Joining M2V & AC3 files for DVD burning, Subtitle creation sub position

[blue2]

Hello. Could someone kindly answer two basic dvd authoring/editing questions, as I'm reasonably new to this.

How does one join a pair of demuxed M2V & AC3 streams into single M2V and AC3 files for burning to a seamless DVD?

I have a long video recorded off air that I have split into two parts and then dubbed to two DVD-RW. (Done in two parts to preserve high quality). Now I have demuxed both of these DVD-RWs on my computer using PgcDemux into the individual streams, is there a simple way to recombine these two M2V and AC3 streams into single files so I can add in a subtitle file and then re-multiplex the recombined M2V, AC3 and sub streams using Muxman and burn them to a single DVD Double Layer using ImgBurn? As there are no DVD+RW DL discs, this seemed to be the only way to create high quality dubs without wasting a DL disc for transferring the temporary file without subs.

Also, is there a tool for determining the display aspect ratio of the M2V file so I can then pre-determine how the position of the added subtitles via Subtitle Creator will then look on a 16:9 TV as my computer is not widescreen? Although SubtitleCreator has a background menu, I have difficulty determing if a video image is 1.66:1 or 1.78:1 or 1.85:1 to judge positioning.

Many thanks for any suggestions.

[manono]

Hi-

How does one join a pair of demuxed M2V & AC3 streams into single M2V and AC3 files for burning to a seamless DVD?

Muxman will do it. Open one, and in the screen that opens up hit "Add" to add the other. Since you mentioned using Muxman, you should know this already.

As for the subs, it takes them in SUP format, so if they're in something else, they'll have to be converted.

Also, is there a tool for determining the display aspect ratio of the M2V file...

A ton of them. One way is to open the M2V in DGIndex and run the Preview (File->Preview). It'll show in the Information screen that opens up.

I have difficulty determing if a video image is 1.66:1 or 1.78:1 or 1.85:1 to judge positioning.

But that's different from the DAR (4:3 or 16:9). If, when done, you don't like the subs' position, you can easily raise or lower them using DVDSubEdit.

[mats.hogberg]

AFAIK, ac3 is headerless, so can be joined by simply concatenating them:

copy first.ac3+second.ac3 b:both.ac3

For the m2v, I'm only guessing, but mpg editors like VideoReDo ought to be able to do that.

/Mats

[blue2]

Hello. Thanks for the replies. I was not sure if Muxman joined the files as one seamless file or if this would create audio/video synch problems and as well if it would break the timing in the subtitle so it would then be out of synch at the junction where the second set of files was added.

Yes, I do know about SubtitleCreator only taking SUP files, and I've converted an SRT using the program. I was wrong calling it the DAR. What are 1.66:1 and 1.78:1 and 1.85:1 called in the background menu and how do I determine which one my file is closer to so I can then position the subtitles accordingly?

Thank you again.

[manono]

Hi-

Muxman joins the M2Vs seamlessly, but there could possibly be 2 frames of corruption if you used Open GOPs and there's active video at the join, as opposed to black screen. I join video all the time and it works well. No pauses or delays at the join. I've never joined audio, but it should work the same way, I'm sure. If you do get out of synch audio after the join, you would have gotten it anyway, and you'll have to start again and delay the part 2 audio by the right amount using DelayCut, so that when you join them again, there's no asynched audio. The subs will be OK, even with joined audio and video.

What are 1.66:1 and 1.78:1 and 1.85:1 called in the background menu...

Hehe, there probably is a term for that. I just call it the movie aspect ratio. I don't use Subtitle Creator for the subs, so I can't help there. But as I said, DVDSubEdit can easily fix them if you're unhappy with the positioning later:

http://download.videohelp.com/DVDSubEdit/UserManual/helpfile.htm

Section 2.7

[borax]

Demuxed M2V & AC3 streams can be joint with Mpeg2Schnitt or Cuttermaran. The result will be new (just joint) M2V & AC3 streams.

[blue2]

Manono, I tried the Muxman option and while the video joins perfectly, so the subtitles remain in synch, the audio is goes out of synch at the join point as I had imagined might happen. Rather than being delayed, it looks advanced to me.

