[FFmpeg-user] Accurate seek times with multiple input files

[Mountain Man]

Hello,

I'm trying to combine part of the video stream of an avi file with some
audio I've already processed.  Frame accuracy for the video is very
important because I will be merging the video back together later.
Unfortunately I haven't been able to figure out how to make this work if I
use -ss after the input file (more accurate).  For example, this command
works as expected:

ffmpeg  -ss 4 -i 100_0290.MOV    -i threesec.wav  -map 0:v -map 1:a  -t
3.003 -acodec copy -vcodec ffv1 -pix_fmt yuv420p -r 29.97  combined.avi

However, when I move the -ss portion to after the input files it is either
ignored or causes the audio to fail to copy (presumably because it is
trying to start 4 seconds in to a 3 second file).  For example, I tried:

ffmpeg   -i 100_0290.MOV  -i threesec.wav  -map 0:v -map 1:a -ss:0 4 -ss:1
0 -t 3.003 -acodec copy -vcodec ffv1 -pix_fmt yuv420p -r 29.97  combined.avi

But this gives me 3.003 seconds of audio and video from the beginning of
both files.  What I want is to start several seconds in from the video
stream but start the audio stream from 0.
Is there a way to map the start time to a specific stream so I can use it
after the input files?  Or do I need to pull out just the video stream and
then later combine it back with the separate audio?

The output of the second command (the one I can't make work) is:

ffmpeg   -i 100_0290.MOV  -i threesec.wav  -map 0:v -map 1:a -ss:0 4 -ss:1
0 -t 3.003 -acodec copy -vcodec ffv1 -pix_fmt yuv420p -r 29.97  combined.avi
ffmpeg version N-38182-g449558d Copyright (c) 2000-2013 the FFmpeg
developers
  built on Jun  4 2013 18:35:01 with gcc 4.6 (Ubuntu/Linaro 4.6.3-1ubuntu5)
  configuration: --extra-libs=-ldl --enable-gpl --enable-libass
--enable-libfdk-aac --enable-libmp3lame --enable-libopencore-amrnb
--enable-libopencore-amrwb --enable-libspeex --enable-libtheora
--enable-libvorbis --enable-libopus --enable-libvpx --enable-x11grab
--enable-libx264 --enable-nonfree --enable-version3
  libavutil      52. 34.100 / 52. 34.100
  libavcodec     55. 15.100 / 55. 15.100
  libavformat    55.  8.102 / 55.  8.102
  libavdevice    55.  2.100 / 55.  2.100
  libavfilter     3. 75.101 /  3. 75.101
  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 '100_0290.MOV':
  Metadata:
    major_brand     : qt
    minor_version   : 0
    compatible_brands: qt
    creation_time   : 2012-11-08 11:32:19
    comment         : KODAK PlaySport Video Camera, Zx3
    comment-eng     : KODAK PlaySport Video Camera, Zx3
  Duration: 00:01:45.71, start: 0.000000, bitrate: 8127 kb/s
    Stream #0:0(eng): Video: h264 (Main) (avc1 / 0x31637661), yuv420p,
1280x720 [SAR 1:1 DAR 16:9], 7991 kb/s, 29.97 fps, 29.97 tbr, 90k tbn,
59.94 tbc
    Metadata:
      creation_time   : 2012-11-08 11:32:19
      handler_name    : Ambarella AVC
    Stream #0:1(eng): Audio: aac (mp4a / 0x6134706D), 48000 Hz, stereo,
fltp, 128 kb/s
    Metadata:
      creation_time   : 2012-11-08 11:32:19
      handler_name    : Ambarella AAC
Guessed Channel Layout for  Input Stream #1.0 : stereo
Input #1, wav, from 'threesec.wav':
  Metadata:
    comment         : KODAK PlaySport Video Camera, Zx3
    encoder         : Lavf55.8.102
  Duration: 00:00:03.00, bitrate: 1536 kb/s
    Stream #1:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 48000 Hz,
stereo, s16, 1536 kb/s
Output #0, avi, to 'combined.avi':
  Metadata:
    major_brand     : qt
    minor_version   : 0
    compatible_brands: qt
    comment-eng     : KODAK PlaySport Video Camera, Zx3
    ICMT            : KODAK PlaySport Video Camera, Zx3
    ISFT            : Lavf55.8.102
    Stream #0:0(eng): Video: ffv1 (FFV1 / 0x31564646), yuv420p, 1280x720
[SAR 1:1 DAR 16:9], q=2-31, 200 kb/s, 29.97 tbn, 29.97 tbc
    Metadata:
      creation_time   : 2012-11-08 11:32:19
      handler_name    : Ambarella AVC
    Stream #0:1: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 48000 Hz,
stereo, 1536 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (h264 -> ffv1)
  Stream #1:0 -> #0:1 (copy)
Press [q] to stop, [?] for help
frame=   90 fps= 37 q=-1.0 Lsize=   28993kB time=00:00:03.00
bitrate=79092.0kbits/s
video:28415kB audio:563kB subtitle:0 global headers:0kB muxing overhead
0.052633%