc
 

In article , Rob
wrote:
Jim Lesurf wrote:

FWIW I've now had a chance to record some mp3 streams 'broadcast' by
some of the net stations. This meant I could write the results onto a
CDRW and listen to them on some players. Have examples at
128/192/256kbps. What I've found interesting is that the results
*didn't* show that the 'higher the bitrate the better the sound'. This
was a totally uncontrolled test, so is suspect, but it does strengthen
my bias towards feeling that the way the specific encoder is used (and
the details of the sound patterns to be encoded) can matter more that
the output bitrate chosen.


I don't suppose it makes a great deal of difference if you record using
a lossless format, but isn't it more logical to just capture the
streamed audio?

Erm... that is what I have been doing. Recording the mp3 stream as an mp3
file on my computer. Then writing these files into a CDRW for playing on
various 'audio'/'video' disc players.

Slainte,

Jim

--
Change 'noise' to 'jcgl' if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

Internet radio - classical music, etc
 

In article , Dave Plowman (News)
wrote:

Those who moan about current 'DAB quality' are almost certainly
listening to pop music stations - as R3&4 have a just about adequate
data rate for the material they carry. Or at least during the times I
listen to them. And *every* pop and light music station is so heavily
processed on all wavebands that - to me - they are simply dreadful to
listen to.

The above sums up my own experience of DAB. Although these days I mainly
listen to DTTV rather than DAB.

Slainte,

Jim

--
Change 'noise' to 'jcgl' if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

Internet radio - classical music, etc
 

In article , Ian Jackson
wrote:
In message , Jim Lesurf
writes


[1] Or 8kHz for those regions of the world where 8kHz spacing was
adopted. 9kHz isn't uniform around the world IIRC.

Out of interest, which region is 8kHz? I thought it was only 9 or 10.
I've had a quick look, but can't find 8.

Afraid I've forgotten! :-) It may be either Africa or the USA, but I
can't recall. I do remember that the World Conferences established some
regions as 8kHz and others 9kHz. Think this was when the BBC on long wave
went from 200kHz to 198kHz to suit. But alas my memory of this is hazy.

IIRC one of the Quad AM tuners also had a choice of notch filter frequency
to cater for the region.

Slainte,

Jim

--
Change 'noise' to 'jcgl' if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

Internet radio - classical music, etc
 

"Ian Jackson" wrote in message
...
In message , Jim Lesurf
writes


[1] Or 8kHz for those regions of the world where 8kHz spacing was adopted.
9kHz isn't uniform around the world IIRC.

Out of interest, which region is 8kHz? I thought it was only 9 or 10. I've
had a quick look, but can't find 8.

Yup, it's 9kHz or 10kHz dependiing on region. There's no 8.

David.

Internet radio - classical music, etc
 

"Rob" wrote in message
om...

I'm of a view that if you do have an opportunity to provide something to a
high standard, you take it. Not everyone will appreciate it, maybe, small
price. I found the whole roll-out of DAB wrong-headed.


How high is high?

David.

Internet radio - classical music, etc
 

In article ,
David Looser wrote:
"Rob" wrote in message
om...

I'm of a view that if you do have an opportunity to provide something
to a high standard, you take it. Not everyone will appreciate it,
maybe, small price. I found the whole roll-out of DAB wrong-headed.


How high is high?

Indeed. Most of these comments come with the benefit of hindsight. DAB was
a long time in the planning - and making radical changes late in that
process would have been difficult.
I remember driving round Birmingham on a coach equipped with a
demonstration system long before actual transmissions started - and the
difference in reception between that and FM was quite astounding.

--
*Wrinkled was not one of the things I wanted to be when I grew up

Dave Plowman London SW
To e-mail, change noise into sound.

Internet radio - classical music, etc
 

On Fri, 06 Feb 2009 09:41:02 +0000 (GMT), Jim Lesurf
wrote:

In article , Rob
wrote:
Jim Lesurf wrote:

FWIW I've now had a chance to record some mp3 streams 'broadcast' by
some of the net stations. This meant I could write the results onto a
CDRW and listen to them on some players. Have examples at
128/192/256kbps. What I've found interesting is that the results
*didn't* show that the 'higher the bitrate the better the sound'. This
was a totally uncontrolled test, so is suspect, but it does strengthen
my bias towards feeling that the way the specific encoder is used (and
the details of the sound patterns to be encoded) can matter more that
the output bitrate chosen.


I don't suppose it makes a great deal of difference if you record using
a lossless format, but isn't it more logical to just capture the
streamed audio?

Erm... that is what I have been doing. Recording the mp3 stream as an mp3
file on my computer. Then writing these files into a CDRW for playing on
various 'audio'/'video' disc players.

Slainte,

Jim

Can you really do that - record an MP3 stream as an MP3 file, I mean?
I thought the file got decoded to straight PCM, the recoded as MP3 for
writing to the file. How else would you generate the file header?

d
--
Pearce Consulting
http://www.pearce.uk.com

Internet radio - classical music, etc
 

In article , David Looser
wrote:
"Ian Jackson" wrote in message
...
In message , Jim Lesurf
writes


[1] Or 8kHz for those regions of the world where 8kHz spacing was
adopted. 9kHz isn't uniform around the world IIRC.

Out of interest, which region is 8kHz? I thought it was only 9 or 10.
I've had a quick look, but can't find 8.

Yup, it's 9kHz or 10kHz dependiing on region. There's no 8.

In that case, my error. I assume I was confusing that with 8kHz. Memory
fault.

