overlay with shortest=1 loops forever if one input is of unlimited duration

[Andrey Utkin]

Summary of the bug:

If we join with overlay=shortest=1 an input file of limited length and an unlimited stream, filtergraph never finishes its shutdown when one of streams has ended.

How to reproduce:

 # /usr/local/src/ffmpeg/ffmpeg -f lavfi -t 1 -i testsrc -vf "testsrc[overlaid];[0:0][overlaid]overlay=shortest=1" -f mpegts -y /dev/null
ffmpeg version N-59909-g3721531 Copyright (c) 2000-2014 the FFmpeg developers
  built on Jan 17 2014 14:02:33 with gcc 4.6.3 (Gentoo 4.6.3 p1.11, pie-0.5.2)
  configuration: --enable-libfreetype --enable-filter=drawtext
  libavutil      52. 62.100 / 52. 62.100
  libavcodec     55. 48.101 / 55. 48.101
  libavformat    55. 23.103 / 55. 23.103
  libavdevice    55.  5.102 / 55.  5.102
  libavfilter     4.  1.100 /  4.  1.100
  libswscale      2.  5.101 /  2.  5.101
  libswresample   0. 17.104 /  0. 17.104
Input #0, lavfi, from 'testsrc':
  Duration: N/A, start: 0.000000, bitrate: N/A
    Stream #0:0: Video: rawvideo (RGB[24] / 0x18424752), rgb24, 320x240 [SAR 1:1 DAR 4:3], 25 tbr, 25 tbn, 25 tbc
Output #0, mpegts, to '/dev/null':
  Metadata:
    encoder         : Lavf55.23.103
    Stream #0:0: Video: mpeg2video, yuv420p, 320x240 [SAR 1:1 DAR 4:3], q=2-31, 200 kb/s, 90k tbn, 25 tbc
Stream mapping:
  Stream #0:0 -> #0:0 (rawvideo -> mpeg2video)
Press [q] to stop, [?] for help
frame=   27 fps=4.2 q=2.0 Lsize=      63kB time=00:00:01.04 bitrate= 497.5kbits/s dup=0 drop=3207    
video:55kB audio:0kB subtitle:0 global headers:0kB muxing overhead 13.815072%
Received signal 2: terminating.
[ERR]
14:07root@whdd.org /usr/local/src/ffmpeg
 # /usr/local/src/ffmpeg/ffmpeg -f lavfi -i testsrc=d=1 -vf "testsrc[overlaid];[0:0][overlaid]overlay=shortest=1" -f mpegts -y /dev/null
ffmpeg version N-59909-g3721531 Copyright (c) 2000-2014 the FFmpeg developers
  built on Jan 17 2014 14:02:33 with gcc 4.6.3 (Gentoo 4.6.3 p1.11, pie-0.5.2)
  configuration: --enable-libfreetype --enable-filter=drawtext
  libavutil      52. 62.100 / 52. 62.100
  libavcodec     55. 48.101 / 55. 48.101
  libavformat    55. 23.103 / 55. 23.103
  libavdevice    55.  5.102 / 55.  5.102
  libavfilter     4.  1.100 /  4.  1.100
  libswscale      2.  5.101 /  2.  5.101
  libswresample   0. 17.104 /  0. 17.104
Input #0, lavfi, from 'testsrc=d=1':
  Duration: N/A, start: 0.000000, bitrate: N/A
    Stream #0:0: Video: rawvideo (RGB[24] / 0x18424752), rgb24, 320x240 [SAR 1:1 DAR 4:3], 25 tbr, 25 tbn, 25 tbc
Output #0, mpegts, to '/dev/null':
  Metadata:
    encoder         : Lavf55.23.103
    Stream #0:0: Video: mpeg2video, yuv420p, 320x240 [SAR 1:1 DAR 4:3], q=2-31, 200 kb/s, 90k tbn, 25 tbc
Stream mapping:
  Stream #0:0 -> #0:0 (rawvideo -> mpeg2video)
Press [q] to stop, [?] for help
frame=   27 fps=2.7 q=2.0 Lsize=      63kB time=00:00:01.04 bitrate= 497.5kbits/s dup=0 drop=5123    
video:55kB audio:0kB subtitle:0 global headers:0kB muxing overhead 13.815072%
Received signal 2: terminating.

This works:

/usr/local/src/ffmpeg/ffmpeg -loglevel debug -f lavfi -i testsrc -vf "testsrc=d=1[overlaid];[0:0][overlaid]overlay=shortest=1" -f mpegts -y /dev/null

[Carl Eugen Hoyos]

Regression since 231e5015
-t 1 is not needed to reproduce:
$ ffmpeg -f lavfi -i testsrc=d=1 -vf "testsrc[overlaid];[0:0][overlaid]overlay=shortest=1" -f null -

[Carl Eugen Hoyos]

The following works as expected:

$ ffmpeg -f lavfi -i testsrc=d=1 -vf "testsrc,overlay=shortest=1" -f null -

[Carl Eugen Hoyos]

Fixed by Nicolas in 2dc5980d - thank you for the report!