splitmuxsink and timestamps

[Filip Štědronský]

Hi all,

I'm trying to use splitmuxsink to split a video into several segments like
this:

    gst-launch-1.0  -e filesrc location=input.mkv ! matroskademux ! h264parse     \
                       ! splitmuxsink location=%02d.mkv max-size-time=15000000000 \
                       muxer=matroskamux

The problem is that all the created segments keep the original
timestamps. For example, the timestamps of the second segment
start at 0:15 instead of 0:00:


    $ mkvinfo -v 00.mkv
    [...]
    | + Duration: 00:00:14.540000000
    [...]
    |+ Cluster
    | + Cluster timestamp: 00:00:00.000000000
    | + Simple block: key, track number 1, 1 frame(s), timestamp 00:00:00.000000000
    [...]

versus:

    $ mkvinfo -v 01.mkv
    [...]
    | + Duration: 00:00:13.964000000
    [...]
    |+ Cluster
    | + Cluster timestamp: 00:00:14.580000000
    | + Simple block: key, track number 1, 1 frame(s), timestamp 00:00:14.580000000
    [...]

This causes problems with seeking e.g. in mpv.

Is this by design or a bug?

Could a "reset timestamps at start of each segment" option be added?
(akin to -reset_timestamps option in ffmpeg)

Is there some other way to fix the timestamps using other gstreamer
elements? (googling hasn't yielded much)

The used test files are (but any mkv file will do):
    http://regnarg.cz/tmp/input.mkv
    http://regnarg.cz/tmp/00.mkv
    http://regnarg.cz/tmp/01.mkv

Thanks for any pointers.

Filip Stedronsky
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[Nicolas Dufresne-5]

Le jeudi 31 mai 2018 à 13:40 +0200, Filip Štědronský a écrit :

> Hi all,
>
> I'm trying to use splitmuxsink to split a video into several segments like
> this:
>
>     gst-launch-1.0  -e filesrc location=input.mkv ! matroskademux ! h264parse     \
>                        ! splitmuxsink location=%02d.mkv max-size-time=15000000000 \
>                        muxer=matroskamux
>
> The problem is that all the created segments keep the original
> timestamps. For example, the timestamps of the second segment
> start at 0:15 instead of 0:00:
>
>
>     $ mkvinfo -v 00.mkv
>     [...]
>     | + Duration: 00:00:14.540000000
>     [...]
>     |+ Cluster
>     | + Cluster timestamp: 00:00:00.000000000
>     | + Simple block: key, track number 1, 1 frame(s), timestamp 00:00:00.000000000
>     [...]
>
> versus:
>
>     $ mkvinfo -v 01.mkv
>     [...]
>     | + Duration: 00:00:13.964000000
>     [...]
>     |+ Cluster
>     | + Cluster timestamp: 00:00:14.580000000
>     | + Simple block: key, track number 1, 1 frame(s), timestamp 00:00:14.580000000
>     [...]
>
> This causes problems with seeking e.g. in mpv.
>
> Is this by design or a bug?

Good question, I doubt it will affect GStreamer much. Though, I wonder
if splitmuxsrc may be relying on that at the moment. The idea is that
the storage produce by splitmuxsink can be played as being 1 media by
splitmuxsrc.

>
> Could a "reset timestamps at start of each segment" option be added?
> (akin to -reset_timestamps option in ffmpeg)
>
> Is there some other way to fix the timestamps using other gstreamer
> elements? (googling hasn't yielded much)
>
> The used test files are (but any mkv file will do):
>     http://regnarg.cz/tmp/input.mkv
>     http://regnarg.cz/tmp/00.mkv
>     http://regnarg.cz/tmp/01.mkv
>
> Thanks for any pointers.
>
> Filip Stedronsky
> _______________________________________________
> gstreamer-devel mailing list
> [hidden email]
> https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel

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