Audio information

[Mikedo]

Hi everyone, I must admit that I've been into the pq of blu ray much more than the aq... I've been looking for some sites/threads with information that give the basics of the different audio formats. The faq lists the different types and which are mandatory and which are optional, however, not much is listed as to where each ranks in terms of quality.

Perhaps this belongs more in the newbie section, thanks for any help and pointers.

[BStecke]

Typically it goes:

Uncompressed PCM
DTS-HDMA (this depends on your setup, as you have to have a player or receiver to decode the signal)
Dolby TrueHD

These are all lossless/uncompressed audio formats
_______________________________

Regular DTS
Regular Dolby Digital

These are all lossy, highly compressed formats

[MatrixS2000]

^ Just to expand on this a little:

Lossless/Uncompressed:
PCM - the real deal but it's disadvantage is that it's file sizes are the largest.

Lossless/Compressed:
Uncompressed during playback and should be equal (not better) than PCM. However, things like Dialog Normalization (DN), can have an effect on the sound.

DTS-MA - few players decode this today, so you will get the core DTS track at 1.5Mb/s
DolbyTHD - most players, if not all, can decode this correctly. DN may be applied.

Lossy/Compressed
DVD quality audio.

DTS
Dolby Digital

Another couple of thing you should look for is the bit depth and sampling frequency.

Bit depth = number of bits/sample. The higher the better. 16/20/24 are common.

Sampling frequency = the number of sample/second being used. Again the higher the better. Common rates go from 8K -> 2.8M, but to keep this focused on HD audio common rates are 44k/48K/96K/192K. A signal needs a minimum of 2 samples to be correctly reproduced. So a sampling freq of 44K means that the highest audio frequency it can sample is 22Khz.


Common combinations of bit depth/sampling freq are 16/44, 16/48, 24/48, 24/96.

Hope this helps....

[DragonSarc]

I thought DTS-MA and DOLBY HD are lossless/uncompressed audio when decoded like PCM on BLU-ray discs?

[mikenike]

Originally Posted by DragonSarc

I thought DTS-MA and DOLBY HD are lossless/uncompressed audio when decoded like PCM on BLU-ray discs?

No, DTS-MA & TrueHD are compressed, meaning they are "squeezed" into a smaller file. Compression here does not necessarily mean loss of quality. The codecs DTS-MA & TrueHD were created to reduce the size of the audio tracks that were hindered by size of PCM tracks. As such, all three are still lossless, meaning no loss of quality and every you hear will be the same across the board once decoded.

[Mikedo]

Thanks to everyone again for all the info.

[Slec]

I think these 2 sites are a tremendous help in understanding. Can't tell you how many times I've used the example that TrueHD and DTSHD-MA are "zipped" vs what people typically think of with compression....

Uncompressed vs Lossess
http://www.highdefdigest.com/news/sh...ess_Audio/1233

Audio Codecs explained
http://www.highdefdigest.com/news/show/1064