Gapless Audio Only DVD?

mr_pickles wrote on 10/17/2004, 12:48 PM
I have some really long, audio only, live performances (one 4 hours, the other 8 hours) I wish to put onto DVD, but I'm having problems with DVDA.

I have cut the audio files into segments and put these into a music compilation. When I preview them in DVDA they play perfectly from one track to the next, but when I burn the project onto disc there's a very brief gap between each chapter -- where the segments are joined.

Is there any way to eliminate this gapping in DVDA or do I need something more robust like DiscWelder?

I know that this can be done somehow with an audio only DVD (not just DVD-Audio) because I have a Morton Feldman audio DVD (String Quartet No. 2 on Mode Records) that's over 6 hours long (24bit 48khz) with 28 chapters and they all segment seamlessly.

Any tips?

Comments

kotsos wrote on 10/17/2004, 3:03 PM
F
mr_pickles wrote on 10/17/2004, 11:25 PM
Ummm... F
I guess I didn't think of that. F might work.

Did you accidently hit "post message" before writing your response or are you the master of cryptic help?

F indeed, Forsooth!
bStro wrote on 10/18/2004, 7:52 AM
Geez, if you don't want to take his advice, then don't. No need to get sarcastic with him. ;)

Incedentally, if you do take his advice and it doesn't work, you could also try...

G

Rob
jetdv wrote on 10/18/2004, 1:34 PM
If they are, indeed, separate files, you will have slight gaps when it changes between files.


Or, possibly... H
Chienworks wrote on 10/20/2004, 8:56 AM
Well, i won't be so bold as to suggest I (in fact, being rather a conservative sort, i'm still trying E). However, i will take a completely different tactic and make an observation.

Recall that DVD players can all behave differently. When you preview in DVD-Architect the preview function simulates a DVD player as best as it can. However, which one is it simulating? Apparently it's simulating one which has a very minimal pause between tracks. Other players may be designed to have larger pauses, either deliberately, accidentally, through cheaper design, sloppy programming, or simply because they are following specifications which allow the pause. That being said, even if your goal was achievable on some players, it might not be on all.

I do agree with the idea that a seamless audio DVD is probably made from a single audio file with chapter points inserted. These would seem consistent with getting seamless video playback from a single file compared with the gaps that result from each chapter being a separate file.
johnmeyer wrote on 10/20/2004, 10:33 AM
Would this work?

1. Put all the audio files in Vegas.

2. Use the Events to Markers script to put markers between each AC-3 file on the Vegas timeline.

3. Render to one big AC-3 file.

This should make a chapter marker file that can be read into DVDA. If not, you can use the script that exports chapter markers into a format that can be read into DVDA.

Since the audio is all in one file, there will be no gaps or pauses.
JSWTS wrote on 10/20/2004, 11:51 AM
I think the problem here is that the audio streams are so long. You could definitely fit the streams on a disc, but you would have to use "I" frame only encoded video stream components (ie still images) to be associated with the audio file. Otherwise, if you use a video stream the file sizes associated with that will be too large to fit on a disc. If you output a ac3 file only and use a chapter script, then my bet is that DVD-A will have to treat that like a movie clip. DVD-A is not set up to take chapter marks within an audio stream. You could associate an audio stream with a slideshow, which would give you 99 chapters. Most authoring apps at this price level allow for 'I' frame only slideshows--ie a single I frame is used to display each slide rather than creating a video stream for the slides. The difference here is the file size differences. With I frame only encoding, the total file size can be only a few mb's. With video stream creation for slides (which is what DVD-A does), the file size will be equal to the duration of the audio stream multiplied by the default encode bitrate set within DVD-A, which is just like any video stream--large. In short, I don't think you can accomplish what the poster wants to do within DVD-A, unless it would be 'OK' to have a 'music compilation' with one or two very long audio files (and no chapters). For some reason, DVD-A will create what appears to be an "I" frame only picture that is associated with the audio stream (but not when a slide show is made--go figure).

Jim
johnmeyer wrote on 10/20/2004, 4:57 PM
I played around with this a little, and have it about 90% of the way figured out.

1. Put your audio on the Vegas timeline.

2. Insert the shortest AVI file you can find onto a video track. Just a few frames.

3. Render the AC-3 file.

4. Open DVDA.

5. Drag the AC-3 file into the project pane (left-hand pane). From there, drag it onto the main menu (DVDA won't let you drag it directly onto the menu, but seems perfectly happy if it comes from the project menu).

6. Double click, in the left-hand project pane, on the AC-3 file.

7. In the right-hand pane, double clik on the Track Media: Video and assign the same small video file to this AC-3 file that you used in Vegas.

8. On the DVDA timeline, you can then assign chapter markers and save them. The "dummy" small AVI file gives DVDA a placeholder for saving them.

9. Double-click on the main menu and delete the background media audio. In step 5 above, the AC-3 file gets assigned simultaneously to the button being placed on the menu, and to the menu itself.

I didn't figure out how to export the chapter marks from Vegas and get DVDA to import them (I need to look at the binary for the SFL file, and I didn't have time).

Also, I didn't try to do this for a really large compilation. Given the 99 chapter limitation, you will have to create multiple AC-3 files if you have more than 99 chapters, and there will be a pause at that boundary.

However, I think this approach will do almost everything the original poster asked for. The two "tricks" are to use a "dummy" short AVI file to act as a placeholder for the chapter marks, and the other is to drag the AC-3 file to the project pane first rather than directly onto the main DVDA menu.

I didn't actually try to burn and play a DVD, and that will be the proof of whether this really works.
JSWTS wrote on 10/21/2004, 5:00 AM
John,

I think you should try building a disc and emulating it (so you can avoid burning a coaster) on your hard drive--it won't work.

