Generic DMABUF to vaapi h264 encoding

[Sreerenj Balachandran]

HI,

On Thu, Jul 23, 2015 at 11:34 AM, Volker Vogelhuber
<v.vogelhuber at digitalendoscopy.de> wrote:
> Hi Nicolas,
>>
>> Le mardi 21 juillet 2015 à 14:47 +0200, Volker Vogelhuber a écrit :
>>>
>>> As this is not a V4L2 exported DMABUF I guess the
>>> usual samples using DMABUF-import from the V4L2 plugins do not work.
>>
>> I forgot to mention that I didn't understand this sentence.
>>
>>    v4l2src io-mode=dmabuf ! vaapipostproc ! vaapiencode_h264
>>
>> Should in theory work. Just like:
>>
>>    ... ! vaapipostproc ! v4l2sink io-mode=dmabuf-import
>>
>> But it all depends on the driver expected format and allocation type.
>> There is also many ways that this won't work. An example, if you use
>> libv4l, it's known limitation that DMABUF cannot be used, color format
>> may not match, padding may not match, etc.
>
> Thanks for your reply. I thought that gstreamer's V4L2 plugins require the
> source for handling DMABUFs to be a V4L2 device, because I seem to remember
> that I saw ioctl calls somewhere in the gstreamer's code handling V4L2
> sources. Is there also the possibility to use v4l2src with DMABUF file
> descriptors coming from somewhere else (intel GPU driver).

The only case that we (or at least I) have tested successfully with dmabuf is:
gst-launch-1.0 v4l2src io-mode=dmabuf-import ! vaapipostproc  ! vaapisink

Also you have to compile the gst-plugins-good with "--without-libv4l2"
option to get it working


>
> Regarding your other suggestion, you were right, that the format was wrong.
> I already got vaapipostproc in my pipeline, but the input format accepted
> seems to be GST_VIDEO_FORMAT_RGBx instead of GST_VIDEO_FORMAT_xRGB.
>
> I can see during debugging that it now continues to run until somewhere else
> a internal data flow error occurs. I'm trying to find out where it stops.
>
> Basically what I want to do is to render into a texture in another
> application. This texture is exported using a DMABUF file descriptor and
> passed to my video recording process. There I want to encode it using the
> VAAPI h264 encoder and after buffer has been processed I can reuse the
> buffer within the rendering application.
>
> Therefore it would be also nice if gstreamer can tell me when it is not
> using the pushed buffer anymore. Is there any callback one could add to
> maybe the vaapiencode_h264 or vaapipostproc element, that notifies me, when
> the buffer pushed via appsrc isn't used anymore by the pipeline?
>
> Kind regards,
>
>    Volker
>
>
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-- 
Regards,

Sreerenj Balachandran
Intel Open Source Technology Center