Why is XVID much slower encoding than DIVX ?

[QUEENFAN]

Hello,

could you please explain to me, why I get 21fps encoding with divx 5.2.1 and only 8fps using XVID 1.1, same settings with AutoGK ???
I have a AMD Athlon XP 1700+, 512MB RAM and Win XP.


Thanks in advance folks.

[shon3i]

same settings with AutoGK ???But not same setings in encoder. Keep using xvid and you see differents in encodings, or try to use DivX 6.1.1. Compare this two codecs and you see why XviD is so slow and quality is better

[QUEENFAN]

Hello shon3i,

thanks for your reply.
I was wondering why everyone seems to encode faster using xvid instead of DIVX. The divx-encoded files where absolutely OK using 5.2.1. Although I'd prefer using xvid, encoding-speed is important to me and if the quality isn't to bad why should I encode slower ?

[mod]

if the quality isn't to bad why should I encode slower ?
For someone else speed isn't a problem, quality is.. :)

[Hard Core Rikki]

why I get 21fps encoding with divx 5.2.1 and only 8fps using XVID 1.1, same settings with AutoGK ???
I have a AMD Athlon XP 1700+, 512MB RAM and Win XP.


Same settings?
Perhaps because XviD has VHQ Optimization set to mode 4 (wide search. NB:veery slow compared with modes 0 and 1)?

VHQ modes set to anything more than 1-Mode Decision help to:

1) improve quality for fixed bitrates.

OR

2) if set to constant quality (constant quantizer), make the video stream smaller in filesize.

However, these gains come at the expense of encoding speed. VHQ is just like that. In your particular case, you seem to be more wary about encoding speed than the (probably negligible, at least for you) quality gains.

For a substantial decrease in encoding time with XviD, I recommend you do not set VHQ to anything more than 1.

I suggest that you try re-encoding with XviD 1.1 again (with VHQ Mode set to mode 1-Mode Decision) and report your results, if anything changed.

[QUEENFAN]

Hello OMEGASAID,

and thanks for your suggestions.
I've just opened the XVID encoder settings and couldn't find anything like VHQ-setting. Could you please give me a hint where to find it ?

Thanks.

[Hard Core Rikki]

VHQ settings are located in the Advanced Options, under the name VHQ Mode.

You have 5 choices available. Basically VHQ is an optimization. However, I myself recommend *not* setting it to 0 (OFF).

If unsure about it, it should be kept at VHQ Mode 1-Mode Decision. Gives some gains without slowing encoding much.

For the best possible compression/smallest filesizes, people tend to set it to 4-wide search. I guess most people here on Doom9 prefer being patient with their encodes and are more concerned about their video's quality. Hey! You only have to encode it once, after all!

The option "Use VHQ for B-Frames" slows encoding as well, while significantly improving quality of b-frames/or reducing their filesize. Should be kept off for you, I suppose.

There's also a Turbo ;-) check available. when checked, give you an *additional* improvement in encoding times when you are using GMC and b-frames, though it comes with a (very insignifiant) quality loss.

If you find the previous recommendations not satisfying enough, you could try checking it.

You should notice a significant improvement in XviD's encoding speed, with quality still on par with (or superior to) DivX.

[CWR03]

It won't matter what changes you make to XviD when you're using AutoGK - it will still encode at the same speed.

[QUEENFAN]

Hi omegasaid and CWR03,

thanks for your replies.
@CWR03: Does this mean that, no matter what changes I make in the Encoding settings of the xvid-codec AutoGK overwrites this ?
Any chance of preventing AutoGK from overwriting the settings or influencing what settings are used in AutoGK for xvid ?

[CWR03]

Does this mean that, no matter what changes I make in the Encoding settings of the xvid-codec AutoGK overwrites this ?
Yes.
Any chance of preventing AutoGK from overwriting the settings or influencing what settings are used in AutoGK for xvid ?
No, but the full Gordian Knot will allow you to adjust that and more.

[QUEENFAN]

Thanks a lot CWR03, I'll give Gordian Knot a try.

[riggits]

Best thing to do is compare the output of XviD and DivX modes. You'll notice that Divx washes out tons of detail, and probably gives a huge number in the compression test. My guess is that Divx is always run in Standard or Fast mode, whereas XviD always is tailored to give the best quality.
Do an encode with each, keeping all your settings the same. Then compare the quality, and you'll see why most people do not bother with DivX in AutoGk.

[Axed]

Queenfan, if encoding speed is quite important to you, and your happy with the quality of DivX just stay with DivX. Gordian Knot is a great program to learn, and im glad to have learnt it when i did (mainly because there was no such thing as AutoGK when i started tho...) but it does take some time, and wasted encodes to get it perfectly right.

AutoGK on the other hand is just click, and your done. Compare a 10 minute or so long dvd file in DivX and XviD and see if the difference is obvious *for you*. Remember, just because doom9 considers XviD better then DivX doesnt mean its better for you. You might prefer the look of DivX as many people do!

For the record, personally im an XviD fanatic having used DivX before..

[QUEENFAN]

Hello Axed, riggits and CWR03,

thanks a lot for your replies.

Because I have many dvb-streams to encode I'm a fan of AutoGK in combination with DIVX, which works like a charm.
I'll give AutoGK an XVid a try.

Do you think that qualitiy-improvement is so good using GK instead of AutoGK ?

I want to keep my films with a size of 10 MB per minute film (more if audio is AC3 ;-).