The Unbiased Insider

Part 2: Capacity

Ok, here is one topic that has caused a tremendous amount of debate. Blu-ray offers 50Gb of storage using dual layer discs while HD-DVD offers 30GB using dual layer discs. The HD-DVD camps states the 30GB is more than enough to deliver master quality video and audio as well as bonus content through the use of more efficient codecs (Mainly VC1 on dual layer discs). Blu-ray discs have been authored in VC1, AVC, and MPEG2 mainly on single layer discs and a few dual layer discs.

While it does appear that HD-DVD’s 30GB capacity is sufficient for most of the releases to date, the ability to offer master quality video and lossless audio in continents other than North America may prove difficult. Europe consists of about nine different core languages. If a disc is to be sold in Europe it should contain lossless audio tracks in all key languages. This was a key decision factor in certain studios choosing Blu-ray over HD-DVD.

One additional item that has not reared its head is that with HDMI 1.3 comes the ability to offer 10bit - 36bit color depths. Each time the bit-depth is increased the amount of space required on the disc goes up drastically. Current DVD’s utilize 8-bit color, if a disc is created that uses 10-bit color it will require 20% more disc space. This may prove to be tasking for HD-DVDs limited capacity.

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Here is part one of a multi-part series of articles about the these two formats. All I am going to discuss are facts about both formats. Hopefully you will find them informative.

Part 1: Picture Quality

Since both formats can use the same video codecs (MPEG2, AVC, and VC1) both formats CAN deliver the same picture quality. If a movie is authored in both formats using the same codec (same elementary video stream) the only difference in picture quality that will be seen is hardware based. When a hardware manufacturer is planning HD optical disc product they must choose key devices that will ultimately effect the picture quality of the discs they play.

• Video Decoder - Decodes the video portion of the disc.
• Video Scaler – Allows the user to tailor the output resolution of the player to your particular display.
• Video Processor – Some manufacturers will add a digital video processor after the video decoder to allow for adjustments like color, contrast, brightness, noise reduction, etc…
• Factory Default Picture Settings – Hardware companies choose the default video settings in the player (color, brightness, contract, NR, etc…)

Each one of these items has an effect on the picture quality.

Note: The MPEG2 video codec has gotten a bad wrap lately. I believe this is completely unwarranted. I understand that the first few titles on the Blu-ray format were not reference quality, however the fact that these titles were encoded using MPEG2 is irrelevant. This should be obvious to anyone who has looked at titles such as Momento, Haunted Mansion, Kingdom of Heaven, Tears of the Sun and others. MPEG2 can deliver transparent-to-the-master picture quality. The main difference in the mandatory codecs is their efficiency with compression.

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