[MPlayer-dev-eng] Howto integrate H.264 hardware decoder?

[Benjamin Zores]

On 7/26/07, Markus Korber <korbse at gmx.at> wrote:
> Hi,
>
> what's the best way to integrate support for a H.264 hardware decoder
> chip into V4L2?  What would I have to do?

Write a V4L2 driver first but it's not the scope of this list.
Have an FFMPEG codec equivalent to the one for MPEG2 with XvMC but for
H.264 i guess.
Out of curiosity, which card actually provide H.264 h/w decoder ?

> So what would be the best way to implement this interface and what
> should it look like?

Best way is to to it through V4L2 to avoid the mess introduced by IVTV
driver and its proprietary ioctls. This was however needed at the time
the driver was first wrote as V4L2 didn't support MPEG streams at this
time.
Now it does but I don't know what's the status with MPEG 4.

> Do I have to do something similar to what ivtv does for hardware MPEG2
> decoding (drivers/media/video/ivtv/* in Linux and libvo/vo_ivtv.c and
> stream/stream_pvr.c in mplayer)?

Well, for vo yes.
stream/stream_pvr is for input only, so encoding, not decoding.
Btw, now that 2.6.22 is out, I plan to update vo_ivtv to vo_v4l2 has
the API has been standardized and do no more depends on IVTV cards.
Though, again, MPlayer can only send MPEG1/2 to h/w decoder as for
now. Anything else will be transcoded first, which is not what you
expect.
So we need to be able to send MPEG4 to h/w decoder first.

> (I guess there won't be a generic solution without patching the video
>  application?)

Good guess, there's no magic involved.
Write the driver against V4L2, write the codec, let me write the vo
driver for MPlayer, write the coded for ffmpeg and then it'll be
generic :p

Ben

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