In article , froggy
wrote:
Le 20/03/13 17:55, Jim Price a écrit :


cat /proc/asound/card0/pcm0p/sub0/hw_params

Of course the numbers may need changing to suit setup.

You now have the chance to try that out on USB.


Thanks for the tip. I tried it out and got the following message:

access: MMAP_INTERLEAVED format: S32_LE subformat: STD channels: 2 rate:
48000 (48000/1) period_size: 1024 buffer_size: 4096

The 48000 figure obviously corresponds to the sample rate JL was
referring to. The fact that the 48k indicator light on the DacMagic lit
up seems to indicate that the BBC has increased the sample rate from
44.1k to 48K.

Not necessarily, I'm afraid.

I just checked, and here both

bbc.co.uk/iplayer/bbc_radio_three/listen_live

and

bbc.co.uk/player/bbc_radio_three

output 44.1k sample rates. (The second I only checked with 'hi' bandwidth
sic selected.)

(The above is using a Cambridge Audio 851C as the USB DAC. And I've set my
systems so the output rate automatically follows the source rate.)

You may find that something in your sound setup is 'mixing' for you,
without you knowing or approving. Pulse Audio has a habit of doing this,
but ALSA also may if the install assumes it is expected.

On computers 'mixing' is used so you can combine audio sources, ete. e.g.
Be able to hear a "mail's here!" noise whilst listening to music, or chat
over VOIP whilst listening to music. But it can interfere needlessly.

If you want to avoid this and have a direct output for best quality you may
find it useful to read the webpages I wrote on this topic. These advise
killing off Pulse Audio and having a simple file to tell the system exactly
what you require. The details are at:

http://www.audiomisc.co.uk/Linux/ALS...reSilence.html
http://www.audiomisc.co.uk/Linux/ALSA/ALSAforUsers.html

Slainte,

Jim

--
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