I am trying to insert an audio channel with a video:

1. first of all I extract the audio from the original video for processing:

   ffmpeg -i lotr.mp4 lotr.wav

2. I then extract all frames for later processing too:

   ffmpeg -i lotr.mp4 -f image2 %d.jpg

3. When done processing audio and video streams, I try to create the video

   ffmpeg -f image2 -r 15 -i %d.jpg new.mp4

4. then merge with the audio:

   ffmpeg -i new.mp4 -i lotr.wav -map 0:0 -map 1:0 new_w_audio.mp4

Result: CPU activity = 100%, the process hangs and never returns. PS: I even tried it without modifying the images or the audio (so just trying to unpack then repack the video) but still the same output

FFmpeg version SVN-r26400, Copyright (c) 2000-2011 the FFmpeg developers
  built on Jan 18 2011 04:07:05 with gcc 4.4.2
  configuration: --enable-gpl --enable-version3 --enable-libgsm --enable-libvorb
is --enable-libtheora --enable-libspeex --enable-libmp3lame --enable-libopenjpeg
 --enable-libschroedinger --enable-libopencore_amrwb --enable-libopencore_amrnb
--enable-libvpx --disable-decoder=libvpx --arch=x86 --enable-runtime-cpudetect -
-enable-libxvid --enable-libx264 --enable-librtmp --extra-libs='-lrtmp -lpolarss
l -lws2_32 -lwinmm' --target-os=mingw32 --enable-avisynth --enable-w32threads --
cross-prefix=i686-mingw32- --cc='ccache i686-mingw32-gcc' --enable-memalign-hack

  libavutil     50.36. 0 / 50.36. 0
  libavcore      0.16. 1 /  0.16. 1
  libavcodec    52.108. 0 / 52.108. 0
  libavformat   52.93. 0 / 52.93. 0
  libavdevice   52. 2. 3 / 52. 2. 3
  libavfilter    1.74. 0 /  1.74. 0
  libswscale     0.12. 0 /  0.12. 0
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'new.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2mp41
    creation_time   : 1970-01-01 00:00:00
    encoder         : Lavf52.93.0
  Duration: 00:00:29.66, start: 0.000000, bitrate: 193 kb/s
    Stream #0.0(und): Video: mpeg4, yuv420p, 200x134 [PAR 1:1 DAR 100:67], 192 k
b/s, 15 fps, 15 tbr, 15 tbn, 15 tbc
    Metadata:
      creation_time   : 1970-01-01 00:00:00
[wav @ 01fed010] max_analyze_duration reached
Input #1, wav, from 'lotr.wav':
  Duration: 00:00:29.90, bitrate: 176 kb/s
    Stream #1.0: Audio: pcm_s16le, 11025 Hz, 1 channels, s16, 176 kb/s
File 'new_w_audio.mp4' already exists. Overwrite ? [y/N] y
[buffer @ 01b03820] w:200 h:134 pixfmt:yuv420p
Output #0, mp4, to 'new_w_audio.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2mp41
    creation_time   : 1970-01-01 00:00:00
    encoder         : Lavf52.93.0
    Stream #0.0(und): Video: mpeg4, yuv420p, 200x134 [PAR 1:1 DAR 100:67], q=2-3
1, 200 kb/s, 15 tbn, 15 tbc
    Metadata:
      creation_time   : 1970-01-01 00:00:00
    Stream #0.1: Audio: aac, 11025 Hz, 1 channels, s16, 64 kb/s
Stream mapping:
  Stream #0.0 -> #0.0
  Stream #1.0 -> #0.1
Press [q] to stop encoding