Phil Leigh;421459 Wrote: > yeah - I get all of that. But replaygain can't possibly know what the > gain of my amplifier is or what the efficiency of my speakers are so it > can't actually know what the absolute replay SPL is going to be... > The thing I don't get is how it could conclude that it is possible to > have an effective RMS level that is higher than the possible max peak > value. The 89 (or 83) dB value is misleading you into associating it somehow with the 96dB dynamic range of 16bit PCM. The two figures are completely unrelated.
The Replaygain algorithm compares the loudness of the track/album in question against the loudness of a -20dB RMS pink noise signal, and simply sets an adjustment to bring down (or up) to the selected target level. The fact that the target level was originally expressed as "83dB" (now usually 89dB) is down to the fact that the SMPTE standard states that pink noise at -20dB RMS shall be played back at 83dB SPL. (If you want to you could play it back at 110dB SPL - it's just a consequence of where you set the playback volume control). As I understand it, Replaygain chose the -20dB RMS pink noise signal as its "base reference level" for no other reason than it was a convenient standard that happened to be in existence. The fact that they also decided to use the SPL playback level as the way to express the target loudness seems strange to me, because it's clearly the source of confusion. (But then again, the guy who developed Replaygain has a doctorate in this area, so he probably knows what he's doing). -- cliveb Transporter -> ATC SCM100A ------------------------------------------------------------------------ cliveb's Profile: http://forums.slimdevices.com/member.php?userid=348 View this thread: http://forums.slimdevices.com/showthread.php?t=57872 _______________________________________________ audiophiles mailing list [email protected] http://lists.slimdevices.com/mailman/listinfo/audiophiles
