[FFmpeg-devel] [RFC] use ff_avc_find_startcode in ff_find_start_code

[Reimar Döffinger]

Hello,
On Tue, Feb 19, 2008 at 03:20:07PM -0000, M?ns Rullg?rd wrote:
> Reimar D?ffinger wrote:
> > On Tue, Feb 19, 2008 at 03:06:37PM -0000, M?ns Rullg?rd wrote:
> >> Reimar D?ffinger wrote:
> >> > On Tue, Feb 19, 2008 at 03:28:27PM +0100, Reimar D?ffinger wrote:
> >> >> For decoding my THX_Science_FLT_1920.gxf, ff_find_start_code in
> >> >> mpeg_decode_frame
> >> >> is called 73754 times for 353 frames, the average amount of data skipped is
> >> >> 1272.626343 bytes.
> >> >
> >> > And uh... yes, this does indeed mean that 90% of the file's data is
> >> > trash...
> >> > Probably there is not much point in concentrating on this kind of thing,
> >> > but I'd expect these kind of long skips might be common for DVDs in
> >> > order to try to get a more constant bitrate as well...
> >>
> >> DVDs generally use the standard MPEG2-PS padding stream, so this should
> >> not be an issue there.
> >
> > I checked that btw., with DVDs there usually (more than 50% of cases) is
> > a 5 byte skip and then the start code.
> > But the Spaceballs DVD has an skip of 140 byte on average in the first
> > 10 minutes, going down to an average of 70 later on.
> 
> Where are these skips?

As said above, by ff_find_start_code in mpeg_decode_frame, i.e. at least
before every slice start.