Slainte,

Jim

--
Change 'noise' to 'jcgl' if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

Internet radio - classical music, etc
 

Jim Lesurf wrote:
In article , Rob
wrote:
Jim Lesurf wrote:

FWIW I've now had a chance to record some mp3 streams 'broadcast' by
some of the net stations. This meant I could write the results onto a
CDRW and listen to them on some players. Have examples at
128/192/256kbps. What I've found interesting is that the results
*didn't* show that the 'higher the bitrate the better the sound'. This
was a totally uncontrolled test, so is suspect, but it does strengthen
my bias towards feeling that the way the specific encoder is used (and
the details of the sound patterns to be encoded) can matter more that
the output bitrate chosen.


I don't suppose it makes a great deal of difference if you record using
a lossless format, but isn't it more logical to just capture the
streamed audio?

Erm... that is what I have been doing. Recording the mp3 stream as an mp3
file on my computer. Then writing these files into a CDRW for playing on
various 'audio'/'video' disc players.


No, you're not capturing the *stream* AIUI, you're capturing the audio
once it's been through your sound card, and you've then converted it
again to mp3.

To use a video analogy, you're allowing video to stream through your
media player, assuming your clockwork computer has such a thing, and
capturing the video using screen capture software. Better to capture the
stream before it hits software.

If you are going to do it your way (recalcitrance on software noted!)
you're better as a point of accuracy to use lossless capture, and then
do whatever you need in terms of compression. You're still taking a
(tiny) hit through the D-A-D conversion though. I think you might also
have a problem if different compression codecs are used at source (radio
station) and destination (your end).

Stream capture captures the data before it hits the sound card - I use
Xstreamripper. Quality isn't that much of an issue for me - but what
capturing the stream does is record the song data which also contains
things like artist, album and song, so you can save it as a nice
labelled file. I happen to listen to non-English stations so this works
well for me. This also happens to be the 'purest' and quickest method of
capturing the audio.

As ever, happy to stand corrected ;-)

Rob

Internet radio - classical music, etc
 

Dave Plowman (News) wrote:
In article ,
Rob wrote:
Dave Plowman (News) wrote:
In article ,
tony sayer wrote:
Perhaps that's the difference between us. I'm only interested in the
sound I hear in my room. I don't really care how it is unacceptably
degraded.

That I find a really odd attitude from someone who works as a sound
recordist;?..
No, IMHO, the correct one. It's the end result that matters - not what
equipment is used.


Rates of pay/unionisation/working
conditions/education-training-apprenticeships; equipment/process:
'green', efficient, effective, reliable, replicable, universal, under
review. And so on really. Tragic IMO - I'd have thought all these things
matter?

And what do they have to do with equipment?

Equipment can be: 'green', efficient, effective, reliable, replicable,
universal, under
review. I would be surprised if none of that was important to you.
It's even of passing interest to me.


I have noticed this 'what matters is what works' has become more
pervasive, although even Labour had the sensitivity/expediency to remove
the phrase from their policy docs.

Sigh. Perhaps I should explain again.

Those who moan about current 'DAB quality' are almost certainly listening
to pop music stations - as R3&4 have a just about adequate data rate for
the material they carry. Or at least during the times I listen to them.
And *every* pop and light music station is so heavily processed on all
wavebands that - to me - they are simply dreadful to listen to. Ones like
R2 the worst - given the amount of speech they transmit.
Of course it obviously doesn't offend others. People are not the same.


I'd agree with all of that - although I'm not an especially critical
radio listener, mainly R4.

Rob

Internet radio - classical music, etc
 

David Looser wrote:
"Rob" wrote in message
om...
I'm of a view that if you do have an opportunity to provide something to a
high standard, you take it. Not everyone will appreciate it, maybe, small
price. I found the whole roll-out of DAB wrong-headed.


How high is high?


Mmm. Quite. Well, firstly it could have been higher:

http://www.digitalradiotech.co.uk/da...ion_of_dab.htm

Secondly, regulation could have enabled higher bitrates. I know it
sounds fruitless, elitist, and I'd be the first to admit that most
people don't seem to care if it's 32kbps or 256, but *I think* it could
have been a bit higher than it is - perhaps at the cost of a few radio
stations. I accept the fact you don't, and really, I don't lose any
sleep over the whole thing.

Rob

Internet radio - classical music, etc
 

On Fri, 06 Feb 2009 15:17:43 +0000 (GMT), "Dave Plowman (News)"
wrote:

In article ,
David Looser wrote:
"Rob" wrote in message
om...

I'm of a view that if you do have an opportunity to provide something
to a high standard, you take it. Not everyone will appreciate it,
maybe, small price. I found the whole roll-out of DAB wrong-headed.


How high is high?

Indeed. Most of these comments come with the benefit of hindsight. DAB was
a long time in the planning - and making radical changes late in that
process would have been difficult.
I remember driving round Birmingham on a coach equipped with a
demonstration system long before actual transmissions started - and the
difference in reception between that and FM was quite astounding.

How come you didn't go on the Kingswood Warren coach? Much more
convenient.

d

Internet radio - classical music, etc
 

In article , Rob
scribeth thus
David Looser wrote:
"Rob" wrote in message
om...
I'm of a view that if you do have an opportunity to provide something to a
high standard, you take it. Not everyone will appreciate it, maybe, small
price. I found the whole roll-out of DAB wrong-headed.


How high is high?


