ErMaC's Guide to All Things Video - Part 7

How to do Awesome DivX Encodes with NanDub


A direct extension of the previous guide, this guide will explain how to make good encodes with NanDub - a 2-pass Smart Bitrate Control DivX encoding tool that is based off of VirtualDub.

I. What you need

First off, for this guide you will need NanDub. Make sure to download the newest version. As of the time of this writing it is 1.0rc2. You should also have TMPGEnc from the previous guide as some steps may need it, as well as VFAPIConv to go with it.

You will also want to have your final project exported as a single file (preferably HuffYUV or DV or something of very high quality.

Again, to reiterate from the last guide: You cannot make a good DivX encode without a good source. If you used bad editing techniques, used poor source, or used improper settings in Premiere (or whatever editing program you used) then there is very little NanDub can do to make things any better. The reason most of my encodes look so good is because I use DVD source footage almost exclusively and always edit in the highest-quality formats possible.

This guide assumes you're working in full 720x480 or 704x480 NTSC resolution. At a minimum you should be working in 480 scanlines (dropping the horizontal resolution isn't that much of a killer). If you aren't (and you really should be) then experiment with the settings.

II. Basic setup

This guide will actually be much easier than the previous one, since I've decided to simply include a VCF file (VirtualDub Configuration File) with all the settings I use for my videos. Just download that, and then once you load your Video File into NanDub (by going File->Open and selecting the file) load that up by going "Load Processing Settings..." from the File Menu.

III. Extra Stuff

Just like with MPEG Encodes, you have the option of Inverse Telecining your video. If you decide to do this, follow the TMPGEnc guide up to the point where you would encode the video, then go back and change your Resolution to it's normal setting (720x480), turn off clipping, and go "Save Project...". Then in VFAPIConv, Open it and create a Frameserver AVI File which you then open in NanDub. You now have used TMPGEnc's excellent IVTC in NanDub. =)

For Manual Keyframe insertion, I've found this really isn't nearly as beneficial with DivX as it is with MPEG1 (Since NanDub has an excellent Scene Change Detection algorithm), but if you want to do it, you can re-use the settings you used in TMPGEnc with a little work, by Saving your Keyframe settings in a separate text file. Go to the Force Picture Type Settings button in TMPGEnc for the project you already did, and Save it as a TXT file. Then for each line which should look like this:


Change it to:

@Frame#: K

For example, the line "6632,I" would become "@6632: K". Save the file as something with the extension "ECF", then in NanDub's Video Menu, go to SBC Control -> SBC Settings, and under the ECF tab input that filename.

IV. The Encode

Now that you've done all your settings, under the File menu select "Two passes..." and put in a filename for your final AVI file, and then a filename for the STATS file. Be sure you do Two Passes, otherwise you're missing one of the biggest advantages of NanDub which is 2-pass VBR encoding.

Note that the first pass will give you some really big filesize estimates - ignore it, the first pass is creating an imaginary AVI file encoded @ 6000kbps DivX to determine the Bitrate Curve.

Your final filesize may vary, because despite the fact that the Average bitrate should be 900, I've enabled the "Minimum Quality" option, which decodes every frame after encoding to make sure it meets a certain quality standard. This is to avoid having the video look like crud if it really needs more than 900 ABR (average bitrate).

Note that encode times may be very long. =) Enjoy.

Next Time - Outputting Your Video to Tape