ffmpeg to replace audio track?

[yetanotherlogin]

Hello

Using ffmpeg.exe N-52045-g694fa00 "built on Apr 12 2013 16:54:51 with gcc 4.8.0 (GCC)", I followed tutorials (here and here) about how to use ffmpeg to replace the audio track in an FLV file, but I couldn't get this to work.

Here's the original FLV...

Input #0, flv, from 'input.full.flv':
  Metadata:
    starttime       : 0
    totalduration   : 608
    totaldatarate   : 676
    bytelength      : 51367355
    canseekontime   : true
    sourcedata      : BD075FE65HH1367193223014001
    purl            :
    pmsg            :
  Duration: 00:10:07.84, start: 0.000000, bitrate: 676 kb/s
    Stream #0:0: Video: h264 (Main), yuv420p, 640x360, 551 kb/s, 29.97 tbr, 1k tbn, 59.94 tbc
    Stream #0:1: Audio: aac, 44100 Hz, stereo, fltp, 131 kb/s

...and the audio track edited in Audacity:

Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'input.audio.edited.m4a':
  Metadata:
    major_brand     : M4A
    minor_version   : 512
    compatible_brands: isomiso2
    creation_time   : 1970-01-01 00:00:00
    encoder         : Lavf52.64.2
  Duration: 00:10:07.95, start: 0.000000, bitrate: 154 kb/s
    Stream #0:0(und): Audio: aac (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 152 kb/s
    Metadata:
      creation_time   : 1970-01-01 00:00:00
      handler_name    : SoundHandler

First, I tried demuxing the video stream:

ffmpeg.exe -i input.flv -vcodec copy -an -f h264 output.h264

While the original FLV file is 10:07, VLC says the extracted H264 video file is now 2:02:00 long, and doesn't play.

Next, I tried simply replacing the audio track with the file edited in Audacity:

ffmpeg.exe -i input.flv -i input.audio.edited.m4a test.flv

It seems like the data is re-encoded, and the audio hasn't changed anyway.

What is the right command to use to simply replace the audio track with with no re-encoding (transcoding)?

Thank you.

[Chris K]

You could try this...

ffmpeg.exe -i input.flv -i input.audio.edited.m4a -vcodec copy -acodec copy -map 0:0 -map 1:0 test.flv

Don't know if you still get issues with the remuxed duration?

[yetanotherlogin]

I found a work-around by extracting the video + audio streams using FLV Extract, but I still wonder why ffmpeg fails extracting the H264 stream, though.