[FFmpeg-devel] Format for fast extraction (was: [PATCH] Dynamic plugins loading)

Tomas Härdin tomas.hardin
Tue Nov 2 08:06:26 CET 2010

On Mon, 2010-11-01 at 21:37 +0100, Nicolas George wrote:
> Le primidi 11 brumaire, an CCXIX, Michael Niedermayer a ?crit :
> > > (On the other hand, if anyone knows a supported format that allows efficient
> > > extraction of two 1-hour shows from a 3-hours recording with commercials, I
> > > would like to hear about it.)
> > 
> > where is the problem with existing formats? mpeg4/h264/mp3/aac in nut?
> They require a lot of disc-to-disc copy. With the example I chose, the
> original file will be about 6 giga-octets and requires two copies of
> 2 giga-octets each.
> The format I have designed splits the video into fragments of about 1 minute
> each, which makes them about 30 or 40 mega-octets, plus a global index.
> Extracting a segments uses mostly hardlinks, only the index and the
> fragments at the cut points are rebuilt. The whole thing is done in less
> than one second. As a bonus, it works even if the disk space is tight.

Just use mov. It supports this via edit lists and drefs. The lavf
demuxer doesn't support edit lists yet though - patch welcome for that I

You still need to split the stream up into separate files, but something
like what Michael suggested probably works. Otherwise you could add an
option to ffmpeg so it starts new files every X seconds, like -fragment
60 output%d.mov or something like that.

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