From 7c90018f2300646dbdec2481b896999fe93e6e62 Mon Sep 17 00:00:00 2001
From: Campbell Barton <campbell@blender.org>
Date: Wed, 14 Feb 2024 00:13:37 +1100
Subject: [PATCH] CLI: make "-noaudio" implicit with "-b/--background"

Running background mode now behaves as if the "-noaudio" was passed in.

The -setaudio command now has a "Default" option which can be used
in the rare cases audio playback is desired in background mode. e.g.

  blender --background -setaudio Default

Ref !118192
---
 source/creator/creator_args.cc | 38 ++++++++++++++++++++++++++++------
 1 file changed, 32 insertions(+), 6 deletions(-)

diff --git a/source/creator/creator_args.cc b/source/creator/creator_args.cc
index f6032324755..9a0c79c3185 100644
--- a/source/creator/creator_args.cc
+++ b/source/creator/creator_args.cc
@@ -889,12 +889,33 @@ static int arg_handle_debug_exit_on_error(int /*argc*/, const char ** /*argv*/,
 }
 
 static const char arg_handle_background_mode_set_doc[] =
-    "\n\t"
-    "Run in background (often used for UI-less rendering).";
+    "\n"
+    "\tRun in background (often used for UI-less rendering).\n"
+    "\n"
+    "\tThe audio device is disabled in background-mode by default\n"
+    "\tand can be re-enabled by passing in '-setaudo Default' afterwards.";
 static int arg_handle_background_mode_set(int /*argc*/, const char ** /*argv*/, void * /*data*/)
 {
   print_version_short();
   G.background = true;
+
+  /* Background Mode Defaults:
+   *
+   * In general background mode should strive to match the behavior of running
+   * Blender inside a graphical session, any exception to this should have a well
+   * justified reason and be noted in the doc-string. */
+
+  /* NOTE(@ideasman42): While there is no requirement for sound to be disabled in background-mode,
+   * the use case for playing audio in background mode is enough of a special-case
+   * that users who wish to do this can explicitly enable audio in background mode.
+   * While the down sides for connecting to an audio device aren't terrible they include:
+   * - Listing Blender as an active application which may output audio.
+   * - Unnecessary overhead running an operation in background mode or ...
+   * - Having to remember to include `-noaudio` with batch operations.
+   * - A quiet but audible click when Blender starts & configures its audio device.
+   */
+  BKE_sound_force_device("None");
+
   return 0;
 }
 
@@ -1538,9 +1559,8 @@ static int arg_handle_audio_disable(int /*argc*/, const char ** /*argv*/, void *
 
 static const char arg_handle_audio_set_doc[] =
     "\n\t"
-    "Force sound system to a specific device."
-    "\n\t"
-    "'None' 'SDL' 'OpenAL' 'CoreAudio' 'JACK' 'PulseAudio' 'WASAPI'.";
+    "Force sound system to a specific device.\n"
+    "\t'None' 'Default' 'SDL' 'OpenAL' 'CoreAudio' 'JACK' 'PulseAudio' 'WASAPI'.";
 static int arg_handle_audio_set(int argc, const char **argv, void * /*data*/)
 {
   if (argc < 1) {
@@ -1548,7 +1568,13 @@ static int arg_handle_audio_set(int argc, const char **argv, void * /*data*/)
     exit(1);
   }
 
-  BKE_sound_force_device(argv[1]);
+  const char *device = argv[1];
+  if (STREQ(device, "Default")) {
+    /* Unset any forced device. */
+    device = nullptr;
+  }
+
+  BKE_sound_force_device(device);
   return 1;
 }