Mmm. Quite. Well, firstly it could have been higher:

http://www.digitalradiotech.co.uk/da...ion_of_dab.htm

Secondly, regulation could have enabled higher bitrates. I know it
sounds fruitless, elitist, and I'd be the first to admit that most
people don't seem to care if it's 32kbps or 256, but *I think* it could
have been a bit higher than it is - perhaps at the cost of a few radio
stations. I accept the fact you don't, and really, I don't lose any
sleep over the whole thing.

Rob

I reckon that Dab as we know it will die away left behind by other radio
tech, and theres still no firm date for digital changeover indeed a lot
of the commercial sector can't afford to run DAB and FM transmissions..

Some are wondering if we really need T-DAB as it stands if we should
have digital then either Internet or satellite for home use .. and well,
Dab for mobile?, except that the receiver's in cars is a tricky one;!..
--
Tony Sayer

Internet radio - classical music, etc
 

In article ,
Jim Lesurf wrote:
The above sums up my own experience of DAB. Although these days I mainly
listen to DTTV rather than DAB.

Indeed - and DDTV tuners are rather cheaper than DAB ones. And most will
already have a UHF aerial. Only slight snag can be selecting the correct
station without having a TV attached.

--
*If a pig loses its voice, is it disgruntled?

Dave Plowman London SW
To e-mail, change noise into sound.

Internet radio - classical music, etc
 

In article 498e8bea.169358828@localhost,
Don Pearce (Don Pearce) wrote:
Indeed. Most of these comments come with the benefit of hindsight. DAB was
a long time in the planning - and making radical changes late in that
process would have been difficult.
I remember driving round Birmingham on a coach equipped with a
demonstration system long before actual transmissions started - and the
difference in reception between that and FM was quite astounding.

How come you didn't go on the Kingswood Warren coach? Much more
convenient.

It was laid on for an IBS meeting taking place at Pebble Mill. I don't
know which came first - but Birmingham bull ring is (was?) notorious for
poor FM reception. Could have been the same coach - it was said to have
state of the art aerials and receivers for both DAB and FM.

--
*Funny, I don't remember being absent minded.

Dave Plowman London SW
To e-mail, change noise into sound.

Internet radio - classical music, etc
 

In article ,
tony sayer wrote:
I reckon that Dab as we know it will die away left behind by other radio
tech, and theres still no firm date for digital changeover indeed a lot
of the commercial sector can't afford to run DAB and FM transmissions..

If enough pull out of DAB it will force the 'rental' costs down. They were
ludicrous to start with.

--
*If at first you don't succeed, try management *

Dave Plowman London SW
To e-mail, change noise into sound.

Internet radio - classical music, etc
 

In article , Rob
wrote:
Jim Lesurf wrote:


Erm... that is what I have been doing. Recording the mp3 stream as an
mp3 file on my computer. Then writing these files into a CDRW for
playing on various 'audio'/'video' disc players.


No, you're not capturing the *stream* AIUI, you're capturing the audio
once it's been through your sound card, and you've then converted it
again to mp3.

Erm, again. My computer doesn't have a 'sound card'. I use an application
(software) that can fetch the steam and this can then either save it to a
file and/or covert it for playing.

To use a video analogy, you're allowing video to stream through your
media player, assuming your clockwork computer has such a thing, and
capturing the video using screen capture software. Better to capture the
stream before it hits software.

You may be right. However I wonder if you know much about how my computer
system works. It is easy to presume that what happens with the OS/hardware
you are accustomed to is 'universal'.

Slainte,

Jim

--
Change 'noise' to 'jcgl' if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

Internet radio - classical music, etc
 

In article , Don Pearce
wrote:
On Fri, 06 Feb 2009 09:41:02 +0000 (GMT), Jim Lesurf
wrote:


I don't suppose it makes a great deal of difference if you record
using a lossless format, but isn't it more logical to just capture
the streamed audio?

Erm... that is what I have been doing. Recording the mp3 stream as an
mp3 file on my computer. Then writing these files into a CDRW for
playing on various 'audio'/'video' disc players.


Can you really do that - record an MP3 stream as an MP3 file, I mean? I
thought the file got decoded to straight PCM, the recoded as MP3 for
writing to the file. How else would you generate the file header?

I've just been judging by results. I record a steam which plays as an mp3
on my computer, and when written as a data file onto CDRW plays as an mp3
on the DVD Video/CD Audio players I have that can recognise mp3. The size
of the file agrees with the bitrates specified for the radio streams.

Not clear to me why the program would have to do more than simply write the
data as it arrives (via the buffering for transfer delays) since I am
recording mp3 from an mp3 stream.

I'll do some experiments to check. I'll also ask the author of the software
as he explained to me how to do recordings in the first place.

Slainte,

Jim

--
Change 'noise' to 'jcgl' if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

Internet radio - classical music, etc
 

On 07 Feb, wrote:
In article , Don Pearce
wrote:
On Fri, 06 Feb 2009 09:41:02 +0000 (GMT), Jim Lesurf
wrote:


Can you really do that - record an MP3 stream as an MP3 file, I mean?
I thought the file got decoded to straight PCM, the recoded as MP3 for
writing to the file. How else would you generate the file header?


I'll do some experiments to check. I'll also ask the author of the
software as he explained to me how to do recordings in the first place.

Now done a quick experiment...

So far as I can tell, the files have no 'file header'. I've just
experimented using a simple application (program) I wrote a few weeks ago.
This allows me to snip up a file into tracks. I just give it the data rate
(kbps per sec) and it then uses an edit list to snip the track at specified
instants with a resolution of 1 second.

