[MPlayer-users] MAX_PACK_BYTES default increase?

Reimar Döffinger Reimar.Doeffinger at stud.uni-karlsruhe.de
Sat Dec 20 15:30:45 CET 2008


On Sat, Dec 20, 2008 at 05:59:33AM -0800, Grant wrote:
> >> When playing back 1080p video on my Linux system, I get numerous "too
> >> many video packets in the buffer" console messages and the the a/v
> >> can't maintain sync.  This happens with both software decoding and
> >> Nvidia VDPAU.  The following patch fixes it.  Can this be changed by
> >> default?
> >
> > The current value is already 8 MB, buffering 134 MB like your change
> > does is insane.
> > Also why do you think this causes A-V desync? The only reason why
> > 8 MB buffer (which btw. even for 50 MBit/s video is enough for more
> > than one second) is not enough is when you already have A-V desync,
> > so in all cases (except broken files) the underlying issue of
> > _both_ desync an "too many video packets in the buffer"
> > is a too slow PC.
> 
> I've shared this patch with many people on forums who have reported a
> large performance increase with HD video.  If increasing the buffer
> increases performance, shouldn't it be increased?

Do you have proof that it indeed increases performance or avoids
A-V desync (note not cases where people just don't notice the desync,
but only cases where A-V and c-t stays below 0.2).

> If I can find a
> lower buffer amount that does away with "too many video packets" and
> sync issues, would it be considered as a new default if it is
> sufficiently low?

Not without an explanation what exactly it fixes and _why_.
Increasing the buffer size or even making it configurable is probably a
good idea for other reasons, but if it has effects on performance (which
are not just because some frames were dropped and thus error correction
causes the slowdown without the change) this is unexpected and needs to
be explained, and there almost certainly is a way to get this
performance improvement without changing the buffer size.

Greetings,
Reimar Döffinger



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