Compression, quality question...

[xCharvelx416]

Here are two movies, with only two minutes total time difference between them.

The Mummy (2hrs 4mins), and Indiana Jones - The Last Crusade (2hrs 6mins).

As see in the shots below, The Mummy started it's quality at 91%, then finished scanning at 100%.

IJ started at 58% and ended at 68%.

How can 2 minutes account for 32% in quality difference?

The Mummy:




Indiana Jones:




I have noticed this quite a bit with CloneDVD... that sometimes longer movies have less compression than shorter ones... however in this case, only two minutes and we cut out a third of the quality.

Log files can be uploaded if needed, but both movies only have CSS protection, nothing else.

I did see that IJ has twice as many chapters... is this what could be the issue?


Here's an example of a shorter movie with more compression. Yes... it's a Disney movie, but with all the protection out of the way, the movie is only 1 hr, 38 mins long.

Compression started at 73% and fully scanned at 81%. I have had longer movies finish at 100...

 

[mmdavis]

It's not the length of the movie but the size of the files. What are the file sizes?

 

[xCharvelx416]

After ripping, file sizes on HDD.

The Mummy: 1.048GB x 4, with last one at 354MB.

IJ: 1.048GB x 4 with the last one at 377MB.


File sizes on DVD (Video_TS folder):

The Mummy: 7.7GB total, 1.048GB x 5, last one is 711MB.

IJ: 6.8GB total, 1.048GB x 6, last one is 550MB.

 

[Moonie]

The Mummy: 7.7GB total, 1.048GB x 5, last one is 711MB.

IJ: 6.8GB total, 1.048GB x 6, last one is 550MB.

And this is the point!
Resolution+Size from the source = quality lost after ripping to dvd5

 

[DrinkLyeAndDie]

I won't claim to be an expert but I believe you are mistaking the length of a movie as the important indicator as to how things should work out for quality when transcoding to DVD-5. I believe the more important matter is the bitrate distribution throughout the movie and in order to reduce the size you lower or redistribute and lower the overall bitrate so that the content is reduced in size.

 

[Moonie]

sure the lenght is important too, but i.e. source with 6GB @300*150/2h is a better quality after trancoding as 8GB @400*250/2h

the first example needs a lower bitrate as you say for the "same" quality

 

[calcu007]

It also depends how much compression was already used by the studios when makes the dvd and as DrinkLyeAndDie said, the bitrate in it was manufactured. The lenght is not everything.

 

[xCharvelx416]

I won't claim to be an expert but I believe you are mistaking the length of a movie as the important indicator as to how things should work out for quality when transcoding to DVD-5. I believe the more important matter is the bitrate distribution throughout the movie and in order to reduce the size you lower or redistribute and lower the overall bitrate so that the content is reduced in size.

Seeing as every movie I purchase, is widescreen... the resolution is a fixed rate of 720*480. But... I am beginning to wonder, if the "versions"... aka, the 1.85:1 vs the 2.35:1 aspect ratios of the original film have more of an effect?