v4l2videodec with imx6 coda

[Philipp Zabel]

Hi,

On Wed, Jul 23, 2014 at 10:01:34AM -0400, Nicolas Dufresne wrote:
> Le mercredi 23 juillet 2014 à 00:16 -0700, Jens Kleintje a écrit :
> > Hi,
> > 
> > I am trying to use the v4l2vídeodec plugin gstreamer version 1.4 with the
> > imx6 coda driver on a imx6q sabre smart device board.
> > 
> > The patches for the driver are available under:
> > http://www.mail-archive.com/linux-media@vger.kernel.org/msg77198.html
> > http://www.mail-archive.com/linux-media@vger.kernel.org/msg76875.html.
> > 
> > Did anyone tried this?
> 
> I haven't got recent feedback about that from the team at Pengutronix
> (now in CC). I know they already have a set of elements that covers
> their needs, so it might not have been prioritized yet. Though, I think
> with recent proposed changes to linux-media tree, to split the encoder
> and decoder to use seperate /dev/videoX node (which endup cleaning up
> things), there shouldn't be to much debugging to get it working, if it
> does not work already. I would really appreciate feedback if by chance
> you have the time to look at it. If you need anything, you can find me
> on IRC too, freenode #gstreamer, my nick is stormer.

I have tried the stock GStreamer 1.4 v4l2videodec element and it decodes a
stream out of the box with the kernel patches that I recently sent applied
on top of the media tree:

http://www.mail-archive.com/linux-media@vger.kernel.org/msg77198.html
http://www.mail-archive.com/linux-media@vger.kernel.org/msg77439.html
http://www.mail-archive.com/linux-media@vger.kernel.org/msg77541.html
http://www.mail-archive.com/linux-media@vger.kernel.org/msg77584.html

I see two issues, currently:
a) v4l2videodec should do a TRY_FMT/S_FMT on the V4L2 capture side.
   Currently only the I420 output format works because that happens
   to be the default. Also, the future CODA JPEG decoder will allow
   downscaling (by factors of 2, 4, and 8) during decompression.
b) At stream end I get a hardware timeout because the v4l2videodec doesn't
   send a V4L2_DEC_CMD_STOP decoder command to tell the CODA it may flush
   its bitstream buffer.

regards
Philipp