From mboxrd@z Thu Jan 1 00:00:00 1970 From: Benno Senoner Date: Mon, 25 Oct 1999 14:32:02 +0000 Subject: Re: streaming from disk to terminatorX added (via mmap) Message-Id: List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-sound@vger.kernel.org On Sun, 24 Oct 1999, David Olofson wrote: > On Sun, 24 Oct 1999, Benno Senoner wrote: > > PS: Now if we could get one of these turntables recorded with special > > static waves (saw waves), we could add add turntable motion detection > > and get the same features as "finalscratch" on BeOS: > > scratching an audiofile in realtime using a real turntable. > > :-) > > Uhm, I have just developed a sensor decoding method that could be > useful for this. It's probably overkill, as it's accurate to some 128 > bits/period of the input signal with input signals of around that > resolution. It's just that I most probably can't release the > details... :-( > David, your solution looks nicely, but I'm more for a plug-n-play solution: 2 turntable players 2 soundcards 1 PC loaded with mp3 use the 2 soundcard's inputs to detect turntable speed (py playing the static waves on the turntable), use the 2 audio outputs for the mix and prelisten (phones) channel. IMHO the precision provided by sampling the turnables's static waves is enough to get decent scratches, and the use of a "noise gate" when the turntable is rotating at default speed will give you the final touch of perfection. :-) David, I'cant remember but what would be the optimal method to detect the speed of the turntables via audio input ? form of the wave ? SAW WAVE , which frequency ? and then the algorithm ? couting the number of zero crosses/sign changes ? how o detect motion inversion ? through looking at the resulting waveform ? : if the next value is less than the previous AND you are not at end of the period (the jump is too big), then you detected motion inversion. right ? The finalscratch people seemed wrong to think that only BeOS can provide the horsepower to run a scratch-mp3s-on-turntable engine. Seems that linux , will soon even begin to eat marketshare into the DJ sector. :-) ( As David said: your next console could be powered by a GPLed audio engine running Linux :-) ) Benno.