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Bitrates in DVD Studio Pro

Determining the proper rate for your tracks and reencoding assets
Bitrate and multiple video angles
Another bitrate problem crops up when you're using multiple video angles in your presentation. A track with multiple angles--i.e., with content in the V1 and V2 slots in DVD Studio Pro's Track window--suffers the same limitations as a track with a single video stream, but adds in a further limitation in terms of the maximum overall bitrate.

If you look at the example below, I have two video streams in my track, plus one AIFF audio file with a bitrate of 1.5 Mbps. I've encoded my video with an average bitrate of 5.2 Mbps, giving me a total of 6.7 Mbps.



All is good.

But what happens if I add in a second 16-bit AIFF audio stream to this track?



It brings my total up to 8.2 Mbps, which is perfectly acceptable, right? Then why do I see this when I'm 90 percent through the build process?



The reason is that tracks with multiple video angles have bitrate limitations lower than those with single video streams. To whit, a track with two to five video angles is limited to 8 Mbps taking into consideration the average video bitrate of all your tracks (not the combined total), plus the combined total of audio and subtitle streams. So while my average video bitrate is still just 5.2 Mbps, when I add in the 3.0 Mbps for my two audio tracks, I exceed the limit.

Ugh.

And, if you work with even more angles, the maximum allowable bitrate for the track goes down further: 7.5 Mbps for six to eight angles, 7.0 Mbps for nine angles.



Reencoding assets in DVD Studio Pro
So what happens if it's too late? You've gotten the "Bitrate Too High" error, but your assets are already encoded, your DVD laid out, basically everything in place for the final build. Do you start over? Not necessarily. Sometimes you just need to reencode your assets. But that doesn't mean you have to start over completely.

Let's say that you've encoded your video using DVD Studio Pro's built-in encoder (in other words, you've imported a QuickTime, AVI or WMF file and let DVD Studio Pro do the encoding for you). And, after trying to build the disc, you've found that the bitrate is too high. Well, to change this, just right-click on the asset in the Assets tab, and select "Encoder Settings" from the contextual menu.



In the dialog that pops up, adjust your bitrate downward.



And the asset will immediately begin reencoding itself (assuming you have background encoding enabled in DVD Studio Pro's preferences).



So not only is DVD Studio Pro's background encoder fast, but it's versatile in that respect.

Looking for more articles on DVD Studio Pro? Check these:

DVD Studio Pro Scripting, Series 1
DVD Studio Pro Scripting, Series 2
Other scripting articles
General design and authoring topics
And, if you have any further questions or would like to request a tutorial on a particular topic, be sure to visit me in our DVD Studio Pro forum by clicking here.



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Related Keywords:dvd studio pro, bitrate, bit rates, encoding, video bit rate too high error, mpeg-2, a.pack

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  • Bitrates in DVD Studio Pro by DMN Editorial at Apr. 13, 2005 5:46 pm gmt (Rec'd 3)

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