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Edited video, too big for DVD?

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MrHoberto
Edited video, too big for DVD?
on Aug 23, 2004 at 11:01:17 am

I've been using the build in Windows Movie Maker, and recently upgraded to Premiere Pro 1.5 (with Audition 1.5). The main reason for the upgrade (investment?) was I'm trying to pull video off of VHS tapes, clean up the audio, do some color correction, and then have the digital copy for archiving and DVD production.

One thing I never really cared about in the past was how much I could fit on a DVD... usually I did one short and put together a DVD image (using an old version of Ulead DVD Workshop) and burned DVDs when people asked for it, as they were separate projects. But now, as my wife's acting career picks up, we're going to want to put multiple shorts on one DVD, and even a summary "reel" for her to send to agents.

When I looked at one of the AVIs that Premiere put out, it's almost 1.7GB... and most of the DVDs I have are 4.3 GB... I'm weirded out because the short is only 5 minutes long and I was expecting to get at least an hour's worth of video on this DVD.

So, what's the real path to putting video on a DVD? Does the DVD authoring software take care of "compressing" the video into something more manageable? Or is the correct path to take the AVIs that Premiere creates, convert them to MPG, then use those to put together the DVD? Will there be a noticable difference in quality?



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John Q
Re: Edited video, too big for DVD?
on Aug 24, 2004 at 4:09:06 am

DV and AVI's are encoded with a different codec than DVD's. DV is encoded at 25 Mb/sec in a fixed compression MPEG-2 I-frame format. DVD's are encoded at a maxium bitrate of 9.8 Mb/sec, but are typically at a lower rate, in MPEG-2 IBP format. The video has to be transcoded from one compression format to another. Done correctly, you can't see the difference.

At 9.8, you can fit about an hour of video on a DVD. You can fit more, but then you'll have to cut the encoding bitrate. If you cut the bitrate too much for the content, you see compression artifacts, i.e. blockiness, in the video.


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MrHoberto
Re: Edited video, too big for DVD?
on Aug 24, 2004 at 2:30:33 pm

Thanks. So I'm guessing this would be a setting in the "DVD" authoring software, correct?

If a DVD can only go as high as 9.8 Mb/sec, if I try to drop an AVI in the authoring software, if has to do some sort of conversion and "ramp down" the throughput.

I am going to check this out. Does the audio affect this at all?


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John Q
Re: Edited video, too big for DVD?
on Aug 25, 2004 at 2:32:19 am

Yes, your video has to be transcoded from your original video format to MPEG2-IBP for DVD authoring. Either the DVD authoring application has to do it, or your video application has to do it, or a separate program has to transcode it.

The audio on the DVD has to be either PCM or AC-3. If you load a multiplexed format, like AVI, then the first thing the DVD authoring program has to do is demultiplex the video from the audio, so you're better off importing separate video and audio files to the authoring program. It saves time and disk space. PCM audio is 48 KHz 16-bit stereo. AC-3 is Dolby Digital stereo. AC-3 is highly compressed, using about 1/8 the bitrate of PCM, so you want your DVD authoring program to convert your audio to AC-3 on long movies to be able to encode your video at a higher bitrate. If you import MPEG audio into your DVD package, it will be uncompressed back to PCM format, again taking more time and disk space.


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Greg Barringer
Re: Edited video, too big for DVD?
on Aug 28, 2004 at 1:16:41 pm

Go ahead and burn the DVD you'll see. The last one I did took a 17 minute .avi file (3.1 GB) and compressed it to 1 GB on the DVD.


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