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Old March 19th, 2008, 07:39 PM   #1
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DVDSP says "Video Bitrate Too High", but why?

I've managed to get my multi-angled tracks' GOPs conformed, etc... now I am getting a "Video Bitrate Too High" message upon building my DVD.

Quote:
Compiling VTS#3 (Drills)...
Writing VTS_03_0.VOB
Muxing VTS_03_1.VOB
Video Bitrate Too High
The track (track 3) that the error is occurring for has three video streams, all of which were encoded with 2-pass VBR (average=4.7; max=7.0). According to DVDSP's inspector window, the average Bits/Second for the video stream is:

V1 = 4,998,041 (or 4.76 Mbps)
V2 = 4,994,258 (or 4.76 Mbps)
V3 = 5,001,921 (or 4.77 Mbps)

There is one audio stream, a 16-bit/48k AIFF with an average data rate of 1,536,000 bits/second (or 1.46 Mbps)

According to the DVDSP (4.1.2 is the version I am using, FYI) user manual, on page 70:

Quote:
Due to the way the DVD specification requires video streams to be multiplexed together, the number of video streams determines the maximum video bit rate you can use. Following is a list of maximum combined bit rates (highest bit rate video stream + all audio streams
+ all subtitle streams) you can use for each multi- and mixed-angle track:

SD Projects
• 5 angles or fewer: 8 Mbps maximum for the track’s combined bit rate
• 6–8 angles: 7.5 Mbps maximum for the track’s combined bit rate
• 9 angles: 7 Mbps maximum for the track’s combined bit rate

HD Projects
• 2 to 9 angles: 24 Mbps maximum for the track’s combined bit rate

Important: When calculating the combined bit rate for a track, you only need to add in the bit rate of one video stream, but it needs to be the stream with the highest bit rate.
Though they are very close, it is my third video stream that is the highest. So V3 + A1 = 4.77 + 1.46 = 6.23 Mbps, leaving me with a 1.77 Mbps margin.

What do you think is going on here?
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Old March 19th, 2008, 07:50 PM   #2
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Remember that when using alt-angles that the total amount of data per track has to be accounted for included the angles. A max bitrate of 7 is too high, try a max of 6 to 6.5 with an average of 5.

Get the Apple Training Series DVDSP4 book; you'll get all the answers and troubleshooting tips you need.
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Old March 19th, 2008, 08:07 PM   #3
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Originally Posted by Robert Lane View Post
Remember that when using alt-angles that the total amount of data per track has to be accounted for included the angles.
I don't understand how I'm not doing that. It says to calculate using the "highest bit rate video stream + all audio streams + all subtitle streams" which, in my case, is 4.77 + 1.46 = 6.23 Mbps (there are no subtitle streams). Is my math bad? Or am I missing something else?
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Old March 19th, 2008, 08:19 PM   #4
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Don't know why, but...

Replacing the AIFF audio streams with their AC3 counterparts solved the issue. However I still don't understand why it was telling me the video bitrate was too high. It's not making sense.

@Robert: that book is certainly on my shopping list!
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Old March 19th, 2008, 11:08 PM   #5
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Quote:
Originally Posted by Mike Barber View Post
Replacing the AIFF audio streams with their AC3 counterparts solved the issue. However I still don't understand why it was telling me the video bitrate was too high. It's not making sense.

@Robert: that book is certainly on my shopping list!
Actually now it makes sense to me; although we normally consider audio files to be small both in size and data rate compared to video, in the MPEG-2 stream a non-compressed audio codec really takes up a lot of system resources during playback, and when you add multiple streams or angles that's an even heavier load.

DVDSP4 while not 100% able to author every aspect of the DVD spec is built around the DVD/ISO specification which, by preference wants to see a compressed audio codec for proper playback. In reality, your build with AIFF's *might* have played fine on newer players, DVDSP4 knows the limitations of the ISO spec and has built-in limits to prevent a bad build-out.

