[FFmpeg-devel] [PATCH v2 1/4] avcodec/mmaldec: use decoupled dataflow

[Ming Shun Ho]

On Fri, Sep 24, 2021 at 5:30 PM Jan Ekström <jeebjp at gmail.com> wrote:
>
> On Fri, Sep 24, 2021 at 12:06 PM Ho Ming Shun <cyph1984 at gmail.com> wrote:
> >
> > MMAL is an fundamentally an asynchronous decoder, which was a bad fit
> > for the legacy dataflow API. Often multiple packets are enqueued before
> > a flood of frames are returned from MMAL.
> >
> > The previous lockstep dataflow meant that any delay in returning packets
> > from the VPU would cause ctx->queue_decoded_frames to grow with no way
> > of draining the queue.
> >
> > Testing this with mpv streaming from a live RTSP source visibly reduced
> > latency introduced by frames waiting in queue_decoded_frames from
> > roughly 2s to 0.
> >
> > Signed-off-by: Ho Ming Shun <cyph1984 at gmail.com>
>
> Hi,
>
> Thanks for the interest towards improving the MMAL hwdec. Do you

MMAL hwdec with MPV happens to be one of the few decent ways to get
h264 1080p video playback on older Rpi (less than 4).

> happen to know if there is a nice docker container or sysroot tarball
> available that can be utilized for CI etc purposes to at least verify
> that a standard sysroot that is similar to raspbian or so (as that is
> the most common setup with raspis, I think?) still works
> building-wise?

Seems like raspbian images on docker are outdated. Personally I grab a
tarball from http://os.archlinuxarm.org/os/ArchLinuxARM-rpi-2-latest.tar.gz
to do my testing. What's differentiates an RPi distro from a more generic
arm image is just the libs and includes in /opt/vc.

>
> Jan
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