VDPAU feature request: Support Plain Decoding for Transcoding and Video Editing Apps

[djtm]

Thanks for the great work!

The Task
I would like to use VDPAU to (more quickly) transcode my 1080i AVCHD home videos to 720p h264.

The Problem
Unfortunately the VDPAU ffmpeg/mplayer patches are currently written in a way that only video output is possible. They are currently not compatible with mencoder for plain decoding. The people in #mplayer said that it is currently implemented as a "vo" not a "vc" (even though you use -vc ... to activate the codec).

The Fix
As I was told VDPAU API lets youget the decoded image from the video and copy it to the system ramto write the support as "vc", as plain decoding compatible with mencoder. That would be really nice, because then I could use the GPU for the decoding part and speed up the process a lot. Also more flexible processing in mplayer and speed ups in other video encoding applications would be possible.

[Dragoran]

This pool is useless, why should anybody vote "no" ?

For transcoding a CUDA/OPENCL based approach would be better suited (and more flexible).

[Gusar]

Originally Posted by Dragoran

For transcoding a CUDA/OPENCL based approach would be better suited (and more flexible).

It wouldn't. The current CUDA encoders produce crap quality and are no faster than x264. And according to one x264 developer, this won't change in the near future.

[Stephen Warren]

This isn't a VDPAU feature request; it's an ffmpeg feature request.

With the pending integration of VAAPI into ffmpeg, the ffmpeg authors are investigating whether to move video decoding entirely within ffmpeg, along with unifying how VDPAU and VAAPI integrate with ffmpeg, which would then probably achieve what you want.

[djtm]

Originally Posted by Stephen Warren

This isn't a VDPAU feature request; it's an ffmpeg feature request.

Yes, true. As I said it's not about the VDPAU API or anything, but about the patches to ffmpeg/mplayer, which were written mainly by NVIDIA afaik. So I thought you might be the right people to ask about this.

[djtm]

Originally Posted by Gusar

The current CUDA encoders produce crap quality and are no faster than x264.

True, x264 is quite fast and scales well. On a simple dual-core I can already reach the limits of the ffmpeg software AVCHD decoder, which unfortunately does not scale well, hence slowing down x264 transcoding.

And the problem about CUDA is that it is pretty hard to implement, which I think is the reason the encoders are still low quality. Also it works only on one platform (nvidia gpus), so I think OpenCL will be better suited for that in the future. Hopefully we'll see some open source encoders which support OpenCL.

But until then, why not use the hardware decoders, which are of fine quality already?

[misse]

Hi,

Sorry to bump this thread, but I just want to know what's the current status is, since I can't find any information on whether it's possible to use mencoder to transcode with vdpau.

Is it a possible feature? If so, is there anyone developing it and is there any usable code to test?

I've got myself an Asrock 330 ION for christmas and would really like to use it to transcode 1080p material to my PS3, but the CPU doesn't have the power to do so.

With XBMC and VDPAU however it does it without even breaking a sweat.

[Gusar]

Originally Posted by misse

Is it a possible feature?

Yes.

Originally Posted by misse

If so, is there anyone developing it and is there any usable code to test?

No.

Originally Posted by misse

I've got myself an Asrock 330 ION for christmas and would really like to use it to transcode 1080p material to my PS3, but the CPU doesn't have the power to do so.

Encoding will still be done by the CPU, so you'll still be extremely limited by it. For fast encoding, get a beast of a CPU with as much cores as possible - like Core i7 (eight logical cores). It's the only way.