[FFmpeg-user] Video concatenation not working.

[ನಾಗೇಶ್ ಸುಬ್ರಹ್ಮಣ್ಯ (Nagesh S)]

>>>Which application shows "some flicker"?
ffplay. I must say that the flicker is less and somewhat unpredictable. It
is the completely blank screen that is more worrisome.

ffmpeg -i output as below:

user at host:~/mp4$ ffmpeg -i video1.mp4
ffmpeg version git-2013-12-01-975110a Copyright (c) 2000-2013 the FFmpeg
developers
  built on Dec  2 2013 02:23:37 with gcc 4.8 (Ubuntu/Linaro 4.8.1-10ubuntu9)
  configuration: --prefix=/home/user/ffmpeg_build
--extra-cflags=-I/home/user/ffmpeg_build/include
--extra-ldflags=-L/home/user/ffmpeg_build/lib --bindir=/home/user/bin
--extra-libs=-ldl --enable-gpl --enable-libass --enable-libfdk-aac
--enable-libmp3lame --enable-libopus --enable-libtheora --enable-libvorbis
--enable-libvpx --enable-libx264 --enable-nonfree --enable-x11grab
  libavutil      52. 56.100 / 52. 56.100
  libavcodec     55. 44.100 / 55. 44.100
  libavformat    55. 22.100 / 55. 22.100
  libavdevice    55.  5.102 / 55.  5.102
  libavfilter     3. 91.100 /  3. 91.100
  libswscale      2.  5.101 /  2.  5.101
  libswresample   0. 17.104 /  0. 17.104
  libpostproc    52.  3.100 / 52.  3.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'video1.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf55.22.100
  Duration: 00:00:05.00, start: 0.000000, bitrate: 42 kb/s
    Stream #0:0(und): Video: h264 (High 4:4:4 Predictive) (avc1 /
0x31637661), yuv444p, 720x486 [SAR 1:1 DAR 40:27], 38 kb/s, 25 fps, 25 tbr,
12800 tbn, 50 tbc (default)
    Metadata:
      handler_name    : VideoHandler

user at host:~/mp4$ ffmpeg -i video2.mp4
ffmpeg version git-2013-12-01-975110a Copyright (c) 2000-2013 the FFmpeg
developers
  built on Dec  2 2013 02:23:37 with gcc 4.8 (Ubuntu/Linaro 4.8.1-10ubuntu9)
  configuration: --prefix=/home/user/ffmpeg_build
--extra-cflags=-I/home/user/ffmpeg_build/include
--extra-ldflags=-L/home/user/ffmpeg_build/lib --bindir=/home/user/bin
--extra-libs=-ldl --enable-gpl --enable-libass --enable-libfdk-aac
--enable-libmp3lame --enable-libopus --enable-libtheora --enable-libvorbis
--enable-libvpx --enable-libx264 --enable-nonfree --enable-x11grab
  libavutil      52. 56.100 / 52. 56.100
  libavcodec     55. 44.100 / 55. 44.100
  libavformat    55. 22.100 / 55. 22.100
  libavdevice    55.  5.102 / 55.  5.102
  libavfilter     3. 91.100 /  3. 91.100
  libswscale      2.  5.101 /  2.  5.101
  libswresample   0. 17.104 /  0. 17.104
  libpostproc    52.  3.100 / 52.  3.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'video2.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: isommp42
    creation_time   : 2012-12-02 05:33:29
  Duration: 00:09:34.60, start: 0.000000, bitrate: 416 kb/s
    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p,
1280x720, 270 kb/s, 15 fps, 15 tbr, 30 tbn, 30 tbc (default)
    Metadata:
      creation_time   : 1970-01-01 00:00:00
      handler_name    : VideoHandler
    Stream #0:1(und): Audio: aac (mp4a / 0x6134706D), 44100 Hz, mono, fltp,
143 kb/s (default)
    Metadata:
      creation_time   : 2012-12-02 05:33:29
      handler_name    : IsoMedia File Produced by Google, 5-11-2011
At least one output file must be specified