Dvd Shrink No compression (is it compressing)

[s_kound]

Hi to all....

I'm backing up MONSTERS INC R2 dvd... one of the best visual dvd's in the market...

I was just wondering... if i compress everything with dvd shrink EXCEPT the main movie (no compression), is there a chance that dvd shrink will compress a liiiiiiiiiiiitle bit the movie (cause of the engine?) or not?


Thank you

[ddlooping]

Hi s_kound. :)

Using "100%" as Ratio can occasionaly compress a title (1-2%), depending on other settings, the use of "Deep analysis" before starting the "Backup!" process,...

"No Compression", however, will leave the title video stream untouched. ;)

[s_kound]

:) Thank you !!!

[ddlooping]

You're welcome. ;)

[bit-wise]

Actually, I'd like to add a follow-up question.

I had to trim 27 megs off a movie to make it fit onto a -R disk. That is after dropping all extraneous audio, subtitles, studio logos, etc. So I figured I would trim the last couple seconds of the credits using DVD Shrink. I made sure the video and audio stream were set to no compression, and trimed the end mark in the Start/End options back a few seconds of video in the last chapter.

The program them prompted me if it should perform Deep Analysis on the video stream when producing the new IFO and VOB files. Not being in any rush, I figured why not. It then processed all 4 VOB files.

My questions are, did it really transcode the entire video stream? I would have expected it to not touch VOB 1 through 3, and *possibly* transcode VOB 4 to trim the end off the stream. And do I loose any video quality, even when the program is set not to compress any of the video or audio?

Thoughts?

[MackemX]

@bit-wise

if the predicted output is less than your DVD blank then just use the no compression setting and not deep analysis

it it doesn't have to shrink the video why analyse it?

you can also use the variable compression method so you can reduce selective parts of the DVD to make it fit

ddlooping's guides will show you how to do this, just click the links in his sig ;)

[bit-wise]

@ MackemX

Therin lies my question. My origional backup was 27 meg bigger than a -R disk, so I trimed the last couple seconds off of the credits, ensuring that the backup needed no additional compression.

Why did DVD Shrink then transcode the entire movie?

bit-wise
CD13
80FC
9090

[MackemX]

are you sure it actually transcoded the movie?

it will still have to copy the data across no matter what you do even if it's transcoding or no. If it's not then it will be faster than if it was

[bit-wise]

I believe it did because it executed a 2-pass on all VOBs when generating the new VOB files. Once for the analysis and a second time to write the files.

In addition, it took about a half an hour to process the 4 VOBs on a PIII 933, which is about the same amount of time it takes when I legitimately shrink the video stream.

So my guess is that it did. Since I didn't do a byte compare on the before and afters of VOB1 through 3, (obviously VOB4 would be different), I can't be 100% sure.

I was surprised, because like you had said, one would expect it to have just copied VOB1-3 and only process VOB4.

bitwise
CD13
80FC
9090

[Got Milk?]

Just wanted to bring this thread back to see if someone could provide an answer: why does DVD Shrink still analyse sections that have been set to no compression?

I blanked out some extras from The Italian Job and opened it in DVD Shrink, I wanted the movie to be original quality so set that to no compression and left the extras and menu at automatic compression.

When it came to the analysis stage, the movie was analysed as well, but when it got to the encoding stage the movie only seemed to be copied as it was considerably quicker than the other parts of the disc.

Sorry for the rambly post, but hopefully someone will be able to make sense of it!

[Kedirekin]

Implementation details. Only DVDShrink (the author) could answer these questions for sure.

However...

It is probably much simpler to implement deep analysis to always do a full analysis. With complicated processes (such as deep analysis) it's often best to keep them as simple as possible - the simpler it is the less likely it is to have bugs.

Also, DVDShrink (the program) is largely IO bound. It probably takes about the same amount of time to simply copy the bits from the source VOB to the destination VOB as it does to transcode them. Since the amount of time is about the same, you can't tell if DVDShrink is transcoding or simply copying. At some point, you either have to trust your eyes and/or have faith in the author of the program.

[Got Milk?]

I trust that it isn't being recompressed as the movie section of the disc is copied at the full speed of the drive whereas the parts that I set to be recompressed take quite a bit longer.

I was simply wondering if there was any reason the uncompressed material is still analysed.