Help with m2t to DivX

[Garde]

I've edited a small piece in HDV 1080i shot on my Sony HDV cam, and now rendered it back to m2t so that I could transfer it back to tape. But I'll also like to convert it to a DivX movie so that I can play it back on PC. So I found this thread https://forum.videohelp.com/topic303573.html and tried the scripts out that soopahfresh provided. I modified them so that I use bob deinterlacing with yadif and also I left out the last avs2avi (->Lagarith) encoding.

So after having run the 1280x720 .bat, I load up the .avs in virtualdub, change compression to use the Divx Codec (1080HD profile) and save that. For 13mins of film I get a resulting file of about 597mb. Now I wanted to make another one with a smaller resolution to get the size down, so I went and changed the resize statement in the .bat to 640x360 but here's where I got surprised - the resulting compressed DivX file is almost exactly the same 597mb in size?! I tried it with 720x576 (with borders to maintain 16:9) too and the same happened??

I'm pretty new to all this codec business, and hoping for some enlightment..

[Soopafresh]

Depends what your bitrate is set to, probably. I use Xvid, so I'm unfamiliar with the codec settings of DivX. Glad to hear the batch scripts work for you

[Garde]

Well the scripts run flawlessly, thanks a bunch for them!.. but I just don't understand how, with the exact same divx settings, different resolutions can wind up in almost exactly the same file-size give or take a few KBs??

I've never tried Xvid before, is it "easy" to setup for this kind of job?

Also, apart from the 1280x720 resolution, which size is usually chosen as a smaller 16:9 format? I kind of made up the 640x360.

[mats.hogberg]

Resolution has nothing with file size to do. Only bitrate (and time).
A 1 hr, 2000x1500 video @ 1000 kbps will be exactly the same (file) size as a 1 hr, 100x75 video @ 1000 kbps.
You can use any resolution as long as it's 16:9, and preferrably be divisible by 8
For standalone playback, never go over 720 px wide tho.

/Mats

[Garde]

Aha! That's where I went wrong then, thanks for that enlightning realization

[Garde]

So are there any general guidelines to which bitrate to encode with for 720p HD content compared to say 640x360 ? The source material is as stated above 1440x1080i .m2t (HDV).

The standard bitrate for DivX 1080HD profile is set to 6000 kbps

[mats.hogberg]

Use a quantizer (=quality) setting that gives you the quality you want, instead of a fixed bitrate. The bitrate will adapt itself to the selected resolution, and use whatever it takes to meet the quality setting.

/Mats