|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
64.81.110.150
In Reply to: Well, it's proprietary... posted by Michi on September 27, 2005 at 01:07:39:
Right from the horse's mouth..."The ReBit process reduces the effective bit-depth of selected channels by resetting the Least-Significant Bits (or LSB - the 24th bit, the 23rd bit, etc.) to zero, either manually or automatically, in 2-bit steps. This reduces the amount of data compression necessary to encode the channel, without reducing the actual number of bits (which is why this is known as "effective bit-depth reduction"). The significance of this is that if the DVD-A player has a "24-bit" indicator, it will stay lit.
ReBit is a "lossy" process, because it reduces the actual bit-depth resolution of one or more channels before encoding (the MLP encoding process itself remains Lossless). If the source material has failed the encode process, the original soundfiles must be altered or be removed from the DVD-Audio disc. In these rare cases, ReBit is an effective solution. "
Luckily it looks like it was desinged as a last resort and most folks probably aren't going to be using it arbitrarily.
I've never had an MLP FIFO failure so I've never had to turn the damn thing on.
... ReBit + Verance ... I dont know... Neither are mandatory. I guess it comes down to 'let your ears be the judge'. I'd have to wonder what Verance at top strength and ReBit at full latitude would really sound like compared to the original. That's another test we could do. (I have access to the Verance encoder as well) A -> verance -> ReBit -> B, compare.
I dont like that one clause though: "The significance of this is that if the DVD-A player has a "24-bit" indicator, it will stay lit." Hurrah for that, I guess.
Follow Ups:
Rebit's purpose is to save space when 24 bits are not needed in one or more channels.In a multichannel recording where the rears are mostly used to record the ambiant sound then the dynamic range in these channels is fairly limited aleady. So re-bit can save some space if the dynamic range isn't used to the full extend. In such a scenario it's perfectly lossless. (A bitcheck of these track easily confirms how many of the bits are actually used.)
The 'keep the 24 bit indicator lit' is just half the story. By padding the decoded word up to 24bits in the MLP decoder the design of the subsequent filter/dac design simpler.
Note that this option helps out with the current limitations of the DVD format.
The other end of the scale of MLP's capabilies is that it can encode up to 63 channels at 24/192ks perfectly lossless.
.
..or absolutely inflammatory at any cost to anyone who may tarnish the jewel of the "team" you cheer for?Nothing I said wasn't factual. But you had to come by and snipe because you know I've listened to SACD and not pissed on it in my time here.
REBIT IS THERE. *MERIDIAN* HAS SAID IT IS LOSSY. But you're more of an authority on MLP than Meridian is I guess.
I suspect there are other reasons that you feel you have a duty to kick dirt on my posts, but that's more of a personal issue.
"In our MLP training information, we point out as a matter of information that the size of a compressed file can be adjusted by using (gentle) low-pass filtering or selection of a word size to suit the project. This is useful background information to a certain type of producer, who may want to free up space on a disc for other assets or simply understand how the process works."
"Gentle" prefiltering? So what? ReBit *IS* LOSSY. Prove otherwise, you big-headed twerp.I guess "Gentle" is now also "Lossless". Oh, no no I know, the MLP process (when not using ReBit) is still lossless - but we'll just *ignore* the fact that a LPF had to happen in order to make MLP more efficient.
Agree to disagree, bury the hachets, whatever, but we're degenerating into name calling and I don't want to close this thread like the one above.
.
This is what: ReBit affects "bit depth". And the article refers to "word size" -- i.e. "bit depth" -- as a factor affecting compressability. Now you can do that within MLP, or you can do it elswhere in the production chain. Adding an optional function to MLP doesn't make it bad. It merely makes it more 'flexible'.> > Gentle" prefiltering? So what? ReBit *IS* LOSSY. Prove otherwise < <
You are saying rebit is lossy. But I am saying MLP -- sans ReBit -- is lossless. I think we agree on both scores.
And you do puzzle me with this loaded statement:-> > LPF had to happen in order to make MLP more efficient. < <
But who in the industry, with practical knowledge of DVDA, has ever proclaimed that MLP is "inefficient"?
Anyway, we now know that these sorts of tricks do apply to SACD, i.e. in order to extend a full six-channel program to more than 65 mins, reducing the dynamics allows the DST compressed file to still fit into the available disc space of a hybrid SACD. That's not rocket science.
Martin said: "Anyway, we now know that these sorts of tricks do apply to SACD, i.e. in order to extend a full six-channel program to more than 65 mins, reducing the dynamics allows the DST compressed file to still fit into the available disc space of a hybrid SACD. That's not rocket science.This is totally WRONG and in a previous deleted post he even said Audiophile companies do it. NO SACD I know of has been released that does not have the full dynamic range of the DSD master tape. Please Martin give as the titles so they can be check out!
Here are the choices taken so far to increase playing time for Multi-Channel programs over 74 minutes. 1) Use 4.0 or 5.0 channels instead of 6.0 to gain extra playing time or 2) release the longer program on 2 SACDs instead of 1 SACD. The first option was used by Telarc for example and the second option is used by Universal and many others.
This quote was given to Martin by an unnamed SACD engineer for an audiophile company and just like his quote that SACD is a virus, I believe this came purely from Martin own head.
Martin says "it's not rocket science" that is true because it is NOT done.
.
This post is made possible by the generous support of people like you and our sponsors: