Is there an effective way to know if a CD/track has pre-emphasis?
I had a few in my collection that were known to have pre-emphasis: an old Dark Side of the Moon, New Order's Low-life (old Nimbus Factory disc), Journey's Frontiers (original US disc and Japan)... But I recently acquired two more discs from Japan on the Canyon label. I wouldn't have known unless dBpoweramp tagged them for me with %PRE-EMPHASIS% = Yes
foo_dsp_effect also has its own deemph postprocessing. But IIRC it uses only PRE_EMPHASIS tag, and not PRE-EMPHASIS.
@eahm : To quote one of Greynol's old posts on the subject "apart from an educated guess? no." On the other hand, they'll probably sound especially bright when not de-emphasized. There's a pretty good list going here and on Steve Hoffman's forum of known pre-emph CDs.
Postprocessing (foo_deemph): works only with lossless sources; always active during playback and ReplayGain scan.
Does it mean that it always performs frequency response correction, no matter if audio has pre-emphasis or not? Or it also needs some flags in audio data to start de-emphasis?
To de-emphasize a track, add a tag named PRE_EMPHASIS or PRE-EMPHASIS with a value 1, on or yes. Other tracks are unaffected.
Use postprocessing if you want to add correct ReplayGain tags to your files.Use DSP if you have lossy files that you want to de-emphasize.Otherwise, there's no difference.
this means that their loudness will always be slightly off
Plugins to do de-emphasis of pre-emphasized CDs:* Postprocessing (foo_deemph): works only with lossless sources; always active during playback and ReplayGain scan.* DSP plugin (foo_dsp_deemph): works with any source
lvqcl: foo_deemph works with any lossless sources (ape, wv) or only flac?