[FFmpeg-user] Most efficient format/container for seeking

[Maxim E]

That answer was all I was looking for, gonna test it asap !

Thanks :)


2013/9/1 Robert Krüger <krueger at lesspain.de>

> On Sun, Sep 1, 2013 at 3:38 PM, Maxim E <maxoumdu35 at gmail.com> wrote:
> > Hi,
> >
> > This question will probably be best answered by developpers themselves,
> I'm
> > looking for the most efficient container for seeking.
> >
> > My problem :
> > I'm downloading a video file that eventually gets very large, and seeking
> > can take a lot of time. I guess the whole file is processed until the
> right
> > frame is found. Is there any container with which the seeking process is
> > more "optimized" ?
> > For instance, instead of processing the whole file, the total duration of
> > the video is calculated somehow, and the file size is used to look at
> some
> > position (if the framerate is constant).
> >
> > An example to make myself clear :
> > I've got a 20 Gb file, in a FLV container. No problem to get the total
> > duration, ffmpeg -i file.flv returns it in just a few seconds (Duration:
> > 55:07:28.35).
> > No problem when I seek to the beginning of the file, for example "ffmpeg
> > -ss 00:02:00.00 -i file.flv -t 10 -c:a copy -c:v copy out.flv" gets
> > executed in a few seconds. However, "ffmpeg -ss 10:02:00.00 -i file.flv
> -t
> > 10 -c:a copy -c:v copy out.flv" takes at least one minute, which makes me
> > think ffmpeg process the file from the beginning until it finds the
> > matching frame.
> > Let's consider the framerate is constant
> > 20 000 Mo x 10 Hours / 55 Hours should return the approximate position at
> > which the frame that is sought is, and starting from there instead of
> > starting from the beginning of the file would make things much more
> > efficient. Is there such a container that supports this type of seeking ?
> > Or is it impossible ? I don't have much experience with development/media
> > files so maybe things are not as easy as I think, but please let me know
> !
>
> mp4 and mov both support what you are looking for. They contain
> metadata where each frame and packet of sound samples is located in
> the file. You can additionally force that metadata at the beginning of
> the file by using the option -movflags faststart, if you have
> situations where you want to seek based on only a partially downloaded
> file, which is what many players support.
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