"Don Pearce" wrote in message
...

Well, at least the listen-again recording is streamed clean.

But has anyone noticed a large reduction in volume (gain)
as I have, the last few days (BBC3 listen again.)

--
Don Phillipson
Carlsbad Springs
(Ottawa, Canada)

On Tue, 30 Aug 2011 12:02:14 -0400, "Don Phillipson"
wrote:

"Don Pearce" wrote in message
...

Well, at least the listen-again recording is streamed clean.

But has anyone noticed a large reduction in volume (gain)
as I have, the last few days (BBC3 listen again.)

Are you sure it isn't just the extra few dBs headroom they give
themselves for live events?

d

Are any conversions from one digital format to another being used i wonder.
Similar things can occur when doing conversions like this, though I have no
idea quite why!

Brian

--
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graphics are great, but the blind can't hear them
Email:
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"Jim Lesurf" wrote in message
...
Anyone else get 'gargling' at the moment on the Proms being repeated via
the iPlayer 320k stream?

I'm getting this again. A concern as it is a repeat of a prom from a few
days ago that showed the same problem when live. The problem apparently
only affects a minority, but - worryingly - seems to be getting more
common.

I get it with both the 320k and 'normal' iPlayer streams for R3. But the
other streams - e.g. R4 - are fine. And checking the iplay diagnostics I
get a nominal bandwidth of over 2Mbps from their server. So not a basic
bandwidth problem.

Slainte,

Jim

--
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http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
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In article , Brian Gaff
wrote:
Are any conversions from one digital format to another being used i
wonder. Similar things can occur when doing conversions like this,
though I have no idea quite why!

It depends what you mean by 'conversions'.

For a live Prom on R3 the BBC send from RAH a 48k/24bit clean LPCM feed to
Coyopa. (The iPlayer server set.) This converts to 44.1k AAC+ at the chosen
bitrates, binds into a Flash transfer wrapper and sends to the plugin in
your browser. That then nominally generates 44.1k LPCM. They don't add any
automated level compression at RAH or along the chain for the live iPlayer.
But may tweak the gain. (I think that these days the only R3 distribution
that gets 'optimodded' is FM and yet olde AM.)

FWIW I've just checked a couple of recent Proms and they still peak at
about -4dBFS - as has been the practice for some time. However this is for
live stream R3. Other paths/streams may be different!

In general, the part that is least well defined is the bit at the
listener's 'computer' end since a given computer+software may do all kinds
of other things. e.g. force poor conversion to 48k, and/or add distortion
or clipping if using the computer's DAC to output analogue.

A secondary issue, though, is lack of end-to-end clock synch. The BBC do
sometimes use asynch resampling in the path, even when not trying to change
rate. This lets them avoid the requirement of having the entire BBC locked
to one reference clock.

That said, I suspect the BBC may try changing the iPlayer to 48k at some
point as that will remove one more factor in the conversions. I also have
my fingers crossed that they will move to 320k for the R3 'listen again'.

Overall I remain very impressed by the quality of the Proms, etc, via the
320k stream. I think the BBC have done a superb job here. The occasional
snags like the gargling are annoying when they happen. But in engineering
terms I tend to put them down to the kinds of bugs you get when trying to
develop and improve a relatively new service.

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
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Audio Misc http://www.audiomisc.co.uk/index.html

"Brian Gaff" wrote in message
...

Are any conversions from one digital format to another being used i
wonder. Similar things can occur when doing conversions like this, though
I have no idea quite why!

The problem is probably not that the conversions were made, but rather
whether the whole system is operating properly. If the links are clean and
your bitrates are high enough (320 K is generally high enough) there can be
a goodly number of conversions without gross artifacts such as clearly
audible gargling sounds.