Different files sizes same video length

[jriker1]

Title is a bit deceiving but figured it was the best way to get attention. I have two videos, both encoded using Lagarith, both at 29.97 frame rate, both listing 261994kbps data rate, both 720x480. These are just some specs Windows is showing. Both rendered using Sony Vegas. Problem is I have one video that is larger than the other and it's smaller:

2 hour 50 minute video: 96GB
3 hour 11 minute video: 62GB

Any idea how this can be? Is it related to the quality? Figured an Lagarith AVI would be the same but perhaps it's related to the bigger file size one being less clean or something and it couldn't reduce the size as much without loss. Any thoughts other than mine?

Thanks.

JR

[DigitAl56K]

I think you posted this in the wrong forum, but to answer your question, if you have two files of different durations, and the longer file has a smaller file size, then the bitrates can not possibly be the same.

96GB / 10200 seconds = ~9.4MB/s
62MB / 11460 seconds = ~5.4MB/s

If you are using a lossless codec then the data rate will be proportional to the texture complexity and spatial/temporal redundancy, assuming the compression takes advantage of such redundancy.

[jriker1]

OK, my appologies. Now the smaller length file is 1GB smaller than the bigger one. Seemed that Lagarith reset itself and was encoding in RGB instead of YUY2. Redid it and now it is more as expected. Sorry about that.

JR

[MarcioAB]

In your first post, the 2:50h had 7.81 BPP (bits per pixels) and the 3:11 had 4.49 BPP.

The range 4 to 5 BPP is what I normally get with lossless Lagarith compression so as you discovered, there was something wrong with the 2:50h.

Now, (with 61GB) your 2:50h has 4.96 BPP, near the top of the range, so this movie is less compressible than the other ...
(more action ? more colorful ? ... ;-)