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Variable bit rate rendering

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Ross Stark
Variable bit rate rendering
on Jan 30, 2015 at 9:46:42 pm

That terrible feeling when you've finished a project: "My DVD won't play." or "MY DVD gets stuck at a certain scene."

Ok, so I'm having a major issue with a project I recently finished. I delivered the DVDs, but I'm getting feedback like the two quotes up top. I was a long program that I worked and rendered in Vegas 11. Put on DVD with DVD architect pro. Took that prepared folder and made my DVDs with my Epson DiscProducer. They are 4.7 gig single layer DVD-R.

Render settings from Vegas 11:

I rendered to MainConcept MPEG2: DVD Architect NTSC Widescreen video stream and then to Wave 44.8khz stereo 16 bit.

because of the length of the program I was running out of room on the DVD. I monkeyed with the variable bit rates on the video stream to decrease the file size. I think this may be where the problem came in. The reason I think that is because outside of the variable bit rate change, these are the same settings/programs/work flow I always use and never have any issues. I have even lowered the bit rates before and didn't run into this.

Any help would be greatly appreciated as I have to get a replacement to these customers pronto.


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Mike Kujbida
Re: Variable bit rate rendering
on Jan 30, 2015 at 11:59:02 pm

Is there a reason for using WAV instead of AC-3? Doing that means a higher video bitrate.


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John Rofrano
Re: Variable bit rate rendering
on Jan 31, 2015 at 12:47:45 am

[Ross Stark] "...because of the length of the program I was running out of room on the DVD. I monkeyed with the variable bit rates on the video stream to decrease the file size."
That could do it depending on the settings that you use. What was your maximum bit rate? I also agree with Mike that using AC3 would have left more room for video at a higher bit rate.

~jr

http://www.johnrofrano.com
http://www.vasst.com



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Ross Stark
Re: Variable bit rate rendering
on Jan 31, 2015 at 3:14:05 am

I guess my use of wav format goes back to my days of audio only before I jumped into video. Is ac3 directly compatible with dvd architect pro, as in no re-rendering?

I wish I knew what the vbr settings were. I just remember that I would lower peak and average bit rates until it got to the right size.


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Mike Kujbida
Re: Variable bit rate rendering
on Jan 31, 2015 at 3:35:39 am

I feed AC-3 files to DVD Architect all the time and never have any problems with re-rendering.
How long is your video? My rule of thumb is to use a CBR of 8,000,000 if it's 70 min. or less. Anything longer and I use a bitrate calculator to determine optimum settings. Do a search on this forum for "Mark's bitrate calculator". I've posted links to it and instructions several times.


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Mike Kujbida
Re: Variable bit rate rendering
on Jan 31, 2015 at 3:38:19 am

I should add that anything over 70 min. uses VBR settings and a 2-pass render for optimum results.a


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John Rofrano
Re: Variable bit rate rendering
on Jan 31, 2015 at 3:34:23 pm

[Ross Stark] "I guess my use of wav format goes back to my days of audio only before I jumped into video."
Unfortunately, they have nothing to do with each other. Audio CD's use 44.1K/16-bit and video requires 48K/16-bit audio so even the wav files are not compatible.
[Ross Stark] "Is ac3 directly compatible with dvd architect pro, as in no re-rendering?"
Yes, they are compatible. In fact, you don't get the Pro AC3 encoder unless you buy DVD Architect. That's it's purpose, to encode audio for DVD with no re-encoding.
[Ross Stark] "I wish I knew what the vbr settings were. I just remember that I would lower peak and average bit rates until it got to the right size."
Peak/Maximum bitrate has nothing to do with file size. The file size is determined purely by the Average bit rate. The Maximum is there to limit how many bits can be used on any particular frame. The DVD spec allows up to 9Mbps. Most people don't go over 8Mbps just to make sure their DVD's play on all players. If, for example, you encoded a DVD with Maximum at 15Mbps and Average at 6Mbps, even though your average is well below the allowable rate, the DVD would probably freeze when it got to a frame that was 15Mbps because it's above the 9Mbps limit. You only need to adjust the Average to change the file size.

~jr

http://www.johnrofrano.com
http://www.vasst.com



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Ross Stark
Re: Variable bit rate rendering
on Feb 2, 2015 at 5:01:11 pm

Thank you all for your comments. I have not been able to recreate the problem my client had, but i have been able to learn a TON from you guys.

In regards to using WAV. I was rendering it at 48khz 16bit stereo so it would be compatible with DVD standards. I'm currently rendering the project with ac3 to see what this new territory is like.

As I'm trying to diagnose the issue I had, all I can think of that I did differently than other projects (of which all worked fine), is that I changed the peak and average bit rates. I lowered both of them. As I've learned on here, lowering the peak did not help lower my file size, which was my goal. I did lower the average bit rate, but nothing crazy. Could this have caused a DVD to become unplayable?

I'm supposed to pick up the culprit disk this afternoon. I've got a chicken dinner riding on the fact that I'm going to find a giant, greasy thumb print on the disc face that is the real problem...


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John Rofrano
Re: Variable bit rate rendering
on Feb 2, 2015 at 10:18:02 pm

[Ross Stark] "I've got a chicken dinner riding on the fact that I'm going to find a giant, greasy thumb print on the disc face that is the real problem..."
lol, won't be the first time. :-D

~jr

http://www.johnrofrano.com
http://www.vasst.com



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