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Multi angle DVD calculating

 
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Reverb



Joined: 26 Jun 2006
Posts: 2

PostPosted: Mon 26 Jun 2006, 11:01    Post subject: Multi angle DVD calculating Reply with quote

HI there,

New to this forum so I hope I place this question in the right board.

I'm trying to make a multi-angle DVD.
I have an original film (DVD) and some footage of a diffrent angle wich I want to add to the original film.
As it is a music video I would also like to add some different audio tracks.

I've used FCP to create the streams to author in DVDSP.

Now I would like the DVD to contain the following:
Video: 2 tracks
Audio: 1 PCM. 2 AC3 dolby 2.0, 1 AC3 dolby 5.1

However I'm having problems with a too high bitrate.
So Maybe I should go for the following configuration:
Video: 2 tracks
Audio: 3 AC3 dolby 2.0 tracks

I've been trying to use the bitrate calculater on this site (wich has helped me a lot in the past) However for the first configuration I came up with a bitrate of 5700. Is that for both video tracks? so that each video track can only be 2850

For the second I come up with 7200.
wich would be 3600 per track if I'm right. Wich is still a bit to low for me.

Ok here are my questions...
Am I right about the calculator that I should use half the bitrate per video track?

Is there another way to get the bitrate/quality of video up?
I've been using QT->mpeg2 exporter, as I've had GOP troubles with compressor.

Thanx
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RMN
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Joined: 04 Feb 2003
Posts: 587
Location: Lisboa, Portugal

PostPosted: Tue 27 Jun 2006, 4:47    Post subject: Reply with quote

Multi-angle support varies between different players, but the specification imposes a limit only on one video track plus all other (audio and subtitle) tracks. In other words, if you have multiple video tracks, you only need to take into account the track with the higest bitrate when calculating the limit. So no, you don't need to divide it (but remember that the limit for multi-angle DVDs is 8 Mb/s, not 9.8 Mb/s).

Regarding the compression, remember that multi-angle DVDs need to use a consistent GOP structure (i.e., picture types must be identical across all video streams), so you'll need to turn scene detection off in your compressor (and place GOPs manually or semi-manually if you want to avoid "dancing blocks" when a scene change lands on a P or B picture).

RMN
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Reverb



Joined: 26 Jun 2006
Posts: 2

PostPosted: Tue 27 Jun 2006, 12:57    Post subject: Reply with quote

Thanx for the helpfull answer...

However I'm still expierencing the "Video Bitrate too High" error in DVDSP3.

Any of you here got expierence with it?

A thought on what might be wrong:
The second angle consists of 18 small clips. Are these seen as individual streams?
If so I understand I have to re-edit these clips into bigger ones so the stream count goes down and my max bitrate goes up.

edit: Nope it ain't that...
It has something to with either GOP structures or the 2-pass VBR
exporting I do using QT conversion.
helpfull stuff can be found on the apple support discussion pages
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RMN
Site Admin


Joined: 04 Feb 2003
Posts: 587
Location: Lisboa, Portugal

PostPosted: Fri 30 Jun 2006, 5:03    Post subject: Reply with quote

Like I mentioned above, the GOP structure needs to be consistent across all angles. In other words, the picture type (I, P or B) of frame N on angle 1 needs to be identical to the picture type of frame N on angle 2 (and so on for other angles, if you have more than 2).

If one of the angles is made up of multiple MPEG-2 clips, it's almost impossible to ensure this consistency.

You need to compile each angle into a complete movie (before MPEG-2 encoding) and then encode each of them to MPEG-2 using the same GOP structure, and no scene change detection.

If you're sure all your streams have the same GOP structure, try reducing the bitrate progressively, until your authoring sofware accepts the files. Make a test with small (ex., 10-second) files, so you don't waste a lot of time encoding.

RMN
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