Invalid PTS from v4l2 mjpeg source [SOLVED]

[Nicolas Dufresne]

Le mer. 16 nov. 2022, 14 h 15, Dave Blanchard via gstreamer-devel <
gstreamer-devel at lists.freedesktop.org> a écrit :

> Fixed this problem by adding 'jpegparse' before jpegdec/avdec_mjpeg.
> Working great now at 30 fps with no errors. Also, very little stream
> latency compared to my previous ffmpeg setup; it's now essentially realtime
> video. Now if gstreamer will work continuously over weeks or months without
> the occasional random crash like ffmpeg, I'll be very happy!
>

Great idea. The parser will protect the decoder from possibly corrupted
frames coming from the camera too, so that may help with stability.

Congrat,
Nicolas


> Thank you!
>
> Begin forwarded message:
>
> Date: Wed, 16 Nov 2022 11:40:39 -0600
> From: Dave Blanchard via gstreamer-devel <
> gstreamer-devel at lists.freedesktop.org>
> To: gstreamer-devel at lists.freedesktop.org
> Cc: Dave Blanchard <dave at killthe.net>
> Subject: Invalid PTS from v4l2 mjpeg source
>
>
> Hi all, I'm trying to use gstreamer to capture video from a MJPEG
> surveillance card. There's one last snag to get through to get this working
> right.
>
> With ffmpeg I use the following command to stream the video to an HLS
> endpoint, which then plays perfectly at 30 fps with no trouble:
>
> ffmpeg -r 30 -video_size 704x480 -i /dev/video1 -c:v mpeg2video -b:v 8M -f
> mpegts http://localhost:5000/publish/camera1
>
> With gstreamer I'm using this command:
>
> gst-launch-1.0 v4l2src device=/dev/video1 !
> "image/jpeg,width=704,height=480,framerate=30/1" ! jpegdec [or avdec_mjpeg]
> ! videoconvert ! avenc_mpeg2video bitrate=8192 threads=0 ! mpegtsmux !
> srtsink uri=srt://:5000 latency=0
>
> I'm able to play the resulting video, but it seems about half of the
> frames are being dropped, and I'm getting a steady stream of PTS errors on
> the console for every other frame:
>
> [...]
>
> [mpeg2video @ 0x259b740] Invalid pts (108003372) <= last (108003372)
> [mpeg2video @ 0x259b740] Invalid pts (108003374) <= last (108003374)
> [mpeg2video @ 0x259b740] Invalid pts (108003376) <= last (108003376)
> [mpeg2video @ 0x259b740] Invalid pts (108003378) <= last (108003378)
>
> [...]
>
> Seems DTS=PTS, which is wrong.
>
> Weirdly, every once in a while these errors will stop, and the video will
> play perfectly for a moment at 30 fps, until the errors begin again and
> it's back to 15 real fps.
>
> Can anyone give me a clue how to fix this? Ideally on the command line
> without any coding, although I can do that as a last resort. I've searched
> and searched and can't figure this out.
>
> Thank you!
>
> --
> Dave Blanchard <dave at killthe.net>
> --
> Dave Blanchard <dave at killthe.net>
>
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