[FFmpeg-user] Audio sample format in alsa?

Nicolas George george at nsup.org
Wed Jul 1 21:22:08 EEST 2020


Simon Roberts (12020-07-01):
> Magic! plughw:1,0 works a treat. Are there any limitations, or caveats,
> that I should be aware of? Is this a risk or tradeoff of any sort? I note
> that the recording seems to be 16le, so I have no immediate evidence of it
> being in any way less than optimal, but since I'm afraid I had never come
> across this, I don't know what I don't know.

With hw, you are talking directly with the sound device, you have to
provide parameters that it accepts, exactly: correct format, correct
number of channels, correct sample rate.

With plughw, you tell ALSA to insert the "plug" plugin before the actual
device, to do automatic conversion. Therefore, it accepts any format,
number of channels, sample rate, but there is a conversion happening and
you do not know what it is.

Regards,

-- 
  Nicolas George
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