Transcoding a part of a Movie


To transcode a part out of a DVD Title-Set or VOB file, the idea is to demux/split the VOB file or Title-Set into its Cell-IDs, first.
Then we can easily access/edit/transcode a single Cell or part with any tool we like. I use ReMPEG2 to transcode movies, so simply transcode the demuxed Cell in that case. After that the transcoded m2v file can be remuxed back into the splitted Cell with VobEdit.
When that is done, we need to join the splitted Cells back to the orignal VOB file or Title-Set, to be able to process it further with IfoEdit, and so to burn it to DVD-R.

Transcoding a part of a movie can be realised by transcoding a couple of cells of the Title Set.
For this example I'll take the movie 'Wing Commander'. It has 5 vob files, and I want to transcode just a part of the 5.th vob file.
First I take a look in VTS_02_5.VOB with VobEdit to see what Cell-ID's are used. I have found at the beginning VobID: 2,CellId: 6, and at the end: VobId: 3, CellId: 1.
Because it is not good to transcode between VOB-ID's, I search for the last cell with VobId 2, and I found CellId: 10.

Okay, so lets say we want to transcode CellId: 7,8,9 and 10. 
I don't transcode CellId 6, because it's not beginning in VTS_02_5.VOB. It's just continued here, and it began in VTS_02_4.VOB.
Below I will show you how to transcode cell 6 too, accross the two vob files VTS_02_4.VOB and VTS_02_5.VOB.

The single steps that are riquired:

  1. Demux the VOB file containing your cells you want to transcode, into its cell components.

  2. Grab the cells you want to transcode, and join them to a single VOB file.

  3. Transcode this VOB file with ReMPEG2

  4. Remux the m2v file back into the single (joined) VOB file.

  5. Demux the single VOB file back to its cell components, and move them to the first demuxed cell vob files.

  6. Join all cell-vob files back to a regular VOB file.

1. Demuxing/Splitting the original VOB file into its Cell-IDs.

Open the VOB file VTS_02_5.VOB with VobEdit.

Press the Button 'Demux', and the following dialog will apear:  

Select the second Option:

If you would like to split a complete Title-Set into its VOB-IDs, then you could check the last option.
If you don't check the last option, then only the current loaded VOB file will be processed.

After clicking okay, you will be prompted to specify a destination directory
(Don't change the filename please!):

After pressing 'Save', the demuxing/splitting begins:

After this is finished, your destination directory will look like this:

As you can see, the filenames itself don't tell much about its content. That's why there's also a log file.

Open it with Notepad or any other editor to see, what we have in which file.  

 

We said, we want to transcode cell 7,8,9 and 10.
So move the files VTS_02_002.VOB - VTS_02_005.VOB to a new empty directory. (You will soon understand why)

Now open VTS_02_002.VOB with VobEdit and choose the Menu-item: 'Edit -> Join CellVob files':

VobEdit will ask you for a destination directory. You can use the same, so just click 'save':

VobEdit is now joining just these 4 vob files together to a new VOB file, that can be better transcoded:

When the joining is finished, we've got one VOB file named VTS_02_1.VOB, containing our Cells.
Now you simply need to open this VOB file in ReMPEG2, and start the transcoding process.

2.  Transcoding a single demuxed Cell-ID with ReMPEG2.

Now you can catch the VOB file containing our Cells, you want to transcode.
So lets open VTS_02_1.VOB with ReMPEG2:

These are the options, I'm using in ReMPEG2:

Hit the encode button, and specify a filename for the transcoded m2v file.

Now we are ready to remux the transcoded m2v file back into VTS_02_1.VOB.

 

3. Remuxing a m2v file back into the demuxed Cell-ID/VOB file.

Open VTS_02_1.VOB with VobEdit:

Select the Menu-Item 'Remux m2v':

Choose the transcoded m2v file, in the filedialog:

A second filedialog apears, where you must select a destination directory, for the remuxed VOB file

Please select a different directory and don't change the filename!:

Now we've got a transcoded VOB file:

Now we need to get this back into our Title-Set.
First we must again demux this VOB file into it's Cell components.
You simply have to repeat the steps of the top of this guide.
So open this transcoded VTS_02_1.VOB file with IfoEdit, and press 'Demux'.
Select again to demux the Cell's, and then specifiy a new empty directory, BUT:
this is the first time you are going to change the filename.
Change the filename to VTS_02_002.VOB, cause later we need to exchange the old demuxed cell-vobs with this new transcoded cell-vobs.

After demuxing, you have a new folder containing these files:

Now simply move this transcoded cell-vob files to your first destination folder, that should look like this:

Great. now just lets join these cell-vob files back to our VTS_02_5.VOB file, and we're finished.

4. Joining the demuxed Cells back to a VOB file or Title-Set.

Open the first VOB file in this directory with VobEdit.

We will open VTS_02_001.VOB:

Select the Menu-Option 'Join CellVob files' to join all files back to a regular VOB file(s):

Again we have to specify a destination directory: (Don't mind the filename! We will change it later to VTS_02_5.VOB)

The joining Process begins:

After that, we've got a regular VOB file back:

That's it.  
Now simply rename it to VTS_02_5.VOB, and exchange it with the original.

Don't forget, the VOB file has got changed, so some navigation pointers in the VOB file aren't correct anymore, and some pointers in the original IFO file doesn't point correctly too.

So if you want to burn this to DVD-R, you must first process the IFO and this VOB file with IfoEdit to correct the ifo-tables, and the vob-unit navigation pointers in the VOB file itself.