amix returns oom although memory is still available

[Carl Eugen Hoyos]

​http://thread.gmane.org/gmane.comp.video.ffmpeg.user/61613
A user provided a testcase that (changes file output and) shows a spurious error message since a08fb398

$ ffmpeg -i in_cut.mp4 -i in.m4a -filter_complex "[0:a][1:a]amix[outA]" -map 0:0 -map [outA] -qscale 2 out.mov
ffmpeg version N-79000-g66edd86 Copyright (c) 2000-2016 the FFmpeg developers
  built with gcc 4.7 (SUSE Linux)
  configuration: --enable-gpl
  libavutil      55. 19.100 / 55. 19.100
  libavcodec     57. 28.100 / 57. 28.100
  libavformat    57. 28.101 / 57. 28.101
  libavdevice    57.  0.101 / 57.  0.101
  libavfilter     6. 39.102 /  6. 39.102
  libswscale      4.  0.100 /  4.  0.100
  libswresample   2.  0.101 /  2.  0.101
  libpostproc    54.  0.100 / 54.  0.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'in_cut.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2mp41
    title           : LP 37
    date            : 2016-03-10
    encoder         : Lavf57.28.101
  Duration: 00:00:05.02, start: 0.000000, bitrate: 3811 kb/s
    Stream #0:0(eng): Video: mpeg4 (Simple Profile) (mp4v / 0x7634706D), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], 3579 kb/s, 60 fps, 60 tbr, 15360 tbn, 60 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 221 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
Input #1, mov,mp4,m4a,3gp,3g2,mj2, from 'in.m4a':
  Metadata:
    major_brand     : M4A
    minor_version   : 512
    compatible_brands: isomiso2
    title           : LP 37
    date            : 2016-03-10
    encoder         : Lavf57.27.100
  Duration: 00:00:05.02, start: 0.021333, bitrate: 131 kb/s
    Stream #1:0(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 128 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
Please use -q:a or -q:v, -qscale is ambiguous
Output #0, mov, to 'out.mov':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2mp41
    title           : LP 37
    date            : 2016-03-10
    encoder         : Lavf57.28.101
    Stream #0:0(eng): Video: mpeg4 (mp4v / 0x7634706D), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], q=2-31, 200 kb/s, 60 fps, 15360 tbn, 60 tbc (default)
    Metadata:
      handler_name    : VideoHandler
      encoder         : Lavc57.28.100 mpeg4
    Side data:
      cpb: bitrate max/min/avg: 0/0/200000 buffer size: 0 vbv_delay: -1
    Stream #0:1: Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 128 kb/s (default)
    Metadata:
      encoder         : Lavc57.28.100 aac
Stream mapping:
  Stream #0:1 (aac) -> amix:input0 (graph 0)
  Stream #1:0 (aac) -> amix:input1 (graph 0)
  Stream #0:0 -> #0:0 (mpeg4 (native) -> mpeg4 (native))
  amix (graph 0) -> Stream #0:1 (aac)
Press [q] to stop, [?] for help
Error while filtering: Cannot allocate memory
frame=  301 fps=276 q=2.0 Lsize=    4106kB time=00:00:05.01 bitrate=6705.1kbits/s speed= 4.6x
video:4020kB audio:79kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.170816%
[aac @ 0x2213940] Qavg: 8620.615

[Michael Niedermayer]

Fixed in abc957e896beb3ce33c5691b9b3701993a381852