Audio Clipping Levels

[g_dagostini]

Hi,

I noticed one thing about audio clipping levels in EDIUS 4 Broadcast today. I extracted (I mean digitally, with a cd ripper) a track from an audio CD to MP3. It was a rock'n'roll track, very very compressed. When I put it in EDIUS timeline, the audio mixer showed me the audio clipping frequently. I reset the little red clipping light, hit play and clipped again. Both the track that my clip was into and the master track were set to 0dB of gain.
So I went to Adobe Premiere Pro 2, put the same audio file in the timeline and no clipping occured. Curious since my Audio Mixer in EDIUS was set to Full Scale and Adobe states that Premiere's master meters are in full scale too. Also, the waveform shown in EDIUS was squared in several points (clipping points) but this did not happen in Premiere. I exported this track from Premiere timeline to a WAV file, with ABSOLUTELY no change in gain, volume rubberband, etc. Imported the resut in EDIUS and no clipping occured, no squared waveform.

So I went to Adobe Audition and generated a 1Khz Sine Wave at -6dB. Both Edius and Premiere stated -6dB when playing this file! So I assume they have the same audio reference. Then I generated the same tone at -3dB, -2db, -1dB and so on. All the clips had the level mesured equally in EDIUS and Premiere. But when I played back the 0dB clip EDIUS lighted on the clipping light all the time. Premiere was just under the last possible level before clipping.

So, Canopus guys, why is this happening??? 0 dBFS shouldn't be always 0 dBFS???

Thanks

[GrassValley_BH]

There are a lot of variables here. The MP3 decoder might be involved, etc.

However, from what you say about your generated tones, it sounds like the question is not whether 0 dB is 0 dB, but rather whether the clipping warning is triggered when the level is at max, or when the level exceeds max.

[g_dagostini]

I think that the test with generated tones tells us exactly this since they are all WAV files and does not involve MP3 decoder.
The files are the same for EDIUS and Premiere and one triggers the clipping led and the other doens't.

But in my opinion an audio at 0 dBFS should not trigger the clipping led, right? Why does EDIUS do that?

[SRsupport]

WHat is the scale set to?
fullscale or audio reference?


and are you on peak or VU?

Steve

[GrassValley_KH]

Also, what version 4.x are you running?

[g_dagostini]

- As said in my first post Edius Audio Mixer is set to FULL SCALE.

- Clipping leds will turn on both in VU Meter and Peak Meter, cause even when I'm in VU Meter there's a peak meter indicator over the average (VU) level.

- I'm running version 4.61 of EDIUS Broadcast. I think is the latest, right?

[GrassValley_KH]

Yes, that's the latest version.

Some older versions suffered from some very nasty clipping problems which was later resolved. So this looks to be a separate issue from that..

[g_dagostini]

It seems the clip itself is not clipped, cause if I import that clip into Premiere and export again then it will be ok in EDIUS.
The waveform changes too!!! First it was squared at the clipping points, but after exporting trough Premiere and importing again in EDIUS the waveform is normal, with ups and downs at those points. Very weird, right?????

[SRsupport]

can we get a sample so we can have a look at it?

[g_dagostini]

How can I send you the file?

Thanks

[g_dagostini]

Sorry,

Here is the link you can download the audio file I'm talking about.

http://www.wikifortio.com/746014/01 - You're Speaking My Language.mp3

Thanks

[SRsupport]

http://www.file-upload.net/

[SRsupport]

Why are you using mp3? Is the mp3 the same sample rate as the audio in your project?
If it is it is one more step in the equation.
The audio you are using is 44100 khz beleive me you need 48 khz .
It is better to do this in an audio app.

[antonsvideo]

I use Easy CD Extractor from www.poikosoft.com

it rips an entire audio CD to wav 48k in 3 minutes or a few seconds if you select an individual track

however, some CD tracks are sooo loud that you need to lower the rubberband to 50%