Re: Bug: Hardware that does not support s32le - sndiod -dd shows s16le

From: Edward Wandasiewicz <w13ntd_at_gmail.com>
Date: Wed Sep 20 2017 - 17:18:46 CEST
On Wed, Sep 20, 2017 at 3:00 PM, Edward Wandasiewicz <w13ntd@gmail.com> wrote:
> If I run
>
> $ mplayer -ao alsa:device=hw=1 -af format=s32le _AUDIO_ONLY_FILE_
>
> On my Chromebook Pixel 2015, mplayer responds with
>
> [AO_ALSA] Format s32le is not supported by hardware, trying default.
> AO: [alsa] 48000Hz 2ch s16le (2 bytes per sample)
>
> Audio plays fine.
>
> I try s32le in 2 different ways, in my $HOME/.asoundrc file,
>
> =============================
> Method 1 - set s32_le in type slave { }
> =============================
>
> $ cat $HOME/.asoundrc
>
> pcm.sndio {
> type asym
> playback.pcm "sndio-play"
>
> hint {
> show on description "OpenBSD sndio"
> }
> }
>
> pcm.sndio-play {
> type plug
> slave {
> pcm "sndio-raw"
> rate 48000
> format s32_le
> channels 2
> }
> }
>
> pcm.sndio-raw {
> type file
> slave.pcm null
>
> format raw
> file "| aucat -f snd/0 -i -"
> }
>
> pcm.default sndio
>
> =======================
> Method 2 - set s32_le in aucat
> =======================
>
> Comment out rate, format and channels in slave { }

# rate 48000
# format s32_le
# channels 2

and append these values to the aucat command in pcm.sndio-raw { }

file "| aucat -r 48000 -e s32le -C 0:1 -f snd/0 -i -"

In both instances of these 2 different .asoundrc config files, I then run

$ mplayer -ao alsa:device=sndio -af format=s32le _AUDIO_ONLY_FILE_

mplayer shows

AO: [alsa] 48000Hz 2ch s32le (4 bytes per sample)
[Mixer] No hardware mixing, inserting volume filter.

but the output from

$ sndiod -dd -f rsnd/1 shows

snd0: 48000Hz, s16le, play 0:1, rec 0:1, 8 blocks of 1024 frames
aucat0: 48000Hz, s16le, play 0:1, 9 blocks of 1024 frames
snd0: device started

with

$ sudo ps -ax | grep aucat
 1690 pts/0    S+     0:00 aucat -r 48000 -e s32le -c 0:1 -f snd/0 -i -

Question: Should the output of sndiod -dd show a message indicating
s32le not supported by hardware, changing to s16le

In both instances, even though the debug message shows s16le, the
stream output sounds different from both .asoundrc config files, and I
would expect them both to sound the same, as they both attempt to use
s32le.

If sndiod is using s16le, as shown in the debug message, neither sound
output from the 2 different .asoundrc files sounds like the stream if
I set the encoding to s16le in the .asoundrc file in either slave { }
or aucat command.

For the sake of completeness, both .asoundrc config files using se16
in slave { } and aucat appear to sound the same.
Received on Wed, 20 Sep 2017 15:18:46 +0000

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