[FFmpeg-devel] [PATCH] qt-faststart: Add mode for probing faststart-ness

[Baptiste Coudurier]

Hey Tomas,

On Sat, Jul 28, 2018 at 1:56 AM, Tomas Härdin <tjoppen at acc.umu.se> wrote:

> lör 2018-07-28 klockan 10:31 +0530 skrev Gyan Doshi:
> >
> > On 28-07-2018 03:33 AM, Tomas Härdin wrote:
> > >
> > > woot! I didn't know the mov demuxer dumped such things. It is quite
> > > slow however, since it will scan through every leaf atom in the
> > > file.
> > > For example, running time ffmpeg -i input.mov -v 56 2>&1 | wc on a
> > > 1.5
> > > GiB MP4 on an SSD takes:
> >
> > Use the subfile protocol to forgo parsing the whole file, e.g.
> >
> >      ffmpeg -i subfile,,start,0,end,10000,,:in.mp4 -v 56 2>&1 | grep
> > -e
> > "type:'moov'" -e "type:'mdat'" | head -1 | grep moov
> >
> > This assumes that at least one of the two targeted boxes moov/mdat
> > start
> > within the first 10000 bytes.
>
> Neat. This is similar to the first suggestion I had to the peertube
> devs, dd:ing off the first MiB or so then probing that. We'll see what
> they say, and what Baptiste thinks I guess


Interesting, I can see the interest of checking this. Could ffprobe do that
somehow ?
Would be an interesting information to report.
Not sure it belongs in qt-faststart, and not sure checking fragmented files
would be in
the scope of qt-faststart. What do you think ?

-- 
Baptiste Coudurier