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

Christophe Gisquet christophe.gisquet at gmail.com
Wed Jan 6 18:55:53 CET 2016


2016-01-06 18:32 GMT+01:00 foo86 <foobaz86 at gmail.com>:
>             dca         dca2        libdcadec
> System 1:   0:11.90     0:11.16     0:19.73
> System 2:   0:57.00     0:55.23     1:21.33
> System 3:   7:41.31     7:00.84     13:16.70

Just to be sure, because I won't check myself: is this an
apple-to-apple comparison for dca vs dca2? I mean, things like
favorable/native output format, eg without conversion, etc ?

> The new decoder appears slightly faster than dca even though it doesn't
> use any assembly optimized code for dcadsp (besides synth_filter).

synth_filter was in my benchmarks (2? years ago, on a non-avx2 system
with 5.1 core dts) around 50% of the execution time. It's good that it
can be reused, but people have "suffered" using dca without it for
near a decade, so they'll probably handle waiting another decade for
it to be rewritten if it needs to be.

But the other parts of dcadsp are probably contributing less than 10%,
so dca2 looks good.

And anyhow, seeing the enthusiastic support for your version,
performance is probably secondary to a lot of people.


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