On 10/26/2016 11:09 PM, Hugues FRUCHET wrote:
Hi,
This RFC aims to start discussions in order to define the codec specific
controls structures to fulfill the low-level decoder API needed by non
“Stream API” based decoders (“stateless” or “Frame API” based decoders).
Several implementation exists now which runs on several SoC and various
software frameworks.
The idea is to find the communalities between all those implementations
and SoC to define a single unified interface in V4L2 includes.
Even if “Request API” is needed to pass those codec specific controls
from userspace down to kernel on a per-buffer basis, we can start
discussions and define the controls in parallel of its development.
Yes, I have sent a one for H.264 decoder and JPEG encoder.
We can even propose some implementations based on existing V4L2 control
framework (which doesn’t support “per-frame” basis) by ensuring
atomicity of sequence S_EXT_CTRL(header[i])/QBUF(stream[i]). Constraint
can then be relaxed when “Request API” is merged.
I would like to propose to work on a “per-codec” basis, having at least
2 different SoC and 2 different frameworks to test and validate controls.
To do so, I have tried to identify some people that have worked on this
subject and have proposed some implementations, feel free to correct me
and enhance the list if needed:
* MPEG2/MPEG4
- Florent Revest for Allwinner A13 CedarX support [1] tested with VLC
-> libVA + sunxi-cedrus-drv-video -> V4L2
- Myself for STMicroelectronics Delta support [2] tested with
GStreamer V4L2 -> libv4l2 + libv4l-delta plugin -> V4L2
* VP8
- Pawel Osciak for Rockchip RK3288, RK3399? VPU Support [3] tested with
Chromium -> V4L2
- Jung Zhao for Rockchip RK3288 VPU support [4] <cannot find the
framework used>
There is rockchip VDPAU driver supporting it, but it is .
* H264
- Pawel Osciak for Rockchip RK3288, RK3399? VPU Support [5] tested with
Chromium -> V4L2
- Randy Li for Rockchip RK3288 VPU support [6] tested with VLC? ->
libVA + rockchip-va-driver -> V4L2
I only tested it with Gstreamer -> VA-API element -> Rockchip VA-API
driver -> V4L2
VLC?
-> libVDPAU + rockchip-va-driver -> V4L2
I can work to define MPEG2/MPEG4 controls and propose functional
implementations for those codecs, and will be glad to co-work with you
Florent.
But it may not work with Rockchip's SoC, you may check the following branch
https://github.com/hizukiayaka/rockchip-video-driver/tree/rk_v4l2_mix
I can help on H264 on a code review basis based on the functional H264
setup I have in-house and codec knowledge, but I cannot provide
implementation in a reasonable timeframe, same for VP8.
Apart of very details of each codec, we have also to state about generic
concerns such as:
- new pixel format introduction (VP8 => VP8F, H264 => S264,
MPG2 => MG2F, MPG4 => MG4F)
I don't think it is necessary.
- new device caps to indicate that driver requires extra
headers ? maybe not needed because redundant with new pixel format
I prefer this one.
- continue to modify v4l2-controls.h ? or do we add some new
specific header files (H264 is huge!) ?
Not huge. You could check rockchip's kernel.
- how to manage sequence header & picture header,
optional/extended controls (MPEG2 sequence/picture extensions, H264 SEI,
…). Personally I have added flags inside a single control structure,
H264 is done in a different way using several controls
(SPS/PPS/SLICE/DECODE/…)
the last one is dpb, except the dpb, it would have the same numbers of
controls to those structures defined in VA-API H264 decoder.
Thanks you to all of you for your attention and feel free to react on
this topic if you are interested to work on this subject.
Currently, I have to pause the process of VA-API drive, and moving to
the other idea I have said before, creating a new API in userspace(but
won't archive the goal I set before in this step). There are some
shortages in VA-API I have said in last email making the performance in
4K video and extending the Gstreamer VA-API is a little difficult job
and need more time.
And the development for the new VPU driver for rockchip would pause a
while as well.
It would not be a long time(a few weeks) and I am still available in my
free time(at home). It is good to know the wheel begin to roll. And do
feel free to assign job to me.
Best regards,
Hugues.
[0] [ANN] Codec & Request API Brainstorm meeting Oct 10 & 11
https://www.spinics.net/lists/linux-media/msg106699.html
[1] MPEG2 A13 CedarX http://www.spinics.net/lists/linux-media/msg104823.html
[1] MPEG4 A13 CedarX http://www.spinics.net/lists/linux-media/msg104817.html
[2] MPEG2 STi4xx Delta
http://www.spinics.net/lists/linux-media/msg106240.html
[2] MPEG4 STi4xx Delta is also supported but not yet pushed
[3] VP8 Rockchip RK3288, RK3399? VPU
https://chromium.googlesource.com/chromiumos/overlays/chromiumos-overlay/+/refs/heads/master/sys-kernel/linux-headers/files/0002-CHROMIUM-v4l-Add-VP8-low-level-decoder-API-controls.patch
[4] VP8 Rockchip RK3288 VPU
http://www.spinics.net/lists/linux-media/msg97997.html
[5] H264 Rockchip RK3288, RK3399? VPU
https://chromium.googlesource.com/chromiumos/overlays/chromiumos-overlay/+/refs/heads/master/sys-kernel/linux-headers/files/0001-CHROMIUM-media-headers-Import-V4L2-headers-from-Chro.patch
[6] H264 Rockchip RK3288 VPU
http://www.spinics.net/lists/linux-media/msg105095.html
--
Randy Li
The third produce department
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