I just snipped up an mp3 radio recording I played. Each of the individual
files plays fine, and the player reports the actual length of that file.

My understanding is that the format works in what I can call 'frames' of
data, so that provided you snip or join in chunks composed of an integer
number of frames you should have no problems. My application makes no
attempt to understand the data, so works also for ac3 files, etc, which
also have this 'framed' approach. It just reads chunks of data from the
source file, and writes them into the sequence of output files indicated by
the edit file list I have given to it.

Perhaps other operating systems tend to use software that adds in a
'header' - e.g. like the way 'WAVE' or 'JPEG' allows a variety of types of
data format. But this does not seem to be the case with the files I've been
working with.

However I am not sure that the recordings are simply the mp3 streams. I'll
check with the author of the program I used to make my recording. I did
base my recordings on his 'C' source code, etc, but without being clear on
all the details as he is a far better programmer than myself! :-)

Slainte,

Jim

--
Change 'noise' to 'jcgl' if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

Internet radio - classical music, etc
 

On Sat, 07 Feb 2009 00:53:33 +0000 (GMT), "Dave Plowman (News)"
wrote:

In article 498e8bea.169358828@localhost,
Don Pearce (Don Pearce) wrote:
Indeed. Most of these comments come with the benefit of hindsight. DAB was
a long time in the planning - and making radical changes late in that
process would have been difficult.
I remember driving round Birmingham on a coach equipped with a
demonstration system long before actual transmissions started - and the
difference in reception between that and FM was quite astounding.

How come you didn't go on the Kingswood Warren coach? Much more
convenient.

It was laid on for an IBS meeting taking place at Pebble Mill. I don't
know which came first - but Birmingham bull ring is (was?) notorious for
poor FM reception. Could have been the same coach - it was said to have
state of the art aerials and receivers for both DAB and FM.

Sounds the same - 12 seater minibus?

d

Internet radio - classical music, etc
 

On Sat, 07 Feb 2009 10:14:47 +0000 (GMT), Jim Lesurf
wrote:

On 07 Feb, wrote:
In article , Don Pearce
wrote:
On Fri, 06 Feb 2009 09:41:02 +0000 (GMT), Jim Lesurf
wrote:


Can you really do that - record an MP3 stream as an MP3 file, I mean?
I thought the file got decoded to straight PCM, the recoded as MP3 for
writing to the file. How else would you generate the file header?


I'll do some experiments to check. I'll also ask the author of the
software as he explained to me how to do recordings in the first place.

Now done a quick experiment...

So far as I can tell, the files have no 'file header'. I've just
experimented using a simple application (program) I wrote a few weeks ago.
This allows me to snip up a file into tracks. I just give it the data rate
(kbps per sec) and it then uses an edit list to snip the track at specified
instants with a resolution of 1 second.

I just snipped up an mp3 radio recording I played. Each of the individual
files plays fine, and the player reports the actual length of that file.

My understanding is that the format works in what I can call 'frames' of
data, so that provided you snip or join in chunks composed of an integer
number of frames you should have no problems. My application makes no
attempt to understand the data, so works also for ac3 files, etc, which
also have this 'framed' approach. It just reads chunks of data from the
source file, and writes them into the sequence of output files indicated by
the edit file list I have given to it.

Perhaps other operating systems tend to use software that adds in a
'header' - e.g. like the way 'WAVE' or 'JPEG' allows a variety of types of
data format. But this does not seem to be the case with the files I've been
working with.

However I am not sure that the recordings are simply the mp3 streams. I'll
check with the author of the program I used to make my recording. I did
base my recordings on his 'C' source code, etc, but without being clear on
all the details as he is a far better programmer than myself! :-)

Slainte,

Jim

An MP3 file has to have a header or the playing software won't know
what to do with it. Of course if you have written your own, so it only
accepts MP3 in a single format, maybe you can do without.


d

Internet radio - classical music, etc
 

Jim Lesurf wrote:
In article , Rob
wrote:
Jim Lesurf wrote:

Erm... that is what I have been doing. Recording the mp3 stream as an
mp3 file on my computer. Then writing these files into a CDRW for
playing on various 'audio'/'video' disc players.


No, you're not capturing the *stream* AIUI, you're capturing the audio
once it's been through your sound card, and you've then converted it
again to mp3.

Erm, again. My computer doesn't have a 'sound card'. I use an application
(software) that can fetch the steam and this can then either save it to a
file and/or covert it for playing.

To use a video analogy, you're allowing video to stream through your
media player, assuming your clockwork computer has such a thing, and
capturing the video using screen capture software. Better to capture the
stream before it hits software.

You may be right. However I wonder if you know much about how my computer
system works. It is easy to presume that what happens with the OS/hardware
you are accustomed to is 'universal'.


I may be wrong - which is it to be? Could you tell me a little about the
'capture' software you use, such as the name?

Cheers, Rob

Internet radio - classical music, etc
 

In article , Dave Plowman (News)
wrote:
In article , Jim Lesurf
wrote:
The above sums up my own experience of DAB. Although these days I
mainly listen to DTTV rather than DAB.

Indeed - and DDTV tuners are rather cheaper than DAB ones. And most will
already have a UHF aerial. Only slight snag can be selecting the correct
station without having a TV attached.

Yes. Particulary annoying with the Nokia DDTV RX box I have in the living
room. This insists on keeping 'radio' and 'TV' stations in distinct lists
so you can't switch between them simply by selecting the channel number
with the remote. With practice I can navigate the menus without the TV
being on, but it is a PITA.

