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Bit-perfect recordings with Logic Pro - Prism Sound Verifile


Steve Crown
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Hi all

I've been using Logic years ago when I switch to Mac (after initially having started with Cubase on Atari), then I've been using Cubase for the last few years but I'm considering switching back to Logic, as I really like the software synthesizers that come with it and some other stuff.

I have a Prism Sound Lyra 2 interface for recording and monitoring, this comes with a software/feature called Verifile. This is basically like a watermark that is put on the digital audio by the converter and there is a software which lets you verify that watermark later on, to guarantee that the recording is bit-by-bit what was sent the audio interface.

Now, when I record some empty bars to test with Cubase, I can check the resulting .wav file (only works with Wave, not with AIFF) and all is fine.

However, much to my surprise, with Logic Pro, the check fails. From what I can gather, something towards the end of the recording gets changed from the original audio stream.

To be clear, what I am checking is the recorded wave file, not some bounce or something like that.

Did anyone else ever did similar tests and come across this or is aware of what could cause this? And for that matter, also if there is a way to change this behavior?

Many thanks!
Steve

Edited by Steve Crown
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Ask yourself this question(s):

If you didn't have that software available, would it make a difference that you can notice when you listen to it? Does it really matter?

And also remember the music we still revere today as great songs and great mixes was done 30 or more years ago with all kinds of imperfections that would most certainly fail all the tests today.

As far as I'm concerned, the most important part in digital recordings is to avoid clipping the converters when you record, and when you bounce. Everything else is subjective and excessive nitpicking.

My 2 cents.

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It’s more a matter of principle and I just wonder what Logic is doing and why.

If your word processor would randomly change or drop a letter here and there, you would probably still be able to get the meaning of the written text perfectly fine. But it’s not something you would expect of a word processor anyway.

Edited by Steve Crown
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Oh it is absolutely nitpicking, but that's fine. I choose to be nitpicking from time to time. I'm also fully aware that this little glitch will neither help me to nor prevent me from winning a Grammy.

But that's not the point here.

I just wonder why Logic does that, whereas some other DAWs don't (and yet some others are much worse). And it's always one sample near the end of the recording, no matter how long the recording is. If it's a stereo recording it's one sample in each channel.

 

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17 hours ago, David Nahmani said:

I'm afraid that's a question only the Logic engineers would be able to answer. 

Probably, yeah. I guess I'll might grab out a hex editor in a free minute and dig around a bit when I'm bothered enough about it.

7 hours ago, Atlas007 said:

I wonder if it has to do with the embedded personal info

I think that would go into the metadata, which should not break the Verifile data. That data is basically encoded in the dither of the audio data, so as long as the audio data is left intact, it should have no effect. But as soon as you would change even one byte of the audio data, it would fail.

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  • 2 months later...
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Finally had some time to look into this a bit deeper, just in case anyone else is nerdy enough to wonder 😄

Apparently, Logic is adding 10 ms of silence at the end of a recording when starting/stopping the recording via transport controls. It doesn't seem to do that when in autopunch mode.

I've actually read something to this end in some older documentation, although there 200 ms were mentioned IIRC.

So, the actual recording before those 10 ms of silence is bit-perfect and OCD-me is happy 😉

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