ReplayGain: Track-Gain

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hornung
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ReplayGain: Track-Gain

Post by hornung » Tue Jul 17, 2007 1:00 pm

there are some tracks where the "Track Gain" is very small (e.g. 0.75). Thus, the track sound really quiet (compared to the 0.9++ tracks)

same thing for whole albums, but rather rarely.

what's the reason for this and is this a bug or a feature?

br,
ch

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sbooth
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Post by sbooth » Tue Jul 17, 2007 10:07 pm

The goal of track gain is for all tracks individually to play at the same (average) loudness, like the songs on a radio. In theory, if all your tracks contain correct track gain information they should play back at the same loudness, on average.

Depending on your preferences, though, Play can alter how the gain is interpreted. First, your preamp setting will determine how much the sound is amplified in addition to the RG adjustment. Second, if you have selected "reduce preamp" for the clipping behavior the gain of the track will be reduced such that the peak value is 1.0.

Did you calculate the RG for the tracks in question using Play? Are they lossless or lossy files?

hornung
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ReplayGain: Track-Gain

Post by hornung » Wed Jul 18, 2007 10:11 am

Thanks for the reply:

1. Preamp is +6 (default)
2. Clipping is "hard clipping" (default) not "reduce preamp"
3. RG is calculated using Play
4. the tracks are .m4a (imported with Max, iTunes)

br,
ch

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sbooth
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Post by sbooth » Wed Jul 18, 2007 4:28 pm

The RG algorithm works by first filtering the signal through an inverted approximation of an equal loudness curve, then calculates the RMS value of the resultant waveform every 50 ms. A value 5% down the RMS value list is chosen as the approximate the loudness of the file.

In your case, I can only guess that for those particular tracks they are mostly quiet but have a loud section that the algorithm is selecting for the RG. Could this be the case? What is the genre/type of music for these tracks?

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