[FFmpeg-devel] [PATCH/RFC] set qscale_type for MPEG-4

[Reimar Döffinger]

On Wed, Feb 03, 2010 at 01:16:02AM +0100, Michael Niedermayer wrote:
> On Tue, Feb 02, 2010 at 11:54:26PM +0100, Reimar D?ffinger wrote:
> > Hello,
> > I have no idea if this actually makes sense, but MPlayer's -vf fspp seems to
> > look a lot better with it for me - no idea if MPEG-4 qscale is more similar
> > to MPEG-2 or MPEG-1.
> 
> mpeg4 has 2 quantizer types, one matches h263 one mpeg2 with a factor of 2
> difference in qscale

So in neither case the patch I made makes any sense?
Or is the H.263 one somewhat close to MPEG-2?

> mpeg1 and 2 depend on the used quant matrixes as well, thus make tripple sure
> your test files use the default matrixes and mpeg4 uses h263 style

The MPEG-4 used H.263 style, quantizer 15. And with fspp and spp the
picture looked far worse than without while with the patch it gave
a decent improvement (particularly any areas of large, identical colour).

> Also the reference is spp not fspp

I generally tried both and did not notice any significant difference.
I probably should go and find some low-quality MPEG-1 and MPEG-2 to
make sure that it's not "intentional" that fspp 

> i hope the recent addition to the qscale types is based on more than this
> patch

That is based on testing with YouTube and other Flash videos and using
one that does not generally butcher the picture even worse than the original.
But I admit it was not based on actually having a clue beyond that.