Still No Sdi Audio?!?!?!

[Jay Kelley]

Still no SDI audio. Still no timetable for it to be activated.

Am I the only one having a problem with this?

Jay

[eon5]

count me in... :(

[Paul Lara]

The issues surrounding SDI audio have been pinpointed, and will be available in the first VT[3] patch late this month.

[wvp]

SDI?
Hell I'd just like to get consistant analoge audio.

[Jay Kelley]

Now I know what's going on.. That is all I ask!

Finally digital audio!!!

WHHHOOOOO-YAHHHH

Jay

[JReble]

Originally posted by wvp
SDI?
Hell I'd just like to get consistant analoge audio.

Count me in with him! How come SDI audio gets this kind of attention and response when we can scarcely get any acknowledgement on the loss in audio level when recording to the drives, not to mention the other analog related issues such as balanced line stereo separation and useless audio meters. C'mon! :mad:

[ScorpioProd]

I'm not saying I agree with it, but the "loss in audio level when recording" IS intentional.

As for the meters, we sure could use REAL dB NUMBERS on the meters...

[mblade]

Intentional? :confused:

Please continue....

[JReble]

Originally posted by ScorpioProd
I'm not saying I agree with it, but the "loss in audio level when recording" IS intentional.

No offense intended, but I've seen you post that before and I have no idea where you are getting your information. Even if Newtek is really messed up and you are right that it were intended, that would not make it any less defective. There is only one correct record level for any audio processing / passing device. That correct record level???.....the one that is input to it in the first place! :rolleyes:

Taken from here.... http://vbulletin.newtek.com/showthread.php?s=&threadid=4504


Rich Deustachio
VT[3] USER

Registered: Feb 2003
Location:
Posts: 96
Paul, this audio level situation has been talk about plenty of times on this forum and I would like to know from you if NewTek is addressing this issue. Even with the Toaster Out slider all the way up, the level you capture is not the level you get on playback and if you raise the level of the clip after capture you get this pop sound that he mentioned.

05-14-2003 04:53 PM


JReble
Registered: Feb 2003
Posts: 93

Yes....what about that Paul. I have seen several users claiming this is an intentional design by Newtek, but I give you guys more credit than that since this is not a very professional way to handle audio. I am of the understanding that this is being worked on and will be corrected. There's plenty on record in this forum about the recorded audio level issue. Computer/CD/etc. sources don't have this problem.

05-15-2003 11:06 AM

Paul Lara
VT[3] demo dood

Registered: Dec 2002
Location: San Antonio, TX
Posts: 631
I don't believe there's any intention for this audio disparity to remain, and our programmers continue working on this.
__________________
Set yourself free with VT[3]!

[Paul Lara]

I believe the next revision gives us boost at the input point and traditionally, the earlier we boost the signal the better. Ideally, we will pass unity plus at least 20+ db of boost available.

[BenBrown]

I am sonewhat ignorant on this issue as I haven't gotten my VT system yet, but Paul, are you saying that VT3 doesn't allow the option of unity (0 cut or boost) on Input? What comes out of my Mackie mixer will NOT be what the VT3 records (level wise)?

BEN

[Gordon]

Ben;
It seems that there is about a 6 dB drop in the conversion from analog to digital audio. This is true with other digital audio recording devices; at least with the Alesis ADAT we have. 0 dB on the ADAT would guarantee distorted audio so on the ADAT we always set the record levels of a 0 dB analog signal at about -12dB. That gives us 12dB of head room.

Because all digital audio starts distorting above 0 dB then it doesn't make any sense to take an analog 0dB level and record it at 0 dB in digital format. There would be no headroom! With analog audio it is common to push this past 0 dB, often to +3 dB and sometimes as high as +12 dB. This would be disastor in the digital realm where 0 dB is a hard limit.

What I would like Newtek to do is to give users the choice of 0 dB = 0 dB or 0 dB=(some other level) dB during the recording of analog signals. (The analog signal may be originating from another digital source therefore it would be safe to allow 0 dB to be equal to 0 dB). That would be the best of both worlds. That way the professionals can get the audio level they need while the vast majority of VT owners would use the 'safer' recording levels, (which should be default).

From the ADAT-XT manual:
Send an audio signal to the track(s) you have placed into record-ready.
Adjust the levels on your mixer so that the “average” level is at -15 dB on the
peak meters of the XT and the loudest section never goes beyond 0 dB.

Digital audio recording is different from analog recording, and therefore requires a different method when setting levels. For more information, see Setting Levels on
page 41 of chapter 4.

And from page 41:
SETTING LEVELS
Unlike analog tape recorders, where signals routinely exceed 0 dB with no apparent ill effects, 0 dB on the XT represents the maximum possible signal level. Signals above 0 dB will be clipped and lead to digital distortion.

Because of the limitations of analog tape, there is always a tradeoff between noise, level and distortion. More level improves the signal-to-noise ratio, but also increases distortion. This distortion increases linearly, which is why signal-to-noise is often specified for a certain amount of distortion typically 3%). You can always record with hotter levels or softer levels, but either more distortion or more noise will result—with analog, you can’t have low noise, high levels and low distortion.

With digital recording, there is a much wider dynamic range, and distortion does not increase with increasing level. Yet once a digital system runs out of headroom and hits 0 dB, that’s it—the onset of distortion is immediate and very noticeable if the signal is sustained several dB above the limit. Even though very short peaks above 0 may not last long enough to cause audible distortion, you aren't capturing the signal in its original form. As a result, because of the XT’s signal to noise characteristics, it’s better to err on the side of setting levels not quite high enough rather than having them distort, especially during live recording when you don’t get a second chance.

