Why do my file sizes vary when using differant versions of Divx?

[David9799]

For example i will use all the same settings in divx.

the file divx 4 made will be smaller than the file that Divx 6.4 made

a 4 min clip will be 41mb with divx 6.4 and the same clip will be 17mb with divx 4

and i can not tell any differance in the pic they both look the same.

What gives?

[jagabo]

GSpot

[David9799]

GSpot

Gspot? I used that to see if they where the same specs. and they where only differance was the version of divx used.

[jagabo]

Did they have the same video bitrates? Did the use the same audio codecs and bitrates?

[Scorpion King]

Without figuring in the audio....

The v6.4 encode bitrate is 1072Kbps
and your v4 encode bitrate is 233Kbps

that is a lot of difference.

B frames?

[David9799]

I have all the settings set to the same bit rate and audio rate......both are using same lame codec for audio.

[jagabo]

Obviously at least one the files has different bitrates than you specified. Nobody will be able to tell you what went wrong unless you provide some information. What were the bitrates you specified? What do Gspot and AviCodec report for the video and audio bitrates? What other Divx settings did you use?

[David9799]

Obviously at least one the files has different bitrates than you specified. Nobody will be able to tell you what went wrong unless you provide some information. What were the bitrates you specified? What do Gspot and AviCodec report for the video and audio bitrates? What other Divx settings did you use?

Umm no the bitrates are the same, i'll try and post a screen shot later of there info.

[celtic_druid]

B frames?
From recollection DivX 4 was SP only, so no bframes. In fact impossible to have the same settings. Why would you want to encode with DivX 4 though? DivX 6.4 should beat it everytime.

[manono]

Umm no the bitrates are the same

Umm no they aren't. If the video source is the same for both (and the same length), and if the audio has the same bitrate, but the file sizes are different, then by definition the video bitrates are different.

[David9799]

Umm no the bitrates are the same

then by definition the video bitrates are different.

Going by Gspot they are the same.

The software i'm using will not let you pick which divx version you can use it comes with divx 4 built in the software i'm trying out lets you pick what version of divx you want to use.

[jagabo]

Regardless of what codecs you're using the relationship between file size and bitrate is simple:

file size = bitrate * running time

If the file sizes are different then the bitrates (audio + video) and/or the running times are different.

[Scorpion King]

This may not be a completely fair test but the best I could do on short notice.

Captured 4 minutes of video using ATI MMC v9.03 and my 9800Pro AIW card since it comes ready with Divx V4. I used the Home Theater Preset which AVICodec reported 1379Kbps video and 128Kbps MP3 audio.

In VirtualDubMod I converted that v4 divx file to uncompressed AVI = 6.19GB

In VirtualDubMod I then encoded that uncompressed version using Divx 6.2.5 2pass 1379Kbps, all other settings=default values.

Results:
(v4) 43.1MB, GSpot=1355Kbps
(v6) 43.6MB, GSpot=1378Kbps

Same bitrate settings=same filesize. In my case the bitrates are off 17Kbps (510,000 by the calculator) or 500KB for the 4 minutes.

Good luck.