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[personal profile] ninjarat
I just discovered why the US Gunbuster release is on 3 dual-layer discs when comparable shows (6 episodes, ~25 minutes per episode) are on 1 or 2 discs.

Back in the day, Laserdiscs used an uncompressed digital audio encoding format called linear PCM (pulse code modulation). This is the same encoding used by CD Audio and in WAV files. CDs and Laserdiscs use 16-bit PCM at 44.1kHz. That's a lot of space for just 2 audio tracks -- about 600MB/hour. The audio for a 2 hour movie with 5 audio channels would take up about 6GB -- more than the capacity of a single layer DVD. So, enter compression like MPEG-1 Layer III (MP3), AC-3 (Dolby Digital), and dts. They offer roughly 10:1 to 20:1 compression ratios.

The audio is uncompressed. 16-bit linear PCM at 48kHz.

Edit: the last episode is letterboxed, but it is of the matted variety rather than an anamorphic transfer. They probably don't *have* an anamorphic master for that :).

Date: 2007-04-10 07:37 am (UTC)
From: [identity profile] ash-3.livejournal.com
How are the discs? I've been considering getting them.

Date: 2007-04-10 07:16 pm (UTC)
From: [identity profile] ninjarat.livejournal.com
Really good. A bit less sharp than I'm accustomed to from newer releases but it looks good. No rainbow artifacts around the edges like the original Iria release. I suspect that along with not compressing the audio they used a very high bit rate for the video. There's plenty of space for it on 3 DVD-9 discs at only about 1 hour of content per disc.

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