[libav-bugs] [Bug 688] New: avconv has high memory usage with start time offset (-ss) and audio conversion

bugzilla at libav.org bugzilla at libav.org
Tue May 20 02:48:58 CEST 2014


http://bugzilla.libav.org/show_bug.cgi?id=688

           Summary: avconv has high memory usage with start time offset
                    (-ss) and audio conversion
           Product: Libav
           Version: 9
          Platform: All
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: Normal
         Component: utilities
        AssignedTo: bugzilla at libav.org
        ReportedBy: drwho at infidigm.net


Created attachment 484
  --> http://bugzilla.libav.org/attachment.cgi?id=484
avconv process output

When doing a conversion with a start time offset (-ss option) and -c:a enabled,
avconv process grows as it seeks through the file.  Once it reaches the start
offset, the memory usage no longer grows.  Disabling audio conversion, memory
usage is normal.  Seeking to 4400 seconds eventually results in "Cannot
allocate memory" on a system with 4GB ram.  Looking at /proc/pid/smaps the heap
is massive and eventually grows to use most of the system memory.

Input video is atsc 1080i ac3 5.1 (recorded using MythTV and HD-HomeRun) and is
16GB.  I haven't tried other sources with different audio codecs.

leaks
avconv -i royal_wedding.mpeg -c:v libx264 -crf 23 -preset veryslow -vf yadif -r
29.97 -c:a libvorbis -ss 4476 -t 6146 /edit/royal_wedding.mkv
avconv -i royal_wedding.mpeg -c:v libx264 -crf 23 -preset veryslow -vf yadif -r
29.97 -c:a libmp3lame -b:a 128k -ss 6146 -t 2546 /edit/royal_wedding.mkv

doesn't leak
avconv -i royal_wedding.mpeg -c:v libx264 -crf 23 -preset veryslow -vf yadif -r
29.97 -an -ss 6146 -t 2546 /edit/royal_wedding.mkv

Using stock avconv with kubuntu 14.04 (9.13-6:9.13-0ubuntu0.14.04.1).  Process
output attached.

I've worked around the issue by first doing

avconv -i royal_wedding.mpeg -codec copy -ss 4476 -t 6146
/edit/royal_wedding.mkv

and then the converting on the modified file without the start time offset.

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