Xvid Speed !!!

[birdy]

hey guys,

I saw many threads talking about xvid slow speed during encodes compared to other codecs specialy divx.

Well there is no doubt that when using xvid with all the great options it has to offer your speed will decreas remarquably and it becomes slower then divx! But for me the loss of speed is really worth the differents I can achive.

But here is why I brought up this subject:

I wanted to bring up ur attension to the speed of XVID durring capture and compared to divx its damn faster! I could never achive a similar quality when capturing with xvid, with divx!

With divx my cpu usage is way too high and I drop frames. But when capturing with xvid I never drop a frame when capturing at 768X576 and my cpu usage is arround 65 to 70 %

Now I know that most of you encode dvds or avi's with xvid and this is what I do now and get the quality I want.

But I would welcome any good tips to get the best out of xvid durring captures.

[Sirber]

Capture is CBR or Quality-based?

[birdy]

Originally posted by Sirber
Capture is CBR or Quality-based?


CBR if you can call it so! As depending on the source video the size changes even if set on cbr.

Here are my settings:

Encoding mode: 1 Pass CBR
Bitrate kbps : 1789!
Motion search precision: Very high
Q type: H263

All the other settings in this tab set to default.

In quantizer tab:
Min i frame=2
Max i frame=4

Min p frame=2
Max p frame=4

and all the other settings are set to default.

When I capture with this settings I get a really excellent quality and sometimes I recompress the movie I captured from digital satellite with this way to make a 1 cd movie 2 pass and the results are really amazing.

I could upload a little demo if needed!

[symonjfox]

Maybe you should try to use Constant Quality and make some tests on the CPU usage. CBR is known to be the worse xvid encoding mode.

By the way, you could try to increase the CPU utilization playing around VHQ=1, Chroma motion and BFrames. Try to make some tests. AFAIK they're all CPU intensive but they will really increase quality / compressibility.

PS: if your goal is capturing to High Quality XVID and then REENCODE to low quality XVID, I'd advise to use Hffyuv for capture and then recompress to Xvid.
If you don't want to use it, but you want to use Xvid, just try Constant Quant = 2, this will give the BEST quality as possible and then reencode.

[mf]

CBR is actually ABR mode in disguise.

[kastro68]

If you are going to re encode what you captured, and if you are low on hard disk space... I'd recommend MJPEG. It takes up even less space than Huffyuv.

[symonjfox]

Maybe in such powerful computer (that real time encodes 720*576 in Xvid) you should try MJPEG2000 codec (it's very slow, but just for testing).

Mjpeg2000 is a great codec, I compared it in lossless mode vs Hffyuv.
Well hffyuv gave me a ~300 MB file, while Mjpeg 2000 gave me ~220 MB (about 2x time).

[slxslxslx]

You can use mjpeg during capture.
It is very fast!

[birdy]

I thank you all for your replys.
I know that using mjpeg and or Huffyuv are the way to go for a right capture and then compress. But with both of them the file size becomes extreamly larg (too larg for me) as I am subscribed to few digital movie channels and sometimes I capture up to 5 or 6 movies a day! With the settings I posted and metioned my captures are about 23MB/m including 16bit 44khz strereo sound. So they shrink a lot after compressing the audio to mp3 and it gives me most of the time a good quality 2CD movies on the fly. If I want to keep that movie or make it 1 cd then I recompress.

But the advice about usinf vhq or other settings during capture is what I was looking for. In fact I am trying to find the best settings to capture with xvid. the quantizer2 capture makes the file become arround 56 MB/m wich is also too big for me.

One setting I would really love to understand is : "Reaction delay factor" in the debug tab and also if I could (should) use chroma optimizer during capture.

I will also myself start testing and will post the best settings i find.

[Teegedeck]

A compromise could also be to restrict I-frame quantizers to 2 and P-frame quantizers to 3 for your purpose. Don't know but maybe it still looks better than CBR.

[JohnMK]

I wish hinted ME were brought back & working. :)

[Nic]

it was decided hinted ME wasn't a good idea generally....even DivX doesnt support it now.

I can understand you guys wanting your "speed" back though. When api-4 is settled down, maybe speed optimisations will become a priority again.

-Nic

[trbarry]

I've been encoding a bunch of things recently using CBR, no b-frames, with pretty good results. But it's usually because I want to keep the playback speed up and CPU down on higher res clips instead of saving the last nickle of disk space.

- Tom

[JohnMK]

Disabling Qpel and I'm now getting around 19fps on my P4 3.06GHz, with all other "best" XviD settings enabled such as VHQ4, ME=6, chroma motion & optimizer. LanczosResize(640,256). Of course, part of this speedup is, for this movie, I'm trying b-frame threshold 255, and I'm pretty sure VHQ4 doesn't process b-frames, only p-frames (and maybe i-frames?). So with a b-frame threshold of 0 maybe I'd only get 15-16fps.

[kastro68]

Hi,

I'm just curious as to how xvid handles b-frames while capturing on the fly.

[CruNcher]

@ birdy
you coult try to save some Space with the usage off the YV12 colorspace by useing MarcFd's VBLE codec :)

[Animaniac]

Originally posted by CruNcher
@ birdy
you coult try to save some Space with the usage off the YV12 colorspace by useing MarcFd's VBLE codec :)

Don't forget ffvfw's YV12 HuffYUV.