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DVD Compression Quick Tip

If you understand the structure of a DVD and what it takes to author one, you are probably familiar with the notion of compressing your media in order to fit it onto this popular optical disc format.  Video editing applications like Final Cut Pro and Adobe Premiere Pro have made presets that assist with doing just that.  Using them can save you lots of time.  If you’re familiar with Adobe’s Media Encoder, you’ll notice that it outputs a .m2v file for video and .wav file for audio.  That .wav file can be quite large and if you are planning on burning long-form content to a disc, may cause you to reduce the quality of your visual output.  That means your video file will require lots of compression in order to fit.  But here is one way to squeeze out better quality video while still using the ease and speed found within presets (it just involves a few added steps)…


1) Step One: export just the .wav audio for your project


2) Turn that .wav file into a more optimized format.  I personally like using Apple’s Compressor app for this task, where I make it a Dolby Digital Professional .ac3 file instead.


3) Next, it’s time to do some math: assuming you’re going to be burning your content onto a standard 4.7GB single-layer disc, round it down to about 4.5GB in your head and make that your starting point (this will allow for some extra room for additional content such as the menus/overall disc formatting)


4) Subtract the size of your newly compressed audio file from that 4.5GB (so in my example here that would be the .ac3 file, not the .wav)


5) The number that gives you is the amount of free space you have on your disc for any additional visual content (such as the looping menu backgrounds/video file); use that number as your encoding’s target goal in AME or similar but if you have additional menu-related content (animation especially) make sure you compress and calculate enough room for these files, too


6) Now return to your video editing application or external compression software of choice and select to only output the video portion of your DVD project.  You don’t need the audio because that’s already been prepared in steps 1 and 2.  Make sure that content does not exceed the allotted free space you came up with in step 5 (tip: if in Adobe Media Encoder, you can easily control this using the target bitrate mbps slider, closely monitoring the projected file size towards the bottom of the window)  If your preset doesn’t allow for you to disable the audio output, it shouldn’t be a big deal since the file is not going to be a muxed mpeg (where audio and video are combined).  That means you can always delete this newer audio created here in step 6 at a later time or opt to just not bring it into your DVD project in step 7.


7) Bring the compressed audio file (.ac3) and the video file (.m2v) into your DVD authoring application and burn your disc. (tip: if the audio and video file names match–not counting their file extension–they’ll probably automatically link up to one another in programs such as Apple’s DVD Studio Pro if you still use that, allowing you to drag and drop just the video file when placing it into your project’s timeline, knowing the audio will automatically follow)