How to concatenate two videos w. ffmpeg -- documented code not working

Question

I'm trying to concatenate two videos with ffmpeg. Nothing fancy; I just want one video that consists of video A immediately followed by video B.

I've tried the code from How to concatenate (join, merge) media files on a freshly built and otherwise-working-fine install of ffmpeg 1.2.1 on Fedora 17, but the following error message appears:

$ ffmpeg -i video_a.mov -i video_b.mov -filter_complex '[0:0] [0:1] [1:0] [1:1] concat=n=2:v=1:a=1 [v] [a]' -map '[v]' -map '[a]' output.mp4

ffmpeg version N-54271-g7f866c1 Copyright (c) 2000-2013 the FFmpeg developers
  built on Jun 29 2013 11:05:42 with gcc 4.7.2 (GCC) 20120921 (Red Hat 4.7.2-2)
  configuration: --enable-gpl --enable-nonfree --enable-pthreads --enable-libx264 --enable-libfaac --extra-cflags=-I/usr/local/include --extra-ldflags=-L/usr/local/lib
  libavutil      52. 37.101 / 52. 37.101
  libavcodec     55. 17.100 / 55. 17.100
  libavformat    55. 10.100 / 55. 10.100
  libavdevice    55.  2.100 / 55.  2.100
  libavfilter     3. 77.101 /  3. 77.101
  libswscale      2.  3.100 /  2.  3.100
  libswresample   0. 17.102 /  0. 17.102
  libpostproc    52.  3.100 / 52.  3.100

Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'v1221-MTQxMzcyNTIxODU2.mov':
  Metadata:
    major_brand     : qt  
    minor_version   : 0
    compatible_brands: qt  
    creation_time   : 2013-03-28 20:34:59
    encoder         : Mac OS X v10.8.3 (CMA 914, CM 926.87, x86_64)
    encoder-eng     : Mac OS X v10.8.3 (CMA 914, CM 926.87, x86_64)
  Duration: 00:00:05.34, start: 0.000000, bitrate: 15837 kb/s
    Stream #0:0(und): Audio: aac (mp4a / 0x6134706D), 44100 Hz, mono, fltp, 221 kb/s
    Metadata:
      creation_time   : 2013-03-28 20:34:59
      handler_name    : Core Media Data Handler
    Stream #0:1(und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], 15512 kb/s, 29.81 fps, 30 tbr, 600 tbn, 1200 tbc
    Metadata:
      creation_time   : 2013-03-28 20:34:59
      handler_name    : Core Media Data Handler

Input #1, mov,mp4,m4a,3gp,3g2,mj2, from 'v1224-MTQxMzcyNTIxODg5.mov':
  Metadata:
    major_brand     : qt  
    minor_version   : 0
    compatible_brands: qt  
    creation_time   : 2013-03-28 20:36:28
    encoder         : Mac OS X v10.8.3 (CMA 914, CM 926.87, x86_64)
    encoder-eng     : Mac OS X v10.8.3 (CMA 914, CM 926.87, x86_64)
  Duration: 00:00:04.13, start: 0.000000, bitrate: 15689 kb/s
    Stream #1:0(und): Audio: aac (mp4a / 0x6134706D), 44100 Hz, mono, fltp, 221 kb/s
    Metadata:
      creation_time   : 2013-03-28 20:36:28
      handler_name    : Core Media Data Handler
    Stream #1:1(und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], 15446 kb/s, 29.79 fps, 30 tbr, 600 tbn, 1200 tbc
    Metadata:
      creation_time   : 2013-03-28 20:36:28
      handler_name    : Core Media Data Handler

Stream specifier ':0' in filtergraph description [0:0] [0:1] [1:0] [1:1] concat=n=2:v=1:a=1 [v] [a] matches no streams.

A few other things to note:

• The two videos I'm working with were shot with the same camera, so there shouldn't be any problems with aspect ratio or other gory video details.
• I'm able to do other things with my ffmpeg installation, like convert one of those videos from .mov to .mp4 (yes, I had to recompile with faac...), which seems to vouch for both the ffmpeg and the video.
• I've tried modifying the above invocation to produce a .mov file at the end, but I get the same error as before.
• I've tried some stupid hacking tricks on the request above, like concatenating two copies of the same video, as well as some other invocations from other places around the web that involve filter_complex. Even on ones that were cited as working, I get the "matches no streams" message.

Answer 1

For each input, specify the video stream first and then the audio stream(s). Because your video stream is stream 1 for each of your inputs, and your audio stream is stream 0, that would be:

ffmpeg -i video_a.mov -i video_b.mov -filter_complex '[0:1] [0:0] [1:1] [1:0] 
  concat=n=2:v=1:a=1 [v] [a]' -map '[v]' -map '[a]' output.mp4

Or better yet, the following command should work regardless of the order of the original streams, and will take the first audio stream if there is more than one:

ffmpeg -i video_a.mov -i video_b.mov -filter_complex '[0:v] [0:a:0] [1:v] [1:a:0] 
   concat=n=2:v=1:a=1 [v] [a]' -map '[v]' -map '[a]' output.mp4