[FFmpeg-user] How can I join video files?

Andrey Utkin andrey.krieger.utkin at gmail.com
Sat Feb 18 20:34:22 CET 2012

2012/2/17 Peter B. <pb at das-werkstatt.com>:
> 2) I agree with you that concat+remux+transcode in one step might be
> "sugarization", compared to subsequent FFmpeg calls, when you only have to
> transcode a handful of files - but with mass transcoding (several hundred
> files per day) of "heavy" stuff (like e.g. FFv1 with 350-600 MB/Minute),
> intermediate steps add up runtime-wise.
> For example:
> At the Austrian Mediathek (=national audio/video archive), we're producing
> several hundred FFv1 encoded minute-sequences per day as archive format.
> Now, transcoding this archive material into e.g. DVD-MPEG or web-videos,
> they need to be concatenated *and* transcoded.
> Intermediately "touching" the harddisk would add a tremendous slowdown of
> this already slow transcoding process (FFv1->MPEG on 3.6Ghz CPU: ~20-25fps).
> I know it's a super-rare-extremely-special-and-not-so-everyday usecase, but
> currently I need to use mencoder for this - but would looooove to use FFmpeg
> (because I think it's better supported).

Merging video in one pass, when full transcoding is acceptable, is
possible using API (i mean requires specific application ATM).
I guess this task can raise timing (and a/v sync) issues when
transcoding variable-framerate files, like FLV.
Well, it is often easy to implement app that works on exact type of
files, and hard to think up how all-purposed app should work. (E.g. i
have made an app that merges certain FLV h264 videos just by remuxing,
a lot later i've realized that it's not guaranteed to work).

But video merging is feature of high demand, i agree ffmpeg should
have such tool.
But i think it's easier to make it separate utility. I just wonder how
can we denote our intention to merge video, how should ffmpeg command
line look like?
If you provide samples of your files, you have a chance to get
supported with such tool from early days, if volunteers appear to put
efforts on it.

Andrey Utkin

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