[FFmpeg-trac] #5429(avcodec:new): mov_text subtitles crash "QuickTime Player" and iOS devices

[FFmpeg]

#5429: mov_text subtitles crash "QuickTime Player" and iOS devices
-------------------------------------+-------------------------------------
             Reporter:  julian       |                     Type:  defect
               Status:  new          |                 Priority:  important
            Component:  avcodec      |                  Version:
             Keywords:  mov_text     |  unspecified
  movtextenc subtitle                |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 1.) download
 https://dl.dropboxusercontent.com/u/7221986/ffmpeg_bug_qtcrash.mkv
 2.) ffmpeg -i ffmpeg_bug_qtcrash.mkv -map 0:1 -map 0:2 -map 0:0 -scodec
 mov_text -vcodec copy -acodec copy -y out.mp4
 3.) open out.mp4 in Quicktime Player on Mac OS X 10.11.4 and watch it
 until second 21 or just scroll forward a bit after opening
 4.) Quicktime Player crashes completely repeatably in
 "com.apple.coremedia.textmediaconverter.callback" with something like

 Thread 26 Crashed:: Dispatch queue:
 com.apple.coremedia.textmediaconverter.callback.0x7fc0a96785b0
 0   libobjc.A.dylib                     0x00007fff8e31a4dd objc_msgSend +
 29
 1   com.apple.CoreFoundation            0x00007fff97c5b8c2
 CFAttributedStringSetAttributes + 914
 2   com.apple.MediaToolbox              0x00007fff98c09b36
 FigTextSampleBufferCopyAttributedString + 3110
 3   com.apple.MediaToolbox              0x00007fff98c523f3 0x7fff98b0b000
 + 1340403


 __
 the change in ffmpeg that introduced this problem was between version
 2.7.2 and version 2.8.0, more specifically it was commit
 "cf9051deac498eed70ab68c562b761c55251d270" [movtextenc.c: Support for
 Bold, Italic and Underlined Styles]

 the problem has not been fixed since, i tried releases up to 3.0.1 as well
 as recent git snapshots "N-79115-g65cff81" (compiled myself) and
 "N-79453-g5256250-tessus" (precompiled)

 if i compile 2.8.6 with movtextenc.c from before the bad commit, the
 problem goes away and the resulting file doesn't crash Quicktime Player
 anymore

 __
 p.s. please host a copy of the file to reproduce the issue

--
Ticket URL: <https://trac.ffmpeg.org/ticket/5429>
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