My objective was to try to transfer a film via DVD+RW in two parts (thereby preserving quality), and then re-assemble them on computer so that I can add subtitles in, and burn to DVD+DL. However, if I have to re-process the audio streams, I wonder if this will end up betting better than simply transfering the material in standard compressed quality on one DVD+RW and avoid having to do any post-transfer re-processing of the streams. I could also transfer via DVD+DL, but then I'd end up wasting a DL disc every time I transfer to add subtitles in.

I can also look into Cuttermaran. But before this, I am now going to try mats suggestion and see if I can simply combine the two audio pieces together BEFORE using Muxman as this perhaps might solve the audio synch problem.

[manono]

Rather than being delayed, it looks advanced to me.

Delay is a general term used when you fix the out of synch audio because a delay can be positive or negative. Like I said, it would have happened anyway (if following mats' suggestion, for example), because the part one video is slightly longer than the part one audio. It's easily fixed. You just have to know the amount of the delay and then add that amount of silence to the beginning of the part 2 audio before muxing again. Other than adding silent audio to the beginning of part 2, the audio is untouched and unreencoded and undegraded. Here's one way to fix the out of synch audio:

Open an out-of-synch VOB file from the 2nd half of the movie in Media Player Classic. Right-click the screen and go Options->Filter->Audio Switcher->check the "audio time shift" box, and fill in an estimate of the amount of asynch. Hit "Apply" and test it out. Negative values are to make the audio play earlier. 1000 ms= 1 second. You'll want a positive value, because you want the audio to play later. Resume playback. Adjust until you get it right. At that point you'll know how much the audio is out of synch and how much to set the delay for the part 2 audio in DelayCut. The fixed audio should be very slightly larger than the original audio, because of the silent audio appended to the beginning. When done, remux with Muxman, this time using the fixed part 2 audio.

When done with MPC, uncheck the box and set the audio time shift back to 0.

[blue2]

Hello manono. I tried mats suggestion but it would not even copy the first file correctly. A 100,000kb audio file resulted in a 5kb copy. It took me some time to discover that the copy command requires a special switch (/b) to work with binary files, i.e. copy /b firstac3file.ac3+secondac3file.ac3 all.ac3 /b.

The resulting file was then out of audio synch after the point where the files joins. What I don't understand is why this happens with a AC3 file, when I used to split or join files in AVI without any synchronization problem. I also can join the two files back together on my salon DVD burner (which I used to split the file in two) and it will join perfectly without this synchronization problem.

When I said that the audio track looked advanced rather than delayed, I was expressing surprise that audio falls behind the video (not surprise that delay can be positive or negative) since I never saw audio in advance of the video in working with AVI files that had synch problems. Inevitably it was always the audio that fell behind.

Of course Muxman allows one to adjust audio synch problems, so I would need to do the hit or miss approach you mentioned in MediaPlayer or another to see how much the synchronization is off, the adjust the audio of that second part and then mux them.

But again, this seems to be an awful lot of work of achieving the simple objective of cutting a file in two to transfer it in high quality via DVD+RW and then re-assemble the two pieces back together on computer.

[manono]

What I don't understand is why this happens with a AC3 file, when I used to split or join files in AVI without any synchronization problem.

AC3 has nothing to do with it. It happens when the part one video is longer than the part 1 audio, no matter what kind of audio it is. You've been lucky until now.

I also can join the two files back together on my salon DVD burner (which I used to split the file in two) and it will join perfectly without this synchronization problem.

I have no idea what a salon DVD burner is, but if they are made into 2 different titles, the issue doesn't occur. But you'll have a slight pause between the 2 titles. You specifically said that you wanted a seamless join.

But again, this seems to be an awful lot of work of achieving the simple objective of cutting a file in two to transfer it in high quality via DVD+RW and then re-assemble the two pieces back together on computer.

So don't do it. Seems pretty simple to me. Once I mux and find out about the audio delay, I find out how much the delay is, fix it in DelayCut, and remux.

[blue2]

Perhaps I have not explained myself well enough.

