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DVDA fial size much smaller than sum of .mpg files
This might be suited for the DVDA forum, but it does relate to Vegas Pro. When I render my mpeg files for use in DVDA they add up to about 4GB. So I would expect the files created by DVDA would be very close to this sum, if not a bit more due to menus. But I consistently see the files add up to much less, like 3.6GB. I am using templates that don’t require re-render by DVD. So why are the sum of the VOB files size much less?
-Jim.
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21 Replies
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DVDA is going to ensure a compliant video. This is to say that Vegas can render an mpeg at 12Mb bit-rate, but this won’t really work in a DVD player. DVDA will re-compress this video, so your product will work. On the File menu in DVDA try the Optimize disk function. If DVDA requires a re-compress, find out why. The best practice I have found is to make all my video so that DVDA does not need to change it.
Now then, if you have used the templates in Vegas and still need to recompress, it is because you have too much video (length-wise) to fit on the medium. This is where a bitrate calculator come in. If you need to take a look at this post: forums.creativecow.net/thread/24/935307#935307
I hope this helps,
Jeff
Windows 7 64-bit, ASUS P6X58D, i7 960 3.20GHz, 24.0GB DDR3, 12TB connected storage
http://www.narrowroadmedia.com -
Most likely, your DVDa project settings, don’t match what your MPEGs files are coming out Vegas.
Most likely, you probably set a DVDa bitrate setting that is smaller than the bitrate setting you used for your Vegas renders. Or you are using a different pixel frame size that is different from what you set for your Vegas renders.
For example, if your DVDa bitrate is 7 Mb/s but your videos are at a bitrate greater than 7 Mb/s, say 8 Mb/s, then DVDa will re-encode your videos to 7 Mb/s. Or if your DVDa frame size is set to 720×480 but your videos are set to 704×480, then DVDa will re-encode your videos to 720×480.
The DVDa project settings apply to both your menus and imported video files. So to prevent DVDa from re-encoding, you have two options:
1. Make sure your DVDa project settings for bitrate is equal-to or greater than your the bitrates of your MPEG videos. Make sure the frame size settings matches too.
or
2. If you want to keep your DVDa project settings as is for your menus, then you need to manually override those settings for each of your videos. In DVDa, the settings are configured during the OPTIMIZATION SETTINGS stage of DVD preparation. There is also a menu option under FILE to set your OPTIMIZATION SETTINGS.
You can manually override the settings for each video (and menu as well) so that DVDa will not re-encode to your global project settings.
That’s it!
Cheers!
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[Jim Greene] “So why are the sum of the VOB files size much less?”
I can’t offer a good reason for this other than stuff happens 🙂
I just finished authoring 5 DVDs and in every single case the VIDEO_TS folder was smaller than the source AC-3 and MPEG-2 files. -
[John Bean] “Most likely, your DVDa project settings, don’t match what your MPEGs files are coming out Vegas.”
John, believe me when I say that I thought long and hard about this post.
I’m not going to bother to pick apart all the errors in your reply.
Most of your responses are not relevant to the OP’s question and will only confuse him and anyone else looking for a solution.I’m sure that you mean well but a lot of your posts are full of information that is not applicable to the question(s) being asked.
In the future, please try to limit your responses to the question being asked and stop going off on several tangents.
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How is it not relevant?
Just because you render using a DVD Architect template from Sony Vegas does not mean DVD Architect will not re-encode your video.
Take the extreme case where the total file size of all your media files exceeds the DVD limit of 4.7 GB.
Clearly, here DVD Architect will have to re-encode your videos with a much smaller bit-rate if you intend to fit it all on one 4.7 GB DVD.
If you do not know how to setup your DVD Architect PROJECT SETTINGS and OPTIMIZATION SETTINGS, it may cause DVD Architect to re-encode your videos even if you are sure you used a DVD Architect template from Vegas.
Cheers!
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The other thing to check is your AUDIO SETTINGS in DVD Architect.
Maybe you’ve rendered uncompressed PCM from Vegas but have DVD Architect setup to do AC3. If this is the case, DVD Architect will encode your PCM audio tracks to AC3, thus reducing your DVD size.
Also make sure that you are not rendering both the video and audio streams out into one MPEG file from Vegas. You need to render video and audio streams separately.
Cheers!
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[John Bean] “How is it not relevant?”
Because in the initial post, the OP said When I render my mpeg files for use in DVDA they add up to about 4GB and went on to say I am using templates that don’t require re-render by DVD.
These two statements tell me that he’s he’s doing everything correctly and was just curious about something.
I looked at 5 DVD files that I had just finished authoring and, to my surprise, discovered the same thing. -
[John Bean] “he other thing to check is your AUDIO SETTINGS in DVD Architect.”
Once again, you’re missing the point.
No where did the OP ask if he was doing something wrong so there was no reason to go into any kind of detailed explanation. -
To the OP’s question:
There really is no file structure on a DVD, though Windows Explorer makes it look like one. When you “make” a DVD in DVDA, you are making single serpentine file. On a normal disk, files are broken into sectors and scattered all over the hard disk. There is a location table (actually two, one is a backup) in the root of the disk that keeps track of the start of every file and points to the first data sector somewhere else on the hard disk. Every sector on the hard disk contains a cluster of data, error correction code and a pointer to the sector containing the next bit of data. Add to that the overhead of formatting the disk which consumes a few bytes for every sector. That ECC and pointer data consumes space – multiply that by the thousands of sectors used to store a single file, and you have a lot of space used in the overhead. On a DVD there are no sectors, no file structure, no pointers (because there’s no sectors) and no ECC, therefore much more efficient. This is why the “Prepared” DVD will always be smaller than the sum of its component parts.
For the purists, I know this is a bit simplified description of how the DVD is organized, and yes, I described the FAT system even though we all use NTFS, but the principles are the same.
Steve Mann
MannMade Digital Video
http://www.mmdv.com -
Steve, thanks very much for the great explanation.
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