Hi,
> > I just read on the MDCP the faq about ATRAC3 at > > http://www.minidisc.org/mdlpfaq.html and it says for Q#10: "What > > bitrates are used?" A:".....In LP2 and LP4 modes 20 bytes of dummy > > data per 212 byte soundgroup......" --> those 20 bytes -- are they a > > fact or just a wild guess? > > Fact. I double checked it with Sony. Sorry, my fault, but I guess I was misunderstood. I understand that ATRAC3 has to be somehow embedded into ATRAC1 and I know that that's a fact. What I meant was whether the number of bytes (20) are a fact or not (Why not 19 or 21 bytes per SG). For, you only need 13 bytes per soundgroup to produce silence. I even could ask differently. If we were ask to define the "new" ATRAC3 algorithm and we know we have to embed it into ATRAC1, why come up with 132kbps? Why waste 7 bytes per SG for nothing? Think about it, we have 775.104 SoundGroups available for recording, that means we are wasting more than 5MB per 74m59s disc and there is "no future use" for that space. > > We know from ATRAC1 that it records at (exact) 292162.5 bits/sec. I > > could not find an exact number for ATRAC3 (LP2) -- is it 132300? > > Yes, and it's easy to calculate: We know that SP mode runs at 172.266 > soundgroups/sec (ref. FAQ Q#10), LP2 mode gets precisely twice the > capacity of SP mode (contrary to Mr. Rat's freely made up facts and > figures), so that's 172.266/2=86.133 soundgroups/sec. Multiply by > (212-20=192) bytes/soundgroup = 132300.288 bits/sec for LP2. LP4 > should be precisely half that: 66150.144 bits/sec. I have really looked hard, but I couldn't find any of those numbers at the faq (though they surely sound correct). And again, you came up with 132300 bits/sec because you used those "20 bytes". > > I also read somewhere that LP uses huffman coding (fact?) -- only on > > computers or on MD decks as well? > > (Well, it's got to be both or neither to be compatible with all > players, right?) I was thinking of "cheap hardware, i.e. cheap dsp" in the MiniDisc players _AND_ small download size of music files from the internet. You download ATRAC3 with huffman coding and send it via USB to the MD player without the huffman coding. (Same as if you zip ATRAC1 data on a computer -- on the md player we know that we never have zipped ATRAC1 data). But I just realised that I am wrong. thanks for your insight. wolfgang ps: last Q: Does anyone know why the very first ATRAC coder [ATRAC1 Version1 (MZ-1)] sounded soo bad. (I know the answer, but before I am going to post it I want to have your thoughts). ----------------------------------------------------------------- To stop getting this list send a message containing just the word "unsubscribe" to [EMAIL PROTECTED]
