add some AU debug message

(if this is encountered, a crash is likely and error log will be useless)

diff --git a/libs/ardour/audio_unit.cc b/libs/ardour/audio_unit.cc
index 047b5e57a2d7e308234f098855d6d7ece11fc8e5..3b1c60a0c269d50ade82849fee3b33d67212e9aa 100644 (file)
--- a/libs/ardour/audio_unit.cc
+++ b/libs/ardour/audio_unit.cc
@@ -1452,6 +1452,7 @@ AUPlugin::render_callback(AudioUnitRenderActionFlags*,
        // name(), inNumberFrames, ioData->mNumberBuffers));
 
        if (input_maxbuf == 0) {
+               DEBUG_TRACE (DEBUG::AudioUnits, "AUPlugin: render callback called illegally!");
                error << _("AUPlugin: render callback called illegally!") << endmsg;
                return kAudioUnitErr_CannotDoInCurrentContext;
        }