From: "Omar Polo" <op@omarpolo.com>
Subject: Re: sndiod: per-program (instead of per-client) level control
To: Alexandre Ratchov <alex@caoua.org>
Cc: tech@openbsd.org
Date: Tue, 17 Jun 2025 14:13:07 +0200

Hello,

Alexandre Ratchov <alex@caoua.org> wrote:
> This diff is to adjust the volume of all instances of the same program
> with a single control. Example, instead of:
> 
> firefox0.level
> firefox1.level
> firefox2.level
> ...
> 
> there will be single "firefox.level" control. There will be no way to
> control individual tracks anymore, but that will not be a big loss
> beacause there's currently no way to know in advance which sound
> corresponds to which firefox instance.
> 
> There's a nice side effect:
> 
> Currently if a web browser has too many tabs/windows, it may consume
> all the controls, preventing other programs from using sndiod. Now,
> the number of connections that a single program can make can be
> increased (the diff cranks it to 32) which fixes the problem in most
> cases.
> 
> OK?

can't provide a valuable feedback on the diff, beside that I'm testing
it and it makes a lot of sense to me, and that it works as advertized.

allow me tho to point out two nits:

> Index: dev.c
> ===================================================================
> RCS file: /cvs/src/usr.bin/sndiod/dev.c,v
> diff -u -p -r1.122 dev.c
> --- dev.c	16 Jun 2025 06:19:29 -0000	1.122
> +++ dev.c	16 Jun 2025 18:17:57 -0000
> [...]
> @@ -1523,98 +1505,34 @@ struct slot *
>  slot_new(struct opt *opt, unsigned int id, char *who,
>      struct slotops *ops, void *arg, int mode)
>  {
> [...]
> +	i = 0;
> +	s = slot_array;
> +	while (1) {
> +		if (i == DEV_NSLOT) {
> +			logx(1, "%s: too many connections", a->name);
> +			return NULL;
>  		}
> +		if (s->ops == NULL)
> +			break;
> +		i++;
> +		s++;
>  	}

I feel like a for loop would be slightly more readable here

	s = slot_array;
	for (i = 0; i < DEV_NSLOT; i++, s++)
		if (s->ops == NULL)
			break;
	if (i == DEV_NSLOT) {
		logx(...)
		return NULL;
	}

> [...]
> Index: sndiod.8
> ===================================================================
> RCS file: /cvs/src/usr.bin/sndiod/sndiod.8,v
> diff -u -p -r1.17 sndiod.8
> --- sndiod.8	3 May 2024 16:47:15 -0000	1.17
> +++ sndiod.8	16 Jun 2025 18:17:58 -0000
> @@ -440,12 +440,13 @@ exposes the audio device clock
>  and allows audio device properties to be controlled
>  through MIDI.
>  .Pp
> -A MIDI channel is assigned to each stream, and the volume
> +A MIDI channel is assigned to each program, and the volume
>  is changed using the standard volume controller (number 7).
>  Similarly, when the audio client changes its volume,
>  the same MIDI controller message is sent out; it can be used
>  for instance for monitoring or as feedback for motorized
>  faders.
> +If there are multiple instances of the same program they will share the same setting.

This line should be folded, (my xterm and) man -Tlint complain it's
longer than 80 column :p


Thanks,
Omar Polo