Does encoding speed matter after certain level of kbps???

[Superturtle]

If I encode a movie that's 138 minutes at a bitrate of 2700kbps will the quality come out any better if I encode at slowest-slowest two past vs standard-standard 2 pass. Does the speed become a non-issue once a video is encoded past a certain quality of bitrate? Do you think the difference in quality would be neglegible and therefore not worth the 17hr encode of slowest-slowest?

[cordraconis]

Originally posted by Superturtle
If I encode a movie that's 138 minutes at a bitrate of 2700kbps will the quality come out any better if I encode at slowest-slowest two past vs standard-standard 2 pass. Does the speed become a non-issue once a video is encoded past a certain quality of bitrate? Do you think the difference in quality would be neglegible and therefore not worth the 17hr encode of slowest-slowest?
Well, I think you are correct, but I don't know the numbers. Maybe somebody else can help you on that.

However ... 2700kbps is very close to a one-pass Q2 encode.
You might want to encode it in one-pass quality based for the best speed with the same quality I think. :)

[Tuning]

Originally posted by Superturtle
Does the speed become a non-issue once a video is encoded past a certain quality of bitrate?

For determining whether you are overkilling the encoded movie, you should do a compressibility test.(Gknot).If the compressibility test return value around 60-75%(Read guides for more...), then you can conclude that the current bitrate is enough for your encode. Other wise is it is above 75% then you are wasting your bitrate because the quality of encode is not going to become better(The codec is at it maximum attainable level). i.e here you are over killing the encode with high btrate.
Guide here (http://www.doom9.org/gknot-divx5.htm)

[Superturtle]

So I take that doing a one-pass quality based encode is a waste of time since it will most certainly be overkill? I've read in other threads where people have wanted the nearest dvd quality they can get...say perhaps reducing the dvd to half the size so they can put two divx movies on one dvd-r...and they speak about using kbps levels of 3000+.

[Tuning]

Originally posted by Superturtle
So I take that doing a one-pass quality based encode is a waste of time since it will most certainly be overkill? I've read in other threads where people have wanted the nearest dvd quality they can get...say perhaps reducing the dvd to half the size so they can put two divx movies on one dvd-r...and they speak about using kbps levels of 3000+.
One-Pass quality based mode has no consideration towards bitrate. it uses the possible bitarte that give the quality you entered. It is actually meant for people who don't bother the final output size. If you are of one of them, then use it and you can save time.(As there is no 2-pass).
If you want to go for perfect calculated manner, then go for two pass method or CBR mode.
In these cases, the maximum possible bitrate needed for optimum quality backup can only found out by a compressibility test. So follow the guide and apply a compressibility test.

Bye

[Superturtle]

Ok...so basically a one pass quality encode will have the same quality as a two pass encode taking into consideration the compression test and settings thereafter. So in reality all that is gained is time in encoding?

[Tuning]

I'm not sure, but experts in forum says that if you have equal output size then both 1-pass and 2-pass will be same quality.

So in reality all that is gained is time in encoding?
That is obvious.
Happy encoding!:)

[Superturtle]

Thanks for the good advice Tuning!!

[SeeMoreDigital]

Originally posted by Superturtle
If I encode a movie that's 138 minutes at a bitrate of 2700kbps will the quality come out any better if I encode at slowest-slowest two past vs standard-standard 2 pass. Does the speed become a non-issue once a video is encoded past a certain quality of bitrate? Do you think the difference in quality would be negligible and therefore not worth the 17hr encode of slowest-slowest? I have not generated any full movie tests at this bitrate for quite a while and certainly not using DivX 5.1.1.

However, from what I remember when I did generate some 136min 2pass VBR encodes using DivX 5.0.2 at it's slowest setting (which is equal to the standard setting of DivX 5.1.1) you could not tell that you were not watching the original DVD!

Given that DivX 5.1.1 is supposed to be superior to DivX 5.0.2, I would suggest that when using the standard setting, your encodes will look spot on. And therefor, the slow or slowest settings would be pointless.

At the end of the day, everybody sees an encoded copy differently. Just keep in mind that it's far too easy to criticise and pull an encode to pieces when you're sitting a few centimetres from your PC monitor. Hell you can even see errors in the original when you do that!

Cheers

[Soulhunter]

@Superturtle
Source:

The Matrix - Lobby Shootout / 3:07 min. @ 25fps / 720x400 pix. (Lancoz)


How much is the compression gain with B-Frames and how much do they reduce quality ???

Results:

QB @ Quantizer 2 / Standard / BiDi / No PVE
File size: 62.810.112 Bytes / Avg. PSNR: 46.90

QB @ Quantizer 2 / Standard / No BiDi / No PVE
File size: 75.253.760 Bytes / Avg. PSNR: 47.22

QB @ Quantizer 2 / Slowest / BiDi / No PVE
File size: 67.260.416 Bytes / Avg. PSNR: 47.05

QB @ Quantizer 2 / Slowest / No BiDi / No PVE
File size: 79.749.120 Bytes / Avg. PSNR: 47.34


How do the different speed settings affect multipass encodes... ???

Results:

MultiPass @ 2000 kbps / 1st Standard / 2nd Standard / BiDi / No PVE
File size: 46.954.496 Bytes / Avg. PSNR: 46.39

MultiPass @ 2000 kbps / 1st Standard / 2nd Slowest / BiDi / No PVE
File size: 46.968.832 Bytes / Avg. PSNR: 46.45

MultiPass @ 2000 kbps / 1st Slowest / 2nd Slowest / BiDi / No PVE
File size: 46.954.496 Bytes / Avg. PSNR: 46.47

@S.M.D.

At the moment Im doing some 1024*576 tests, as you suggested... ;)

Bye

[SeeMoreDigital]

I think I'll generate an Mpeg4/DivX encode of T2 Extreme (156min) using Superturtle's suggested bitrate of 2700kbps over the weekend.

Just to see what happens!

Cheers

[Soulhunter]

I think I'll generate an Mpeg4/DivX encode of T2 Extreme (156min) using Superturtle's suggested bitrate of 2700kbps over the weekend.
As T2 is my favorite movie, I would love it to have a German release of T2 Extreme...

But I think this is just dreaming !!!

Already thought about getting it and then muxing the German AC3 from my T2 Ultimate Edition to it... ;)

PS: Do you wanna use original or changed framesize for your encode ???

Bye

[SeeMoreDigital]

Originally posted by Soulhunter
Do you wanna use original or changed framesize for your encode ???
I'm going to stick with the original image pixel frame size of 720x480.

However, if I have time I will encode the movie twice. At film speed (23.99 fps etc) and again at 30fps!

Cheers