Slainte,

Jim

--
Change 'noise' to 'jcgl' if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

Internet radio - classical music, etc
 

In article 498e68ba.225887281@localhost, Don Pearce (Don Pearce) wrote:
On Sat, 07 Feb 2009 10:14:47 +0000 (GMT), Jim Lesurf
wrote:


An MP3 file has to have a header or the playing software won't know what
to do with it. Of course if you have written your own, so it only
accepts MP3 in a single format, maybe you can do without.

Nope. I didn't write the software used for playing. And it plays a variety
of formats. Main ones I've been using are mp3 and ac3, but it does others
and some of the internet stations I've been listening to are non-mp3.
However RO machine associate a filetype with a file (not part of the name),
so the filer can be used to tell the player without a need for a header.

But the point here is that the files play OK even when data snipped from
the middle of a recording. So no header information seems present at the
file level. There is other info - e.g. the bitrate is recognised - even
though the filetype give no clue to this. I can't see how the player could
recognise the bitrate from a chopped up section if it needed a file header
I haven't provided.

So far as I know, any 'header' may simply be a convenience for filer
systems that don't provide a filetype mechanism. But the mp3 and ac3 files
I've experimented with seem fine even when you snip out a section and don't
add any 'file header'. Datarate is recognised OK. I presume this info is
present at frame level as part of the data decoding process. (Hence the
existence of variable rate formats.)

I will investigate further. But so far as I can tell, I am recording the
streams as they arrive with no lossy conversions. I'll check by recording a
non-mp3 stream and see how that works. I am now curious about this...

Slainte,

Jim

--
Change 'noise' to 'jcgl' if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

Internet radio - classical music, etc
 

In article , Rob
wrote:
Jim Lesurf wrote:


I may be wrong - which is it to be? Could you tell me a little about the
'capture' software you use, such as the name?

It is based on a RO application called !DigitalCD. With this you can get a
set of modules that decode/play various formats, etc. There is also a
utility to record what is being presented for playing and I've been
experimenting with that. The utility will also fetch the stream if given a
URL so works even with the player not playing. So I can record with or
without listening as I wish. (The snag being knowing when to start/stop
recording if I canna hear what is happening!)

Note that you need a RO machine for the system to work. (It may work with
an emulator, but I can't say.) However the code for what I'm using is based
on source code provided as an example. This is in 'C' so if you can follow
'C' you can read it.

http://users.skynet.be/Andre.Timmerm...r/download.htm

The above is the URL for the main page about this.

if you download the zips, note that the example program for recording is
buried in one of the documents folders (directories). IIRC To find this,
look in the 'docs.zip' file's Docs.Disksample.Example directory for the
DiskPlay command line tool. I've been basing my recordings on this code. It
allows you to choose either the input stream or the results decoded to
LPCM.

Note again that the compiled versions *don't* run under windows or macs or
linux. They require ARM type CPUs and the RO hardware and architecture. But
the 'C' should be clear to programmers. But I'm afraid I can't comment on
how you'd do this on other systems as it involves things like interrupt
controlled buffers, etc. I've modified what is given, but can't say I fully
understand it! Happy enough with what I can do with my "clockwork
computer"... :-)

Good luck. :-)

Jim

--
Change 'noise' to 'jcgl' if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

Internet radio - classical music, etc
 

On Sat, 07 Feb 2009 13:19:45 +0000 (GMT), Jim Lesurf
wrote:

In article 498e68ba.225887281@localhost, Don Pearce (Don Pearce) wrote:
On Sat, 07 Feb 2009 10:14:47 +0000 (GMT), Jim Lesurf
wrote:


An MP3 file has to have a header or the playing software won't know what
to do with it. Of course if you have written your own, so it only
accepts MP3 in a single format, maybe you can do without.

Nope. I didn't write the software used for playing. And it plays a variety
of formats. Main ones I've been using are mp3 and ac3, but it does others
and some of the internet stations I've been listening to are non-mp3.
However RO machine associate a filetype with a file (not part of the name),
so the filer can be used to tell the player without a need for a header.


The header is much more than that. It specifies the sampling rate, the
coding type, mono or stereo - and that is without all the metadata.
The filetype (three letter extension) is a purely visual matter. A
..wav file can contain just about any compressed or uncompressed
format, based on the format of the header (look up RIFF for info).

But the point here is that the files play OK even when data snipped from
the middle of a recording. So no header information seems present at the
file level. There is other info - e.g. the bitrate is recognised - even
though the filetype give no clue to this. I can't see how the player could
recognise the bitrate from a chopped up section if it needed a file header
I haven't provided.


Thinking about it, I can believe that it is quite possible to chop a
section out of an MP3 stream and write a header to fit it. All the
information is there.

So far as I know, any 'header' may simply be a convenience for filer
systems that don't provide a filetype mechanism. But the mp3 and ac3 files
I've experimented with seem fine even when you snip out a section and don't
add any 'file header'. Datarate is recognised OK. I presume this info is
present at frame level as part of the data decoding process. (Hence the
existence of variable rate formats.)


No the header is specified in some detail by the MPEG. It is a great
deal more than a convenience.

I will investigate further. But so far as I can tell, I am recording the
streams as they arrive with no lossy conversions. I'll check by recording a
non-mp3 stream and see how that works. I am now curious about this...

