What determines an AVI video bitrate?

DVDFab 6 .0.0.0 (May 15, 2009)
DVD to Mobile
Profile user.avi.xvid.audiocopy

I am just trying to understand how to make a good “home theatre” AVI in order to store my DVD collection on a USB external hard drive for use with a WD HD TV media player. What determines the final AVI video bitrate (as reported by AVIcodec)?

Original generic profile had a video bit rate of 900 kbps. I noticed most AVIs has a final AVI video bitrate greater than 1,000 kbps. I created a user profile with a video high quality 2-pass and bitrate of 2000 kbps. A few AVIs had a final video bit rate greater than 2000 kbps, some had a final video bit around 20xx kbps, but most had a final video bit rate less than 1500 kbps.

The smallest DVD ISO image I have saved to my hard drive is Catch and Release.
With 1 pass encoding, video bitrate 1024Kbps, the final video bit rate was 1033Kbps.
With 1 pass encoding, video bitrate 2048 Kbps, the final video bit rate was 1650 Kbps.
With 1pass encoding, video bitrate 4096 Kbps, maxbitrate 8192 kbps, the final video bit rate was 1833Kbps .

I Ripped the DVD again and saved the VOBs to my hard drive. The VOBs video bit rate was 9800Kbps.

What is going on? Am I doing something wrong? Help!

Hello BeagleMan50,

It’s hard to compare DVD VOBs (mpeg2 format) with AVI (mpeg4 format).

Please go to wikipedia and search with the keywords “DivX” and “XviD”.

This helps you to understand the differences between the codecs.

There are a lot things to learn, I know.

good luck.

The ultimate determinant of the AVI video bitrate is what bitrate was selected when the AVI was encoded.

As for what bitrate should be used for the best quality/compression ratio, this depends on a number of factors:

  1. the frame size e.g. 720x576 - 4:3 PAL, 720x480 - 4:3 NTSC etc.
  2. the frame rate e.g. 23.976fps NTSC, 25fps PAL
  3. the type of movie e.g. an action film will require a higher bit rate to achieve an equivalent quality when compared to a film with a lot of mostly still scenes

There’s an excellent guide for converting DVD to good quality Xvid AVI here: http://www.bobsomers.com/files/xvidac3tutorial.pdf.

Personally I’ve found that aiming for a “two CD” AVI when using 720x??? and 6ch AC3 sound produces pretty good results with most films.



Generally I use an1100 bitrate for most movies. My Samsung TV will play H264 (generic.avi.h264.audiocopy) from a USB disk and my HDD & network media players will play H263 (generic.avi.xvid.audiocopy) and the 1100 bitrate works fine for both profiles.

I generally end up with about a 1.2gb file for a 90 min movie maintaining the 5.1 surround sound.

It is subjective though, and I have had to sneak it up to 1300 in fast action scenes such as in the Matrix series.

The best idea is to encode the same movie (or chapter thereof) with various parameters and see which ones you feel are best.

I generally maintain the same frame size as the original DVD and let the TV do any upscaling as the upscalers in the TV appear to do a better job than doing it in the encoding.

Hope this helps.

Lots of useful and practical information. I thank you all.

fyi: I am trying to backup/convert my personal DVD collection to AVIs in order to store and play from my WDtv. Previously, I saved a DVD-5 sized compressed ISO image to hard drive using AnyDVD and CloneDVD2.

I am trying to encode at a fixed video bitrate of 2000 kbps. My question/problem is about the encoded AVI that is created.

How come sometimes the AVI video bitrate is 2010 kbps (expected) and other times the video bitrate is 1289 kbps or 16xx kbps (much lower).

Based on the premise of Garbage In means Garbage Out, I assume it has something to do with the original DVD source.

Is there a utility to determine the video bitrate of a DVD movie?

Next series of tasks will be to encode an AVI directly from disc using only DVDFab.

fyi I bought a 1TB Western Digital My Book Home edition. While I could compress the DVD more with either different codec or settings, I am satisfied with the space savings of converting from DVDs to AVIs. Once I fill the hard drive, I will look for a CLI encoder, and probably re-encode everything yet again to save more space.

Get MediaInfo. It is free and does a great job with most file types. VLC media player is also free has an excellent utility (Tools->Media Info->Statistics) that shows the bitrate in real time while the files is being played. The bitrates and file sizes in DVDFab are estimates (but are usually very close).

[QUOTE=BeagleMan50;2293584]I am trying to encode at a fixed video bitrate of 2000 kbps. My question/problem is about the encoded AVI that is created.

How come sometimes the AVI video bitrate is 2010 kbps (expected) and other times the video bitrate is 1289 kbps or 16xx kbps (much lower).[/QUOTE]

The codecs are ‘intelligent’ in their use of bit-rate; there is no point in using a fixed bit-rate of 2000kbps if the image is hardly changing at that point in the film; it’s just a waste of space (Indeed, if the image is very still, then the codec will not actually be able to provide a high bit-rate because not that much data is required to build the image). Using a two pass variable bit-rate encode with VirtualDubMod ensures that the max bit-rate is used where it is needed and a reduced bit-rate is used when appropriate.