jschneier

Ok, I didn't even have a TV until recently but since we are taking the plunge I decided to do some research into Blu-ray and I thought I would share it here. I had no idea that the prices were now comparable to DVD players and most of the movie prices are pretty affordable now also so we decided to go in that direction. Anyway, here is what I found out:

How much content can a Blu-ray Disc hold?
The majority of Blu-ray Discs on the market are single-layer or dual-layer, with capacities of 25GB and 50GB, respectively.
This means nine hours of high-definition video will fit on a 50GB disc; 23 hours of standard-definition will fit on the same size disc.
Also, since there is support in the format multi-layer discs, we can anticipate eventual storage capacities of 200GB.

What formats does Blu-ray come in?
BD-ROM - read-only format for distribution of HD movies, games, software, etc.
BD-R - recordable format for HD video recording and PC data storage.

BD-RE - rewritable format for HD video recording and PC data storage.


There are also plans for a BD/DVD hybrid format, which combines Blu-ray and DVD on the same disc so that it can be played in both Blu-ray players and DVD players.
What is the writing speed of Blu-ray?
Currently, 2x write speeds allow you to write 9MB/sec (By comparison, a 40X write CD-ROM = 6MB/sec.) However, much higher speeds are supported by the format. Speeds up to 12x are physically possible, so the BDA plans to raise the speed to 8x, or even higher, in the coming years. Essentially, it depends on the Blu-ray player, not on the disc itself.

Which audio and video codecs are supported by Blu-ray?

Audio:
(Required)
Linear PCM (LPCM) - up to 8 channels of uncompressed audio.
Dolby Digital (DD) - for DVDs, 5.1 surround sound.
DTS Digital Surround - for DVDs, 5.1 surround sound.

(Optional)
Dolby Digital Plus (DD+) - extension of Dolby Digital, 7.1 surround sound.
Dolby TrueHD - lossless encoding of up to 8 channels of audio.
DTS-HD High Resolution Audio - extension of DTS, 7.1 surround sound.
DTS-HD Master Audio - lossless encoding of up to 8 channels of audio.

Video:
MPEG-2 - enhanced for HD, also used for playback of DVDs and HDTV recordings.
MPEG-4 AVC - part of the MPEG-4 standard also known as H.264 (High Profile and Main Profile).

SMPTE VC-1 - standard based on Microsoft's Windows Media Video (WMV) technology.


All Blu-ray players and recorders will have to support playback of these audio and video codecs; it’s still be up to the studios which video codec(s) they will use.

Do you need an Internet connection to use Blu-ray?
No, but you will only need an Internet connection if you wish to access extra features (see BD-LIVE below). You will also need it authorize managed copies of Blu-ray movies that can be transferred over a home network. Blu-ray supports mandatory managed copy (MMC), allowing you to make legal copies to be viewed within your home network. Basically, movie studios have to offer this — manufacturers can choose whether or not their hardware will support this feature.

Will I be able to play back my DVDs and CDs in the same drive?
Yes. All manufacturers use a BD/DVD/CD compatible optical head, so you don't have to worry about your existing DVD collection becoming obsolete. In fact, most of the Blu-ray players support upscaling of DVDs to 1080p/1080i, so your existing DVD collection will look better, too.