how do you export to DVD and use up the full disc space?

[Vincent Rosati]

For VBR, the compression setting are probably something like…
8000/6000/3825

These are high settings. Anything higher and the program wouldn’t play reliably on DVD hardware, if at all.

To ensure the best quality, ensure that you are using 2-pass VBR encoding.

Vince

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[Jeff Pulera]

As mentioned, you can’t fill the disc with only 30 minutes of material – at the high limit of 8000, the disc will hold 60 minutes of video.

That said, the general consensus I have seen over the years on the forums is to not use the full 8000 encode setting, as some players might choke during playback (remember, the audio stream is also added on top of the 8000, and we’re talking home-burned media as well). The end viewer will never see the difference between 7000 quality and 8000 quality. Most of my event videos are two hours, encoded at 4500, and after making literally thousands of duplicates over the years, I’ve never had a single complaint about image quality.

My opinion is not to exceed 7000 on the video encode, and for shorter programs, I don’t see the value of VBR and recommend CBR encoding. Much faster anyway.

The benefit of Two-Pass Variable Bit Rate encoding is that for long programs, rather than encoding ALL the material at the same, low data rate (quality) setting, the encoder will first analyze all the video (first pass) to determine the complexity of each scene. Using this information, the bitrate is then “allocated” to each scene (second pass), set higher for complex scenes (lots of detail/motion), and lower then for scenes like a static title for instance, in such a way as to create an average (target) bitrate that allows all the material to fit the disc.

In this way, quality is maximized, applying higher bitrates where needed, and lower bitrates for simple scenes that will look fine at a lower bitrate.

That said, I don’t see the advantage of using VBR for anything less than 60 minutes, since I can simply use the maximum quality all the way through – why lower the bitrate (quality), if I have space to encode all of it at a high quality? I don’t need to budget the bits at all. In fact, I have seen VBR cause issues, for instance when there is a sudden change in the video, like a photo flash, I might see some mosaic (compression artifacting). Maybe this only affects certain players, but the idea is that the data rate might be low for a bit, then it suddenly spikes at the flash. Why not simply use a consistent high quality?

For videos over an hour, I found a formula at Adobe.com that works well to determine the bitrate for encoding – it is simply 560/minutes, and maybe round down just a bit to be safe.

560/90=6.2, call it 6. 560/120=4.66, call it 4.5, never fails. Make sure to use Dolby Digital AC-3 audio when authoring – if you use PCM audio, it takes up huge amounts of space on the disc, then the video won’t fit! Hollywood movies all use AC-3, quality is great.

These are just my opinions, based on my experiences, and there are plenty out there 😉

Jeff Pulera

[Scott Davidson]

Great! Thanks for all the info, that clears up a lot… Ill probably go with the CBR encoding, that makes sense. I’m burning a master to send in to get duplicated so I’m trying to get the best quality.