Quote:
Originally Posted by sptrout /forum/post/18167242
Actually, I understand very well how they work and have for many, many years. I think if you read what I said more closely you will see that we are saying nearly the same thing; you just a little better than my brief explanation.
That may be true.
Quote:
Originally Posted by sptrout /forum/post/18167242
1. I agree lossless tracks sounds to most to be far better than lossy, but as I am sure you have read, there have been blind A vs. B testing done where most listeners could not tell the difference. Not sure that I buy into that, but some so. Yet, you may be right that the testing was with higher bitrate CODECs, but I think it was with with standard DD & DTS. I do not have the time to find the link to the paper at this moment. In any case, many have written on this board that they cannot tell the difference.
Yes, the article you referenced is comparing the decoded results of lossless compression codecs (DD True HD/DTS HD-MA) to the decoded results of lossy compression codecs (legacy DD/DTS) on
Blu-Ray. The fact that the medium is Blu-Ray is very important because the data rate of even the lossy legacy codecs is higher than that used on standard definition DVD.
Quote:
Originally Posted by sptrout /forum/post/18167242
2. An AVR cannot "decompress" a lossy track because that would mean that the AVR is recovering the bits that have been rejected when the audio is compressed in the first place, they do not. They just do the best they can to recreate what was eliminated. The DD & DTS tracks are "decoded" not "decompressed."
On this point I have to disagree. Quite simply, anytime you "compress" a file, you must go through a reciprocal "decompression" step to recover the data. That's a fact of digital life. The amount of data recovered during decompression is dependent on the type of compression used. "Lossy" compressed files, when decompressed will result in a file that is similar to but not identical to, the original file because data has been thrown away. Think JPEG compression. When you take a picture using JPEG compression, recreating the picture (decompressing the data) results in a picture pretty close to the original, but not quite. Some data has been lost. "Lossless" compressed files, when decompressed will result in an exact reproduction of the original file. Think TIFF compression. TIFF is lossless and when decompressed will result in an exact reproduction of the original picture.
Quote:
Originally Posted by sptrout /forum/post/18167242
3. I agree that TrueHD & DTS-HD MA are lossless, compressed formats, and that the decoders on the user's side (either in the AVR or Blu-ray player) uncompress and then decode these tracks back to their original full PCM.
See the above explanation. Any compression scheme, lossy or lossless, requires a reciprocal decompression scheme to recover the data.
Quote:
Originally Posted by sptrout /forum/post/18167242
I think we are just mixing terms "decoded" & "compression" here more than anything. DD & DTS are "decoded" to PCM, and HD formats are "uncompressed" and then "decoded" to PCM. That is the way I keep things straight in my mind.
Nope. As explained previously.
Quote:
Originally Posted by
sptrout /forum/post/18167242
Here is the link to the article I was referring to:
http://www.hemagazine.com/node/Dolby...compressed_PCM
There is an error in the article. The article says at the end: "The
lossless, Dolby Digital Plus, and DTS-HD High Resolution compressed tracks were just a little more open and airy."
DD Plus and DTS HD High Res still use a lossy compression scheme. It is just "less" lossy than legacy DD and DTS.