[Bug 783470] New: qtmux with x264 causes offset in video timestamps
GStreamer (GNOME Bugzilla)
bugzilla at gnome.org
Tue Jun 6 12:52:09 UTC 2017
https://bugzilla.gnome.org/show_bug.cgi?id=783470
Bug ID: 783470
Summary: qtmux with x264 causes offset in video timestamps
Classification: Platform
Product: GStreamer
Version: 1.12.0
OS: Linux
Status: NEW
Severity: minor
Priority: Normal
Component: gst-plugins-good
Assignee: gstreamer-bugs at lists.freedesktop.org
Reporter: jpa at gnobug.mail.kapsi.fi
QA Contact: gstreamer-bugs at lists.freedesktop.org
GNOME version: ---
I'm generating a file like this:
gst-launch-1.0 -v videotestsrc num-buffers=10 ! identity silent=false ! x264enc
! qtmux ! filesink location="tmp.mp4" | grep -o "pts: *[^ ]*"
pts: 0:00:00.000000000,
pts: 0:00:00.033333333,
...
and decoding it by:
gst-launch-1.0 -v filesrc location="tmp.mp4" ! qtdemux ! avdec_h264 ! fakesink
silent=false | grep -o "pts: *[^ ]*"
pts: 0:00:00.066666666,
pts: 0:00:00.100000000,
...
The PTS of the first frame appears to change for some reason, always by two
frame durations. This causes offset in lipsync if the file has audio in it.
I haven't git bisected yet, but the bug is present in 1.12.0 and 1.8.3. In
1.3.3 the output begins at 0 as expected. Files generated in 1.3.3 however show
the offset when decoded in newer versions, and files generated in newer
versions show the offset also in 1.3.3. Muxing raw video (without x264enc)
gives correct timestamps in all versions.
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