I don't believe it has been luck and I still don't understand why video would be longer than audio. By salon dvd burner I was referring to a stand alone dvd recorder/hard drive. When one dubs from hard drive to DVD+RW, cutting a recording into two pieces, the cut is perfect. They become two separate titles and the resulting files are two seperate dvd files with separate dvd structures.

Now that I have two dvd files, I take them to my computer to add subs, and would then like to find a way to re-join the two pieces back together into one dvd file to burn onto a DVD double layer. However, when I try to re-join the demuxed elements of these two pieces back together on computer, the video joins perfectly but the audio is out of synch after the join point. I don't get that. Why would the video be of a different length than the audio since they come from an original file cut into two and if the length is wrong on one piece, it should be wrong on the other piece as well!

In fact, I'm sure that if I went back to the two original dvd pieces (before they were demuxed into elements) and joined them on the dvd recorder/hard drive, the joined piece would be in perfect synch. So the issue seemed to me to have to do with how AC3 files are joined, or how two AC3 files are remuxed back together.

Let me use an analogy. If a cut a piece of paper into two pieces, write on each of them, I can join them back together perfectly. So it seems hard for me to understand why cutting a video file into two pieces creates a synchronization problem when I try to re-join them.

[manono]

If you had done as I had suggested (fix the delay using DelayCut and remux), you'd be finished by now. I'm getting tired of repeating myself. Maybe someone else wants to take over. Good luck.

[blue2]

That's ok, you don't have to help me. I'm not trying to make you repeat yourself. I am trying to understand why something that doesn't seem logical would occur. Perhaps that is too much to ask.

I was also trying to be sure you understood what I did, as it was not clear to me that you realize that as you stated "I have no idea what a salon DVD burner is, but if they are made into 2 different titles, the issue doesn't occur." AND THAT IS EXACTLY WHAT I HAVE DONE (created two different titles) AND THE ISSUE DOES OCCUR. Perhaps someone else, with more patience, can explain that.

I also asked what are 1.66:1 and 1.78:1 and 1.85:1 called in the background menu of SubtitleCreator and how do I determine which one my M2V file is closer to so I can then position the subtitles accordingly? Obviously they were put into the program so one can choose the right one and I was asking how one does that, guess? Rather than having to install and use yet another program to re-position them as you suggested, I merely asked if the video file provides this information. Again, this is being too inquisitive I guess.

In any case, if this is too much trouble, I can go somewhere else and ask my questions or simply give up. It isn't a problem.

[borax]

Have you tried joining with mpeg2schnitt or cuttermaran yet?

Concerning your paper analogy:
A multiplexed video is not like a single piece of paper. You could rather think of two papers (video and audio) which have been sliced and put together in alternating slices. If you now cut at a specific position, you may cut within the video, within the audio or between them. Either way there may be some loss of one or the other. It depends on the cutting program, what it does at the cut point. It could add some empty ac3 frames at the end of piece one to keep video and audio the same length, or do something similar at the beginning of part 2.

Your salon player may be able to join them back seamlessly because of some meta information it stores somewhere, but no other program can interpret this information even if the meta information is stored in the structure.

[blue2]

Hello Borax. Thank you for that helpful explanation. I always like to know why something happens, because it may suggest other ways to solve the problem.

I have downloaded Cuttermaran and will try it. Obviously everyone has their favorite program and as I don't do this all the time, I always try to see try to see if the programs I already have can solve it first, as programs have a habit of replacing DLLs and creating other problems.

So if I understand correctly, one cannot "splice" and rejoin video without possibly creating synchronization problems. Can one minimize this then by cutting video at places where there is no audio and video, such as black frame transitions?

Do you also know if there is a way to look at a M2V file and determine if it is 1.66:1 or 1.78:1 or 1.85, so I can chose accordingly in SutitleCreator?

[borax]

On DVDs (except DATA DVDs with avi files) the only permitted ratios are 4:3 or 16:9. As this is usually a flag in the mpeg file, cuttermaran will show you which one it is.

Concerning cut and join... You can cut and rejoin without any problems, but it is not easy, and it is only possible at 'special' positions. These are determined by the structure of mpeg files, not by 'content' like black frames. 'Good' cut programs like mpeg2schnitt or cuttermaran have a special logic to keep sync problems as small as possible (< 1 frame).