[pulseaudio-discuss] Alsa -> pulseaudio 24-bit playback support for hardware that doesn't support 24 bits

[Lennart Poettering]

On Thu, 20.11.08 11:38, Baek Chang (baeksan at ccrma.stanford.edu) wrote:

> I can't seem to resolve this issue in ALSA/pulseaudio where playing S24_LE
> pcm data does not seem to work.  My hardware does not support 24 bits, but I
> was under the impression that alsa would do a conversion to 32 bits when
> using -D plug.
> 
> 
> I get the following errors:
> 
> aplay -D plug:pulse test-sound-files/sine_1kHz_24bit_stereo_44kHz.wav -vvvv
> Playing WAVE 'test-sound-files/sine_1kHz_24bit_stereo_44kHz.wav' : Signed 24
> bit Little Endian in 3bytes, Rate 44100 Hz, Stereo
> *aplay: set_params:1022: Unable to install hw params:*
> ACCESS:  RW_INTERLEAVED
> FORMAT:  S24_3LE
> SUBFORMAT:  STD
> SAMPLE_BITS: 24
> FRAME_BITS: 48
> CHANNELS: 2
> RATE: 44100
> PERIOD_TIME: 125000
> PERIOD_SIZE: (5512 5513)
> PERIOD_BYTES: (33072 33078)
> PERIODS: (3 5)
> BUFFER_TIME: 500000
> BUFFER_SIZE: 22050
> BUFFER_BYTES: 132300
> TICK_TIME: 0
> 

PA only supports unpacked 24bit samples. Normally the plug module for
ALSA should be able to convert this properly for you. If that fails,
then please make sure to file that as a bug to ALSA.

Lennart

-- 
Lennart Poettering                        Red Hat, Inc.
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