divx multi passes and filters

[mtamimi]

i want to encode a dvd to divx, i am using divx 6.xxx. i was curious since i am going to crop/resize and add some filters, shall i do this in the 2nd pass only or it should also be defined in the 1st pass??!!!!


thnx in advance,

p.s. the dvd is interlaced any suggestions...??!!!!

i've been following this site since 99 or 2000....yet this is the 1st time to make a post...!

[jagabo]

You should use the same filter process in each pass. During the first pass Divx will be examining each frame to see how much bitrate it will need. During the second pass it will use that information to allocate bitrate to meet your average bitrate requirement. If the video is very different between the first and second passes the information gathered during the first pass will no longer be valid.

If you're concerned about speed and don't need files of a specific size, use "one pass quality based" encoding.

Deinterlace or, if possible, inverse telecine. Divx supports interlaced encoding but a lot of players will simply display both fields at the same time (on a computer), showing comb artifacts. Set top players usually don't handle interlaced Divx very well.

[mtamimi]

Thnx

what about cropping/resizing?...the problem is that i did try to crop/resize in the 1st pass....and left the same conditions in the 2nd pass...the final size was totally different than what i defined!!!! what went wrong??


*edit* can u suggest a good deinterlace filter??

[jagabo]

What software are you using?

If you're using VirtualDub or one of the variants, Donald Graft's Smart Deinterlace is probalby about the best. If you're using AVISynth LeakKernelDeint() is one of the best.

Regarding the 2-pass bitrate: aside from the obvious things like, did you take into account the audio?, there are some internal setings in Divx that can cause the bitrate to miss the mark. For example, if you select the Mobile Profile and ask for a very high bitrate, you won't get it. The file will turn out smaller than expected.

[mtamimi]

I am not encoding the audio, I will do that separately. I started by cropping the upper and bottom black areas, and then I resized the movie to 608x320 and started the 1st pass at 950 kbps w/o any other filters. When Vdub finished, I selected "multi pass nth pass" and started encoding over again w/o altering any other settings. When Vdub finished, I checked the file and it was 576x... !!!! I do not know what caused that!!!

Btw, I am using the last stable version of Vdub and Divx 6.5.1.

thnx for the help,

P.S. Sorry if I was not clear in my previous posts, my problem is the frame size, not the bitrate.

[mtamimi]

[jagabo]

Go to the Video tab of the Divx Codec Properties dialog and make sure it isn't set up to resize and make sure it's set to square pixel:



I think your scaling wrong. The final size should be more like 608x272. You can use FitCD to get the right dimensions for resizing.

And you shouldn't use Nearest Neighbor as the resizing filter. Try Lanczos3.

I hadn't tried Alparysoft's deinterlace filter before. It seemed to work pretty well on a quick test. I'll have to play around with it some more.

[mtamimi]

thnx...you are right...that was my problem...

can u explain more about this "608x272"??

[jagabo]

I could only see a part of your source video and I'm just eyballing it but the source appears to be an anamorphic 16:9 encoding of a ~2.25:1 aspect ratio movie.

After cropping away the black borders the right height for the picture with a square pixel encoding would be about 272 (for a width of 608).

[mtamimi]

Sorry, but how did you know that the source was actually 2.25:1?? i am struggling to identify this.

regards,

[jagabo]

Sorry, but how did you know that the source was actually 2.25:1?? i am struggling to identify this.

There are only two display aspect ratios on DVD. 4:3 and 16:9. Both use a 720x480 frame size. Any movie that is not one of those aspect ratios has to be padded with black letterboxing or pillarboxing. Since your source has black bars top and bottom and the people look too thin I'm guessing it's a 16:9 encode. A 2.25:1 movie encoded on a 16:9 DVD would be about 370 lines out of the 480 -- the size you have.

http://lipas.uwasa.fi/~f76998/video/conversion/
http://www.hometheaterhifi.com/volume_6_4/feature-article-enhanced-widescreen-november-99.html

[mtamimi]

thnx