metronom.sf renders all zeros

[abegehr]

How can I play the rendered ArrayInt16 in a player like flutter_sounds?

I've tried the following but it doesn't work:

    // Render the waveform (3 seconds)
    final buf16 = ArrayInt16.zeros(numShorts: sampleRate * 3);
    synth.renderMonoInt16(buf16);

    // play
    final bytes = buf16.bytes.buffer.asUint8List();
    player.startPlayer(
      fromDataBuffer: bytes,
      codec: Codec.pcm16,
      whenFinished: () => debugPrint("Calibrator.play – finished."),
    );

DO zou have an example for how to play the ArrayInt16?

[abegehr]

Actually, it looks like the bites are all 0:

    // Render the waveform (3 seconds)
    final buf16 = ArrayInt16.zeros(numShorts: sampleRate * 3);
    synth.renderMonoInt16(buf16);
    final bytes = buf16.bytes.buffer.asUint8List();
    debugPrint("bytes are 0? ${bytes.every((e) => e == 0)}");

=> flutter: bytes are 0? true

[abegehr]

Debugging a bit, it seems the reason for this is that synth._voices is empty because in the noteOn() calls, the presetId evaluates to 0 whereas _presetLookup only has values for keys 115 and 8388656 and the noteOn() returns on preset == null.

[abegehr]

I've tried the soundfont from the readme akai_steinway.sf2 and it works! Before I was trying metronom.sf and it produced values in _presetLookup of 115 and 8388656 which non of the values 0..16 for channel produce. Looking at the code, all channel values have bank_number 0 except for channel 9 which has bank_number 128 (see here). Am I missing something for how to use metronom.sf? 🤔

[chipweinberger]

This code is pretty new! There definitely could be some bugs.

Do other synths work with metronom.sf? Importantly, does C# MeltySynth work with it?

If you figure out the issue, please open a PR!

On Sat, Mar 5, 2022 at 6:53 AM Anton Begehr @.***> wrote:

I've tried the soundfont from the readme akai_steinway.sf2 https://www.polyphone-soundfonts.com/documents/10-pianos/303-akai-steinway-iii and it works! Before I was trying metronom.sf http://www.mirbsd.org/~tg/soundfont/ and it produced values in _presetLookup of 115 and 8388656 which non of the values 0..16 for channel produce. Looking at the code, all channel values have bank_number 0 except for channel 9 which has bank_number 128 (see here https://github.com/chipweinberger/DartMeltySoundFont/blob/main/lib/channel.dart#L95 ). Am I missing something for how to use metronom.sf? 🤔

— Reply to this email directly, view it on GitHub https://github.com/chipweinberger/DartMeltySoundFont/issues/5#issuecomment-1059778039, or unsubscribe https://github.com/notifications/unsubscribe-auth/AAOHB7RVDXKL2VBXVUAGQUTU6NYNZANCNFSM5P7XGNYQ . You are receiving this because you are subscribed to this thread.Message ID: @.***>

[sinshu]

C# MeltySynth works with the following code.

// Create the synthesizer.
var sampleRate = 44100;
var synthesizer = new Synthesizer("Metronom.sf2", sampleRate);

// Change the instrument to the metronome (preset #115).
synthesizer.ProcessMidiMessage(0, 0xC0, 115, 0);

// Play a note (the metronome supports only two keys, 76 or 77).
synthesizer.NoteOn(0, 76, 100);

// The output buffer (1 seconds).
var left = new float[1 * sampleRate];
var right = new float[1 * sampleRate];

// Render the waveform.
synthesizer.Render(left, right);

[chipweinberger]

Appreciate your input @sinshu!! Were you able to see how your code differs from

"produced values in _presetLookup of 115 and 8388656 which non of the values 0..16 for channel produce."

@abegehr, I wont be able to debug this for 1-3 weeks or so. But if you find the issue happy to merge.

[chipweinberger]

Oh, perhaps the issue was needing to set this line?

// Change the instrument to the metronome (preset #115).
synthesizer.ProcessMidiMessage(0, 0xC0, 115, 0);

Does setting that line work with DartMeltySoundFont?

[sinshu]

In the C# version, the keys of presetLookup were 115 and 8388656 as in the Dart version. These values should be correct, since Metronom.sf2 has the following two presets.

• Bank #0, Patch #115 (for normal channel)
• Bank #128, Patch #48 (for drum channel)

You therefore have to set the instrument to #115 via the program change command (0xC0) to use the metronome.

akai_steinway.sf2 works without this process because the piano is assigned to #0, the default instrument for normal channels.

[chipweinberger]

Ya that makes sense. Thanks for looking into it =)

[chipweinberger]

Pushed a readme change to make this more clear.

[chipweinberger]

@sinshu , you should consider this readme change too =)