DVD authoring apps typically trim the audio to fit the video, so if you have a short video file, the audio would be trimmed to match it. Perhaps some will just put in 'filler' blank video space to match the audio (which I doubt), but even if it did, it would make a long video stream with a huge file size.

DVD-video discs are 'video' driven (unlike dvd-audio). It is the video asset that defines the duration of playback. You can have a 'music' compilation, but it really is a still pic with audio in the background. Even if you don't set an image for you music pieces, DVD-A will put a black background still. It's encoded as a single "I" frame, and the ifo file tells your player how long it should be displayed. If you used a one hour ac3 file as one of your music compilation pieces, that sinlgle frame would only be a few kb or so. If you used it as a slideshow in DVD-A (one pic to display for one hour), the file size would be gigabytes since DVD-A converts it to a video stream to match the audio.

Jim
johnmeyer wrote on 10/21/2004, 1:51 PM
I think you should try building a disc and emulating it (so you can avoid burning a coaster) on your hard drive--it won't work.

Well, based on that challenge, I went ahead and prepared the disc and then played it in WinDVD.

It works perfectly.

I get ten seconds of video at the beginning of the audio (which is the length of the random AVI file I grabbed to put on the timeline), and then I got the audio. The chapter stops worked perfectly. The video simply went black after the five seconds of audio.

The size of the input twenty minute AC-3 file was 31 KBytes. The size of the main VOB file was 74 KBytes. I assume that most of this small difference was the few seconds of video.

I didn't burn a test disc, but I'm pretty sure it would work. Bottom line: it works, and the audio is seemless, just like Mr. Pickels wanted. I think I may try using this technique to create a mega audio DVD that will play in my media setup.
JSWTS wrote on 10/21/2004, 4:09 PM
Go for the gusto and use a 4 or 8 hour ac3 file like the poster listed and use the 10 second clip. I'd be curious as to if that works, especially on a set top player. Software emulation on a PC is more forgiving, but it looks like you may have passed that hurdle. I may have to reload DVD-A and try it myself, but I just cleaned out my system. I'd be curious to see how a set top player handles chapter marks with essentially no video or image associated with it.

If you want to make a mega-audio dvd, you already can with the music compilation. You can have a jacket picture of the song or cd as your background pic as the song plays, or just a blank background. In either case, DVD-A treats it as an I frame only encode and the video piece of the overall file size is quite small. You probably could make a disc that lasts for days.

jim
johnmeyer wrote on 10/21/2004, 8:44 PM
Go for the gusto and use a 4 or 8 hour ac3 file like the poster listed and use the 10 second clip.

I don't have the time for that test, but I will go ahead and burn the twenty minute AC-3 file that I mated with a five second clip. I'm burning to a DVD-RW right now, and when it's finished I'll play it on a Pioneer DVD-525 set top player.

I'll report back shortly ...

[Edit] It's five minutes later ... yup, it worked perfectly. It played "gapless" through the chapter stops, and it played at the beginning, middle, and end of the twenty minuts of audio. The five seconds of video played at the beginning, and then the TV went blank.

I really do think that this works ... honest!

JSWTS wrote on 10/22/2004, 5:15 AM
I'm not doubting you john, and it certainly wouldn't hurt for the poster to give it a try. I just wouldn't be surprised if the disc doesn't navigate back and forth between chapters reliably when all is said and done. If it's for one's own personal use and it works on your player(s), it really doesn't matter. If it is something that will have a broader audience and the potential for playback on a number of players, then I still would have some reservations. It's tricking DVD-A to do something it 'doesn't' do on paper. I've made music compilations with dvd-a (several hours long) and navigation between songs didn't always work like it did on my PC, often jumping to the wrong spot (and this is a supported feature).

Jim
johnmeyer wrote on 10/22/2004, 9:19 AM
Jim,

You are the definition of a tough sell. I guess I could burn twenty copies and send them to friends, but I've come to the end of what I'm willing to do on this. I am reminded, however, of the old story about the bumblebee:

According to all engineering calculations, the bumblebee has a body that is too big, and wings that are too short to allow it to fly. However, despite these calculations, the bumblebee continues to fly.
JSWTS wrote on 10/22/2004, 11:03 AM
john,

I'm sold, I truly believe you.

Maybe I spend too much time on professional forums, where getting it to work on one's own computer/set top is not good enough. Without trying to presume too much, it sounds like the original poster is doing it for his/her own use. If it works for them, who am I to argue? My only point here was that it was done by 'tricking' DVD-A. Unless you are using Scenarist, most, if not all, of the authoring apps out there use abstraction layers to insulate the user from the 'code' of dvd authoring. Abstraction layers in themselves can create problems with playback. You don't have to stroll very long on this or other forums dealing with other authoring apps to find people who have had playback issues. Doing something with an app that is somewhat outside of what it was designed to do only increases the odds of problematic playback. The greater the audience, the greater the chance for failure and it would be better to find an app that does this without 'tricking' if your business depends on it. I have an Apex player that you can throw just about anything at it. I have a Sony that barely reads a DVD-R. I have had problems with music compilations made within DVD-A. They were actually audio books with each chapter in the compilation associated with a chapter in the book. Navigation back and forth was sporadically correct, and highly variable depending on the set top player. They always played on my computer just fine. This has happened to more than one disc, so unfortunately the experience is reproducible. It generally would only require me to reload the disc and try again, so it wasn't 'fatal'. However, I definitely wouldn't mass produce such a disc. I post this not to question your efforts, but as a cautionary note. Nothing more or less.

Jim