EBU-R128 batch audio measurement tool
[ Fully compliant with EBU R128 Minimum Conformance Test Docs 3341 & 3342 ]
I took extra care to ensure that it is entirely stand-alone Lispworks code. None of my usual proprietary stuff, except in commented-out test stubs. Everything should run just fine out of the box.
The tool allows you to process one or a batch of .WAV and .AIFF files to measure Program Loudness (PL) and Loudness Range (LRA), along with True Peak Level (TPL). Program loudness is provided in both absolute and -23 dBLU relative measures. And there is an additional measure called Peak Ratio (PR) which measures the peak 3-sec loudness against the overall PL.
The code has been sped up to about 120x playback rate (!! -- that's a whopping 5.7 MSamp/sec !!). An 80 minute sound track is analyzed in about 45 seconds. It allows you to measure all the songs of an album, and find the correct normalization based on the loudest song. It is a non-destructive tool, merely measuring what resides in the audio files, and reports results in a plist.
Side benefits in this code include a standardized way of making CAPI prompt for files with a memory of your last location, as well as uncovering the secrets for WAV and AIFF formats.
Example:
(r128-rating) ;; prompts for a file to analyze
==> (:FILE #P"/Users/davidmcclain/projects/Music/Sine -18dBFSpk 32flt.wav" :TPL -18.0 :PL -18.0 :LU23 5.0 :LRA 0.0 :PR 0.0)
Entry points:
(R128-RATING &optional ) scans the file and reports the R128 statistics. Prompts for a file if the argument filename is omitted.
(R128-RATINGS &optional ) scans the files and reports the R128 statistics for each file. Prompts for multiple files if the argument list is missing.
(R128-ALBUM-RATING &optional ) scans the files and reports the overall album R128 statistics. Prompts for multiple files if the argument list is missing.
No restrictions are placed on this code.
References:
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ITU-R BS.1770-3 Algorithms for Audio Measurements
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EBU-Tech 3343 Implementation of R128
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David McClain
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Refined Audiometrics Laboratory, LLC
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Tucson, AZ, USA