[Ffmpeg-devel] alsa input / output

Måns Rullgård mans
Wed Mar 21 09:45:51 CET 2007

Vladimir Mosgalin <mosgalin at VM10124.spb.edu> writes:

> Hi Rich Felker!
>  On 2007.03.20 at 21:38:17 -0500, Rich Felker wrote next:
>> > That's exactly the problem you get with device interface; it is just
>> > supposed to "work". But with alsa accessed through library interface,
>> > you can do anything you desire, when your applications doesn't support
>> > this. And you mean application should _always_ use built-in
>> > resamplers? THAT is the right way to get painful-to-listen-to sound,
>> > because most of resamplers will suck. With alsa, however, you just
>> > choose whatever you want, depending on your CPU and personal choice
>> > (believe it or not, but SRC_SINC_FASTEST sounds better than
>> > SRC_SINC_BEST_QUALITY and all other SRC_SINC libsamplerate filters to
>> > me).
>> > 
>> > Want to make pseudo-surround 5.1 out of stereo music? easily! Just want
>> > [......]
>> This does not belong at that layer.... If you want this, use a sound
>> server. That way it's portable and doesn't break the symbol namespace
>> of the app playing sound. Unix does things the unix way for very good
>> reasons. ALSA breaks all of that.
> True. But 1) there is no sound server as advanced as alsa and
> 2) sound server means library interface. Since most users need
> some of these features, it means that end-user applications should
> always use library interfaces and never devices (otherwise they are
> broken and don't fit into the system).

X has always used a library interface as the primary means to access
graphics services.  I suppose this concept could be extended to audio
as well.

That said, I don't at all like the sneaky dmix thing they have, as
default no less, in ALSA.

M?ns Rullg?rd
mans at mansr.com

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