In the studio, where you have more control over levels or are using compressor/limiters, it’s OK to light up the MAX LED on the meter on the very loudest peaks, as long as you're sure that signals aren't going beyond that point (by using the meters on your console, if they go beyond +15 dB).
However, since 0 dB on the XT equals the maximum level, the input reference level is set below 0 VU.
With the XT, a 0 VU signal on a +4 dBu mixer plugged into the XT’s +4 dBu connectors (or a 0 VU signal on a -10 dBV mixer plugged into the XT’s -10 dBV connectors) will register -15 dB on the XT’s meters. Therefore, you can run the mixer over 0 VU and still have 15 dB of headroom on the XT before distortion occurs.

Just remember that no matter what, if the XT’s meters indicate over 0 dB, distortion is occurring or is on the verge of occurring.

Here's a translation on the italics portion:
0 vu on the mixer = -15 db on the ADAT

The full manual is available for download from here:
Alesis-XT Digita Audio Recording (http://www.alesis.com/downloads/manuals/ADAT-XT_Manual.pdf)

[BenBrown]

I understand about the concept of recording digital audio below 0Db (anywhere from -6 to -15). Being an ADAT user myself, I understand and agree with your procedure. But on my adat and mixer, I can set levels so 0VU on the board = anything on the adat (including 0=digital clipping=bad:)) In fact, The adat doesn't care, it will set and clip all day if I want.

----What you are saying is that VT has a sort of automatic gain reduction at input to prevent digital clipping?
-Is it consistent enough to calculate the difference and make up for it?
-Are the inputs and meters not calibrated to a standared reference level like "-10" or "+4"?

-With regard to VT, the system does not perform the analog-Sigital conversion at Unity gain?

There is a difference between gain and reference level. (the output signal of the adat should be the same volume is the input, even of the mixer says 0VU while the adat says -15db)


-Is there no input gain setting, or is the setting just inaccurate?
-Same question-Is it consistient enough to work around until a fix?

What about output levels? Or for that matter Singnal-to-noise ratio in the system? Is the gain structure through the system inconsistient through the entire "virtual mixer" signalpath?

Any chance of access to an external sound card? Digital inputs for external converters? Or how about this - ability to slave to time code for use with an external DAW (like Pro Tools)

Perhaps these issues will be more clear after I get my system, but it has me somewhat concerned.

Thanks

BEN

[Gordon]

Hi Ben;
The long and the short of it is that with VT[3] I can get the output volume level to be the same as the volume level in. I just ignore the markings on the audio mixer and move the sliders while watching the build-in meters. (I also check the audio level meters on the deck we are using.) There even seems to be some gain on the inputs available. I know that when we mix on our 24 channel Studiomaster and feed that to VT[3], I can easily overdrive the audio by moving the sliders on the VT Audio Mixer too close to the top. (In VT[2] there never was enough gain to do this.)

The suggestions by users is to give them a yardstick on the VT audio mixer that would tell them, "If you move the slider here then it will be at unity, here you have +3dB gain, etc." Presently, there is no yardstick - there are marks but nobody seems to know what they mean and how accurate they are. I use the meters on the record deck and a decent set of speakers to monitor the audio.

[wvp]

I can understand that digital levels vs. analog levels may differ but...
What is the point of a mixer if you can balance the levels of your audio sources?
I run a variety of decks into a Mackie switcher. Output this into the toaster (and quite often striaght through to a record deck). At times I also send audio from an internal VT source.
Getting these levels to match is almost impossible.
There are no level indicators where you can say "set here for an analog input" "set here for a digital output"
There has to be a way to set the analog input so that you get a level that is consistant, one that is compatible with a digital source.
Audio clips at zero in VT? - Fine, show me where zero is. Let me set an audio source (analog/digital/ted/ddr, etc) with a level near zero and get that level on my recorder consistantly.

[ScorpioProd]

Yeah, the issue is not the level being cut because of where zero is for digital versus analog.

I was told long ago by Newtek that there is a drop of 6dB when digitizing audio into the Toaster. The reason was to prevent overmodulation when the user put more than one audio track playing at the same time in TEd.

That's what I'd been told. Again, I didn't agree with the concept, but that was the idea, AFAIK. I've never heard of this policy being changed.

Note, this is SPECIFICALLY for recording that I'm describing. What I'm talking about doesn't affect live switching type applications of Toaster.

As for where is zero on the meters, no one knows.

I use my Mackie for input and output from Toaster, so everything gets corrected there for analog audio, so I honestly don't worry about it.

For editing, I assume zero (in the analog sense, since the meters in Toaster are in the analog sense), to be where the provided 0dB tone that comes with the Toaster registers on the meters at unity gain. Convieniently, this is also the same zero I get when firewiring in DV to VT[3]. So, this makes me think that the analog and digital sources actually do have a consistent zero in VT[3]. This is quite important for things like DVD authoring and mastering to DV/DVCAM/DVCPRO via firewire.

[JReble]

Well I could care less about the digital metering vs analog metering which seems to have some confused based upon previous posts. We've already established that the Toaster audio meters are still amost useless so this is all pointless anyway.

The point is, a properly working recording device will record the input level you feed to it. If you feed too high a level it distorts; too low, you get low signal to noise. If a device records the level it's supposed to record, you know what you are getting. This has nothing to do with digital vs analog audio.