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Date:   Mon, 6 Sep 2021 16:56:47 +0200
From:   LABBE Corentin <clabbe@baylibre.com>
To:     Hans Verkuil <hverkuil@xs4all.nl>
Cc:     gregkh@linuxfoundation.org, mchehab@kernel.org,
        linux-kernel@vger.kernel.org, linux-media@vger.kernel.org,
        linux-staging@lists.linux.dev, mjpeg-users@lists.sourceforge.net
Subject: Re: [PATCH 0/8] staging: media: zoran: fusion in one module
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Le Mon, Sep 06, 2021 at 04:11:16PM +0200, Hans Verkuil a ?crit :
> On 06/09/2021 15:49, LABBE Corentin wrote:
> > Le Mon, Sep 06, 2021 at 01:03:56PM +0200, Hans Verkuil a ?crit :
> >> Hi Corentin,
> >>
> >> I finally had the opportunity to test the staging zoran driver.
> >>
> >> I found several issues when running v4l2-compliance -s (I posted a patch
> >> for that), but more seriously is the fact that trying to capture MJPG
> >> at resolutions 384x288 or less just hangs my PC. It works OK with 768x576.
> >>
> >> I discovered this when running 'v4l2-compliance -s -a -f'.
> >>
> >> BTW, why isn't the initial format equal to MJPG 768x576?
> >> I would expect that for these boards that should be the default format.
> >>
> >> Another issue is that the TODO should mention that for video output there
> >> should be a second video device node. And that's really something that
> >> has to be done before the zoran driver can be moved out of staging.
> >>
> >> It shouldn't be that hard to implement, I think.
> >>
> >> Right now it is impossible to run the compliance test for the output, since
> >> it doesn't even see it as an output.
> >>
> >> Regards,
> >>
> >> 	Hans
> > 
> > I work on having a second device for output, (it is the reason of "staging: media: zoran: move videodev alloc" which will help).
> > 
> > But I still have the problem of non working output.
> > 
> > Does output is really needed for going out of staging ?
> > Probably nobody have it working for ages. The only way to had it was to use an old mplayer output which is broken since so many time.
> > Note that this plugin will never work again.
> > 
> > The only way to work on output is to use ffmpeg which just recently have suport for writing non-raw video to V4L.
> 
> Then just remove it. The code for output remains in the git history so if someone wants to
> resurrect that, then that's always possible.
> 
> The point is that I don't want to have half-baked output support in mainline.
> 
> But what exactly is the problem with getting output to work? Doesn't it just decode
> MJPEG frames? (Sorry if you explained it before, it's so long ago that I looked at this
> that I forgot the details)
> 

The first problem is that zoran dont like comment COM/APP0 markers.
This imply a per buffer filtering but this is already handled in my next branch.

But the remaining problem is that any output is like http://kernel.montjoie.ovh/zoran_out.png.

I hacked the driver to grab a working buffer when doing input and overrun output buffer later.
And the result is a working static output.
So the hw handling is good and the problem came from the data feeding/handling.

I believe that something is wrong in what ffmpeg negociate/send.

Regards