add emms-volume-sndioctl

[Omar Polo]

Hello,

Apologies if this isn't the correct mailing list to submit EMMS patches,
I couldn't find a better place to send this to.

The following patch adds another emms-volume backend for OpenBSD'
sndioctl(1).  OpenBSD used to use mixerctl(8) to adjust the volume, but
with the previous release (or the one before?  I don't remember)
sndioctl(1) was added and mixerctl(8) is something reserved for lower
level tasks and requires root now IIRC.

Note that I've added the check for the `sndioctl' executable before the
others: this is needed to prevent emms to automatically choose mixerctl
(or pactl since it's not unusual to have pulseaudio installed due to
some dependency.)  Should I add a comment noting this?

I already did the copyright paperwork.

Thanks,

Omar Polo

>From 185ee21071ae01176ee0f984f6fafb2088f7da1a Mon Sep 17 00:00:00 2001
From: Omar Polo <op@omarpolo.com>
Date: Thu, 9 Sep 2021 20:06:45 +0200
Subject: [PATCH] Add emms-volume-sndioctl

sndioctl(1) is the utility to manipulate audio device controls on
OpenBSD.
---
 emms-volume-sndioctl.el | 71 +++++++++++++++++++++++++++++++++++++++++
 emms-volume.el          |  3 ++
 2 files changed, 74 insertions(+)
 create mode 100644 emms-volume-sndioctl.el

diff --git a/emms-volume-sndioctl.el b/emms-volume-sndioctl.el
new file mode 100644
index 0000000..4bfb574
--- /dev/null
+++ b/emms-volume-sndioctl.el
@@ -0,0 +1,71 @@
+;;; emms-volume-sndioctl.el --- a mode for changing volume using sndioctl -*- 
lexical-binding: t; -*-
+
+;; Copyright (C) 2006, 2007, 2008, 2009, 2019 Free Software Foundation, Inc.
+
+;; Authors: Omar Polo <op@omarpolo.com>
+
+;; This file is part of EMMS.
+
+;; EMMS is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation; either version 3, or (at your option)
+;; any later version.
+;;
+;; EMMS is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+;;
+;; You should have received a copy of the GNU General Public License
+;; along with EMMS; see the file COPYING.  If not, write to the
+;; Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
+;; Boston, MA 02110-1301, USA.
+
+;;; Commentary:
+
+;; This file defines a few simple functions to raise or lower the
+;; volume using sndioctl. It can be used stand-alone, though it's
+;; meant for usage with EMMS, particularly with emms-volume.el
+
+;;; History:
+
+;; Sep 09 2021: Based on emms-volume-mixerctl.el by Omar Polo
+
+;;; Code:
+
+(defcustom emms-volume-sndioctl-stream "output"
+  "The stream to change the volume with.
+Usually it's the global \"output\".  For a full list of available
+controls, run `sndioctl' in a shell."
+  :type '(choice (const :tag "output" "output")
+                 (string :tag "Something else: "))
+  :group 'emms-volume)
+
+(defcustom emms-volume-sndioctl-device nil
+  "The card number to change volume.
+The card is identified by a number.  For a full list run `ls
+/dev/mixer?*' in a shell."
+  :type '(choice (const :tag "none" nil)
+                 (string :tag "Device: "))
+  :group 'emms-volume)
+
+;;;###autoload
+(defun emms-volume-sndioctl-change (amount)
+  "Change sndioctl level by AMOUNT."
+  (message "Playback channels: %s"
+           (with-temp-buffer
+             (when (zerop
+                    (apply #'call-process
+                           "sndioctl" nil (current-buffer) nil
+                           `("-n"
+                             ,@(when emms-volume-sndioctl-device
+                                 `("-f" ,emms-volume-sndioctl-device))
+                             ,(format "%s.level=%s%f"
+                                      emms-volume-sndioctl-stream
+                                      (if (> amount 0) "+" "")
+                                      (/ (float amount) 100)))))
+               (string-trim-right (buffer-string))))))
+
+(provide 'emms-volume-sndioctl)
+
+;;; emms-volume-sndioctl.el ends here
diff --git a/emms-volume.el b/emms-volume.el
index bb92a31..3275e38 100644
--- a/emms-volume.el
+++ b/emms-volume.el
@@ -52,6 +52,7 @@
 (require 'emms-volume-amixer)
 (require 'emms-volume-pulse)
 (require 'emms-volume-mixerctl)
+(require 'emms-volume-sndioctl)
 
 ;; Customize group
 (defgroup emms-volume nil
@@ -61,6 +62,7 @@
 ;; General volume setting related code.
 (defcustom emms-volume-change-function
   (cond
+   ((executable-find "sndioctl") 'emms-volume-sndioctl-change)
    ((executable-find "amixer") 'emms-volume-amixer-change)
    ((executable-find "pactl") 'emms-volume-pulse-change)
    ((executable-find "mixerctl") 'emms-volume-mixerctl-change)
@@ -71,6 +73,7 @@ If you have your own functions for changing volume, set this."
                  (const :tag "MPD" emms-volume-mpd-change)
                 (const :tag "PulseAudio" emms-volume-pulse-change)
                 (const :tag "Mixerctl" emms-volume-mixerctl-change)
+                 (const :tag "Sndioctl" emms-volume-sndioctl-change)
                  (function :tag "Lisp function")))
 
 (defcustom emms-volume-change-amount 2
-- 
2.33.0