I've seen in extreme cases where code-monkeys have hacked DVDSP4 to lose the various warnings when bitrates get too high in an attempt to maximize playback but they almost always create playback issues with most set-top DVD players.

In short, DVD audio needs to be 2 things for both a good encode and for proper sound: it needs to be the AC3 (or other compressed format allowed by the DVD spec) and max/peak levels need to be preset in editing at -12db. (You can also use Compressor's built-in audio filters to bring the audio down to the -12db level if all your FCP sequences were edited with audio peaking at maximum.)

Trust me, once you get the book you'll have so many "I didn't know that..." moments you'll wonder how you ever got along without it.
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Old March 20th, 2008, 12:19 AM   #6
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Quote:
Originally Posted by Robert Lane View Post
DVDSP4 while not 100% able to author every aspect of the DVD spec is built around the DVD/ISO specification which, by preference wants to see a compressed audio codec for proper playback. In reality, your build with AIFF's *might* have played fine on newer players, DVDSP4 knows the limitations of the ISO spec and has built-in limits to prevent a bad build-out.
I sooooo need to get that book!

OK, here's another one for you. I have a successful build, burned fine and plays well in both my Samsung and Panasonic DVD players (and fine on both Macs through DVD Player). The only oddity is playback on the Samsung, one of the tracks (the same one, every time) seems to skip a bit as if it was playing back at 2x speed. Not in the Panasonic, not on the Macs... so I am leaning to assume it is just my one DVD player acting up. The section of the disc where the section of data lays is about the middle of the disc, not either inner or outer rim, and there are no scratches/dust/fingerprints/etc.

I don't know what to do to further debug. I've never seen this before. And I am a bit nervous about sending in my DDPs to the replication house if this is going to turn up on other people's players -- I know there's always the possibility, but I want to make sure I CMA (Cover My A**).
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Old March 20th, 2008, 08:26 AM   #7
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It could be that's where your layer-break is? Try using different media for the burn; Ridata and Verbatim seem to be the media of choice.

Also, the Pioneer DVR-112D or newer seems to be the best DVD burner for the Mac (many MacPro's shipped with that as the Apple-branded SuperDrive).

Unless you've got DVDAFterEdit to help you check the proper build of the actual DVD image there's no way to know exactly what is causing the skipping, but try the above and see what happens.
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Old March 20th, 2008, 10:20 AM   #8
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Quote:
Originally Posted by Robert Lane View Post
It could be that's where your layer-break is? Try using different media for the burn; Ridata and Verbatim seem to be the media of choice.
The layer-break happens at the near end of this particular track track, however the issue arises from the beginning of the track. It perplexes me that only the one DVD player exhibits the behaviour, which makes me want to trust that it builds properly -- but it does concern me.

Verbatim DVD+R DL is the media I am using with an external LaCie FW drive (my Mac came with the combo drive... I'm on a dinosaur dual-867 G4 MDD).

Quote:
Originally Posted by Robert Lane View Post
Unless you've got DVDAFterEdit to help you check the proper build of the actual DVD image there's no way to know exactly what is causing the skipping, but try the above and see what happens.
I downloaded the demo, however seems to crash when I try to open the VIDEO_TS folder!
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Old March 20th, 2008, 11:30 AM   #9
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Quote:
Originally Posted by Mike Barber View Post
Replacing the AIFF audio streams with their AC3 counterparts solved the issue. However I still don't understand why it was telling me the video bitrate was too high. It's not making sense.
One of the processes during DVD burning or file builds is the "muxing" of the MPEG2 video track and the audio track into one file that conforms to the DVD specs. While either track can contribute to a data rate too high for the now ancient DVD disc standard, DVDSP makes the assumption that the video track is the culprit. Since Compressor uses VBR compression it might say 6.2Mbps in the info box for the video track but it could be peaking at higher than that for various images.

