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Subject: Re: [PATCH v4 0/4] media: meson: vdec: Add compliant H264 support
From:   Piotr Oniszczuk <piotr.oniszczuk@gmail.com>
In-Reply-To: <cc8defafcf4849f48786c41d94c4e44414903fac.camel@ndufresne.ca>
Date:   Mon, 10 Feb 2020 11:16:16 +0100
Cc:     Neil Armstrong <narmstrong@baylibre.com>,
        "mchehab@kernel.org" <mchehab@kernel.org>,
        "hans.verkuil@cisco.com" <hans.verkuil@cisco.com>,
        "linux-amlogic@lists.infradead.org" 
        <linux-amlogic@lists.infradead.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-arm-kernel@lists.infradead.org" 
        <linux-arm-kernel@lists.infradead.org>,
        "linux-media@vger.kernel.org" <linux-media@vger.kernel.org>
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References: <20200116133025.1903-1-narmstrong@baylibre.com>
 <371bccfa68c4a9924137f087ef45c732e64bf808.camel@ndufresne.ca>
 <970b4e5b89db7f055217676a07281e37f6dcd35a.camel@ndufresne.ca>
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To:     Nicolas Dufresne <nicolas@ndufresne.ca>
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> Wiadomo=C5=9B=C4=87 napisana przez Nicolas Dufresne =
<nicolas@ndufresne.ca> w dniu 08.02.2020, o godz. 22:08:
>=20
> I'm currently running Fedora 31 (Debian unstable should provide the
> same), with the stock GStreamer 1.16.1. And doing playback with:
>=20
> gst-play-1.0 Videos/bbb_sunflower_1080p_30fps_normal.mp4 =
--videosink=3D"kmssink" --flags=3Dvideo
>=20
> With this player, you can seek with the arrows (left/right), or go =
back
> to the start using 0 key. When you seek, the streaming stalls. If you
> switch the --videosink to fakevideosink as an example, seeking works
> perfectly, and kernel does not complain anymore. Same if you don't use
> a zero-copy path, like fbdevsink.
>=20

Nicolas,

Are You using streamer compiled with internal gst FFmpeg?
If so - then IIRC 1.16 gst build-in ffmpeg is at 4.2.1 level and it has =
missing some ffmpeg master v4l2 commits which are improving amlogic =
vdec<->ffmpeg cooperation.

Also I personally found adding =
https://github.com/tmm1/FFmpeg/commit/196bab90a29323722050111e936532ac9ac9=
bfda makes mythtv on s912/panfrost with DRM_PRIME =
EGL_LINUX_DMA_BUF_EXPORT working well - at least with H264 bluray =
content (progressive; probability of stream errors=3Dlow).
=20
Playback of TV interlaced content however still has issues on current =
vdec (5.5.2+Neil's v5 ML patch series): video playback sometimes becomes =
jumpy.=20
At this moment I suspect it is because bitstream errors (TV recordings =
recorded from SAT so stream errors are highly probable) are confusing =
vdec and vdec hw + ffmpeg v4l2 are not able to deal/recover with =
this=E2=80=A6.
(this more demanding error handling is IMHO general attribute of =
stateful decoders when compared to state-less)

Generally I think vdec error recovery in vdec<->ffmpeg needs be =
inspected and maybe there is place to improvement=E2=80=A6..
   =20