On Sat, Nov 28, 2020 at 8:55 PM Michael Koch <astroelectro...@t-online.de> wrote:
> Am 28.11.2020 um 19:18 schrieb Paul B Mahol: > > On Sat, Nov 28, 2020 at 5:18 PM Michael Koch < > astroelectro...@t-online.de> > > wrote: > > > >> Am 28.11.2020 um 14:48 schrieb Paul B Mahol: > >>> On Sat, Nov 28, 2020 at 2:46 PM Paul B Mahol <one...@gmail.com> wrote: > >>> > >>>> On Sat, Nov 28, 2020 at 2:24 PM Michael Koch < > >> astroelectro...@t-online.de> > >>>> wrote: > >>>> > >>>>> Am 28.11.2020 um 13:44 schrieb Paul B Mahol: > >>>>>> On Sat, Nov 28, 2020 at 1:35 PM Michael Koch < > >>>>> astroelectro...@t-online.de> > >>>>>> wrote: > >>>>>> > >>>>>>> Am 28.11.2020 um 12:57 schrieb Paul B Mahol: > >>>>>>>> On Sat, Nov 28, 2020 at 12:41 PM Michael Koch < > >>>>>>> astroelectro...@t-online.de> > >>>>>>>> wrote: > >>>>>>>> > >>>>>>>>> Am 27.11.2020 um 20:50 schrieb Paul B Mahol: > >>>>>>>>>> On Fri, Nov 27, 2020 at 8:24 PM Michael Koch < > >>>>>>>>> astroelectro...@t-online.de> > >>>>>>>>>> wrote: > >>>>>>>>>> > >>>>>>>>>>> Am 27.11.2020 um 19:25 schrieb Paul B Mahol: > >>>>>>>>>>>> On Fri, Nov 27, 2020 at 7:09 PM Michael Koch < > >>>>>>>>>>> astroelectro...@t-online.de> > >>>>>>>>>>>> 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. > >> The previous example was "showfreqs" which has a frequency domain > >> output. Not suitable for analyzing filters which contain delays. > >> Now I'm using "showwaves" which has time domain output. That's a > >> different thing. Of course delay lines can be analyzed in time domain. > >> > >> > >>>> That command can not show you the action of delayed input as it is not > >>>> designed for it. > >> A step signal contains all frequencies and is the best possible source > >> for analyzing unknown black boxes that may contain delays. You can > >> replace the input by any other source, but you will never find any > >> difference in the two outputs. It's a fact, "wet" and "feedback" are > >> interchangeable. > >> > > Nope, you are very mistaken. Try with real audio. > > You can use this example with any real audio input you want: > > set "A=0.4" > set "B=0.7" > > ffmpeg -i dog.mp3 -lavfi > asubboost=dry=0.3:wet=%A%:decay=0.4:feedback=%B%:delay=50 -y out1.wav > ffmpeg -i dog.mp3 -lavfi > asubboost=dry=0.3:wet=%B%:decay=0.4:feedback=%A%:delay=50 -y out2.wav > ffmpeg -i out1.wav -i out2.wav -lavfi [0][1]amerge,aeval=val(0)-val(1) > -y out.wav > > out.wav is the difference between out1.wav and out2.wav, and it's > perfect silence. Which means the two inputs are equal. > Ok, made the wet option do actually apply gain to final output. > Michael > > _______________________________________________ > ffmpeg-user mailing list > ffmpeg-user@ffmpeg.org > https://ffmpeg.org/mailman/listinfo/ffmpeg-user > > To unsubscribe, visit link above, or email > ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe". _______________________________________________ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".