[FFmpeg-devel] [PATCH] libavcodec: add h.264 dxva2 decoder to ffmpeg

[Hendrik Leppkes]

On Wed, Dec 26, 2012 at 7:18 AM, Wei Gao <highgod0401 at gmail.com> wrote:
> From 8dddb4d8712ea5bcd91455b393e9563507fc9852 Mon Sep 17 00:00:00 2001
> From: highgod0401 <highgod0401 at gmail.com>
> Date: Wed, 26 Dec 2012 14:05:38 +0800
> Subject: [PATCH] add h.264 dxva2 decoder to ffmpeg
>

I'm not sure this patch as a whole is a good idea, because i'm not
seeing the benefits, and a whole bunch of technical issues.
On any half-competent system, the software decoder is significantly
faster then the hardware decoders in most GPUs, which makes it
somewhat useless for transcoding in ffmpeg.
The only real use-case for hardware acceleration is in playback on
low-end hardware or in mobile applications to reduce power usage.

On the technical side of things, why do we have HWAccels if every
HWAccel gets its decoder "wrapper"? Personally i prefer the concept of
the HWAccel, even if the implementation isn't perfect.
Especially with DXVA, which has so many variables to control, a
generic decoder is probably not a good idea, and would end up a
maintenance nightmare (i know, because i maintain my own user-code
which uses the DXVA HWAccel, the fun never ends)

And another point, a lot of the code seems to be copy/pasted from VLC,
without attribution to the original authors.