[Shotimes] OT: DVD burner

[Titus Lloyd]

I found this information on a Macintosh site, but it references using a
PC. The page I got this from is here:
http://www.macintouch.com/audioconvert02.html

Hope it helps.

Toren Kelly Smith
  In response to Will Collier's mail about capturing Dolby Digital
streams from LaserDiscs: I've done this, albeit on a PC --
unfortunately I've never had the opportunity to try it on a G5. To do
this you need the following:
	 	 If your LD player's AC3 output (AC3 = Dolby Digital) is AC3-RF,
then you either need a separate AC3 demodulator, or a receiver that has
an AC3-RF input and a digital output. LaserDiscs store Dolby Digital
streams as an RF-modulated signal, which must be demodulated before it
can be fed to a normal digital input.
	 	You need an audio capture device with a digital input that will not
alter the digital signal being captured; many PC sound cards will
resample incoming digital audio to their own clock signal, which
destroys the AC3 signal. I found that sound cards based on the C-Media
8738 chip will capture the exact bits being sent, and worked perfectly.
I don't know whether the G5's Toslink input resamples the inputs or not
-- given its pro-audio appeal, I would sure hope not.
	 	Your sound card will need to be able to capture a non-PCM stream as
if it were PCM. (PCM = uncompressed audio) Digital audio streams
containing an AC3 signal have the "private data" bit set, which should
tell devices that they should not interpret the information as
uncompressed audio. My sound card's driver has an option to ignore this
bit, so it can capture the signal regardless. Some other sound cards
are too dumb to notice the bit either way. I'm not sure how the G5
handles this.
	 	Once those are satisfied, you'll be able to capture the AC3 signal
in its transport format, which embeds the compressed AC3 information
inside a 48KHz PCM uncompressed audio stream. Since the S/PDIF (and
Toslink, its optical format) standard is designed to transmit PCM audio
data, AC3 signals are padded out to this larger size. The resulting
file will sound like buzzing garbage as a PCM AIFF file, and isn't a
valid AC3 file. For that you'll need a program which can strip out the
padding of the file and write out the smaller AC3 file. I wrote a quick
& dirty program for this on Windows for my purposes, but there may be
such a thing for MacOS or UNIX -- I'm not sure.

After all that, you'll end up with a valid AC3 file that should be able
to be imported into DVDSP or another DVD authoring program. It is
definitely the case that the AC3 signal stored on LaserDiscs matches
that of DVDs: it's a 48KHz Dolby Digital stream, just RF-modulated for
storage.

On Jan 11, 2005, at 3:51 PM, Mike wrote:

> A lot of folks don't remember that LDs were the first to come out with
> DTS
> and DD/AC3.  The problem is maintaining the 5.1 and recording
> alongside the
> video.  I already checked the doom site and there were some old posts
> with
> no resolution to the question.  I was hoping something newer had come
> along.
> Mike
>
>
> ----- Original Message -----
> From: "Carl Prochilo" <gr8sho@prochilo.myserver.org>
> To: <shotimes@autox.team.net>
> Sent: Saturday, January 08, 2005 4:13 PM
> Subject: Re: [Shotimes] OT: DVD burner
>
>
>> That's probably not such an oddball thing, but I don't have any
>> laserdiscs.  Try www.doom9.org.  Basically you will want to rip the
>> laserdisc into either .mpg or .avi format and then author it into a
>> DVD.
>> I like Pinnacle Studio for the latter.
>> --
>> Cheers,
>> Carl Prochilo
>> 92 Ultra Red Crimson
>>
>> On Mon, January 10, 2005 3:33 pm, Mike said:
>>> With all the computer guys here, does anyone have any experience or
>>> knowledge
>>> of software that will let me copy my laserdiscs that have either AC3
>>> or
>>> DTS
>>> onto DVD?  I don't want to decode the digital audio into 2
> channel........
>>> Mike
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