From 0d2f081d41bb47015ae16743491a0032bdc869fd Mon Sep 17 00:00:00 2001
From: Arkadiusz Hiler <[EMAIL REDACTED]>
Date: Thu, 30 Oct 2025 20:06:09 +0200
Subject: [PATCH] pulseaudio: Match channel map to SDL's chosen order
pa_channel_map_init_auto() with PA_CHANNEL_MAP_WAVEEX does the wrong
thing as it just takes the lest significant bits of
WAVEFORMATEXTENSIBLE's dwChannelMask in order. This doesn't match SDL's
chosen channel ordering.
The implementation here mirrors what we do for PipeWire.
---
src/audio/pulseaudio/SDL_pulseaudio.c | 70 +++++++++++++++++++++++++--
1 file changed, 67 insertions(+), 3 deletions(-)
diff --git a/src/audio/pulseaudio/SDL_pulseaudio.c b/src/audio/pulseaudio/SDL_pulseaudio.c
index 7c2b99172de40..c81fd00f33366 100644
--- a/src/audio/pulseaudio/SDL_pulseaudio.c
+++ b/src/audio/pulseaudio/SDL_pulseaudio.c
@@ -602,6 +602,71 @@ static void PulseStreamStateChangeCallback(pa_stream *stream, void *userdata)
PULSEAUDIO_pa_threaded_mainloop_signal(pulseaudio_threaded_mainloop, 0); // just signal any waiting code, it can look up the details.
}
+// Channel maps that match the order in SDL_Audio.h
+static const pa_channel_position_t Pulse_map_1[] = { PA_CHANNEL_POSITION_MONO };
+static const pa_channel_position_t Pulse_map_2[] = { PA_CHANNEL_POSITION_FRONT_LEFT, PA_CHANNEL_POSITION_FRONT_RIGHT };
+
+static const pa_channel_position_t Pulse_map_3[] = { PA_CHANNEL_POSITION_FRONT_LEFT, PA_CHANNEL_POSITION_FRONT_RIGHT,
+ PA_CHANNEL_POSITION_LFE };
+
+static const pa_channel_position_t Pulse_map_4[] = { PA_CHANNEL_POSITION_FRONT_LEFT, PA_CHANNEL_POSITION_FRONT_RIGHT,
+ PA_CHANNEL_POSITION_REAR_LEFT, PA_CHANNEL_POSITION_REAR_RIGHT };
+
+static const pa_channel_position_t Pulse_map_5[] = { PA_CHANNEL_POSITION_FRONT_LEFT, PA_CHANNEL_POSITION_FRONT_RIGHT,
+ PA_CHANNEL_POSITION_LFE,
+ PA_CHANNEL_POSITION_REAR_LEFT, PA_CHANNEL_POSITION_REAR_RIGHT };
+
+static const pa_channel_position_t Pulse_map_6[] = { PA_CHANNEL_POSITION_FRONT_LEFT, PA_CHANNEL_POSITION_FRONT_RIGHT,
+ PA_CHANNEL_POSITION_FRONT_CENTER, PA_CHANNEL_POSITION_LFE,
+ PA_CHANNEL_POSITION_REAR_LEFT, PA_CHANNEL_POSITION_REAR_RIGHT };
+
+static const pa_channel_position_t Pulse_map_7[] = { PA_CHANNEL_POSITION_FRONT_LEFT, PA_CHANNEL_POSITION_FRONT_RIGHT,
+ PA_CHANNEL_POSITION_FRONT_CENTER, PA_CHANNEL_POSITION_LFE,
+ PA_CHANNEL_POSITION_REAR_CENTER,
+ PA_CHANNEL_POSITION_SIDE_LEFT, PA_CHANNEL_POSITION_SIDE_RIGHT };
+
+static const pa_channel_position_t Pulse_map_8[] = { PA_CHANNEL_POSITION_FRONT_LEFT, PA_CHANNEL_POSITION_FRONT_RIGHT,
+ PA_CHANNEL_POSITION_FRONT_CENTER, PA_CHANNEL_POSITION_LFE,
+ PA_CHANNEL_POSITION_REAR_LEFT, PA_CHANNEL_POSITION_REAR_RIGHT,
+ PA_CHANNEL_POSITION_SIDE_LEFT, PA_CHANNEL_POSITION_SIDE_RIGHT };
+
+#define COPY_CHANNEL_MAP(c) SDL_memcpy(pacmap->map, Pulse_map_##c, sizeof(Pulse_map_##c))
+
+static void PulseCreateChannelMap(pa_channel_map *pacmap, uint8_t channels)
+{
+ SDL_assert(channels <= PA_CHANNELS_MAX);
+
+ pacmap->channels = channels;
+
+ switch (channels) {
+ case 1:
+ COPY_CHANNEL_MAP(1);
+ break;
+ case 2:
+ COPY_CHANNEL_MAP(2);
+ break;
+ case 3:
+ COPY_CHANNEL_MAP(3);
+ break;
+ case 4:
+ COPY_CHANNEL_MAP(4);
+ break;
+ case 5:
+ COPY_CHANNEL_MAP(5);
+ break;
+ case 6:
+ COPY_CHANNEL_MAP(6);
+ break;
+ case 7:
+ COPY_CHANNEL_MAP(7);
+ break;
+ case 8:
+ COPY_CHANNEL_MAP(8);
+ break;
+ }
+
+}
+
static bool PULSEAUDIO_OpenDevice(SDL_AudioDevice *device)
{
const bool recording = device->recording;
@@ -690,9 +755,8 @@ static bool PULSEAUDIO_OpenDevice(SDL_AudioDevice *device)
PULSEAUDIO_pa_threaded_mainloop_lock(pulseaudio_threaded_mainloop);
const char *name = SDL_GetHint(SDL_HINT_AUDIO_DEVICE_STREAM_NAME);
- // The SDL ALSA output hints us that we use Windows' channel mapping
- // https://bugzilla.libsdl.org/show_bug.cgi?id=110
- PULSEAUDIO_pa_channel_map_init_auto(&pacmap, device->spec.channels, PA_CHANNEL_MAP_WAVEEX);
+
+ PulseCreateChannelMap(&pacmap, device->spec.channels);
h->stream = PULSEAUDIO_pa_stream_new(
pulseaudio_context,