Audio only thru 1394 seems like a very cool idea and we've kicked it around here quite a few times. There are many issues involved in making this work correctly so don't expect this to happen soon, if ever.

SonicEPM: Thanks for the reply. If Audio only via firewire is not on the near horizon, perhaps you can explain to me (in more pricise terms than I know) what I give up by taking the obvious shortcut and arming an audio track for recording via my sound card's analog sound input.

For me the biggest advantage of firewire input is the convenience of dispensing with level checks. If the source signal to my Digi8 was good when I recorded the LP, I don't have to worry with checking peaks and setting levels when I transfer to my HD. Additionally, of course, the capture file size is much smaller. This only becomes a concern only when disk space gets tight because of lengthy capture sessions. After I delete the video track and render the audio track to WAV I delete the entire capture file anyhow.

My question is this . . . how much fidelity do I give up if I choose analog over firewire input? My sound card is a SB 128-voice PCI which appears to offer the audio setup choices as VV's capture settings (although my expertise is basically limited to aural evaluation . . . and, I admit, my CD's seem to sound good no matter which method I use).

Thanks again for your repsonse.

Caruso

Using the SB audio card to capture audio from a camcorder would (in every config I'm aware of) involve a D/A conversion, then an A/D conversion. That's something you avoid if you capture audio thru 1394- you stay digital all the way thru.

Sonic:
Thanks for the reply. I understand the routing and conversions. Same would be true if my system used a video card with anog in/out. In video, of course, what you give up in terms of generational degradation is quite obvious to me. As for audio, I'm not so clear. Before I obtained my cam with firewire, DA-->AD was the only route I could take with my audio only projects. In the case of live performance, I recorded using a non-firewire cam that had digital sound capability. The sampling rate wasn't as high as today's cams, but it did (does) do a nice job. All ins/outs on that cam are analog. In the case of LP's, of course, there was yet another conversion involved (which is true no matter what cam I use . . . I don't plan on connecting my turntable directly to my sound card).

I guess my question wasn't stated clearly enough in my previous post, but, what do I give up in those conversions, if anything? Will they make an audible difference in my final output CD's? It would appear that SF to date considers the tradeoff acceptable since audio-only firewire continues to reside below other issues on the priority list (and I can say the same for everyother audio/av editing package I've used). I admit that I've not convinced myself that I can hear a difference between audio captured DD over that captured AD, sometimes I think I can hear a difference, but, I'm not certain whether its aurally or "mentally" caused.

If you are able to comment furhter, I'd appreciate your thoughts.

Thanks again for the reply.

Caruso

There are three main sources of decreased quality by going through
the analog capture. One is simply that no conversion hardware is 100%
accurate so every extra step is going to garble the signal slightly.

Secondly, analog and digital are two vastly different ways of storing the
signal. There are nuances to an analog signal that simply won't be
stored the same when converted to digital, and vice versa. Each
additional conversion will accumulate these errors and introduce more
slight distortions. For this same reason, you should avoid resampling
whenver possible, and if it's absolutely necessary, try to resample
only once.

Thirdly, There's an old electrical engineering rule of thumb that every
signal conversion results in a 3dB loss of signal to noise ratio. This
ratio is the measure of how much good sound you hear compared to the
bad noise in the background introduced by the equipment and recording
medium. While this may or may not hold exactly true in every situation,
it's still a useful figure.

LPs usually have a S/N ratio of about 50dB, which means that the noise
is about 0.32% of the sound you hear. When you record from the output
of your sound system to the camera, you lose 3dB of that and the noise
is now about 0.45% of the total sound. If at this point you capture with
FireWire, you will retain this low noise level. However, if you use analog
you will go through two more conversions, dropping your S/N ratio to
around 41dB and the noise level is now about 0.89%.

Still under 1%, which most people would consider inaudible. The true
test is, what does it sound like? You've mentioned that it still sounds
good. Maybe it's good enough. Have some friends come over and play
the final CDs through your good sound system for them. Have them
compare CDs prepared both ways, but don't tell them which one is
which. If they can't tell the difference, then why worry about it?