Video bitrate too high (multi angle)

Hi all,

I'm trying to make a DVD of a concert with multi angle view (one angle showing the edited version, and one angle showing top camera only). When I want to build a test DVD in DVDSP2, I get the error 'video bitrate too high'.

Here are the settings:
VBR 6.00 (maximum 7.00)
AC3 encoded audio

The duration of the track on the test DVD is about 10 minutes. The final DVD will have 2 or 3 tracks of 10 minutes (all tracks with multi-angles).

Appearantly I need to lower my VBR, but what is a generally good setting? (Or isn't there one?)

Marco

In addition: my AC3 is surround sound, 5.1 with a data rate of 448 kps. This is the correct setting I guess?

If anyone can help me with a suggestion, that would be great.
Thanks!

Marco

I lowered the video bitrate to 6.0 / 6.5 (maximum), again the 'bit rate too high' error! How is this possible?

Please can anyone advice?

An average bit rate of 6 is still a bit high. My programs all have a lot of motion, so I'm bit rate sensitive. Still, using max of 7 and average of 4 seems to cover even the more demanding scenes.

Two things to note:

- Always strive to use the lowest average bit rate you can get away with.

- My understanding is that in DVDSP, changing the bit rate for the encoder (in Preferences) only affects NEW assets. You need to re-load the existing assets if you change the VBR in Preferences, or they will remain at their original setting. That could be why you still get bit rate errors after lowering the bit rate settings.

Multi-angle or mixed angle work requires particular accuracy with your encoding. The GOP structures must be identical so that the viewer can switch angles during playback with no problems. If the GOP structures are out of line then you will get the bit rate error.

When you create this footage you need to encode it as closed GOP CBR. Additionally, you must not use an encoder which detects scene changes... a cut through the timeline in FCP is effectively a scene change and unless ALL your footage has these cuts in the exact same spot you will get problems - the encoder will place an 'I' frame at the cut.

In the past I have exported the footage from FCP as a self-contained .mov file, then re-imported it so that it appears as a single piece of footage. I then export this to MPEG, which means that it is free of cuts. It's a workaround, but not a good one!

The way you set up the angles on the v2/3/4 track is also important - you must use the same number of alternate angles throughout the track - it is no good using four alternate angles in one section and only two in another. Also, all of the alternate sections must be the same length, to the frame.

There is a really good section on all this in Martin Sitter's DVD Studio Pro books - it explains it all far better and you would do well to get a copy or at least find it in the library :-)

Thanks for the explanation! In fact I'm encoding it with VBR 5.0 and 6.0 max (using Quiktime conversion), this seems to work fine. I have one timeline with cuts, and one with no cuts at all (Chapter markers are on the same place in both timelines though) - but it seems to work in DVDSP2. I tried 6 different tracks, all with 2 angles.

So if I don't get the bitrate error during the build, than I can assume that the GOP structures are OK, even with different cuts of the timeline? Or can viewers have problems with switching angles after all then?

Marco

I'll be interested to see how you get on. I was referring to the FCP timeline rather than DVDSP, and the encoder is crucial here. Some have automatic scene detection which means where it finds a cut it will encode it as a GOP boundary. if the GOP boundaries don't line up precisely the angle won't work.

I would be surprised if you are encoding this with open GOPs and VBR and it still works... but then again, stranger things have happened :-)

Let us know how you get on with it.

I believe that Quicktime conversion in FCP always uses closed GOPs.