B-Frame Question

[TheDarkInfluenc]

I have done many many many rips and I've noticed that the divx 5.0.2pro disabling the nonpro feeatures works best for me. I say that 5.0.2 pro is more accurate then 5.0.2 in finnal file size.

I am just wondering this... Does B-Frames degrade the quality of the movie even though that its making it smaller and alot more? The rips that i do when comparing are both the same exact settings and size. The only diffrence is me enabling and disabling the pro features including B-Frames. This being said you can see a good 40-50 less mb diffrence when you have B-Frames enabled.

Is it me or do B-Frames degrade the quality a little?

[khp]

Using B-Frames wil both increase and decrease the image quality.

By default Divx5 will double the qualtizers used for the B-frames. Which means that the B-frames will be encoded at a lower quality, this frees up alot of bits which is then used for the I- and P frames.

I suspect that the encoding you are doing without B-frames, is very high quality or you are using quality based encoding. In such cases B-frames can cause degraded quality because the quantizers are doubled for the B-frames, but the codec can't use the space savings in the I- and P frames, because they are already at maximum quality. Or in the case of quality based encodeing the quantizers are fixed.

In bitrate controlled mode (preforably 2-pass) the codec will always try to reach the desired bitrate, while respecting your settings. With B-frames enabled the maximum useable bitrate for any given clip is lower, than when encoding without B-frames.

[TheDarkInfluenc]

I have just 2 more questions that I need answers to then I'll stop being a pest.

1. Are there any added features to the Pro codec over the Nonpro codec cause when i did a few rips with both codecs, the Pro codec (having the Pro features disabled) would always hit the finnal size more accuratly then the nonpro codec?

2. How does the Pro codec with pro disabled compare to the quality of divx 4.12? When I do rips with both I can't tell a visual diffrence and I'm not that critical in this. I want someone who is critical that can see a diffrence.

Thanks now I'll go into my views about the diffrences of the codecs this way if someone asks I'll just link it here.

Personaly my taste does not go with divx 3 and thats why I stay with divx5pro. Yes divx 3 has more detail then divx 4/5 but, it also has more blocks unless you uncompress the video even more over average. I do like the fact that divx3 can achieve the quality of the mpeg2 of the dvd disc closer then divx 4/5 when we set the bitrate to 9999. Divx3 was the only codec to come closer to the dvd quality having 6 cds in total for gladiator (just video) vs 5 cds from divx4/5. I can visually see a diffrence between 3 vs 4/5 in that case. Even though you are setting 9999 bitrate for the codec there still is a small percentage of compression so you'll never be able to get full uncompressed video with these codecs that's why Svcd can come alot closer to the dvd quality then divx or xvid when we allow it to use unlimited space in the Hd to create the video. If we are going for average rips like 1 or 2 cd then my personal taste goes with divx 5.0.2Pro (disabling Pro) over all even xvid. I'm now learning more about Ogg over Mp3 which will allow more room for video by maintaining lower bitrate yet still having the same quality as the higher bitrate in Mp3. I think that is a far more superior diffrence then comparing the diffrences of codecs themself. Comparing codecs to me is really nonsences cause I'm mainly looking for a codec that can accuratly hit the final file size I set and still maintain great quality. If you want better quality then a 1 cd then make it 2 cd etc etc. I'm not for arguing about codecs but, I see it pointless since all you need to do is just add 1 more cd to gain more bitrate and allow better audio quality. I don't see a problem with holding 3 disc movie and thats me.

[UncasMS]

How does the Pro codec with pro disabled compare to the quality of divx 4.12?

i never deactivated the pro-features (b-frames + gmc)
the difference i see comparing divx5 with 4 is this:

- divx4 is not that sharp

- the final output file size with divx4 was sometimes bigger than i wanted it to be => overall predictability of the file size in divx5 is fine, in 4 it wasnt so

[TheDarkInfluenc]

Do a test of disabling the pro features (if you get free time) and tell me if you see a diffrence between the pro and non pro which basicly involves the B-Frames. Thanks

[khp]

Originally posted by TheDarkInfluenc

1. Are there any added features to the Pro codec over the Nonpro codec cause when i did a few rips with both codecs, the Pro codec (having the Pro features disabled) would always hit the finnal size more accuratly then the nonpro codec?

No. With the pro feratures disabled, the pro version will preform identically to the standard version. I have tested this on several occasions, there are no hidden extra features in the pro version.

[TheDarkInfluenc]

Why was it that when I did a few rips with the nonpro codec that it didn't meet the finnal size that I set vs the pro codec with the pro disabled? Keep in mind that every setting that I had for both codecs for the video/audio were both identical.

[khp]

Originally posted by TheDarkInfluenc
Why was it that when I did a few rips with the nonpro codec that it didn't meet the finnal size that I set vs the pro codec with the pro disabled? Keep in mind that every setting that I had for both codecs for the video/audio were both identical.

Are you absolutly sure ?.
Try testing with GKnot, it's the only tool I would trust for such a comparison.

[TheDarkInfluenc]

That is what I'm currently using and what I have used when I did all my tests. And yes I am absolutly sure.