[alsa-devel] [PATCH] pcm: 2nd round of pcm_misc DSD fixes

[Takashi Iwai]

At Fri, 15 Aug 2014 15:02:35 +0600,
Alexander E. Patrakov wrote:
> 
> 15.08.2014 12:43, Jurgen Kramer wrote:
> > Functions 'snd_pcm_format_silence_64' and 'snd_pcm_format_size' also need to be
> > able to handle the DSD formats.
> 
> 0 is not a DSD silence value. It is the most negative value, similar to 
> -32768 for S16 samples. We need something that will average to zero.
> 
> ffmpeg uses a repeating pattern of 0x69 here, with this comment:
> 
>          /* 0x69 = 01101001
>           * This pattern "on repeat" makes a low energy 352.8 kHz tone
>           * and a high energy 1.0584 MHz tone which should be filtered
>           * out completely by any playback system --> silence
>           */
> 
> https://ffmpeg.org/pipermail/ffmpeg-cvslog/2014-April/076427.html

Good point.  We need a fix in the kernel side, too.


Takashi