Gstreamer support for GPU codecs

[Aaron Boxer]

On Tue, May 17, 2016 at 2:13 PM, Nicolas Dufresne <
nicolas.dufresne at gmail.com> wrote:

> Le samedi 14 mai 2016 à 10:41 +0300, Sebastian Dröge a écrit :
> > On Fr, 2016-05-13 at 08:34 -0400, Aaron Boxer wrote:
> > >
> > > I have a question about how the streaming architecture works with
> > > GPU acceleration.
> > >
> > > Since discrete cards are sitting on the PCI bus, best performance
> > > happens when data is
> > > moved to the card in a pipeline and the host gets notified when
> > > data has been processed
> > > and moved back to the host.
> > >
> > > Also, it is sometimes more efficient to process N frames at a time.
> > >
> > > So, for best perf, the flow would be:
> > >
> > > A) host keeps a list of N host-side memory buffers
> > > B) host waits for a host buffer to become available
> > > C) when buffer is available, host copies memory into that buffer,
> > > and queues the buffer
> > > to be copied over to the card
> > > D) when N buffers have been processed, and copied back to host, the
> > > host receives an event
> > > E) host can use the processed buffers, and when it is finished,
> > > that buffers becomes available
> > > for another frame
> > >
> > > Would this workflow work with GStreamer?
> > Yes, you just need to ensure that latency is reported accordingly by
> > your element.
>
> Note, it's arguably not the most efficient way. Ideally, you should
> implement a V4L2 mem-to-mem driver for your card. The videobuf2 and/or
> v4l2_mem2mem framework will provide you an appropriate queue mechanism,
> and efficient memory allocation model. Those drivers are already
> supported by GStreamer.
>


Thanks, Nicolas. I am not completely sure about the actual workflow for J2K
streaming,
but I don't think the encoding and capture would necessarily happen on the
same machine.

So, one machine would capture uncompressed, then send to a second one to
compress and stream
to others. And for viewing, one endpoint would receive the compressed
stream, decompress, and display.

So, I don't think mem-to-mem copying from card is necessary. But, as I
said, streaming is pretty new
to me, so perhaps more experience folks can chime in here.

Aaron




>
> Nicolas
> _______________________________________________
> gstreamer-devel mailing list
> gstreamer-devel at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.freedesktop.org/archives/gstreamer-devel/attachments/20160517/3a3f34b1/attachment.html>