Midi control for QTractor

I made a little patch, so that qtractor now happily obeys volume/pan controllers from my midi controller. I'm not sure this is "the right way" to do it. It is channel based, meaning that for every volume change received the program tries to find midi tracks corresponding to that channel. This may be a bit awkward, but I don't know how to do it otherwise. Also, qtractorTrackGainCommand with its redo/undo system is omitted; volume and pan is set directly through track->setPanning() and setVolume(). I did this because the first implementation had some feedback issues, events not coming back soon enough; there is a lot of happening if you push many faders at once :) I also had some crashes in appendMessages(), so I commented that out temporarily. Need to investigate that some more.

Below is what I added to void qtractorMainForm::midiControlEvent ( qtractorMidiControlEvent *pCtlEvent )

Bye, Marko

    // handle volume controls
    if (pCtlEvent->controller() == 7) {
        for (int i = 0; i < m_pSession->tracks().count(); i++)  {
            qtractorTrack* pTrack = m_pSession->tracks().at(i);
            if (pTrack && (pTrack->trackType() == qtractorTrack::Midi) &&
                    pTrack->midiChannel() == pCtlEvent->channel()) {
                float fGain  = float(pCtlEvent->value()) / 127.0f;
                // Set track gain directly bypassing undo/redo system
                // to avoid feedback issues with motorized external
                // controllers
                pTrack->setGain(fGain);
                qtractorMidiBus *pMidiBus
                    = static_cast (pTrack->outputBus());
                if (pMidiBus)
                    pMidiBus->setVolume(pTrack, fGain);
                qtractorMixer *pMixer = mixer();
                if (pMixer) {
                    qtractorMixerStrip *pStrip  
                        = pMixer->trackRack()->findStrip(pTrack->monitor());
                    if (pStrip && pStrip->meter())
                        pStrip->meter()->updateGain();
                }
                sCtlText += tr("(track %1, gain %2)").arg(i).arg(fGain);
            }
        }
    }

    // handle pan controls
    if (pCtlEvent->controller() == 10)
    {
        for (int i = 0; i < m_pSession->tracks().count(); i++) {
            qtractorTrack* pTrack = m_pSession->tracks().at(i);
            if (pTrack && (pTrack->trackType() == qtractorTrack::Midi) &&
                    pTrack->midiChannel() == pCtlEvent->channel()) {
                float fPanning  = (float(pCtlEvent->value()) - 63.0f) / 64.0f;
                pTrack->setPanning(fPanning);
                qtractorMidiBus *pMidiBus
                    = static_cast (pTrack->outputBus());
                if (pMidiBus)
                    pMidiBus->setPanning(pTrack, fPanning);
                qtractorMixer *pMixer = mixer();
                if (pMixer) {
                    qtractorMixerStrip *pStrip
                        = pMixer->trackRack()->findStrip(pTrack->monitor());
                    if (pStrip && pStrip->meter())
                        pStrip->meter()->updatePanning();
                }
                sCtlText += tr("(track %1, panning %2)").arg(i).arg(fPanning);
            }
        }
    }

Hi,

I'm not sure it is CVS ready. I'm getting some really random crashes, meaning: sometimes none after 5 minute intensive control flood, other times immediately after moving one fader.

#0 0x00007fe0f8f8d5f4 in ?? () from /lib/libc.so.6
#1 0x00007fe0f8f8ba45 in memmove () from /lib/libc.so.6
#2 0x00007fe0fbb2253e in snd_seq_drain_output () from /usr/lib/libasound.so.2
#3 0x00000000004aef00 in qtractorMidiEngine::capture (this=0x297b500, pEv=0x2d52380) at src/qtractorMidiEngine.cpp:949
#4 0x00000000004b0b21 in qtractorMidiInputThread::run (this=0x2bf0a70) at src/qtractorMidiEngine.cpp:222
#5 0x00007fe0f9a90362 in ?? () from /usr/lib/libQtCore.so.4
#6 0x00007fe0fac043ea in start_thread () from /lib/libpthread.so.0
#7 0x00007fe0f8feec6d in clone () from /lib/libc.so.6
#8 0x0000000000000000 in ?? ()


But almost certainly there would be the following abort when exiting qtractor application. Note that this doesn't happen when not using bcf.

#0 0x00007f1226a7dfd5 in raise () from /lib/libc.so.6
#1 0x00007f1226a7fb43 in abort () from /lib/libc.so.6
#2 0x00007f1226abefa8 in ?? () from /lib/libc.so.6
#3 0x00007f1226ac4938 in ?? () from /lib/libc.so.6
#4 0x00007f1229665d3d in snd_seq_close () from /usr/lib/libasound.so.2
#5 0x00000000004ac6bc in qtractorMidiEngine::clean (this=0x1775740) at src/qtractorMidiEngine.cpp:1306
#6 0x0000000000465170 in qtractorEngine::close (this=0x1775740) at src/qtractorEngine.cpp:191
#7 0x00000000004fe58c in qtractorSession::close (this=0x17751b0) at src/qtractorSession.cpp:181
#8 0x0000000000565e60 in qtractorMainForm::closeSession (this=0x7fff31ce2880) at src/qtractorMainForm.cpp:1498