Similarity Forum

General Category => General => Topic started by: muse2u on July 14, 2015, 17:16:47

Title: Pleasurize Music TT Dynamic Range Offline Meter vs Similarity Max (abs)?
Post by: muse2u on July 14, 2015, 17:16:47
Many use the TT Dynamic Range Meter as a tool to distinguish between audio tracks with a high dynamic range and those that have "loudness", "brickwall" issues. My understanding is that the DR Meter algorithim determines the difference (the range) between the highest and the lowest volume. The higher the DR value (eg 13-14 range) the greater the dynamic range and the less "brickwalled" an audio track is. Therefore for many a higher DR value translates to a higher quality audio track.
As far as I can tell, in Similarity the Max (abs) is the closest analysis result to a dynamic range evaluation. My understanding is that the closer this value is to 1.0, the higher the quality of the audio track. But more often than not I find that an audio track with a high TT DR value does not necessarily have a high Max (abs). I assume that the algorithms being used are different. As far as I can tell, the TT DR Meter measures the actual dynamic range whereas the Max (abs) algorithm measures the dynamic range relative to the maximum potential range for the characteristics of the track (bit rate, sample rate, etc).
For example an audio track could have a high dynamic range (ie high TT DR) but due to the characteristics of the track, is not making use of the full range potential and therefore gets a lower Max (abs).
Am I interpreting the Similarity algorithm correctly? I am a little nervous about deleting audio tracks I have with high TT DR values while Similarity's "quality" rating penalizes them due to lower Max (abs) values.
Title: Re: Pleasurize Music TT Dynamic Range Offline Meter vs Similarity Max (abs)?
Post by: wat on September 08, 2015, 22:02:13
The following is very simplified:

DR value = distance from peak to average volume; reflects an estimated relative/local dynamic range

Max(abs.) = distance from peak to zero signal amplitude; reflects the potential maximum absolute/global dynamic range

One extreme example would be a sine tone: it always gives you a DR of 0, and a Max(abs.) equal to its amplitude - 1.0 at full "volume", 0.5 at roughly -6 dB, 0.25 at roughly -12 dB, 0.0 when turned all the way down to digital silence.

On the whole Max(abs.) has relatively little to do with actual perceived dynamic range (tech: it just tells you how far away the recorded signal is from digital quantization noise induced by limited sample bit depth - give or take dithering)