[FFmpeg-cvslog] r22197 - trunk/libavformat/matroskaenc.c

[Reimar Döffinger]

On Thu, Mar 04, 2010 at 09:27:53PM +0000, M?ns Rullg?rd wrote:
> Reimar D?ffinger <Reimar.Doeffinger at gmx.de> writes:
> > On Thu, Mar 04, 2010 at 07:42:05PM +0000, M?ns Rullg?rd wrote:
> >> Reimar D?ffinger <Reimar.Doeffinger at gmx.de> writes:
> >> > So above code adds the assumption that seeking backwards will be either
> >> > reasonably fast or fail even in the url_is_streamed case, while the
> >> > documentation would not even give someone implementing a protocol any hint
> >> > about this - they might reasonably say "well, seek is so horribly slow
> >> > we absolutely need avoid it, so we set is_streamed, however we would still
> >> > be able to somehow play formats that absolutely require seeking, so we implement
> >> > it anyway". If they wanted it to work well with the matroska muxer too they
> >> > now would have to add a special hack...
> >> 
> >> The protocol seek function _is never called_ in this case.  No, the
> >> documentation of url_fseek() doesn't mention this.  Patches welcome.
> >
> > Either I'm blind again or you have no idea what you are talking about...
> > The seek function is called even for is_streamed if it is considered
> > necessary, and I consider than good and sensible behaviour, however
> > it somewhat clashes with this newly added code.
> > Now it's not such an important issue, but considering that at least one
> > of us is confused I conclude it wasn't such a bad idea to mention it anyway.
> 
> The low-level seek function is only called if the seek target is
> outside the buffer.  This is handled in generic code, and protocols
> need not worry.  Why don't you go and read the source yourself?

I've been talking only and exclusively about the case when the seek
is outside the buffer, and this new code assumes basically that url_fseek
will fail if the seek went outside the buffer and is_streamed is set.