[FFmpeg-devel] [RFC] avcodec: Add native DCA decoder based on libdcadec.

Rostislav Pehlivanov atomnuker at gmail.com
Sun Jan 3 20:03:49 CET 2016


>IMO this should replace the current dca decoder. Based on what i saw from
libdcadec
>yours is cleaner, more feature complete, you're a knowledgeable
maintainer, and
>since the current developer for ffdca over at libav is porting code from
yours to
>get bitexact xll working the code duplication would be considerable if we
keep both.

I agree.

On 3 January 2016 at 18:24, James Almer <jamrial at gmail.com> wrote:

> On 1/3/2016 2:49 PM, foo86 wrote:
> > This is initial version of libdcadec DCA decoder port I hacked together
> over
> > the last week. This patch is of RFC/inquiry type and not meant for
> immediate
> > inclusion.
> >
> > Any comments about the code are appreciated, as well as suggestions
> concerning
> > how should I proceed with this patch. Should I aim for including it as a
> > separate decoder or a replacement for existing DCA decoder? Or it might
> be that
> > you prefer to continue improving existing decoder instead and not merge
> this at
> > all.
>
> IMO this should replace the current dca decoder. Based on what i saw from
> libdcadec
> yours is cleaner, more feature complete, you're a knowledgeable
> maintainer, and
> since the current developer for ffdca over at libav is porting code from
> yours to
> get bitexact xll working the code duplication would be considerable if we
> keep both.
>
> >
> > Attached decoder is feature complete enough to fully decode any
> practically
> > available DTS stream configuration. It supports any possible
> combinations of
> > XCH, XXCH, XBR and X96 core extensions to deliver up to 7.1 ch, 96 kHz
> floating
> > point output. It also implements lossless decoding of XLL extension to
> deliver
> > up to 7.1 ch, 192 kHz fixed point output. Bit rate managed XLL streams
> are
> > supported. Downmixing to 5.1 and stereo using embedded coefficients is
> > supported.
> >
> > Performance wise, this decoder used to be around 10% slower than pure
> floating
> > point version of existing native DCA decoder. However, after native DCA
> decoder
> > has been partially converted to fixed point, this decoder became 5%
> faster than
> > native one. Measurements were done looping over 5.1 core only stream in
>
> Another reason to have this replace the current one, then.
>
> Thanks.
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