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Author Topic: Expressions in calculated fields: I need some help  (Read 1397 times)

negopus

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Expressions in calculated fields: I need some help
« on: June 26, 2006, 12:03:17 pm »

Where can I find info about expressions in calculated fields? I cannot find them in the online documentation, nor by searching the forum.

I would like to:
•   Convert the peak level into dBFS [PK dBFS]=20*log10([Peak Level])
•   Determine the average track level (in dBFS) from [AVG dBFS]=-20-[Replay Gain]
•   Calculate the difference of the two, obtaining an overall value of the track's dynamics in dB [DYNAMICS]=[PK dBFS]-[AVG dBFS]
•   Compare the result with the value of Compression/Intensity

Also, I would like to know the algorithm used to determine Compression/Intensity. Peak Level should be obvious, and Replay Gain is well documented.

Thanks.
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Matt

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Re: Expressions in calculated fields: I need some help
« Reply #1 on: June 26, 2006, 12:07:37 pm »

You'll need to copy and paste to a spreadsheet for advanced things like this.
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Matt Ashland, JRiver Media Center

negopus

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Re: Expressions in calculated fields: I need some help
« Reply #2 on: June 26, 2006, 12:16:34 pm »

If I am not using logarithms and advanced stuff like that, where can I find information about expressions in calculated fields?
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marko

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Re: Expressions in calculated fields: I need some help
« Reply #3 on: June 26, 2006, 01:24:17 pm »

I may be missing your point entirely, and hopefully you won't find me overly obtuse if I point out that, as far as I'm aware, "calculated" in an MC field, really only means that the field is derived from an expression, or other group of existing metadata, rather than any mathematical calculation.

It's been requested a few times, but so far, we cannot use expressions to do maths.

============

you've doubtless seen the Database Expressions page already?

If you open MC, go, 'tools > options > library' and then click the add button, you will see, in the lower right corner of the dialogue, the entry fields for any "calculated" field you may wish to create. You place the expression in the template entry, and MC then 'calculates' the data for your new field.
The beauty of using this method, rather than an "advanced expression" based pane in a viewscheme, is that as an actual field, it becomes available as a choice in library browser views like any other field.

-marko.

negopus

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Re: Expressions in calculated fields: I need some help
« Reply #4 on: June 26, 2006, 01:57:25 pm »

I may be missing your point entirely,
In this example I was trying to do some maths on fields computed by Analyze Audio. Using these results, I think I'll come out with a proposal for a level meter to be implemented in MC.

Quote
and hopefully you won't find me overly obtuse if I point out that, as far as I'm aware, "calculated" in an MC field, really only means that the field is derived from an expression, or other group of existing metadata, rather than any mathematical calculation.
I was looking for general info about expressions in calculated fields, however.

Quote
It's been requested a few times, but so far, we cannot use expressions to do maths.
So, only string operations are supported. By the way, using cut-and-paste data are exported to a spreadsheet as text, so if has to be further manipulated in order to obtain their numerical value (and then do some maths).

Quote
you've doubtless seen the Database Expressions page already?
That's exactly what I was looking for. Thank you.

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