On Mon, 12 Jan 2004, G. Vincent Castellano wrote: > If the relative phase of the input signal is immaterial to the encoding > process, then there's no problem with my stereo recordings. Hmm, since > I've got the tools to show a mis-phased signal by visual inspection, I > suppose I could just go do some tests and see for myself.
I decoded one of my non-downmixed mono MP3s (encoded with --r3mix) and found that the signals were still out of phase. So I guess I'm stuck, unless it's possible somehow to flip the phase on one of the channels of an MP3. --gvc > On Mon, 12 Jan 2004, alexander lerch wrote: > > > Hi, > > > > In Broadcast, the downmix from a stereo source to a mono > > destination was often done with a phase shift of 90 degree in > > one channel. > > However, if I understood correctly, your source is already > > mono but recorded in stereo with the phase inverted in one > > channel. Then, the way to go would be to extract only one > > channel as Claus suggested. > > I do not see a way of inverting the phase without decoding. > > > > Regards, > > Alexander > > > > CB Maillist wrote: > > > > > Just adding the channels (even with the phases right) won't necessarily > > > work. If the stylus has been just slightly turned/twisted adding the > > > channels will phase out frequencies matching wave length (or harmonics) > > > of the length of the stylus L/R-track difference. In this case you may > > > be better of just preserving on channel as the mono signal. > > > > > > Just FYI > > > > > > mvh > > > Claus Bruun > > > > > > > > > > > > -----Original Message----- > > > From: [EMAIL PROTECTED] > > > [mailto:[EMAIL PROTECTED] On Behalf Of G. Vincent > > > Castellano > > > Sent: 9. januar 2004 18:58 > > > To: [EMAIL PROTECTED] > > > Subject: [mp3encoder] Inverting phase in an MP3 file > > > > > > > > > I need to find a way to invert the phase on a single channel of an MP3 > > > file. I've not seen any utilities that perform this, and I know enough > > > to do this with sox, except I've been assured that re-encoding MP3s is a > > > Bad Thing. I'd be willing to > > > hack the lame source if someone knowledgeable said this was > > > a feasible approach. > > > > > > Any suggestions would be welcome. > > > > > > Background for those who might wonder how I came to this turn: I've been > > > digitizing my album collection, and after about 750 disks, decided to > > > save a bit of space by downsampling a couple of monaural disks to single > > > channel. This turned out to be > > > a great way to remove the signal and leave me with a recording of mostly > > > surface noise. On headphones or even computer speakers, I could live > > > with bad phasing, but someday I hope to hook this up to a real stereo > > > and I'd like to get this right. Flipping the phase on the sound card > > > output won't cut it either, as I also have a lot of ripped CDs for which > > > the phasing is of course correct. I think the guys who sold me the > > > turntable must have wired the cartridge wrong--I would administer a > > > dope-slap except that I've got several test albums and never applied > > > them. I've even seen the phase inversion while looking at .WAVs in snd, > > > but it never occurred to me what was happening. --gvc > > > > > > > > > -- _______________________________________________ mp3encoder mailing list [EMAIL PROTECTED] http://minnie.tuhs.org/mailman/listinfo/mp3encoder
