Replaced Credits in PGCedit/VOBblanker & lost audio

[meRobs]

I have a DVD with 2 audio streams (5.1 and 2-ch) and I wanted to delete the 5.1 stream then replace the 2-ch with an edited (smaller) version of the Credits. I want to replace the 2-ch stream because my route for editing is via Premiere which can only output stereo and then in MediaCoder I can convert to AC3 for muxing back into VOBblanker.

First, in PGCedit, I forced the audio stream to stereo (stream 1) then used Trace to Jump to PGC on DVD insert. Then hopped into VOBblanker to strip stream 0 and back into PGCedit. Back into VOBblanker I extracted the credits cell to VOB, which I converted to AVI in MediaCoder, edited in Premier and exported as M2V/WAV and converted the WAV to 2-ch AC3 in MediaCoder. Then I muxed the M2V with the AC3 and used the muxed VOB to replace the credits cell (second last) in VOBblanker and returned to PGCedit. The last cell was only 14 frames.

The new credits in the movie plays with audio when directly previewed in PGCedit (??), but not when played via Trace. Similarly, the last VOB in the VTS and the VIDEO_TS.IFO when in a software player (WinDVD) plays audio everywhere but in the credits segment.

What to do?
I did a similar replacement for a DVD with only one stream (5.1) and even though the replacement VOB had stereo audio (thus not matching) it worked!

[r0lZ]

In preview mode, PgcEdit can use any stream, and it tries to pre-select the "best" audio stream automatically. It uses the virtual player config to select the preferred language whenever possible, and it avoids the streams that the player cannot play (DTS, MP3...) Of course, if there is only one stream, it tries to play that stream.

In trace mode, the audio stream is determined by the navigation and the configuration of the virtual player. If the stream to play has been forced by a SetSTN command, then SPRM is not equal to 15 and the stream number in SPRM 1 is used. If it has not been forced, PgcEdit determines the stream to play based on SPRMs 15, 16 and 17, like a real player should do.

In your case, I suppose that the player gets confused by the presence of the two streams in the first part of the movie. IMO, it is better to remove the 5.1 stream before processing the other stream. (You can do that easily, for example with DVDShrink.) Since there will be only one stream remaining, there is no need to force it with a SetSTN command. Be sure to encode the audio stream exactly with the same settings than in the original stream. (BTW, it might be easier to demux the whole PGC, with both audio streams, convert and modify the audio, then remux the whole movie with only the stereo stream. You will be sure that there is no encoding differences in the original and edited parts of the audio stream.)

Good luck!

[meRobs]

Thanks r0lZ
However, the movie had two streams and stream 0 was 5.1 which I first deleted in VOBblanker leaving only the stereo stream. Then, I replaced the Cedits cell by a VOB with stereo. So even though there was then only one stream, all cells except the replacement played audio. The problem may have been due to my forcing audio to stream 1 before stream 0 was deleted!

In my next try I kept both streams, no forcing, and replaced the cell with the VOB with stereo. It played when the 5.1 stream was selected on the menu but nothing with stereo was selected. This suggests that the new VOB with a single stream was taken as the first stream, even though it had the wrong characteristice -- it was 2-ch and not 6-ch -- all else being the same.

This was confirmed when I re-burnt to DVD with DVDshrink with the 5.1 stream deselected (only the stereo remained) -- the credits played with no audio!

Hence, can I assume that when matching characteristics for the audio, the only ones that count are the format (AC3) and sampling rate (48 kHz), not kbps or number of channels?

[r0lZ]

Some players are very "tolerant" because they do not take the IFO stream into account (except for the language code) and they get the stream characteristics from the VOB only, but IMO it is dangerous to assume that all players do it. You should copy the stream characteristics of stream #1 to stream #0, then strip or delete the stream #1. (That's easy to do with PgcEdit: in the Domain Stream Attributes dialog, click on the stream characteristics button of stream #1. In the new window, click on Copy. Use the same method to paste the info in stream #0. You may need to change also the language code in the main DSA window.)

Note that deleting a stream in PgcEdit removes the stream reference in the IFO only. The VOB file is not modified, so it is usually not a good idea to remove the IFO reference before stripping the stream, as the program might not know that a stream exists in the VOB if it is not declared in the IFO. (It's the case of DVDShrink, but I don't know for VobBlanker.) Also, if you remove stream #0, PgcEdit removes also automatically the "decoding stream numbers" of all PGCs of the domain. That's not what you want. The program that you use to strip the stream should do it.

[meRobs]

Thanks again for your prompt reply!

Are you suggesting that if I add a stereo cell into a 5.1 stream it works only because the player is tolerant? In other words I should not mix the two types (2-ch nd 56-ch) regardless of the domain data in the IFO?

Then, if a DVD doesn't have a stereo version of the movie I would have trouble adding in a stereo cell!

When you suggested I copy the attributes of stream 1 (stereo) to stream 0 (5.1), was this because both streams would then be listed as stereo in the IFO so that when the actual 5.1 stream was deleted in VOBblanker (leaving only a stereo) the correct IFO data would be present? This assumes VOBblanker doesn't correct the IFO?

