Percentage acceptable for 1 disc backup?

vbimport

#1

Hi!

I’m a noob to DVD backuping, so i’d appreciate your opinions. This is highly subjective matter, but still.

How high encoding/transcoding compression rate do you consider acceptable for a 1 disc backup?

In other words, at which percentage do you choose to split into two discs instead of one?

Thank you


#2

It really depends on your playback equipment, me personally I choose to split at 65%-70%.


#3

besides the equipment, it also depends on the original source, since a movie that started out with a much higher bitrate can obviously be compressed much more than one that started out at a lower bitrate.


#4

Good point about bitrate. I wish that DVDShrink reported not only % compression but also the target bitrate, so one time 60% is good, and other time 80% is not enough…


#5

wow…that’s something i never concidered, and it explains alot. thxs.


#6

too many users are concerned with having hard and fast guidelines regarding what percentages are acceptable when there are so many variables involved that such guidelines really don’t exist. as an extension on Goudo’s example, let’s say that movie “A” has a constant bitrate of 9800kbps (the max allowed for a dvd). compressing it to 50% will still have it looking great. on the other hand, let’s say movie “B” has an average bitrate of 4000kbps. compressing this movie to 50% will look horrible.


#7

I hope this is not too dumb a question, but how do you get the information on the bitrate of a movie?


#8

Adding to Agent_007’s question (since I don’t know the answer :wink: ):

What is considered a lower limit bitrate for a “good quality DVD”?


#9

relatively few people know how to view the bitrate of a dvd. i really only know of one program myself, which is Bitrate Viewer. if anyone has other programs that they use to view dvd bitrates (i know of plenty for avi), feel free to reply.

as for the lower limit, i’d say to try to stay above 2500kbps, and this is assuming you’re using a quality encoder like CCE. this is also dependent on the source (not talking about bitrate this time, but the actual onscreen action, etc), as there are movies that are inherently harder to encode than others as a result of motion, images, etc.


#10

@AZImmortal,

With Bitrate Viewer, do you know of a way to load all the VOBs for a movie in one go instead of having to run them through one by one ? The file open dialog does not allow for multi-selection ?

IFOEdit has a bitrate calculator tool where you enter the size of the move in MB, the duration, number of audio streams, and number of subpics. It then gives you a rate in MBps. Not sure how accurate this can be though … a DTS stream can be twice as large as a DD5.1 ( although I could just not be understanding how the calculation is made ! ).

nwpsys


#11

This turned out to be relatively active thread. Great!

As a noob I neither came to think of bitrate. How stupid can you get.

Which of the available transcoding and encoding applications report the average bitrate (instead of just percentage) for a 1 disc backup?


#12

it’s not really a matter of stupidity, but rather that most programs only tell you the percentage that the video will be compressed, so that’s the only thing that automatically enters everyone’s mind. as far as i know, none of the available transcoders report the average bitrate, and the only CCE frontend that i know of that reported the average bitrate was ReAuthorist (which is part of the Big 3 method, and which is explained at doom9 if anyone’s interested in it, although it’s not as automated as dvd rebuilder).

i don’t think there’s any way to load up more than one vob at a time with bitrate viewer, although if you really wanted to, i guess you could combine all the vobs into a single vob before passing it on to bitrate viewer, but that takes the extra time to combine the vobs in addition to still running it all through bitrate viewer. as for the ifoedit bitrate calculator, i was referring more to a program that directly analyzed the bitrate (instead of something you had to calculate manually).


#13

Nero Recode displays the bitrate - after importing the title, look at the tabs at the bottom of the window. The last tab has the bitrate info on it.


#14

My TV is only 30", its hard to tell the differance between a SVCD and a DVD on it.

I let it go as low as needed (around 50%), however if it looks really bad I re-author the disc with just the main movie and english audio+subs.

Ben :slight_smile:


#15

When you speak of the lower limit, are you speaking of the AVG. bitrate or the low? because I’ve just started backing up my movies and the last one I set up with an 8 pass-vbr was something like 4500/350/3800 (Hi/Low/Avg).

Also, after reading through multiple sources it seems that there is some disagreement on the number of passes to use. I’ve been choosing the number of passes I use based on the length(and size) of the video files. Does anyone know of a more standardized guideline for VBR passes, or even a calculator?


#16

Many experienced persons say 3-4 passes is enough, any more gives only minuscule improvement. Personally, I’d give CCE more latitude and set the max higher, but as AZIImmortal says, much depends on the source material.


#17

the lower limit i’m speaking of is the average. i agree with fritzi in saying that you should set the max bitrate to something higher (even up to 9000 is ok) and you should also set the min to zero so that CCE is allowed to distribute the bits where it sees fit. there’s no standard agreement on the number of passes to use, but most tend to agree that there’s little to no quality improvement above six passes.


#18

Well then I won’t try any more 9-pass encodes. As for setting the bitrates I assume that I would actually have to do some tweaking to CCE to achieve this instead of letting DVD-Rebuilder do all the work.

And although this is off topic, if anyone has any suggestions for Programs for Re-authoring DVD’s (To remove Extra’s and play with Menu’s) asside from DVD-Shrink, could you PM me.

Thanks for the help guys


#19

Oh, I don’t know, DVD-RB does pretty well without me messing with it. :wink: This is interesting, though, and not really off topic. We’re talking bitrates, the higher the better. Between 6 Mbps and 9 Mbps, you don’t need to worry, below that you MAY begin to see compression artifacts. Go much below 4Mbps and you’ll start to have some, alright. Artifacts not related to compression can be poor encoding or display problems. For example, if your TV has sharpness set too high, well, that’s a mistake.

According to my bitrate calculator, a 2 hour movie with a 224 kbits/s audio track can be done at an average bitrate of 4,853. (Or 4.853 Mbps). This is on the basis of 4480 MB available and 92 MB overhead, 196 MB for audio. So you can see why some folks just reauthor with one audio track. If you have a really big TV, it pays to compress the least amount possible.

TitlesetBlanker and VobBlanker are popular freeware apps for discarding extra stuff and unwanted audio tracks without buggering the menu. Naturally, this can improve available bitrate, sometimes a great deal. :slight_smile:

Uh, JMHO and all that. Feel free to disagree.


#20

Most software DVD players have an option to display stream information to the screen (Cyberlink PowerDVD to be specific.) select that when you are watching and you can get a feel for the bitrate. But the stand alone ones mentioned are really the best.