[alsa-devel] Query about SNDRV_PCM_FORMAT_S24_LE

Takashi Iwai tiwai at suse.de
Thu Feb 28 09:45:56 CET 2013

At Thu, 28 Feb 2013 00:08:46 -0800,
Patrick Lai wrote:
> Hi,
> The DSP I am working with currently supports 24-bit PCM sample in
> 32-bit data space but with LSB padded. Based on the discussion I found
> on line, SNDRV_PCM_FORMAT_S24_LE is defined to be 24-bit PCM sample in
> 32-bit data space with MSB padded. Also, there is no format macro
> defined for the format which my DSP supports. Please correct me if I am
> wrong. Furthermore, which software layer in audio stack of a typical
> linux distribution such as ubuntu handles the padding. I don't think
> it's handled by the alsa library. Does application or pulseaudio handle
> the padding? I would think it's done in pulseaudio. I have not study
> pulseaudio codec extensively but would think someone on the mailing
> list can give a quick answer.

In that case, the format itself is identical with S32_LE.
You can inform the msbits width via snd_pcm_hw_constraint_msbits() if


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