Help with Merging Vob Files

[banzemanga]

Hello everyone. I have been using VOBBlanker for a while to extract specific cells and chapters from DVDs in their original quality and VOB format.

Since most of the times i would extract cells in sequence like:
cell 1, cell 2, cell 3 and cell 4. I would not have any problem.

But now i am trying to extract cells by skipping some of them like:
cell 1, cell 2 and cell 4. Meaning i am skipping cell 3.

I would extract the files in one merged VOB file. But for some reason when i played the video, it plays the sequence of cells alright but the one off sequence won't be played or will be fast forwarded. With the previous example it would play cell 1, cell 2 and then won't play or will fast foward cell 4.

I tried various things like extracting all the separate cells and then merging them with other software (in case it was some bug with VOBBlanker) and i got the same results. I used software like JoinVobFiles.exe and VOBMerge.exe.

Thne i thought that it was VOBBlanker that might be doing the extracting incorrectly so i tried to to it with DVD Decripter and only extract the chapters and cells i wanted (skipping the unwanted ones) and still got the same result.

So any ideas of the problem or solutions? :(

[banzemanga]

Here is what i found out so far but i still don't have a proper solution.

The total time interval that the merge video produces is larger than the clips merged together.

Let's take our previous example of skipping cells.
-I have cell 1, cell 2 and cell 4 (skipping cell 3).
-Each cell is 1 minute length.
-The merged file should total 3 minutes but it appears in the player 4 minutes of length as if cell 3 was included.

So, DVDs are encoded vbr, i think that if i am right - the video has to be re-encoded and cannot just be extracted and put together because some of the bitrate information is in the previous cell?

Though i hate re-encoding cause i wanted the original data and there might be some loss of quality in re-encoding.

[r0lZ]

You don't need to re-encode. Remuxing should be sufficient. Use PgcDemux to extract the video, audio and subpic streams from the original DVD, and remux them with Muxman.

[banzemanga]

Here is the thing. Let's say i extract 1 cell of the a DVD video into VOB format using VOBBlanker; it makes a file with 286MB size.

If i first demux the one cell using PGCDemux, mux it back using muxman, and then extract the VOB file using VOBBlanker - i acutally get a file of 280MB. Where did the 6MB go?

I thought that demuxing and muxing videos would not change or re-encode the information of the video. I am loosing quality from the original video file?

[r0lZ]

I am loosing quality from the original video file?Certainly not. The video and audio streams are not reencoded, simply because a muxer is not an encoder!

When muxing, the muxer adds some necessary information to the VOB file: the nav packs. Muxman might be smarter than the original muxer, and add less nav packs. It might also have deleted some unnecessary stuffing packs. (I've already noticed that you can gain some disc space by demuxing and remuxing a DVD that has been shrunk with DVDShrink, because less nav packs are necessary when the VOB file is shorter.)

Also, the beginning or end of the audio stream might have been cut at a slightly different point, as Muxman may have changed the start offset.

Also, are you sure you have remuxed all streams? A diff of 6 MB could be caused by a missing subpic stream.

[blutach]

More likely a missing audio stream if just 1 cell.

Losing 6Mb on a mux (of just 1 cell) is not just navpacks and efficiency.

Regards

[banzemanga]

When muxing, the muxer adds some necessary information to the VOB file: the nav packs. Muxman might be smarter than the original muxer, and add less nav packs. It might also have deleted some unnecessary stuffing packs. (I've already noticed that you can gain some disc space by demuxing and remuxing a DVD that has been shrunk with DVDShrink, because less nav packs are necessary when the VOB file is shorter.)

Also, the beginning or end of the audio stream might have been cut at a slightly different point, as Muxman may have changed the start offset.

Also, are you sure you have remuxed all streams? A diff of 6 MB could be caused by a missing subpic stream.

-What are nav packs and stuffing packs?
-The length of the video have not changed at all. Not even one second of difference.

More likely a missing audio stream if just 1 cell.

Losing 6Mb on a mux (of just 1 cell) is not just navpacks and efficiency.

Regards

It only had one audio stream with it can't be the reason.

Edit: Found some more interesting information. After i demux the audio and video for the first time. They total 282MB (although it kinda make sense since they are separate streams so it should be slightly smaller)

Edit2: I guess you guys are right. I repeated the muxing and demuxing cycle with the new muxed and demuxed files and after the first shrinkage; it did not happen anymore. Probably Muxman did disregard unnecesary information.

P.S.> By the way i still want to know what are nav packs.

Edit3: Ya, it was the subpics (subtitles- had to research about it) streams that i did not re-mux cause i didn't need it. Thanks for everything.

[blutach]

Look at mpucoder's site for info about various packs.

http://www.mpucoder.com/DVD/index.html

Regards