Do you have a hex editor? Have a look at the start of one of your
saved files and compare it to this

http://www.mpgedit.org/mpgedit/mpeg_...MP3Format.html

d

Internet radio - classical music, etc
 

In article 498d6859.225789953@localhost,
Don Pearce (Don Pearce) wrote:
It was laid on for an IBS meeting taking place at Pebble Mill. I don't
know which came first - but Birmingham bull ring is (was?) notorious for
poor FM reception. Could have been the same coach - it was said to have
state of the art aerials and receivers for both DAB and FM.

Sounds the same - 12 seater minibus?

No - a full sized one. 40? seater. There would have been a riot if it had
been small given the attendance at IBS meetings in those days. As it was I
think they had to do two trips to cover everyone. So the hospitality would
have taken a bashing during the wait. ;-)

--
*The statement above is false

Dave Plowman London SW
To e-mail, change noise into sound.

Internet radio - classical music, etc
 

In article ,
Jim Lesurf wrote:
Indeed - and DDTV tuners are rather cheaper than DAB ones. And most
will already have a UHF aerial. Only slight snag can be selecting the
correct station without having a TV attached.

Yes. Particulary annoying with the Nokia DDTV RX box I have in the living
room. This insists on keeping 'radio' and 'TV' stations in distinct lists
so you can't switch between them simply by selecting the channel number
with the remote. With practice I can navigate the menus without the TV
being on, but it is a PITA.

I have a Sony which is only used for radio - since the TVs have now built
in tuners. I have only the radio stations I want on the favourites list
which makes things rather easier.

--
*It's lonely at the top, but you eat better.

Dave Plowman London SW
To e-mail, change noise into sound.

Internet radio - classical music, etc
 

On Sat, 07 Feb 2009 14:40:05 +0000 (GMT), "Dave Plowman (News)"
wrote:

In article 498d6859.225789953@localhost,
Don Pearce (Don Pearce) wrote:
It was laid on for an IBS meeting taking place at Pebble Mill. I don't
know which came first - but Birmingham bull ring is (was?) notorious for
poor FM reception. Could have been the same coach - it was said to have
state of the art aerials and receivers for both DAB and FM.

Sounds the same - 12 seater minibus?

No - a full sized one. 40? seater. There would have been a riot if it had
been small given the attendance at IBS meetings in those days. As it was I
think they had to do two trips to cover everyone. So the hospitality would
have taken a bashing during the wait. ;-)

The day at Kingswood Warren included an inspection of the encoding
kit, which occupied a serious amount of rack space back then. Also I
got chatting with the audio research chaps and had a good nose around
the audio labs and listening rooms. I got my first listen to a really
well implemented sub there, and it inspired me to build mine.

One particularly interesting thing was two adjacent rooms. They
measured identically for reverb time at all frequencies, but one was
well diffused while the other had large areas of flat wall. The
difference in sound between them was astounding, particularly the
stereo image, which was pin-sharp in the diffuse room and almost
unlocatable in the specular one.

d
--
Pearce Consulting
http://www.pearce.uk.com

Internet radio - classical music, etc
 

In article 498f921e.236483187@localhost, Don Pearce (Don Pearce) wrote:
On Sat, 07 Feb 2009 13:19:45 +0000 (GMT), Jim Lesurf
wrote:

In article 498e68ba.225887281@localhost, Don Pearce (Don Pearce)
wrote:


The header is much more than that. It specifies the sampling rate, the
coding type, mono or stereo - and that is without all the metadata. The
filetype (three letter extension) is a purely visual matter. A .wav file
can contain just about any compressed or uncompressed format, based on
the format of the header (look up RIFF for info).

Yes. I know that formats like WAV format can do that, and that headers can
be useful. But so far as I can tell, the mp3 data files I'm using don't
have headers at the file level. They may have them at the 'frame' level,
but that is a different matter.

But the point here is that the files play OK even when data snipped
from the middle of a recording. So no header information seems present
at the file level. There is other info - e.g. the bitrate is recognised
- even though the filetype give no clue to this. I can't see how the
player could recognise the bitrate from a chopped up section if it
needed a file header I haven't provided.


Thinking about it, I can believe that it is quite possible to chop a
section out of an MP3 stream and write a header to fit it. All the
information is there.

I'm sure it would be. But I *did* write the program I am using to snip up
mp3 and ac3 files. It simply lifts chunks of data from one file with a 'C'
fread() and writes them to another with an fwrite(). The program certainly
does not add or alter any file header info. And such info at the start of
the source file of data would only appear at the start of the first output
file in a sequence as I create them. None of the following files would have
such info.

I've just checked, and the snipped mp3 files play fine as mp3 files on my
Rega Apollo as well as computer, so I suspect they will also play OK with
the other machines I have.



Do you have a hex editor? Have a look at the start of one of your saved
files and compare it to this

http://www.mpgedit.org/mpgedit/mpeg_...MP3Format.html

I'll have a look. But as I say, since I know how the files I've snipped by
editing are created I can be sure that those other than the first won't
have any header that only appears at the start of the source data file. Yet
they play OK.

Slainte,

Jim

--
Change 'noise' to 'jcgl' if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

Internet radio - classical music, etc
 

In article , Dave Plowman (News)
wrote:
In article , Jim Lesurf
wrote:
Indeed - and DDTV tuners are rather cheaper than DAB ones. And most
will already have a UHF aerial. Only slight snag can be selecting
the correct station without having a TV attached.

Yes. Particulary annoying with the Nokia DDTV RX box I have in the
living room. This insists on keeping 'radio' and 'TV' stations in
distinct lists so you can't switch between them simply by selecting
the channel number with the remote. With practice I can navigate the
menus without the TV being on, but it is a PITA.

