Use MIDI to make a drum pattern with drum samples

[samuelbraun04]

I have a hi hat MIDI file and a hi hat sample file. I was wondering how I could make a clip where the hi hat sample is played to the midi notes? I've tried:

hihat = engine.make_playback_processor("hihat", self.load_audio_file(pathHihat))
hihat.load_midi(midiHihat, beats=True)

but that obviously doesn't work, but the idea is sort of there. Thank you.

[DBraun]

One way is to use the SamplerProcessor, which is missing good examples...

sampler = engine.make_sampler_processor("sampler", self.load_audio_file(pathHihat))
# later you can call set_data
# sampler.set_data(self.load_audio_file(pathHihat))
sampler.load_midi(midiHihat, beats=True)

However, that sampler will pitch the notes according to the MIDI note, which you may not want. It also comes with many ADSR features which you'll have to set to your needs.

I'd also recommend adapting the polyphonic Faust example here: https://github.com/DBraun/DawDreamer/blob/main/tests/test_faust_poly_sampler.py
and Faust code here: https://github.com/DBraun/DawDreamer/blob/main/tests/faust_dsp/polyphonic_sampler.dsp

It currently plays back a cymbal with polyphony, and the MIDI note affects the pitch and speed of the sample. To not let the MIDI not affect the pitch/speed, you'd change the definition of ratio to ratio = 1; Then the MIDI note of 60 would be a neutral playback speed.

You may want to remove envVol. It's just there as an idea for applying an amplitude envelope to each note.

[samuelbraun04]

The SamplerProcessor was exactly what I was looking for – thank you. However, when I do the following:

        hihat = self.engine.make_sampler_processor("hihat", self.convertAudioFile(self.pathHihat))
        hihat.set_data(self.convertAudioFile(self.pathHihat))
        hihat.load_midi(self.midiHihat, beats=True)

        hihat_graph = [
            (hihat, [])
        ]

        self.engine.load_graph(hihat_graph)
        self.engine.render(16., beats=True)
        wavfile.write(self.WORKSPACE_CONTAINER_PATH+'\\'+'hihat.wav', self.SAMPLE_RATE, (self.engine.get_audio()).transpose())

I get an audio file that plays short digital clicks in the pattern of the midi file. Is there something I'm missing?

[DBraun]

Maybe you need to transpose the result from convertAudioFile too.

[samuelbraun04]

Yes that seems to be the problem – how can I tranpose the MIDI down? If I transpose the exported file it looks a lot of the quality.

Also, how can I get rid of the clicking that occurs between the instances of the sample playing? (The audio: http://sndup.net/bzqs)

[samuelbraun04]

Found a way to transpose the MIDI keys via the music21 module.

However, I'm still getting the clicks between sounds when they play right after one another (as seen in the previous reply's example).

[samuelbraun04]

Figured everything out!