Missing sound when playing file

Wed Sep 11 11:11:12 UTC 2019

Hello,
The sound is missing after playing an mkv file for about 20 seconds.  My
pipeline decodes video and audio individually to rtp, like this

  filesrc location=av.mkv ! decodebin ! compositor ! ... ! udpsink 
  filesrc location=av.mkv ! decodebin ! audiomixer ! ... ! udpsink

then I will play an SDP file by setting the right settings.

It works for many other mkv/mp4 files but not this file, the debug info
shows 6,000 lines of similar info:

0:00:33.906471062 [336m 1409[00m 0x7f047c03c590 [33;01mWARN   [00m [00m 
matroskareadcommon
matroska-read-common.c:711:gst_matroska_read_common_parse_skip:<matroskademux1:sink>[00m
Unknown CueTrackPositions subelement 0xb2 - ignoring
0:00:33.906476633 [336m 1409[00m 0x7f03f0042800 [33;01mWARN   [00m [00m 
matroskareadcommon
matroska-read-common.c:711:gst_matroska_read_common_parse_skip:<matroskademux0:sink>[00m
Unknown ChaptersTitles subelement 0x437c - ignoring
0:00:33.906477142 [336m 1409[00m 0x7f047c03c590 [33;01mWARN   [00m [00m 
matroskareadcommon
matroska-read-common.c:711:gst_matroska_read_common_parse_skip:<matroskademux1:sink>[00m
Unknown CueTrackPositions subelement 0xf0 - ignoring
0:00:33.906482331 [336m 1409[00m 0x7f03f0042800 [33;01mWARN   [00m [00m 
matroskareadcommon
matroska-read-common.c:711:gst_matroska_read_common_parse_skip:<matroskademux0:sink>[00m
Unknown ChaptersTitles subelement 0x437c - ignoring
0:00:33.906483195 [336m 1409[00m 0x7f047c03c590 [33;01mWARN   [00m [00m 
matroskareadcommon
matroska-read-common.c:711:gst_matroska_read_common_parse_skip:<matroskademux1:sink>[00m
Unknown CueTrackPositions subelement 0xb2 - ignoring
0:00:33.906492194 [336m 1409[00m 0x7f047c03c590 [33;01mWARN   [00m [00m 
matroskareadcommon
matroska-read-common.c:711:gst_matroska_read_common_parse_skip:<matroskademux1:sink>[00m
Unknown CueTrackPositions subelement 0xf0 - ignoring
0:00:33.906495337 [336m 1409[00m 0x7f047c03c590 [33;01mWARN   [00m [00m 
matroskareadcommon
matroska-read-common.c:711:gst_matroska_read_common_parse_skip:<matroskademux1:sink>[00m
Unknown CueTrackPositions subelement 0xf0 - ignoring

After my test I found:
1) play from start: no sound after 20 seconds
2) seek to 60 seconds of the file:  sound is back

What could be the issue then, please help, thank you

--
Sent from: http://gstreamer-devel.966125.n4.nabble.com/