[FFmpeg-devel] [RFC 00/10] AV_SAMPLE_FMT_DSD

[Peter Ross]

On Tue, May 06, 2014 at 09:15:37PM +0200, wm4 wrote:
> On Tue, 6 May 2014 22:37:32 +1000
> Peter Ross <pross at xvid.org> wrote:
> 
> > RFC:
> > 
> > Direct Stream Digital (DSD), a.k.a One bit audio (OBA), is an alternative to PCM.
> > It can be found in Super Audio CDs and hi-res downloadable music.
> 
> Can I ask what warrants treating DSD as sample format instead of a
> codec? FFmpeg is very conservative about sample formats and defines
> only a few. For example, we don't support 24 bit audio directly, we
> don't support unsigned or other-endian formats, we don't support stuff
> like adpcm or a-law as sample formats.

Thanks. I posted as RFC for this very reason.

Agree that its not as compelling as ther other SAMPLE_FMTs... except maybe 
SAMPLE_FMT_DBL. Here's what motivated me:

* Bit perfect playback -- feeding original DSD samples into external DAC.
  All the tools to do this current are for Windows.

* MPEG-4 DST is a lossless compression for DSD samples. I am toying with decoder,
  and want to manipulate the output directly.

* Avoid floating point PCM conversion, so therefore can use crc & framecrc 

Another justification might be file format conversion. e.g. dsf -> dff

> It seems usually we only add sample formats that are easy to manipulate
> (e.g. filtering). DSD doesn't seem to fit into this schema.

Agree.

> DSD also seems to be quite obscure and didn't seem to be overly
> successful commercially. I don't find any hints that DSD is in any way
> superior to PCM either.

Agree.

-- Peter
(A907 E02F A6E5 0CD2 34CD 20D2 6760 79C5 AC40 DD6B)
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