[libav-bugs] [Bug 786] New: Memory growth while seeking when cutting and converting from MP4 to MPEG

bugzilla at aruru.libav.org bugzilla at aruru.libav.org
Mon Dec 1 19:58:02 CET 2014


https://bugzilla.libav.org/show_bug.cgi?id=786

            Bug ID: 786
           Summary: Memory growth while seeking when cutting and
                    converting from MP4 to MPEG
           Product: Libav
           Version: git HEAD
          Hardware: X86
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: ---
         Component: general
          Assignee: bugzilla at libav.org
          Reporter: manuel.hohmann at ut.ee

Created attachment 513
  --> https://bugzilla.libav.org/attachment.cgi?id=513&action=edit
avconv output

I try to convert selected chunks from a MP4 video to MPEG in order to create a
DVD from the resulting output files. For this I have a script that takes a cut
list, calculates the -ss and -t parameters as well as the optimum bitrate for
the DVD and runs avconv. During the seek phase (before any output is written,
avconv status shows that 0 frames have been converted) the memory consumption
grows (something in the order of 1-2 GB / hour of video), until it runs out of
available memory and finally crashes, if the seek point is too late in the
video.

The same problem (reported here for GIT HEAD) occurs also in the released
versions 11 and 9.16-6:9.16-0ubuntu0.14.04.1 (packaged with Ubuntu 14.04). It
does not (!) occur if I use version 0.8.16.

Sample command line used for producing the attached log:

LD_LIBRARY_PATH=/opt/libav-11/lib /opt/libav-11/bin/avconv -v 9 -loglevel 99 -i
"/space/Konzerte/Tallinn_5.mp4" -target pal-dvd -aspect 16:9 -b:v 2800k -ss 20
-t 10 -ac 2 -map 0:0 -map 0:1 -threads 4 -y test.mpg

For this short sample of 20 seconds seek / 10 seconds conversion one does not
see the effect of memory consumption, to reproduce it increase the seek time to
at least a few minutes or more and watch how the memory consumption grows.

I also attached a valgrind log with the same parameters, but valgrind reports
no memory leak.

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