I've documented (hopefully) the VP62 quality fluctuations that Tommy was speaking about in Sagittaire's [New Test] XviD vs Other Codec ... ;-)
I'd like to add that i made this test after noting some strange things in my own (not very) scientific search for a good codec.
Details below:
The source was the first (DVD)chapter of Gladiator scaled to 672x288 @23.976fps
For XviD 1.0.1 the following settings were used;
Defaults + vhq4+ turbo + qpel + gmc + trellis + MPEG mtrx + 2pass 1100Kbit/s
Decoding done with xvid (PP: Y+UV deblocking)
For VP6.2 the following settings were used;
Default VP62HSP + 7 sharpness + 2pass best quality @1100Kbit/s
Decoding done with PP4
Results:
Reference;XviD;VP62;
Samples;
XviD
VP62
According to above my personal choice at this bitrate would be XviD as i prefer (real) sharpness and some minor blocking over non-predictable lack of details and fuzziness.
But that's MHO
Regards
Per
Perhaps the problem comes from the Rate Control: Perhaps VP6 takes less bit for this part ... The RC for the VP6 and XviD is not identical and XviD could be better on short part -gt; ScreenShoot doesn't prove anythingPost small sample ... please
- We can see the local differences for each codec
- We can see the size for each sample and see the influance of RC
- We can see info (quant, size, bitrate, frame type ...) with XviD and ffdshow
They cause sudden sharpening in the video, which can be quite bothering.
Hopefully you meant sudden softening or did a misunderstand you ?
Small samples on their way
Regards
Per
XviD and VP62 samples
XviD
VP62
Regards,
Per
These spikes are not scene-changes, but frames with increased quality in pans and slow scenes. They cause sudden sharpening in the video, which can be quite bothering. And this is not a bug, the developers said it's all intentional to bring back the details.
Exactly the same observation for Bframe and XviD in IPBBP sequence with bframe 2/1.50/1.00 ... Pframe are very better than Bframe
Code: Mean Max Max Absolute Mean Pos. Neg. Frame Dev. Dev. Dev. Dev. PSNR (dB)
-----------------------------------------------------
35107 0.6955 +0.0025 12 -13 46.5627 P35108 0.7718 +0.0027 19 -20 45.1428 B35109 0.7694 +0.0169 15 -22 45.4611 B35110 0.6718 +0.0405 12 -14 46.7728 P35111 0.7319 +0.0031 18 -26 45.5608 B35112 0.7689 +0.0063 18 -28 45.4177 B35113 0.6403 +0.0366 12 -18 47.0537 P35114 0.6855 +0.0356 27 -21 45.9458 B35115 0.6176 -0.0219 25 -27 46.4438 B35116 0.6124 +0.0582 13 -15 47.2732 P35117 0.6488 +0.0015 20 -20 46.7304 B35118 0.6274 +0.0350 22 -21 46.7175 B35119 0.5874 +0.0436 15 -15 47.7563 PSamples;
XviD
VP62
According to above my personal choice at this bitrate would be XviD as i prefer (real) sharpness and some minor blocking over non-predictable lack of details and fuzziness.
I am convinced... it's true for detail/sharpness
But it's a very high compressibility level (q2 and q3 for I,P compressibility gt; 75%) and all codec are very good for this compressibility ... if you want sharp DivX3 or RV10 could be better with compressibility gt; 75%
- High Compressibility 75%: Really difficult to compare and it's really subjective: RV10, VP6, XviD, WMV9 then DivX3
If your favorite codec for high compressibility is XviD ... why not ... it's a good choice and all the choise are good ... IMHO my fovorite is RV10.
i must say that i both dont find them *really* good encodes...
i favor XviD a little bit though because with VP6 the guys beard and the area between the eyes constantly keeps 'moving'. its very annoying to watch, its like crazy ants or something .
BTW - PSNR metrics dont mean anything when it comes to perceptual quality. here's a nice review on objective and subjective quality measurements.
For me SSIM is better than Overall PSNR and very better than Average PSNR.
SSIM is an objective video quality metric ...
SSIM is the metric which approaches the most my visual impressions
my quot;SSIM testquot;and my quot;blind testquot;
- Low Compressibility 25%: VP6, RV10 or WMV9 are very better than XviD or DivX3.
- Medium Compressibility 50%: VP6 and RV10, then WMV9 and XviD but differences are small except for DivX3 ...
- Medium Compressibility 75%: Really difficult to compare and it's really subjective: RV10, VP6, XviD, WMV9 then DivX3
- High Compressibility 100%: Too much difficult to compare ...
-gt; make test with low and medium compressibility (1CD encoding) ... for high and very high compressibility it's really subjective
last about this, before we go off-topic:
SSIM is still an image based comparison. Video is a series of images and therefor should not be judged with such a metric. In that link you gave it is explicitely used on JPEG compression, not on video.
SSIM is still an image based comparison. Video is a series of images and therefor should not be judged with such a metric. In that link you gave it is explicitely used on JPEG compression, not on video.
