Rockbox Technical Forums

Rockbox Development => Feature Ideas => Topic started by: asymsucon on January 04, 2018, 02:03:05 AM

Title: LUFS analyzer plugin?
Post by: asymsucon on January 04, 2018, 02:03:05 AM
I have looked into EBU R128 and was wondering if it would be possible to program rockbox plugin based on their loudness measurements.
There's already a project on github: https://github.com/jiixyj/loudness-scanner

The idea is to show LUFS Integrated, short-term and LRA on WPS, which would greatly help when shuffling through unknown music (e.g. to have a loudness readout before the song even begins). And to have plugin which could do those measurements online.
Title: Re: LUFS analyzer plugin?
Post by: saratoga on January 04, 2018, 11:17:13 AM
You have to decode a file before you can get loudness information, so I am not really sure what you want to do here. A replaygain scanner plugin? Yes in theory, although it will take a very long time given how slow most mp3 players are, much longer than plugging into a computer.
Title: Re: LUFS analyzer plugin?
Post by: asymsucon on January 06, 2018, 06:48:18 AM
Apologies, I explained incorrectly - what I meant was firstly support for reading ID3 LUFS tags so that those can be displayed on WPS and also a plugin able to do the measurement online for those files that are not tagged and/or to get more precise short term and momentary readout while the track is playing.
Title: Re: LUFS analyzer plugin?
Post by: saratoga on January 06, 2018, 01:08:49 PM
We already support reading and showing the replaygain tags in the wps AFAIK.

A scanner plugin has been discussed before, it's just a lot of work and of limited use. I don't think anyone would mind if you wanted to work on it, although keep in mind we have no software available in rockbox for writing tags, so you would need to provide that for a number of formats.
Title: Re: LUFS analyzer plugin?
Post by: asymsucon on January 07, 2018, 07:44:26 AM
EBU R128 recognizes multiple loudness values:

Integrated
Short-term
Momentary
LRA
and True Peak (in dBTP)

It's measurement is not directly comparable to replaygain or RMS average.

But now as I see it it'll be probably easiest to format the values in comments tag and have it shown on WPS.
Title: Re: LUFS analyzer plugin?
Post by: saratoga on January 07, 2018, 11:26:18 AM
The replaygain tag value is the r128 Integrated value, at least if you use foobar. Foobar writes the sample peak rather than true peak, but the two values are within a fraction of a dB of each other, so the difference isn't relevant.

If you want the last few hundred milliseconds loudness on the wps, that'd have to require more significant changes to the wps. The peak meter does something similar although without the weighting. That might be a starting point.
Title: Re: LUFS analyzer plugin?
Post by: asymsucon on January 08, 2018, 02:25:12 AM
Is it possible to place logarithmic peak meter on WPS with visible dBFS (or dBTP) readout on X-axis?
%pm, %pV, %pR just show a line with no readout values