[FFmpeg-devel] [PATCH/RFC] set qscale_type for MPEG-4
Wed Feb 3 19:12:46 CET 2010
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
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.
More information about the ffmpeg-devel