~zwang/files/papers/vssim.pdf
from the article (conclusions)
In order to improve the proposed algorithm, many other issues also need further investigations in the future. One important issue is related to motion. The current SSIM index is oriented for comparison of still image structures. Notice that there are several significant outliers in the scatter plots of the proposed algorithms (in the lower-left parts of Figs. 5(c) and 5(d), where the models give much lower scores than they should supply). In fact, most of these significant outliers corresponds to the video sequences with large global motions (such as src5, src9 and src19 in the VQEG Phase I test dataset).
thx for making my point
SSIM isn't a perfect test ... but very better than PSNR for exemple.
If for first video sequence SSIM = 65 and for second video sequence SSIM = 70 then second sequence is always very better than first sequence
If for first video sequence SSIM = 80.5 and for second video sequence SSIM = 79.5 then a conclusion is difficultPSNR isn't a perfet test ... but it's a very good test for codec improuvements and Rate Contol observation ...
for exemple: HP II 640*272 ~3000 frames
VHQ4, Ultra High, GMC, Qpel, AQ, Trelli, q2 for I,P et B
Bframe 0/1.00/0.00 et sensivity=0: 33 374 Ko
Bframe 1/1.00/0.00 et sensivity=0: 33 180 Ko
Bframe 2/1.00/0.00 et sensivity=0: 33 264 Ko
Bframe 3/1.00/0.00 et sensivity=0: 33 260 Ko
Bframe 1/1.00/0.00 et sensivity=100: 33 322 Ko
but 2 pass with Bframe 2/1.50/1.00 is very better for PSNR than 2 pass with Bframe 2/1.00/0.00 -gt; visual quality for 2/1.50/1.00 is better than 2/1.00/0.00Between 25% and 50% compressibility XviD is really worse than VP6/RV10/WMV9. VP6/RV10/WMV9 could be very better for quot;low compressibility sourcequot; (~150 min 1CD or very high motion movie 1CD)
Between 50% and 100% for compressibility all codec are good and for very high compressibility DivX3 is a good choise. It's useless to want to compare the codec in these compressibility zones: it's too subjective (~100 min 1CD or medium motion movie 1CD)
Originally posted by stephanV
i must say that i both dont find them *really* good encodes...
i favor XviD a little bit though because with VP6 the guys beard and the area between the eyes constantly keeps 'moving'. its very annoying to watch, its like crazy ants or something .
BTW - PSNR metrics dont mean anything when it comes to perceptual quality. here's a nice review on objective and subjective quality measurements.
Maybe some small amount of pre-filtering could have helped a bit
I agree on the quot;crazy antsquot; - the (VP62)picture seems to be in constant motion most of the time - very annoying...
A note regarding PSNR, SSIM etc. - the input of an human eye is really hard to measure but Feng Xiao's Video Quality Metric (VQM) looks interesting though
To conclude download these sample
VP6 25%
RV10 25%
WMV9 25%
XviD 25%
DivX3 25%
VP6 50%
RV10 50%
WMV9 50%
XviD 50%
DivX3 50%Not need to make test SSIM, stop image or zoom screenshoot ...
Both encodes look very good when outputted to an 32quot; widescreen TV using RGB.
It would have been better if you had encoded something a little brighter and faster but they're OK.
Something is not quite right with the bottom matte though. It's showing a couple of 'rolled' pixel lines. You can't see it so much on an PC monitor but you can on an TV.Cheers
I must say that using postprocessing in the test is not very clever because even there are no artifacts or blocking PP turned on will blur the image. I suggest turning it OFF for comparison.
VP6 25%
RV10 25%
WMV9 25%
XviD 25%
DivX3 25%
I must say that using postprocessing in the test is not very clever because even there are no artifacts or blocking PP turned on will blur the image. I suggest turning it OFF for comparison.
there are no artifacts with XviD PP4 or DivX3 PP4 ... ???
I suggest turning it OFF for comparison. ... ???
Finally the problem must come from my eyes ... lol.
Originally posted by Mario Bros
I must say that using postprocessing in the test is not very clever because even there are no artifacts or blocking PP turned on will blur the image. I suggest turning it OFF for comparison.
I simply used the settings most pleasing for my eyes while watching
Regards
pernas could you post the source plz?
VP6 can do quite well in some situations, I hope the developers haven't stopped tuning/updating it because it has really good potential. VP6 can beat XviD with PP off in some situations and with PP on it has a really big advantage, personally I think VP6 has one of the best PP engines cause it doesn't make the image blurry and pastey, and yes I think it's better than RV's. You can see in this thread showthread.php?s=amp;threadid=77014 and where VP6 beats H.264 and XviD, also take a look at dfein/inbox and yes I did everything proper. VP6 can be sharper as well where as XviD has to use a custom matrix that increases filesize, VP6's sharpness settings do not increase filesize. XviD does beat VP6 however with 2-pass rate control and it's many features which VP6 does not have, these file saving/picture saving methods allow for the bitrate to be used more efficiently and allows more for more bits to be saved and thus more headroom if needed. |
Post at 2011-4-15 16:07
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