96 Khz/24 bit DAC!!! I'm seeing this splattered on ads for everything that processes sound noadays... Mixers, CD/DVD players, sound cards. . . Then there's always another channel being added. First Mono, then stereo, then 3 channel Dolby and Quadrophonic. Then Dolby Digital comes along providing 5.1 and now 7.1 and bigger! My question is, why is there absolutely no format out there to really make full use of the capabilities this hardware provides? We're sitting here with 8 speakers hooked up, and 96Khz/24 bit audio processors conencted to them, but there is absolutely no such thing as a 96Khz/24bit/8 channel audio format?
Think about it... DVD-A uses 96Khz/24 bit, but only on two channel mode. As soon as you switch to the 5.1 mode, you drop to a compressed 48Khz 16 bit stream for each of the 6 channels Why does this have to be, I ask?
Also, even though most sound cards (to include Creative's new X-FI) sport these high capacity DACs, they still don't come anywhere close to using the bandwidth made avaliable to them on an old 33 Mhz PCI bus from ten years ago! And we're pushing everything to PCI-E because PCI isn't fast enough?
Most digital formats have progressively gained in resolution over time. We've gone from PAL and NTSC to HDTV, we've got all these really cool toys, but why haven't audio formats improved? Why are we only using 192KB/sec streams on stereo, and why oh WHY is everything still maxing out at 48Khz??? (barely more than the 44.1Khz that has been used since the 70's
I did the math to figure out just what specs would be on a stream that modern technology would be capable of recording, and reproducing on modern 7.1 channel hardware. Put a 96Khz 24 bit DAC on each of the 8 channels, and you're talking about a 192KB/s stream per channel or 1.5, no, I'll be generous and call it a 1.6 MB/sec stream to get 8 descrete channels. Don't tell me there's no transport that can handle that! my 10/100 Ethernet got twice that without breaking a sweat the other day and I thought it was slow.
OK, so we've got the PCM format, and how to encode or decode it.... And we have a way to get it from point A to point B using technology that is already commonplace. Granted most recievers don't know what to do with this PCM format, but they have multi channel analog inputs so we can use our own decoder that really uses what it has, the same as is already done for SACD and DVD-Audio.
Next question: Storage. What format of media are you going to put this on? When I first started to do the math, I wasn't sure there was going to be a format already existing that could hold enough data to provide more than a couple minutes of play time. Turns out, that a DVD would have no problem storing at least some 50 minutes of audio in this format, more than enough for most recordings. And that's using a 4.7 GB DVD-R. make that a 7 or 8 GB dual layer disk, and you needn't worry about play time. Sure, you wouldn't have room on a 45 minute or longer recording for many extras. But it's ment to be an audio disc first and foremost, not a movie or slideshow. And there's nothing to say you couldn't add some neat features to shorter recordings or on a higher capacity disc if you wanted anyway. The numbers should be similar to current DVD-video, which often even includes a seperate DVD of extras....
for refrence, here's my computational notes. They're ment to give an idea, so may not be 100% accurate. But they'll be close
96000 / 24 bit
1536KB/sec/8ch descrete audio
With a commercial DVD-R holding 4.7 GB, gives 52 minutes playing time
Even a standard CD would have the capacity to make a Single, giving a play time of almost 7:15
Maybe the question is processing? Sorry. no go there either. Processing hundreds of channels of 44.1Khz 16 bit audio is commonplace. I can sit here on the machine I type this on and do it if I wanted to. You're goint to tell me that chips that can keep up with that can't keep up with processing a live audio stream at 1.5 MB/sec?
Poet and seeker of knowledge