[XviD-devel] VHQ

[Christoph Lampert]

Hi,

I did one more test, now with xvid_bstat, so PSNR is available: 
QCIF "Miss America" (very easy), maxb=2, bquant_ratio=2.00

without BITS, fixed quant 4 
Q0  size 291 enc: 87.4 fps, dec: 371.1 fps PSNR P: 40.70  B: 40.86
Q1  size 239 enc: 72.6 fps, dec: 336.7 fps PSNR P: 41.93  B: 41.23
Q2  size 239 enc: 70.0 fps, dec: 320.9 fps PSNR P: 41.93  B: 41.23
Q3  size 234 enc: 66.1 fps, dec: 312.1 fps PSNR P: 41.94  B: 41.24
Q4  size 234 enc: 62.7 fps, dec: 341.2 fps PSNR P: 41.93  B: 41.24
Q5  size 206 enc: 40.5 fps, dec: 204.7 fps PSNR P: 41.89  B: 41.52
Q6  size 206 enc: 35.5 fps, dec: 190.4 fps PSNR P: 41.87  B: 41.50

with BITS , fixed quant 4 
Q0  size 290 enc: 82.3 fps, dec: 389.6 fps PSNR P: 40.69  B: 40.84 
Q1  size 230 enc: 71.1 fps, dec: 392.3 fps PSNR P: 41.79  B: 41.15 
Q2  size 230 enc: 70.4 fps, dec: 394.1 fps PSNR P: 41.79  B: 41.15 
Q3  size 220 enc: 60.6 fps, dec: 388.4 fps PSNR P: 41.74  B: 41.09 
Q4  size 221 enc: 54.3 fps, dec: 389.9 fps PSNR P: 41.73  B: 41.08 
Q5  size 196 enc: 31.1 fps, dec: 205.6 fps PSNR P: 41.66  B: 41.33 
Q6  size 196 enc: 29.3 fps, dec: 208.0 fps PSNR P: 41.68  B: 41.34 


>From this you can see that PSNR _drops_ for BITS, but size drops, too,

without BITS, bitrate 128 (effective only 40-49)
Q0 size  248 enc: 88.5 fps, dec: 393.4 fps PSNR P: 39.84 B: 40.17 
Q1 size  235 enc: 86.5 fps, dec: 392.1 fps PSNR P: 41.81 B: 41.13 
Q2 size  235 enc: 86.4 fps, dec: 394.2 fps PSNR P: 41.81 B: 41.13 
Q3 size  235 enc: 84.0 fps, dec: 393.6 fps PSNR P: 41.89 B: 41.21 
Q4 size  236 enc: 74.7 fps, dec: 392.0 fps PSNR P: 41.96 B: 41.24 
Q5 size  232 enc: 40.7 fps, dec: 207.7 fps PSNR P: 42.20 B: 41.80 
Q6 size  232 enc: 37.9 fps, dec: 208.2 fps PSNR P: 42.20 B: 41.79 

with BITS, bitrate 128 (effective only 40-49) 
Q0 size  248 enc: 82.4 fps, dec: 392.2 fps PSNR P: 39.84  B: 40.16  
Q1 size  237 enc: 69.9 fps, dec: 390.1 fps PSNR P: 41.85  B: 41.22  
Q2 size  237 enc: 69.9 fps, dec: 390.4 fps PSNR P: 41.85  B: 41.22  
Q3 size  237 enc: 59.7 fps, dec: 386.9 fps PSNR P: 41.98  B: 41.28  
Q4 size  236 enc: 53.8 fps, dec: 385.0 fps PSNR P: 41.98  B: 41.27  
Q5 size  235 enc: 30.3 fps, dec: 200.0 fps PSNR P: 42.28  B: 41.88  
Q6 size  234 enc: 28.6 fps, dec: 201.4 fps PSNR P: 42.24  B: 41.84  


Like in my other tests, BITS led to _better overall PSNR_, but 
its not 100% sure, because filesize also is about 1% higher as well. 
At home I'll test with more "intelligent" clips...


Still, it should be possible to create a BITS variant where fixed quant 
PSNR does not drop, but bitrate is nevertheless reduced... 

gruel