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  1. Hello to everybody,

    I was trying to improve a custom edit of a film to include a small multi-angle segment at the beginning. For everybody to understand it, the film is Star Wars and the multi-angle chapter is the one containing the initial scrolling text in different (two, to be precise) languages.

    I have the main film file, which I've previously used to author a single-angle version without any problem. Then, I have the alternative scrolling text segment encoded as another M2V file. I've created a Multi-Angled VTS inheriting the previous single-angle structure (to keep Menus, which are meticulously done). Then, I've used the main movie M2V file as Angle 1 and I've added the alternative scrolling text file as angle 2. Audios and subtitles remain the same as they were in the single-angle version, so I just drag them to their places.

    To "invoke" the alternative scrolling text of Angle 2 at the precise moment, I added an VM Command at Chapter 2 of the main movie, which contains the original scrolling text. Following the DVD-lab PRO help file, I used "SetSTN (audio=1 angle=2)" to make the alternative scrolling text angle 2 appear when audio 1 is selected.

    Theoretically, up to here everything is fine. But there is one great problem: For an unkwonw reason, the compilation fails everytime. At the "Interleaving VOB streams" step, I get a Runtime Error which says "Abnormal program termination".

    I've tried removing the VM Command line, but it will fail anyway.

    I don't know what I'm missing. The Multi-angle part of the help file is really poor, and I've not found a lot more on the internet.

    Thanks a lot!
    Last edited by trotskito; 25th Oct 2021 at 09:02.
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  2. Member DB83's Avatar
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    From that same help file :-


    Encoding Video for multi-angle Title


    Very important part of creating multi-angle title is the encoding. The angles must be encoded all with the same parameters, most importantly bitrate and GOP structure. That means you should encode each angle using the same MPEG encoder and same settings. The video must be encoded using Closed GOP (check settings of your encoder) otherwise there will be a very visible picture disintegration during angle change.





    Parameter

    GOP
    Closed GOP
    Bitrate
    max 8000kbps per angle
    GOP structure
    fixed, same in all angles (not variable GOP structure)







    GOP structure - it is important that all angles have the same GOP structure (same sequence of IPB frames, same number of frames per GOP). Few encoders will create a "flexible" GOP structure - that is they will sometimes add or remove frames within GOP as they see it fit and therefore no two angles will have the same GOP structure. (TMPGENC and standalone encoders are known for creating flexible GOP)


    This may result in a player lockup or even a crash.


    Mainconcept Encoder and Video editing Tools based on Mainconcept Encoder usually work well for this purpose.
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  3. Hi DB83 and thank you for your answer.

    The two files are encoded with the same parameters. Both were done with AVStoDVD (raw output) using HCEnc 2 pass, closed GOPs and, although variable, practically the same bitrate.

    By diving in old threads here at VH and in other forums, I am guessing the problem may have to do with the two files not being the same length, as one is the whole film and the other just a tiny chunk at the beginning. Could it be that DLP does not allow the same stream having Multiangle parts and single ones? Albeit this would be extremely limiting, it seems that DLP is not very friendly to Multiangle purposes...

    Thanks again!
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  4. Member DB83's Avatar
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    This is not something I have actually done and, TBH, I have not seen a multi-angle dvd in a heck of a long time


    I do not think an angle has to be the entire length of the main video. Surely you can place it on the timeline just where you want it to start.


    But I would still look at the encoding. HCEnc is stand-alone and the text does mention a GOP length issue.
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  5. Member Cornucopia's Avatar
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    IIRC, while the multi-angle doesn't need to be in use throughout the timeline, it does need to have the same multi-angle option throughout that title (or chapter?). IOW, if you plan on having for example 3 angles for a segment, it has to be provisioned for 3 angles for that whole timeline segment.
    Also, The GOP structure needs to be identical between the different angles, at their sync points, so if Angle 1 is closed GOP, rigidly IBBPBBPBBPBB... starting from 00:10:32:00 and going to 00:16:24:18, then angles 2 and 3 would need to be that exact same structure at those exact same points in time. Because, both (or more) of them are in memory, and the I frames need to sync up so that the transition from stream to stream is as instantaneous as if it stayed on the same stream.

    There are also ADDITIONAL bitrate constraints when dealing with multi-angle streams, because without it, there would be buffer over/underruns. The documentation should say. I wrote it out here on VH long ago, so you might find it here as well.
    So, if normal Vid max is 9.8Mbps, with 2-3 angles it might be 8.0, 4-5 angles might be 7.6, and 6-9 angles might be 7.1, or something like that.


    Scott
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  6. Yay! It seems this multi-angle business is way more complex than I expected. It seems I will have to recode the original main video too to begin properly with it.

    Thank you very much for your answers!
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