On Sun, Sep 12, 2010 at 7:22 PM, Dan Dennedy <d...@dennedy.org> wrote: > On Sat, Sep 11, 2010 at 11:54 PM, Alexandre Prokoudine > <alexandre.prokoud...@gmail.com> wrote: >> Hi, >> >> I was going through rather amusing inherited translation of pitch >> related audio effects and noticed that the actual implementation is >> quite broken. >> >> Pitch shift is OK, except below 100 you get the same sound, whatever >> value you use. This is really not reproducible with the original AM >> pitchifter LADSPA plug-in. Above 100 it works as expected though. > > works for me. the pitch lowers when below 100. > >> Rate Scaler. For some reason default value is 10, which in Kdenlive > > Kdenlive divides its value by 10 before passing it to LADSPA. This is > how it provides float values. Other effect parameters may have > different denominators. > >> corresponds to normal playback. However the original Rate Shifter >> LADSPA plug-in doesn't work like that. It has a range of values >> between -4 and 4, and 1 (10 in Kdenlive) corresponds to actually >> speeding audio up. If you dive a bit further, you'll find out that 0 >> in LADSPA corresponds to no changes, whereas in Kdenlive zero >> corresponds to no sound at all. No, wait, I can hear clicks :) >> Finally, with negative values sounds goes backwards as expected. > > I get the same result as you, but it does the same thing that
I take that back. 10 in Kdenlive is normal and does not speed it up for me. > standalone Jack Rack does when I route Kdenlive's output through Jack > and Jack Rack and load rate_shifter_1417. However, MLT's LADSPA > integration code is based entirely on Jack Rack. So, maybe there is a > bug in Jack Rack that I inherited. Do you know of another tool similar > to Jack Rack that makes it easy to try out LADSPA filters on Jack > streams? Meanwhile, I will spend a little time with a WAV file and > another tool that does LADSPA to get a comparison. When I use Audacity and load the Rate Shifter, it sounds the same as in Kdenlive. 1 is normal, not 0. 0 gives me silence in both Kdenlive and Audacity. >> Pitch scaler suffers from same bug as in Pitch shift: everything below >> 100 means silence. > > This works for me as well - values below 100 are not silence. Pitch scaler works the same for me when comparing Kdenlive, Jack Rack, and Audacity. Same goes for Pitch shift. What locale are you using? >> So, I really don't know who to blame -- Kdenlive or MLT. Please tell >> me which bug tracker to poison with this report :) >> >> Also, I'm not entirely sure it makes a lot of sense to have plug-ins >> with such names and functionality. Being an Audacity user for almost a > > They are named for their respective LADSPA plugins. I am of the > opinion that we should use RDF to make all of them available. > >> decade I'm sort of addicted to names and functionality like "Change >> Speed/Pitch/Tempo". Audacity's implementation relies on libsamplerate >> which works rather well. the application also makes a good use of >> SBSMS library that works really well with any kind of sound, but >> unfortunately is not entirely good for real-time processing. Now, >> RubberBand is a rather good choice for RT, but reportedly has its >> limits in terms of quality when it comes to something other than >> percussion. Don't know if that's of any use to you. > > Those are completely different implementations not available through > SoX or LADSPA, right? So, someone would need to implement that, and > you sound like the right person to do it. :-) > >> Alexandre Prokoudine >> http://libregraphicsworld.org > -- > +-DRD-+ > -- +-DRD-+ ------------------------------------------------------------------------------ Start uncovering the many advantages of virtual appliances and start using them to simplify application deployment and accelerate your shift to cloud computing http://p.sf.net/sfu/novell-sfdev2dev _______________________________________________ Kdenlive-devel mailing list Kdenlive-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kdenlive-devel
