Redoing the soundtrack in a flv file

[LETMO]

I have a promotional video in flv format. The soundtrack is currently in English, but I want to have versions in other languages. Does anyone know how I can strip out the present soundtrack & add in a new one?

Thanks in advance.

[poisondeathray]

It depends on the type of video & audio in the flv container. If you don't know, you can use mediainfo

Avidemux will work for many types; other tools that may assist with this are flvextract, and ffmpeg (command line tool). ffmpeg will work for 99% of the usual types of flv

[LETMO]

Thanks for the speedy reply, I analysed the file using MediaInfo. It gave the following output:

Format : Flash Video
File size : 6.23 MiB
Duration : 3mn 20s
Overall bit rate : 259 Kbps
totalduration : 201.968
totaldatarate : 259.186
bytelength : 6543679.000
canseekontime : Yes
sourcedata : B4A7DD1C7

Video
Format : H.263
Duration : 3mn 22s
Bit rate : 187 Kbps
Width : 320 pixels
Height : 180 pixels
Display aspect ratio : 16/9
Frame rate : 24.613 fps
Bits/(Pixel*Frame) : 0.132

Audio
Format : MPEG Audio
Format version : Version 2
Format profile : Layer 3
Duration : 3mn 22s
Bit rate mode : Constant
Bit rate : 64.0 Kbps
Channel(s) : 1 channel
Sampling rate : 22.05 KHz
Resolution : 16 bits
Writing library : LAME3.97 (beta)

[poisondeathray]

You might have difficulties, because the video might be VFR (variable frame rate). The odd frame rate suggests this might be the case.

If you use flvextract, it will generate a timecodes txt file, which you can examine. If the intervals vary, you have a VFR video. Basically it speeds up and slows down at different intervals, and it will be difficult to get back into sync as a .flv file (you could do it with .mkv or .mp4 easier, because you just mux it back into the container with the same timecodes file)

You can try avidemux, it will only be in sync if the video is CFR (constant frame rate)

video=>set to copy
audio=>set to copy
format=>set to flv

audio (top menu)=>main track=>audio source=>external MP3 (point to the audio file you want to "swap")

press save with extension (e.g. "mynewvideo.flv")