Difference in file size with similar coded files

[Kmanz]

I have 2 similar video clips and they are encoded similarly with DIVXmpeg4 320x240 and one is a minute longer but double the size. Here is a listing of the two comparisons in Virtual Dub:

_______ A _________________________________ B ________________
320x240 29.971fps 333666 us__________320x240 29.971 fps 333666us
(#frames) 21131 (11:45)_______________(# frames) 22903 (12:44)
(key frames) 353_____________________ (key frames) 382
(min/avg/max keyframes)______________(min/avg/max keyframes)
427/7306/13351k_____________________415/7547/18883k
(min/avg/max delta frames)____________(min/avg/max delta frames)
42/2474/20523 (50204k)_______________127/5074/35467 (111603k)

Some reason the only major difference is the delta frames. I am not sure what delta frames are, but can they be re-encoded to use less or something so as not to make the file so huge? Thanks for any help you can provide.

[Kmanz]

I am hoping to get the collection of the other files to remain close or near the 50000K threshold, and not bloating to double the size for an additional minute of video/audio.

[Kmanz]

Any thoughts on this?

[KingJohn]

A keyframe is a frame that can be decoded on its own, a non-keyframe, or delta frame, is a difference from the previous frame and cannot be decoded if the frame before it is missing.

The less key frames you have the harder it will be to edit/skip forward, keyframes every 10 is good if you want to edit later, if its just for playback then keyframes every 300 is fine

You don't say what the audio is in the above either, that can make the file double the size

[Kmanz]

King John the audio in both were relativbely the same as far as size in KB. Thery were both recorded 44100 Stereo 16 bit wavs. Still doesn't clear up the discrepancy with size. How can I re-encode it to make it smaller?

[Kmanz]

What application TMPGEnc? to re-encode different keyframe or deltas frames? And how is it done? Thanks.

[KingJohn]

You can really shrink them down in AVI

If Vdub was used and DivX 3.11 Alpha (Slow motion) with a MP3 audio, that would shrink right down. In the video codec settings you can specify how many keyframes you want and what bitrate (500 is good) depending on how good the source is you can low that even further. Same with the MP3 codec bring it down to 96K

Each codec is good for a particular type of movie, if you have many fast scene's, then you would find some of the codec's would be jerky. Then some of them are used for animation. A good all rounder is 3.11 Alpha.

Its like comparing Winzip, WinRar and WinAce they all do the same, but some compress certain things down better than others.