[r0lZ]

As a rule, you should NEVER mix streams that do not have exactly the same characteristics. If you want to replace the stream of a cell with a stereo stream, you have to convert the stream to stereo in the whole domain. (I'm assuming that VobBlanker cannot patch the audio stream you provide in the replacing cell so that it matches the characteristics of the other cells, but again I don't know.) Anyway, if the stream characteristics change abruptly during the playback, that's even worse than defining wrong characteristics in the IFO, as even if the player ignores the IFO characteristics, it will probably use the characteristics of the first VOB cell it has to play and it may hang when the characteristics change.

I may not have understood correctly the method you have explained in post 1. I have assumed that the original stream #1 was stereo, and that you have removed the stream #0. If it's the case, you can, of course, replace the credit cell stream with an edited stereo stream (if they have the same characteristics), but in that case, you should not need to "force the audio stream to stereo (stream 1)", as you did. So, I repeat my suggestion: demux everything, edit the whole stream, and remux everything.

I have a preferred method, and I have never had any problem: I use PGCDemux to demux the whole PGC (all streams + celltimes.txt), I remux everything with muxman (minus the streams I don't want to keep), I re-import the remuxed title with PgcEdit, and finally I fix the SetSTN commands (so that the audio or subpic menus continue to work as expected). The advantage is that you can do almost what you want with the streams, as you rebuild them completely. However, that method is easy only if the VTST domain contains only one PGC, with no angles. And I don't use Premiere, so I don't know if what it does is compatible with my method.

[meRobs]

(1) When you say demux the whole PGC, do you mean the entire movie (4-6 VOBs)? In other words, somehow Extract all cells in the movie via VobBlanker to one large VOB, demux to M2V and 1 or more audio streams. Then, to edit the credits section I would need to convert the M2V to AVI, say, and bring it into Premiere with the AC3. Once edited, it would export to M2V and PCM (or MP2) and I could convert the PCM to AC3 in MediaCoder. Trouble is, I may lose sync over the movie and I would lose the chapters.

(2) If the movie has only one stream, say 5.1, and I extract the last non-empty cell to edit the credits and to replace the cell with a 2-ch version, I gather the worst that can happen is that a Player will not play the audio in this edited cell, just the video?

(3) If the movie has a 5.1 version and a 2-ch version of the normal dialogue and I wish to delete the main stream (stream #0) and edit a cell with only the second stream (was #1 but then changed to #0 after removal of the 5.1) so that all will be stereo, I assume that I could do this by going to VobBlanke to strip the 5.1 stream and replace the last cell of the remaining stream. If I need to return to PGCedit to fix the IFO by 'deleting' stream #0, then not doing so may have been my mistake (I had assumed either VobBlanker had fixed the IFOs or that on returning to PGCedit, it would notice the change and auto fix the IFOs)!

[r0lZ]

You should not demux the individual cells, but the whole PGC as a single m2v, + one file per audio and subpic streams, and the celltimes.txt file to rebuild the chapter points later with muxman.
Not sure why you would need to convert the m2v to AVI. If Premiere can only load AVIs, then use a better authoring program ;-) or try to frameserve the m2v to Premiere.
I'm not familiar with the A/V sync problems of NTSC material, but with PAL DVDs, I have never had sync problems.

Some picky players may even completely hang if they get confused by a stream characteristics change.

Anyway, if you prefer to edit only one cell, you should strip the useless stream FIRST, create a copy of the DVD with only one stream, and change the credits cell on that DVD. I suppose that VobBlanker appends the audio stream #0 of your replacing cell to the audio #0 of the original DVD. That's obviously not what you want.
Also, the stream ID in the VOB must match, so IMO it is best to remux everything before processing the credit cells anyway (just to be sure that the remaining stream occupies really the first "slot" in the VOB files.)

IMO, you are doing a very complex job just to shorten the credit cell. Is it that important? Do you know that it is possible to use DVDShrink in Re-Authoring mode to shrink the credits much more than the rest of the movie? You can also truncate the end credits (but the audio will be abruptly truncated). You can even replace the credits by stills (however, the resulting video does not play well on some players).
Another solution is Womble Mpeg Video Wizard DVD. It can truncate the VOB file where you want, and you can create a fade out in the sound and/or the video. It re-encodes only the modified parts. But it is not free, I hate its GUI, and you will have to generate a new DVD, and re-import the new title over the original with PgcEdit.
Anyway, it seems that Premiere has too many limitations to be really usable to edit a DVD.

[meRobs]

Thank you for all this effort on your part!

Just to finish up: Premiere like most pro editors is an NLE pgm and is designed for DV AVI input or other quality files (all frames I-frames -- not compressed). My main reason for editing the credits is to (a) reduce the size, (2) add a short ending video of my own creation and take out segments or re-arrange them for more interest to me -- all smoothly. Not truncated! I can truncate a VOB and remove all but one audio stream in AviDemux and export as another VOB.

Looks like too much trouble?!!

By the way, how do I demux the entire PGC? I must have missed that somehow.

[r0lZ]

You can perhaps use frameserving to open the VOB files directly in Premiere. Search the D9 forums and help. This technique has already been discussed several times. Its main advantage is that you don't need to convert to AVI. The frame server provides a "fake AVI" to the application, that thinks it is a real uncomprerssed AVI. It's really a fine technique, but somewhat complicated to understand, and you have to use the right tool so that Premiere will accept it.

By the way, how do I demux the entire PGC? I must have missed that somehow.
Use PGCDemux (by jsoto) in PGC mode.