I have a Sony which is only used for radio - since the TVs have now
built in tuners. I have only the radio stations I want on the favourites
list which makes things rather easier.

The Nokia won't allow you to put both 'TV' and 'radio' stations on the same
favourites list! However a cheap Philips DTTV box will do this, and makes
no distinctions so you can select any by channel number. This is a flaw in
the user interface of the Nokia, but I continue to use it for the AV system
as it delivers good sound via its SPDIF output and good pictures. The
Philips is poorer IMHO.

Slainte,

Jim

--
Change 'noise' to 'jcgl' if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

Internet radio - classical music, etc
 

On 07 Feb, wrote:
In article 498f921e.236483187@localhost, Don Pearce (Don Pearce) wrote:
On Sat, 07 Feb 2009 13:19:45 +0000 (GMT), Jim Lesurf
wrote:


http://www.mpgedit.org/mpgedit/mpeg_...MP3Format.html

I'll have a look. But as I say, since I know how the files I've snipped
by editing are created I can be sure that those other than the first
won't have any header that only appears at the start of the source data
file. Yet they play OK.

Just had a quick look at the above page. It seems to confirm what I thought
was the case. This is that the MPEG relies on *frame* headers, *not* a file
header. This means that with fixed bitrates you can snip the files OK
provided you know the correct bitrate for that file and each snip is at a
frame boundary.

So if I snip something like a 10min file into two 5min sections I don't
need to add or change the 'headers' as each frame will still have the
header for that frame.

Thanks for the URL. I'll need to look at it in more detail as it has info
I've wanted. But IIUC it confirms what I was saying. Just as well, given
that devices like my players seem happy with the results.

I'll write a utility that examines the frame headers. I'll also check that
against FFmpeg results if I can. That might allow me to produce a better
snipper that deals with VBR and adjusts the rate according to header info.
At present I tell the editor what fixed bitrate to assume.

Slainte,

Jim

--
Change 'noise' to 'jcgl' if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

Internet radio - classical music, etc
 

On Sat, 07 Feb 2009 16:52:57 +0000 (GMT), Jim Lesurf
wrote:

On 07 Feb, wrote:
In article 498f921e.236483187@localhost, Don Pearce (Don Pearce) wrote:
On Sat, 07 Feb 2009 13:19:45 +0000 (GMT), Jim Lesurf
wrote:


http://www.mpgedit.org/mpgedit/mpeg_...MP3Format.html

I'll have a look. But as I say, since I know how the files I've snipped
by editing are created I can be sure that those other than the first
won't have any header that only appears at the start of the source data
file. Yet they play OK.

Just had a quick look at the above page. It seems to confirm what I thought
was the case. This is that the MPEG relies on *frame* headers, *not* a file
header. This means that with fixed bitrates you can snip the files OK
provided you know the correct bitrate for that file and each snip is at a
frame boundary.

So if I snip something like a 10min file into two 5min sections I don't
need to add or change the 'headers' as each frame will still have the
header for that frame.

Thanks for the URL. I'll need to look at it in more detail as it has info
I've wanted. But IIUC it confirms what I was saying. Just as well, given
that devices like my players seem happy with the results.

I'll write a utility that examines the frame headers. I'll also check that
against FFmpeg results if I can. That might allow me to produce a better
snipper that deals with VBR and adjusts the rate according to header info.
At present I tell the editor what fixed bitrate to assume.

Slainte,

Jim

Interesting. Presumably the player just ignores the first data chunks
until it finds a frame header, then uses the info from that to read
the succeeding stuff.

d
--
Pearce Consulting
http://www.pearce.uk.com

Internet radio - classical music, etc
 

Jim Lesurf wrote:
In article , Rob
wrote:
Jim Lesurf wrote:


I may be wrong - which is it to be? Could you tell me a little about the
'capture' software you use, such as the name?

It is based on a RO application called !DigitalCD. With this you can get a
set of modules that decode/play various formats, etc. There is also a
utility to record what is being presented for playing and I've been
experimenting with that. The utility will also fetch the stream if given a
URL so works even with the player not playing. So I can record with or
without listening as I wish. (The snag being knowing when to start/stop
recording if I canna hear what is happening!)

Note that you need a RO machine for the system to work. (It may work with
an emulator, but I can't say.) However the code for what I'm using is based
on source code provided as an example. This is in 'C' so if you can follow
'C' you can read it.

http://users.skynet.be/Andre.Timmerm...r/download.htm


Ah, right, I see. I can't see the stream capture plugin, but that was
all I meant - and you seem to be using it. I was confused by your
original phrase 'recording a stream of music'. I'd just adopted
'capture' because that's what the young people tend to use: record
sound, capture data.

And what a marvellous piece of software function over style it seems :-)

The above is the URL for the main page about this.

if you download the zips, note that the example program for recording is
buried in one of the documents folders (directories). IIRC To find this,
look in the 'docs.zip' file's Docs.Disksample.Example directory for the
DiskPlay command line tool. I've been basing my recordings on this code. It
allows you to choose either the input stream or the results decoded to
LPCM.

Note again that the compiled versions *don't* run under windows or macs or
linux. They require ARM type CPUs and the RO hardware and architecture. But
the 'C' should be clear to programmers. But I'm afraid I can't comment on
how you'd do this on other systems as it involves things like interrupt
controlled buffers, etc. I've modified what is given, but can't say I fully
understand it! Happy enough with what I can do with my "clockwork
computer"... :-)

Good luck. :-)


Luck, a grim determination, work and money.

