[MPlayer-dev-eng] [PATCH] mencoder, B-frames, and video/audio delay

[Loren Merritt]

On Sun, 22 Jan 2006, Corey Hickey wrote:

> But first, let me digress to x264. My tentative understanding of the way
> x264 handles decoding delay is to put it into a header*. Loren pointed
> me to x264/encoder/set.c:187
>
> sps->vui.i_num_reorder_frames = param->b_bframe_pyramid ? 2 :
> param->i_bframe ? 1 : 0;
>
> So, it looks like I don't have to worry about the decoder delay for
> x264. Like I said, though, that's only a tentative understanding on my
> part. This is the first time I've ever looked at x264 source.
>
> Anyway, does MPEG-4 have any kind of similar facility for putting
> anticipated decoding delay into a header? If not, then adjusting the
> muxer stream timer seems like the only reasonable recourse.

It's always eithyer 0 or 1, specified by s->low_delay

> * I can see that it's an SPS, but despite lots of googling I can't find
> what an SPS is. Can someone give me a quick definition?

SPS is "the header containing stream-global settings".
As opposed to PPS, which is "the other header containing more 
stream-global settings" :)

The difference is supposed to be that SPS contains info about the decoded 
stream (resolution, colorspace, interlacing, delay, etc), whereas PPS 
contains info that only the codec needs to know (quant matrices, cabac, 
weighted prediction, etc). But the segregation isn't perfect.

--Loren Merritt