[FFmpeg-user] Audio sample format in alsa?

[Simon Roberts]

On Wed, Jul 1, 2020 at 12:22 PM Nicolas George <george at nsup.org> wrote:

> 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.
>
>
> Ah, so it will be (a little?) less efficient, right, and it could
conceivably lose some qualtiy.

I guess I should persevere with trying to work out how to use hw: directly
then.

Thanks that's good to know.