Hi! Can you give me an example on how to use the "fluid_synth_write_s16" function?

[SlackerNReckless]

Well, I'm wanting to write an application that renders midi, preferable interleaved stereo to uncompressed PCM raw data, or simply wave data.

I just need an example in C/C++.

Thanks. :-)

[derselbst]

fluidsynth/src/drivers/fluid_sdl2.c

Lines 45 to 52 in 724b8c8

	SDLAudioCallback(void *data, void *stream, int len)
	{
	fluid_sdl2_audio_driver_t *dev = (fluid_sdl2_audio_driver_t *)data;
	len /= dev->frame_size;
	dev->write_ptr(dev->synth, len, stream, 0, 2, stream, 1, 2);
	}

Where dev->write_func can be either fluid_synth_write_s16 or fluid_synth_write_float. len is the length of the buffer in bytes. frame_size is 2*sizeof(int16_t).

[SlackerNReckless]

Thanks. But I'd like a complete example. And not a callback function. I'd like to know the length of the buffer, the size. The functions I need to pass before a call to "fluid_synth_write_s16". About the buffer, I'd like to know if it's an array of Signed Int 16. Or Smallint

Like the "fluid_synth_process" function found here: https://www.fluidsynth.org/api/group__audio__rendering.html Do I need to use it? How?

I know how to initialize the library, the synth, load a soundfont, the player, and add a MIDI file to the player. do I need to call "fluid_player_play" to start the process of feeding the buffer data? Well, I don't think so.

These functions:

"new_fluid_settings", "new_fluid_synth", "new_fluid_audio_driver", the player using "new_fluid_player", "fluid_synth_sfload" to load the soundfont and add a MIDI file to the player using "fluid_player_add"

And if I need to use it inside a "while" statement like this:

while (?)
{
fluid_synth_write_s16(...);
and feed the buffer (the uncompressed RAW WAVE data) using another call to a play function of an audio library. I'm intending to use BASS by Un4seen Developments https://www.un4seen.com/ Actually the BASS_StreamCreate and BASS_StreamPutData from the BASS library.
}

Can someone give me a more detailed example? What I really want is a complete example of MIDI to WAVE RAW uncompressed PCM data. And I don't want a callback function, I need something inside a "while" statement.

I asked for a C/C++ example, but actually I'm intending to develop this using Pascal, Lazarus FreePascal, I'm using the DLL "libfluidsynth-3.dll" with the headers converted to pascal code found here: https://gitlab.com/bunnylin/pasfluidsynth

By the way, I know a lot about BASS. They at least provide .pas files for Delphi/Lazarus along with their BASS library.

The documentation here lacks a proper example of a simple MIDI to WAV or PCM RAW converter using "fluid_synth_write_s16". I'm saying about here: https://www.fluidsynth.org/api/examples.html

And no,.. I'm not wanting to render the file to WAVE file. I know there are "render" functions for this. I want to feed the buffer, the uncompressed RAW PCM WAVE data coming from "fluid_synth_write_s16" to BASS_StreamPutData https://www.un4seen.com/doc/#bass/BASS_StreamPutData.html like I said above, inside a while statement.

BASS has two add-ons called BASSENC and BASSENC_MP3 where I can directly convert to MP3 and I'm intending to build a MIDI to MP3 converter along with a MIDI player as BASS has equalizer/reverb/chorus functions in BASSFX,

Thanks again and sorry for the long talk. :-P

[derselbst]

So you want to do something like this: https://www.fluidsynth.org/api/FileRenderer.html

But instead of fluid_file_renderer_process_block(renderer) you would call fluid_synth_write_s16(). And yes, the rendering buffer is an array of 16 bit signed integers. That's why the rendering function is called s16 ;)

The length of that buffer is up to you. But using a multiple of fluid_synth_get_internal_bufsize() will work most efficient.

[spessasus]

Maybe slightly out of topic, but since you're already using BASS, why not just use BASSMIDI instead? It's essentially an sf2 synthesizer, much like fluidsynth and it would be easier to integrate into BASS.

[SlackerNReckless]

Well, @spessasus, there are differences. The MIDI/SoundFont rendering engine of BASS is different. Fluidsynth seems more reliable. It's almost the same as playing a MIDI file in a real SoundBlaster card like AWE32/SBLive/Audigy, you know those cards with EMU8000, EMU10K1 and EMU10K2 synthesizers.

By the way, I already have/developed a player using BASSMIDI and other BASS addons. Actually it's a complete Audio player supporting a lot of formats like MP3, OGG, WMA, M4A, AAC, FLAC and module formats like XM, IT, S3M. MOD with encoding support and even archive support.

I already have/developed a Fluidsynth player using the playing engine of Fluidsynth, but now I'm intending to integrate it with BASS because I want to put a 10 bands equalizer, reverb, chorus and other features of BASS library including MP3 encoding support.

[SlackerNReckless]

And Mr. @derselbst I will try that code and I will see what I can do.

By the way, it's not my first time here: I already asked for this subject: "Please add a 'fluid_player_get_total_time' and 'fluid_player_get_current_time' functions in milliseconds and pause/resume functions too." #1151. It would be so simple to implement this but I managed to do in my Fluidsynyh player already mentioned above.

Thanks for the replies! Cheers! :-)

[SlackerNReckless]

Hey guys! I solved here! :-D

But not with "fluid_synth_write_s16" function, I'm using "fluid_synth_write_float" now and it works now. BASS supports float samples with the BASS_SAMPLE_FLOAT flag. https://www.un4seen.com/doc/#bass/BASS_StreamCreate.html Looks like the library "libfluidsynth-3.dll" was compiled with libsndfile support and even there is another DLL called sndfile.dll in the main Fluidsynth distribution.

Well, I checked the source code of Fluidsynth to get an example of how to use the function, especially the file "fluid_filerenderer.c" found in "src/bindings" and I noticed the file renderer, the function "fluid_file_renderer_process_block" uses "fluid_synth_write_float" instead of "fluid_synth_write_s16" due a conditional compiler directive callled "LIBSNDFILE_SUPPORT".

Anyway, thanks for the replies and I think you can close this subject as it's solved. See ya! ;-)