On Sat, Nov 28, 2020 at 2:46 PM Paul B Mahol <[email protected]> wrote:
> > > On Sat, Nov 28, 2020 at 2:24 PM Michael Koch <[email protected]> > wrote: > >> Am 28.11.2020 um 13:44 schrieb Paul B Mahol: >> > On Sat, Nov 28, 2020 at 1:35 PM Michael Koch < >> [email protected]> >> > wrote: >> > >> >> Am 28.11.2020 um 12:57 schrieb Paul B Mahol: >> >>> On Sat, Nov 28, 2020 at 12:41 PM Michael Koch < >> >> [email protected]> >> >>> wrote: >> >>> >> >>>> Am 27.11.2020 um 20:50 schrieb Paul B Mahol: >> >>>>> On Fri, Nov 27, 2020 at 8:24 PM Michael Koch < >> >>>> [email protected]> >> >>>>> wrote: >> >>>>> >> >>>>>> Am 27.11.2020 um 19:25 schrieb Paul B Mahol: >> >>>>>>> On Fri, Nov 27, 2020 at 7:09 PM Michael Koch < >> >>>>>> [email protected]> >> >>>>>>> wrote: >> >>>>>>> >> >>>>>>>> Hello, >> >>>>>>>> >> >>>>>>>> I have a few questions about the asubboost and asupercut filters. >> >>>>>>>> >> >>>>>>>> -- In asubboost it's not yet clear how the block diagram of the >> >> filter >> >>>>>>>> looks like. Especially the "decay" and "feedback" options are >> >> unclear. >> >>>>>>>> What's the input of the the delay line? Before or after the low >> pass >> >>>>>>>> filter? Where does the feedback go to? Before or after the >> lowpass >> >>>>>>>> filter? I have attached a sketch of a possible block diagram, but >> >> it's >> >>>>>>>> only a wild guess. >> >>>>>>>> >> >>>>>>> This filter just adds delayed sub frequencies set by cut off >> >> frequency >> >>>>>> back >> >>>>>>> to output. Decay sets decay of old sub echo in buffer and feedback >> >> sets >> >>>>>> how >> >>>>>>> much >> >>>>>>> new sub frequencies are added to the delay buffer. >> >>>> I did try to reverse engineer the asubboost filter from its output >> >>>> signal. Is the attached sketch correct? >> >>>> It seems the "feedback" parameter is unnecessary because it does >> exactly >> >>>> the same thing as "wet". >> >>>> >> >>> No, your reasoning is invalid. >> >>> >> >>> I do not have time to draw graphs or do consulting for free. >> >> When you swap the values of "wet" and "feedback", the output does >> always >> >> remain the same. >> >> If you think that I'm wrong, please show an example to prove the >> opposite. >> >> >> > Make sure that you take into account decay parameter, delay buffer is >> still >> > used. >> >> When you swap the values of "wet" and "feedback", the output does always >> remain the same, regardless which values you use for "dry", "decay" and >> "delay". >> As can be shown with this example: >> >> set "A=0.4" >> set "B=0.7" >> >> ffmpeg -f lavfi -i aevalsrc='0.5*gt(t,0.1)':d=1 -lavfi >> asplit[a][b];[b]asubboost=dry=0.3:wet=%A%:decay=0.4:feedback=%B%:delay=50[c],[a][c]join,showwaves=draw=full:s=800x300:r=1 >> >> -frames 1 -y out1.png >> >> ffmpeg -f lavfi -i aevalsrc='0.5*gt(t,0.1)':d=1 -lavfi >> asplit[a][b];[b]asubboost=dry=0.3:wet=%B%:decay=0.4:feedback=%A%:delay=50[c],[a][c]join,showwaves=draw=full:s=800x300:r=1 >> >> -frames 1 -y out2.png >> >> ffmpeg -i out1.png -i out2.png -lavfi vstack -y out.png >> >> >> Red is input step signal, green is output step response of the asubboost >> filter. In the lower half of the output image the "wet" and "feedback" >> values are swapped. >> > > What we said previously about delay buffers and that above command? > It was literally less than 24h. > That command can not show you the action of delayed input as it is not > designed for it. > More precisely input which is single impulse and rest is 0 can not give you different output ever. Try it on real bassy music. > >> >> Michael >> >> _______________________________________________ >> ffmpeg-user mailing list >> [email protected] >> https://ffmpeg.org/mailman/listinfo/ffmpeg-user >> >> To unsubscribe, visit link above, or email >> [email protected] with subject "unsubscribe". > > _______________________________________________ ffmpeg-user mailing list [email protected] https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email [email protected] with subject "unsubscribe".