When I make demo discs for clients that are very short, I have created some presets at 7.2Mbps but due to the VBR scheme that Compressor uses I must use AC3 audio since AIFFs will require too much data for the DVD standard. I have yet to experiment with higher CBR compression in the new version of Compressor.
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Old March 20th, 2008, 11:45 AM   #10
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Originally Posted by William Hohauser View Post
When I make demo discs for clients that are very short, I have created some presets at 7.2Mbps but due to the VBR scheme that Compressor uses I must use AC3 audio since AIFFs will require too much data for the DVD standard...
As I say, although the DVD spec allows for AIFF's in playback the ISO standard for a DVD image requires compressed audio especially when encoding for 5.1 or greater.

It's important to know, that the only reason AIFF/CDFF files can playback from an MPEG-2 stream is because DVD players are designed to also act as stand-alone audio playback devices - a built-in CD player if you will, hence the actual DVD ISO image will technically support having an AIFF in the track. However, DVD players were never optimized to have uncompressed audio *alongside* a video track which is why the AC3/Dolby compression format was created almost 20 years ago.

This same scheme applies to the Blu-Ray spec; while bitrates are significantly highly for BR both in audio and video compressed audio is still the authoring standard, period.
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Old March 20th, 2008, 02:04 PM   #11
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That's interesting information. AIFFs encode much faster than AC3 which is why I like to use them when possible (not much anymore).

I wonder why Apple chose to not have a 60 minute preset in Compressor 3. Standalone DVD recorders manage to get around 9Mbps video tracks so it would be nice if I could coax something like that from Compressor.
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Old March 20th, 2008, 02:09 PM   #12
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Standalone DVD recorders manage to get around 9Mbps video tracks so it would be nice if I could coax something like that from Compressor.
IIRC, though 9.8 Mbps can be achieved, 8 Mbps is the highest usable bitrate due to limitations of some consumer DVD players.
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Old March 20th, 2008, 05:18 PM   #13
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Quote:
Originally Posted by William Hohauser View Post
AIFFs encode much faster than AC3 ...
Well, of course. There is really no encoding going on if your source is AIFF and you store PCM audio on the DVD, because the two are really one and the same (except for sample rate and bits/sample, which are easy to convert. When you want to store AC3 on the disc, however, there is real compression (*) going on in the AIFF-to-AC3 encoding, which requires the use of complicated (and time consuming) algorithms.

- Martin


(*) "compression" as in "reducing the size of the data", not "reducing the dynamic range of the audio"
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Old March 21st, 2008, 12:00 AM   #14
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IIRC, though 9.8 Mbps can be achieved, 8 Mbps is the highest usable bitrate due to limitations of some consumer DVD players.

My old Panasonic DVD recorders made MPEG2 and AIFF audio files at all bit rate setting. I know this since I regularly demux the DVDs for other projects. My newer JVC DVD recorders record in AC3 for all settings. These recorders make MPEG2 video files that have higher bit rates then I can get out of Compressor. Anyone have a formula for Compressor to get the highest video file bit rate possible?
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Old March 21st, 2008, 09:58 AM   #15
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Without knowing the model number you're most likely referring to the combo models that have DVD-VHS-MiniDV built in? Those recorders are designed to capture and record *tracks* not create a fully authored disc with menus, subtitle functions, alt-angles etc.

Important too, is that since those devices burn tracks only bitrates can be higher all around.

Compressor nor any other software-based encoder can replicate what a hardware encoder can do, which is what you've got in those combo machines. In fact, if it were possible (and it's not, so don't worry about trying to figure out how) to take these hardware encoders and grab the MPEG-2 file it creates and then import that into DVDSP4 you'd have a superior looking output.

That's why anything encoded with Compressor, BitVice and other software-based engines will never look as good as what the big Hollywood studios output does - because the studios are *always* using a hardware encoder to create their MPEG-2 and AAC/AC3/Dolby compliant files, period.

If you really want to maximize your encodes, get an XP-based machine and purchase one of the few hardware MPEG-2 encoders and use those files to import into DVDSP4. They're not cheap but currently there's nothing that compares to a good hardware-based encode.
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