� for me, the application would be in a time-domain time-scaling or pitch-shifting alg where one is splicing out (for time-compression or down-shifting) or splicing in (for time-stretching or up-shifting) extra segments of audio that are short.� it's about what to do for the case where the spliced audio is perfectly correlated or perfectly uncorrelated or anywhere in between. BTW, i took my 2014 post about this and posted it as an answer to a similar question at StackExchange: �https://dsp.stackexchange.com/questions/14754/equal-power-crossfade/49989#49989� that might be more readable. ---------------------------- Original Message ---------------------------- Subject: Re: [music-dsp] Blend two audio From: "Magnus Jonsson" <jmagn...@gmail.com> Date: Wed, June 20, 2018 6:55 pm To: "robert bristow-johnson" <r...@audioimagination.com> music-dsp@music.columbia.edu -------------------------------------------------------------------------- > What kind of application is this for? > > On Wed, Jun 20, 2018 at 4:37 PM, robert bristow-johnson < > r...@audioimagination.com> wrote: > >> >> >> okay, Benny, i am changing your "a(t)" to "x(t)", because i have been >> using "a(t)" for the crossfade gain function. >> >> now if you want to splice from x(t) to x(t+T) when T is "estimated", does >> that mean you can add or subtract a couple of milliseconds to T for the >> purpose of minimizing the glitch that may result in the splice? i might >> recommending doing that. >> >> so that, given an initial T, what i might recommend doing is evaluating >> the cross-correlation between x(t) and x(t+T+tau) >> >> <x(t), x(t+T+tau)> = integral{ x(t) x(t+T+tau) dt} >> >> where tau is a variable, either positive or negative and no larger than 5 >> or 10 milliseconds, that offsets T a little. look for the value of tau >> that makes the cross-correlation maximum and adjust T with that value. >> >> then crossfade. whether it's an equal-voltage or equal-power crossfade is >> something that the little "theory of optimal splicing" post is about. >> someone brought up this 2016 DAFx paper by Marco Fink, Martin Holters, Udo >> Z�lzer that appears to be about the same topic. i hadn't known about this >> before so i am gonna be reading through it. it already appears that they >> have an equation that is common with one from my post on music-dsp longer >> ago. (i sorta wish they made a reference to it, but i am not sore about >> it.) >> >> L8r, >> >> r b-j >> >> ---------------------------- Original Message ---------------------------- >> Subject: Re: [music-dsp] Blend two audio >> From: "Benny Alexandar" <ben.a...@outlook.com> >> Date: Wed, June 20, 2018 1:11 pm >> To: "Nigel Redmon" <earle...@earlevel.com> >> "music-dsp@music.columbia.edu" <music-dsp@music.columbia.edu> >> -------------------------------------------------------------------------- >> >> > Hi Nigel, >> > >> > The delay will be estimated one time in the beginning and it remains >> constant. After that the audio which is ahead is buffered for that much. >> > When switching it has to align so that after switching to other audio, >> it should be glitch free and seamless meaning user should not notice the >> switching. >> > >> > For eg: two same audio sources one x(t) and other x(t + T) where T is >> the delay between the two audio. >> > >> > -ben >> > ________________________________ >> > >> From: music-dsp-boun...@music.columbia.edu <music-dsp-bounces@music. >> columbia.edu> on behalf of Nigel Redmon <earle...@earlevel.com> >> > Sent: Tuesday, June 19, 2018 4:44 AM >> > To: music-dsp@music.columbia.edu >> > Subject: Re: [music-dsp] Blend two audio >> > >> > Suggestions of crossfading techniques, but I’m not convinced that >> > solves >> the problem the OP posed: >> > >> > "given [two] identical audio inputs...A1 is ahead of A2 by t sec, when >> switch from A1 to A2...it should be seamless” >> > >> > If the definition of “seamless” is glitch-free, crossfading >> > will solve >> it. But then why mention “identical" and “ahead”? >> > >> > I think he’s talking about synchronization. And it’s unclear >> > whether t >> is known. >> > >> > >> > On Jun 16, 2018, at 10:45 AM, Benny Alexandar <ben.a...@outlook.com >> <mailto:ben.a...@outlook.com>> wrote: >> > >> > Hi, >> > >> > I'm looking for an algorithm to blend two audio. My requirement is >> > given tow identical audio inputs say A1 & A2. >> > A1 is ahead of A2 by t sec, when switch from A1 to A2 >> > it should be seamless and vice versa. >> > >> > -ben >> > >> > _______________________________________________ >> > dupswapdrop: music-dsp mailing list >> > music-dsp@music.columbia.edu >> > https://lists.columbia.edu/mailman/listinfo/music-dsp >> >> >> >> >> >> >> >> >> -- >> >> r b-j r...@audioimagination.com >> >> "Imagination is more important than knowledge." >> >> >> >> >> >> >> >> >> _______________________________________________ >> dupswapdrop: music-dsp mailing list >> music-dsp@music.columbia.edu >> https://lists.columbia.edu/mailman/listinfo/music-dsp >> > � � � -- r b-j� � � � � � � � � � � � �r...@audioimagination.com "Imagination is more important than knowledge." � � � �
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