[SDL] SDL_Mixer : Mix_VolumeMusic() and windows native midi, a painful journey ; )

[Benjamin Babut]

I come finally to a solution quite satisfying, that is to say patching  
SDL_mixer so that the midi volume function changes the volume of ALL  
midiout devices that have the MIDICAPS_VOLUME set in their capabilities  
(MIDIOUTCAPS.dwSupport).

Thus, if there's a "master" device for midi volume, which seems to happen  
on my machine, it is also affected by a call to Mix_VolumeMusic and  
everything is fine. Thus, my solution :

SDL_Mixer : native_midi_win32.c :
=================================

void native_midi_setvolume(int volume)
{
	int calcVolume;
	MIDIOUTCAPS capabilities;
	int i = 0;
		
	if (volume > 128)
		volume = 128;
	if (volume < 0)
		volume = 0;
	calcVolume = (65535 * volume / 128);
	
	//Device loop
	for(i=0;i<midiOutGetNumDevs();i++)
	{
		//Get device capabilities
		midiOutGetDevCaps(i,&capabilities,sizeof(capabilities));
		
		//Adjust volume on this candidate
		if((capabilities.dwSupport&MIDICAPS_VOLUME))
			midiOutSetVolume((HMIDIOUT)i, MAKELONG(calcVolume , calcVolume));
	}
}

My remaining questions are : do you think is this method safe ? robust ?  
resource consuming ? or simply OK ?

In any case, it solved my problems :)

Ben



On Wed, 01 Feb 2006 17:37:06 +0100, Benjamin Babut <marty at whyme.fr.fm>  
wrote:

> On Tue, 31 Jan 2006, Sam Lantinga <slouken at devolution.com> wrote:
>
>> Can you test this with some other programs that use MIDI_MAPPER?
>> If you explicitly open the SB Live! MIDI device and change the
>> volume on that while it is the currently selected default device,
>> does that work?
>> What happens with the system midi volume slider when you have the
>> SB Live! device selected?
>
>
> After some tests : if if I open explicitly the SB Live! MIDI device,
> midiOutSetVolume has the same behaviour. It returns 1 and the Volume does
> not change in spite of the good value of the field capability structure
> (I've verified that field again and again and again).
>
>
> However, changing the volume with Windows volume controler "MIDI" slider,
> the volume is affected : so, the slider is able to command the volume of
> my SB, whereas the midiOutSetVolume function does not.