[Bug 786111] New: tsdemux: mistaking byte sequence in PES header for PTS time stamp
GStreamer (GNOME Bugzilla)
bugzilla at gnome.org
Thu Aug 10 13:50:37 UTC 2017
https://bugzilla.gnome.org/show_bug.cgi?id=786111
Bug ID: 786111
Summary: tsdemux: mistaking byte sequence in PES header for PTS
time stamp
Classification: Platform
Product: GStreamer
Version: git master
OS: Windows
Status: NEW
Severity: normal
Priority: Normal
Component: gst-plugins-bad
Assignee: gstreamer-bugs at lists.freedesktop.org
Reporter: boxerab at gmail.com
QA Contact: gstreamer-bugs at lists.freedesktop.org
GNOME version: ---
Test file: http://s3.amazonaws.com/fox_misc/aperi_tr01_1s_pkts-C.cap.gz
Unzip and rename to test.cap.
Test pipeline:
GST_DEBUG=3 gst-launch-1.0 -v filesrc location=~/test.cap ! pcapparse !
tsdemux ! jpeg2000parse ! openjpegdec ! videoconvert ! imagefreeze ! ximagesink
Warnings:
0:00:01.070779503 8815 0x1831050 WARN pesparser
pesparse.c:416:mpegts_parse_pes_header: bad PTS value
0:00:01.070781019 8815 0x1831050 WARN tsdemux
tsdemux.c:2253:gst_ts_demux_parse_pes_header: Error parsing PES header. pid:
0x45 stream_type: 0x6
0:00:01.070788151 8815 0x1831050 DEBUG pesparser
pesparse.c:140:mpegts_parse_pes_header: header_size : 14
0:00:01.070821307 8815 0x1831050 WARN pesparser
pesparse.c:416:mpegts_parse_pes_header: bad PTS value
0:00:01.070823313 8815 0x1831050 WARN tsdemux
tsdemux.c:2253:gst_ts_demux_parse_pes_header: Error parsing PES header. pid:
0x42 stream_type: 0x6
Reading the beginning of the PES header in method mpegts_parse_pes_header, I
get the following bytes:
0x80 0x0a 0x1b 0xd2 0xbd 0xfe
0x80 is a flag indicating a PTS, but the next byte
should have its low bit set. Since it doesn't, the PTS
is rejected.
This same byte pattern appears for each PES packet, so it doesn't look like
corruption, as it is the same pattern.
This can't be a PTS time stamp, because it doesn't change.
So, it looks like tsdemux is incorrectly parsing these bytes as a PTS
time stamp.
Please note that the steam type is 0x6, indicating a private stream.
Also
#define ST_PS_VIDEO_MPEG2_DCII 0x80
So, perhaps this private stream is mistaken for a PTS.
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