Actually, not *too* much money - about £300 for cutting edge hardware,
£30 for something that works. Pleased to see they outstrip Intel's
latest on power consumption. And pleased, obviously, that you're happy
with it.

You can't budget for irrationality. I'd prefer to travel by steam train
and listen to music amplified by valves. All to do with the journey,
apparently.

Rob

Internet radio - classical music, etc
 

Dave Plowman (News) wrote:

I remember driving round Birmingham on a coach equipped with a
demonstration system long before actual transmissions started - and the
difference in reception between that and FM was quite astounding.

A high bit rate I'd imagine, it being a demo, not the real commercial world.

Internet radio - classical music, etc
 

In article , Don Pearce
wrote:

[big snip]

Interesting. Presumably the player just ignores the first data chunks
until it finds a frame header, then uses the info from that to read the
succeeding stuff.

I will be doing some more checking later today if I get a chance. But IIUC
I am editing by snipping at chunk (frame) boundaries. That is certainly
what I am trying to get my edit program to do. If so, here will be a frame
header at the start of each output file because it was present at the
relevant point in the source file.

I do have a (three, actually) general editor(s) that display hex. So will
check that way. Can also then scan for hex patterns (sequences) to find
where header declarations repeat. May also write a simple util for this.

Thanks for giving me the URL for the info on the mpeg file format. It means
I can modify my track editor to read the file and determine the frame size
and data rate. At present I have to tell it the value in kbps to get the
times and durations of the snipped files correct.

Is there a similar spec for ac3 (Dolby)? I'm also looking at files of that
type. I can export the ac3 stream from home-recorded video VOB files and
then play these on my computer. Can also edit them, but again I have
currently to tell my track editor what bitrate to presume as I don't know
how to read this from the actual ac3 data.

At some point I'd also like to be able to transcode ac3 to mp3 - ideally
with no 'losses' if that is possible. At present I'd have to convert via
using LPCM as an intermediate. That is fine, but slower and probably gives
more scope for losses - although I suppose I could use 32bit LPCM to
minimise this. :-)

FWIW I'm currently writing a series of articles and utility applications
for a RO computer mag - and for my own use. This in turn is useful as a
basis for finding out things that might then pop up in HFN. So am finding
this very interesting.

Slainte,

Jim

--
Change 'noise' to 'jcgl' if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

Internet radio - classical music, etc
 

In article , Rob
wrote:
Jim Lesurf wrote:

Note that you need a RO machine for the system to work. (It may work
with an emulator, but I can't say.) However the code for what I'm
using is based on source code provided as an example. This is in 'C'
so if you can follow 'C' you can read it.

http://users.skynet.be/Andre.Timmerm...r/download.htm


Ah, right, I see. I can't see the stream capture plugin, but that was
all I meant - and you seem to be using it. I was confused by your
original phrase 'recording a stream of music'. I'd just adopted
'capture' because that's what the young people tend to use: record
sound, capture data.

I'm more used to the idea that we record data or music. For getting the
info from a URL I'd be more likely to say 'fetch' and then 'record'.

RO is 'modular', so any program can call on other sections of the code
provided. This makes it easy for a program to treat a URL as if it were a
file on your machine - provided the fetching then can work OK. e.g. you
haven't bungled the URL and have a suitable connection. The advantage is
that RO programs can avoid repeated re-inventions of wheels. This means
most RO applications are quite compact, as is the OS.

But that means that to understand the process fully you'd also need to see
what the PlaySample module and the URL fetching code are doing. I can't
comment on that as I haven't looked at it. Just use them via the interfaces
they provide.

And what a marvellous piece of software function over style it seems :-)

Not sure if you are referring to Andre's programming style or the way RO
tends to work. ;-

My own programs are nightmares as I rarely comment and often hack until it
sort-of-works...

[snip]
....

Luck, a grim determination, work and money.

Actually, not *too* much money - about £300 for cutting edge hardware,
£30 for something that works. Pleased to see they outstrip Intel's
latest on power consumption. And pleased, obviously, that you're happy
with it.

You can't budget for irrationality. I'd prefer to travel by steam train
and listen to music amplified by valves. All to do with the journey,
apparently.

The drawbacks with RO machines tend to be limited hardware, and lack of
'compatability' with widely used proprietary filetypes/methods. Hence the
snag when people use some formats for net radio. 'Real' because of its
proprietary nature, 'aac' because no-one has yet done the decoder for RO.
:-)

But the advantage (for me) is that the RO systems are quite simple to use,
and work with an efficiency that belies the crude measures like cpu speed
and available ram.[1] Of course, this also is because it is what I'm used
to and like. Just like a preference for steam train or valve amps. What
suits best depends on who you are, what you wish to do, and the style in
which you wish to do it. :-)

[1] Analogy here with the point about not just judging cameras by
'megapixels' but also checking things like the lens capability and how well
the images are encoded.

However the above is all straying OT... :-)

Slainte,

Jim

--
Change 'noise' to 'jcgl' if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

Internet radio - classical music, etc
 

In article ,
Mike O'Sullivan wrote:
I remember driving round Birmingham on a coach equipped with a
demonstration system long before actual transmissions started - and the
difference in reception between that and FM was quite astounding.

A high bit rate I'd imagine, it being a demo, not the real commercial
world.

Nope - IIRC the same bitrates as used at the start of the service. the
current reduced ones came later.

But just to point out, bitrates have little to do with actual reception.

--
*Why is 'abbreviation' such a long word?

Dave Plowman London SW
To e-mail, change noise into sound.