#Redbook sound good enuf?
18 messages in this thread
Just for my personal curiosity, why isn't the redbook sound good enough for
many CD-ROM discs? I don't see why a disc like Sharlock Holms requires a
sound board. Do they, the publisher, expect that the users of the disc are
all (since they do not offer a choice) high quality sound buffs. One of our
CD-ROM readers is hooked up onto a boonbox and working very nicely with an
good enough sound. As a matter of a fact, it plays much better than some of
the FM stations. John
Redbook audio is very good the problem it also takes up quite a bit of
space on the disc. SO the tradeoff is between audio (red book) in data one
has to make cuts somewhere to get the program to fit.
How and why is, for lack of a better word, 'sound card audio' different
from Red Book? I *think* I know, but I'd love to have it explained to me
clearly once and for all. (For a smart guy, I can be pretty dense
sometimes <g>)
-Bill
Red book is 44.1khz/ 16-bit/stereo and sound card audio can be 8-bit mono
to 16-bit stereo. I think most support the 8-bit sound quality since Sound
Blaster pro has quite a few units out there.
There might be some other differences too but that is the only thing I can
think of off the top of my head.
Thank you Albert, and let me ask further; the Red Book audio is on the CD,
just the same as audio, 0's and 1's in digital format, 70-odd minutes worth
at most. Now take, say, a game on CD that uses the sound card for its
sound; how does it do this? Is there hardware on the sound card that
understands an instruction from the PC to "Play A-Flat for 45 ms"? Do you
understand what I *don't* understand? I *think* I understand what I don't
understand..<g>.
-Bill
Bill,
I'll just speculate. <grin> I'll assume that a player program for a Sound
Blaster like card can be on a floppy or hard disk and play the required
tones. So I would assume that it could also reside on a CD-ROM without any
problem as well. The same would hold true for digitized sound as well.
I dunno Albert, I don't think I'll ever have real good understanding of
this. Below a certain level, I go blank. Sometimes when I'm hooking or
un-hooking a cable wire from a TV, I stop and just stare at that tiny
single strand of copper and wonder how in hell it can carry all that video,
audio, (in stereo and surround yet) and on a bazillion channels- all at the
same time.
Thanks for trying, though!
-Bill
Computer audio except for WAV files remains digital; the standard
formats interleave audio and video at a fast enough rate they appear to be
simultaneous. Regular CD audio requires a D/A converter to analog and kind
of insists on total access to the output channel.
So the software tells the sound board to do "X, Y, and Z" and the sound
board does it right? I think I may be getting a vague understanding of
this, thanks….
-Bill
Albert, Thank you for your reply. I guess 600 MB is no longer good enough
in today's standard. <g> What's next? Albert, will you be kind enough to
read my msg addressed to Peter on software emulating sound board.
I've haven't heard anything about such technology. I would just assume
using Red Book audio could give you everything and more when compared to a
sound card.
In 1984 or in Atari's Laservideo (laserdisc) arcade game FireFox. They had
some write a complete score and it would all come to get there seemlessly
regardless of where one was flying. It was pretty impressive and used an
complete orchestra for the background music. I even have the music on tape
somewhere.
(remove the OR in the first sentence after 1984).
So I would assume that using a similar technique you can get similar
results.
Albert,
RedBook audio is great if all you want to do is play audio. While redbook
is playing, the player is dedicated to playing audio. If you want Imagery
at the same time, It must be in memory. With a sound card you have the
option of having audio and/or data in memory, The audio data is also much
less of the CD bandwidth. i.e. 11kps vs 176kps.
What you need to do the equivalent to the videodisc game you mentioned is a
full XA compatable player that has the ADPCM audio decoders on them. This
allows the data and audio interleaving that is similiar to what was done in
the videodisc games. This interleaving is one of the great features of the
CDI machines.
Back in the 80's my company did similar things in Multimedia (Sorry
videodisc <g>). The video production was awesome. A simple example would
be to interleave 4 (or more) video segments on a frame by frame basis. Then
you might have different audio tracks for each sequence. When you played
the disc back you told the player to play at 4X and only play every 4th
frame. To get seamless transitions of events took lots of planning.
Glen Chapman
Glen,
Thanks makes sense! Does ADPCM decoders have to be on a seperate card or
can they be in the same housing as a drive? From what I remember the Sony
CD-ROM drives needed a special card to handle it. Couldn't one get the
same effect just encoding red book audio in the data track and then sending
out the data as audio? It seems like it would allow for any CD-ROM drive
regardless of system to support audio and data without too much of a
problem. Then XA would be needed unless someone wanted to do compression
of audio.
What do you think?
The decoder chip and buffers could be either place. Now that I think about
it, it may make more sense to have it as a part of the drive. This would
allow both Redbook and Compressed audio to come out the same audio level
jacks. The only advantage to having on a controller card in the PC would
be that it MIGHT give the user the capability to playback/merge sound maps
that had been stored im memory or on hard disk. i.e. add a variable voice
track over a musical score.
As far as the second part, I'm not quite sure what you are getting at.
One problem with it is that if you store the audio in data tracks, even as
raw mode sectors, you would get a glitch for each of the 75 sectors per
second. All data tracks have some header information while Redbook is
stored as a continious data stream.
Thanks for your reply. Unfortunately, I can not play Nautilus disc with
another computer that we have simply because it does not have a sound
board. It does not plave .WAV either. I installed SPEAK.EXE but Nautilus
still wants a device, which I believe it means a sound board. I have no
problem with CD-Track which is Red Book audio. Oh well, I might have to
invest on another sound board!! My smart computers do not know that X'mas
Visa bills are now hitting me so hard. <g>
Having been involved with the Sherlock product, I feel obliged to answer
your question. Sherlock Holmes features live video, and thus has to
interleave the audio data with the video information to provide
semi-synched audio and video. Also, the CD ROM drive can work with either
data or CD Redbook audio, but not both simultaneously. If you are playing
redbook, then no data can be read from the disc.
Peter, Thank you for your easy to understand explanation. Meanwhile, I
heard there is/are software bypasses soundboard and use the existing
circuit of CD-ROM to emulate sound board. Do you know where such a software
can be obtained. I know CD-ROM, Inc. will be publishing a software called
Soft Audio for such application but won't be available for next two months.
I did hear such a system at the recent COMDEX show and I was very
unimpressed with the quality. They are in essence trying to send data fast
enough through the circuitry to emulate CD redbook audio. However, the
computer does not have the ability to process data that fast, a DSP is
truly needed for this. The quality was similar to a less scratchy speaker
driver.