FFmpeg freezes during conversion - ffmpeg

Question

I am trying to run a merge between a mp4 video and a m4a audio files. Several other were generated properly, but this one starts and freezes at time 00:02:54.08. If I stop it (ctrl+c) several minutes afterwards, the output.mp4 file have 0 bytes. I do not have a lot of clues why it happens. Anybody experienced something similar?
[]# ffmpeg -i 91dff482-213e-45f7-84ea-a176f255c118.mp4 -i 91dff482-213e-45f7-84ea-a176f255c118.m4a -c:v copy -strict -2 -c:a aac -b:a 160k output.mp4
ffmpeg version 2.6.8 Copyright (c) 2000-2016 the FFmpeg developers
built with gcc 4.8.5 (GCC) 20150623 (Red Hat 4.8.5-4)
configuration: --prefix=/usr --bindir=/usr/bin --datadir=/usr/share/ffmpeg --incdir=/usr/include/ffmpeg --libdir=/usr/lib64 --mandir=/usr/share/man --arch=x86_64 --optflags='-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic' --enable-bzlib --disable-crystalhd --enable-gnutls --enable-ladspa --enable-libass --enable-libcdio --enable-libdc1394 --enable-libfaac --enable-nonfree --enable-libfdk-aac --enable-nonfree --disable-indev=jack --enable-libfreetype --enable-libgsm --enable-libmp3lame --enable-openal --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libvorbis --enable-libv4l2 --enable-libx264 --enable-libx265 --enable-libxvid --enable-x11grab --enable-avfilter --enable-avresample --enable-postproc --enable-pthreads --disable-static --enable-shared --enable-gpl --disable-debug --disable-stripping --shlibdir=/usr/lib64 --enable-runtime-cpudetect
libavutil 54. 20.100 / 54. 20.100
libavcodec 56. 26.100 / 56. 26.100
libavformat 56. 25.101 / 56. 25.101
libavdevice 56. 4.100 / 56. 4.100
libavfilter 5. 11.102 / 5. 11.102
libavresample 2. 1. 0 / 2. 1. 0
libswscale 3. 1.101 / 3. 1.101
libswresample 1. 1.100 / 1. 1.100
libpostproc 53. 3.100 / 53. 3.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '91dff482-213e-45f7-84ea-a176f255c118.mp4':
Metadata:
major_brand : isom
minor_version : 512
compatible_brands: isomiso2avc1iso6mp41
encoder : Lavf56.25.101
Duration: 00:05:00.00, start: 0.133333, bitrate: 30 kb/s
Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 320x240 [SAR 1:1 DAR 4:3], 29 kb/s, 15 fps, 15 tbr, 15360 tbn, 30 tbc (default)
Metadata:
rotate : 90
handler_name : VideoHandler
Side data:
displaymatrix: rotation of -90.00 degrees
Input #1, mov,mp4,m4a,3gp,3g2,mj2, from '91dff482-213e-45f7-84ea-a176f255c118.m4a':
Metadata:
major_brand : isom
minor_version : 512
compatible_brands: isomiso2iso6mp41
encoder : Lavf56.25.101
Duration: 00:05:00.15, start: 0.000000, bitrate: 14 kb/s
Stream #1:0(eng): Audio: aac (LC) (mp4a / 0x6134706D), 8000 Hz, mono, fltp, 13 kb/s (default)
Metadata:
handler_name : SoundHandler
[aac # 0x1b761a0] Too many bits per frame requested, clamping to max
Output #0, mp4, to 'output.mp4':
Metadata:
major_brand : isom
minor_version : 512
compatible_brands: isomiso2avc1iso6mp41
encoder : Lavf56.25.101
Stream #0:0(eng): Video: h264 ([33][0][0][0] / 0x0021), yuv420p, 320x240 [SAR 1:1 DAR 4:3], q=2-31, 29 kb/s, 15 fps, 15 tbr, 15360 tbn, 15360 tbc (default)
Metadata:
rotate : 90
handler_name : VideoHandler
Side data:
displaymatrix: rotation of -90.00 degrees
Stream #0:1(eng): Audio: aac ([64][0][0][0] / 0x0040), 8000 Hz, mono, fltp, 48 kb/s (default)
Metadata:
handler_name : SoundHandler
encoder : Lavc56.26.100 aac
Stream mapping:
Stream #0:0 -> #0:0 (copy)
Stream #1:0 -> #0:1 (aac (native) -> aac (native))
Press [q] to stop, [?] for help
frame= 2612 fps= 33 q=-1.0 size= 1568kB time=00:02:54.08 bitrate= 73.8kbits/s

Answer 1

Run
ffmpeg -ss 02:50 -i video -ss 02:50 -i audio -c:v copy -strict -2 -c:a aac -b:a 160k test.mp4.
If this stops after few seconds, there's some anomaly in one of the bitstreams and you'll have to remux one or both of the input files and try again i.e.
ffmpeg -i video -c copy -an newvideo.mp4
ffmpeg -i audio -c copy -vn newaudio.mp4