[Ffmpeg-cvslog] CVS: ffmpeg/libavcodec mpegvideo.c, 1.503, 1.504 mpegvideo.h, 1.234, 1.235 h263.c, 1.298, 1.299

[Corey Hickey]

Michael Niedermayer wrote:
>>>Update of /cvsroot/ffmpeg/ffmpeg/libavcodec
>>>In directory mail:/var2/tmp/cvs-serv26933
>>>
>>>Modified Files:
>>>	mpegvideo.c mpegvideo.h h263.c 
>>>Log Message:
>>>fixing bframe strategy 2
>>>  bits vs. bytes factor of 8 error
>>>  16 byte offset error
>>>  some other minor things
>>
>>
>>This shows a large improvement over my previous vb_strategy=2 tests and
>>nets a significant (but a bit varied) improvement. First, my base command:
>>
>>for i in 1:turbo 2 ; do
>>  mencoder matrix.vob -aid 128 -oac copy -vf \
>>crop=718:356:0:60,scale=640:272 -sws 9 -ovc lavc -lavcopts \
>>vcodec=mpeg4:vbitrate=581:psnr:vpass=$i:mbd=2:mv0:trell:cbp:\
>>precmp=2:cmp=2:subcmp=2:predia=2:dia=2:preme=2:vme=5:v4mv:\
>>last_pred=2:vqcomp=0.6:qpel:sc_factor=6 -ofps 24000/1001 -o test.avi
>>done
> 
> 
> could you rerun the vmax_b_frames=2 vb_strategy=0 and 2 brd_scale=0 without
> turbo mode? the reason why that could be interresting is that the b frame
> decission is done only in first pass

Ok, here are some results without turbo. You can compare them to the
ones with turbo I sent previously.

----
vmax_b_frames=2:vb_strategy=0
  pass 1:
PSNR: Y:41.30, Cb:44.86, Cr:45.29, All:42.23
user    253m39.752s
  pass 2:
PSNR: Y:42.16, Cb:45.20, Cr:45.92, All:43.02
user    249m51.763s
frame counts: I:   3461  1%  P:  61895 31%  B: 130710 66%
average qps:  I: 2.619763    P: 2.876145    B: 5.117818

Removing turbo gives this +0.05 dB PSNR and, on average, a very very
slight visual quality improvement. Nothing looked significantly better
or significantly worse.


----
vmax_b_frames=2:vb_strategy=2:brd_scale=0
  pass 1:
PSNR: Y:41.44, Cb:44.89, Cr:45.36, All:42.35
user    643m10.931s
  pass 2:
PSNR: Y:42.23, Cb:45.21, Cr:45.94, All:43.08
user    244m30.827s
frame counts: I:   3450  1%  P:  71906 36%  B: 120710 61%
average qps:  I: 2.655072    P: 3.014825    B: 5.098998

This encode gets +0.04 dB PSNR. The visual quality improvement is slight
but substantial; aside from a few frames, this one looks consistantly
better. Of course, the first-pass encoding time is rather drastic. An
interesting thing to note is that this encode uses 5% more B-frames than
the one with turbo did. The number of I-frames is almost the same (6
frames more without turbo).


----
vmax_b_frames=3:vb_strategy=0
  pass 1:
PSNR: Y:41.17, Cb:44.85, Cr:45.27, All:42.12
user    200m11.908s
  pass 2:
PSNR: Y:42.07, Cb:45.20, Cr:45.93, All:42.96
user    198m23.891s
frame counts: I:   3449  1%  P:  45569 23%  B: 147048 74%
average qps:  I: 2.514642    P: 2.810090    B: 5.057750

This one gets +0.07 dB PSNR. It looks a lot better than the counterpart
encode without turbo, but not quite as good as
vmax_b_frames=2:vb_strategy=0:turbo.


----
vmax_b_frames=3:vb_strategy=2
  pass 1:
PSNR: Y:41.45, Cb:44.92, Cr:45.40, All:42.37
user    729m40.550s
  pass 2:
PSNR: Y:42.25, Cb:45.24, Cr:45.99, All:43.11
user    188m33.290s
frame counts: I:   3424  1%  P:  65680 33%  B: 126962 64%
average qps:  I: 2.607185    P: 3.043849    B: 5.030922

This one takes the crown PSNR-wise, with a +0.07 dB increase over using
turbo. Compared to vmax_b_frames=2:vb_strategy=2:brd_scale=0 (without
turbo), though, it doesn't really look better. Some parts looked a bit
better and some looked worse, but, on average they both looked about the
same.


-Corey