Re: [LAD] Replaygain for video?

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To: linux-audio-dev <linux-audio-dev@...>
Date: Saturday, December 10, 2011 - 8:42 pm

Excerpts from Adrian Knoth's message of 2011-12-10 15:01:54 +0100:

This page tells you that peak normalization is not sufficient, but
that's nothing new, it's logical that the highest peak has basically no
relation to the perceived loudness of a piece of audio.

> I have to admit I'm not too familiar with the details of replaygain, but

Exactly, no equalisation, no compression, that's why purists like it.

> According to the wiki, they store four values:

I agree, album mode makes little sense unless we have music video albums
or similar.

> Let's assume we're brave and normalize to 0dBFS, then this is obviously

Wrong. This is in short how (track) replaygain works:
1) Calculate the tracks loudness. Loudness implies psychoacoustics. It
uses some algorithm that takes the human perception into account.
2) Compare the measurement value to a reference (pink noise at -14 dB)
and store the difference as metadata.
3) The audio player reads the metadata and adjusts its output level
according to the metadata.

The result: levels of 'loud' songs get lowered to the reference level,
levels of 'soft' songs get raised to the reference level. No
compression, now eq, no need to twist the volume knob all the time.
Again, the reference level is below 0 dBFS, loud songs get attenuated.
Peak normalization in contrast just tries to make everything as loud as
possible and doesn't take human perception into account at all.

> > > There are special tools. If nothing helps, vlc and mplayer can do this.

Ok, thanks.

> > > > After that, the scanning process should work as with any audio file.

This should be possible, shouldn't it? The player needs to be able to
identify those anyway.

> It could be easier to work on the audio streams directly, but this would

Yes, especially with all those containers and formats out there.
However, I'd start with one where it's reasonably easy to do :)

> [jackd connection handling]

I don't have such a mixer. The html approach is probably outside the
scope of this class, it's a beginner C/C++ class.

> Other idea: a P1722 streamer, no idea if Christoph Kuhr is still working

I guess my teacher could like it, but I know basically nothing about
network stuff at this point.

> Or ask Paul if he needs some help with jack3. ;)

Haven't heard of that one yet and I doubt we need another implementation
:)

Thanks for your help,
regards,
Philipp

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Messages in current thread:
[LAD] Replaygain for video?, Philipp, (Fri Dec 9, 8:20 pm)
Re: [LAD] Replaygain for video?, Robin Gareus, (Sat Dec 10, 2:26 pm)
Re: [LAD] Replaygain for video?, Philipp Überbacher, (Sat Dec 10, 10:04 pm)
Re: [LAD] Replaygain for video?, Robin Gareus, (Sun Dec 11, 11:49 am)
Re: [LAD] Replaygain for video?, Fons Adriaensen, (Sun Dec 11, 12:19 pm)
Re: [LAD] Replaygain for video?, Robin Gareus, (Sun Dec 11, 1:28 pm)
Re: [LAD] Replaygain for video?, Philipp Überbacher, (Sat Dec 24, 12:11 pm)
Re: [LAD] Replaygain for video?, Jörn Nettingsmeier, (Sat Dec 10, 12:04 pm)
Re: [LAD] Replaygain for video?, Adrian Knoth, (Sat Dec 10, 10:38 am)
Re: [LAD] Replaygain for video?, Philipp Überbacher, (Sat Dec 10, 12:10 pm)
Re: [LAD] Replaygain for video?, Adrian Knoth, (Sat Dec 10, 2:02 pm)
Re: [LAD] Replaygain for video?, Philipp Überbacher, (Sat Dec 10, 8:42 pm)
Re: [LAD] Replaygain for video?, Fons Adriaensen, (Sat Dec 10, 2:22 pm)