pulse-server: convert between client cubic volume and linear

src/modules/module-protocol-pulse/format.c

@@ -283,7 +283,7 @@ static void channel_map_to_positions(const struct channel_map *map, uint32_t *po
 		pos[i] = channel_pa2id(map->map[i]);
 }
 
-struct cvolume {
+struct volume {
 	uint8_t channels;
 	float values[CHANNELS_MAX];
 };

src/modules/module-protocol-pulse/message.c

@@ -22,6 +22,27 @@
  * DEALINGS IN THE SOFTWARE.
  */
 
+#define VOLUME_MUTED ((uint32_t) 0U)
+#define VOLUME_NORM ((uint32_t) 0x10000U)
+#define VOLUME_MAX ((uint32_t) UINT32_MAX/2)
+
+static inline uint32_t volume_from_linear(float vol)
+{
+	uint32_t v;
+	if (vol <= 0.0f)
+		v = VOLUME_MUTED;
+	else
+		v = SPA_CLAMP((uint64_t) lround(cbrt(vol) * VOLUME_NORM),
+				VOLUME_MUTED, VOLUME_MAX);
+	return v;
+}
+
+static inline float volume_to_linear(uint32_t vol)
+{
+	float v = ((float)vol) / VOLUME_NORM;
+	return v * v * v;
+}
+
 struct descriptor {
 	uint32_t length;
 	uint32_t channel;
@@ -203,11 +224,11 @@ static int read_volume(struct message *m, float *vol)
 	uint32_t v;
 	if ((res = read_u32(m, &v)) < 0)
 		return res;
-	*vol = ((float)v) / 0x10000U;
+	*vol = volume_to_linear(v);
 	return 0;
 }
 
-static int read_cvolume(struct message *m, struct cvolume *vol)
+static int read_cvolume(struct message *m, struct volume *vol)
 {
 	int res;
 	uint8_t i;
@@ -336,7 +357,7 @@ static int message_get(struct message *m, ...)
 		case TAG_CVOLUME:
 			if (dtag != tag)
 				return -EINVAL;
-			if ((res = read_cvolume(m, va_arg(va, struct cvolume*))) < 0)
+			if ((res = read_cvolume(m, va_arg(va, struct volume*))) < 0)
 				return res;
 			break;
 		case TAG_PROPLIST:
@@ -462,16 +483,16 @@ static void write_channel_map(struct message *m, struct channel_map *map)
 static void write_volume(struct message *m, float vol)
 {
 	write_8(m, TAG_VOLUME);
-	write_32(m, vol * 0x10000U);
+	write_32(m, volume_from_linear(vol));
 }
 
-static void write_cvolume(struct message *m, struct cvolume *cvol)
+static void write_cvolume(struct message *m, struct volume *vol)
 {
 	uint8_t i;
 	write_8(m, TAG_CVOLUME);
-	write_8(m, cvol->channels);
-	for (i = 0; i < cvol->channels; i ++)
-		write_32(m, cvol->values[i] * 0x10000U);
+	write_8(m, vol->channels);
+	for (i = 0; i < vol->channels; i ++)
+		write_32(m, volume_from_linear(vol->values[i]));
 }
 
 static void write_props(struct message *m, struct pw_properties *props)
@@ -545,7 +566,7 @@ static int message_put(struct message *m, ...)
 			write_channel_map(m, va_arg(va, struct channel_map*));
 			break;
 		case TAG_CVOLUME:
-			write_cvolume(m, va_arg(va, struct cvolume*));
+			write_cvolume(m, va_arg(va, struct volume*));
 			break;
 		case TAG_PROPLIST:
 			write_props(m, va_arg(va, struct pw_properties*));

src/modules/module-protocol-pulse/pulse-server.c

@@ -97,7 +97,7 @@ struct device {
 	enum pw_direction direction;
 	struct pw_properties *props;
 	struct sample_spec ss;
-	struct cvolume volume;
+	struct volume volume;
 	struct channel_map map;
 	bool muted;
 	struct device *monitor;
@@ -139,7 +139,7 @@ struct stream {
 	struct buffer_attr attr;
 	uint32_t frame_size;
 
-	struct cvolume volume;
+	struct volume volume;
 	bool muted;
 
 	struct device *dev;
@@ -1178,7 +1178,7 @@ static int do_create_playback_stream(struct client *client, uint32_t command, ui
 		fail_on_suspend = false,
 		relative_volume = false,
 		passthrough = false;
-	struct cvolume volume;
+	struct volume volume;
 	struct pw_properties *props = NULL;
 	uint8_t n_formats = 0;
 	struct stream *stream = NULL;
@@ -1413,7 +1413,7 @@ static int do_create_record_stream(struct client *client, uint32_t command, uint
 		relative_volume = false,
 		passthrough = false;
 	uint32_t direct_on_input_idx;
-	struct cvolume volume;
+	struct volume volume;
 	struct pw_properties *props = NULL;
 	uint8_t n_formats = 0;
 	struct stream *stream = NULL;
@@ -1795,7 +1795,7 @@ static int do_set_stream_volume(struct client *client, uint32_t command, uint32_
 	uint32_t channel;
 	struct stream *stream;
 	int res;
-	struct cvolume volume;
+	struct volume volume;
 
 	if ((res = message_get(m,
 			TAG_U32, &channel,
@@ -3146,7 +3146,7 @@ struct pw_protocol_pulse *pw_protocol_pulse_new(struct pw_context *context,
 			.format = SAMPLE_FLOAT32LE,
 			.rate = 44100,
 			.channels = 2, },
-		.volume = (struct cvolume) {
+		.volume = (struct volume) {
 			.channels = 2,
 			.values[0] = 1.0f,
 			.values[1] = 1.0f, },
@@ -3169,7 +3169,7 @@ struct pw_protocol_pulse *pw_protocol_pulse_new(struct pw_context *context,
 			.format = SAMPLE_FLOAT32LE,
 			.rate = 44100,
 			.channels = 2, },
-		.volume = (struct cvolume) {
+		.volume = (struct volume) {
 			.channels = 2,
 			.values[0] = 1.0f,
 			.values[1] = 1.0f, },
@@ -3191,7 +3191,7 @@ struct pw_protocol_pulse *pw_protocol_pulse_new(struct pw_context *context,
 			.format = SAMPLE_FLOAT32LE,
 			.rate = 44100,
 			.channels = 2, },
-		.volume = (struct cvolume) {
+		.volume = (struct volume) {
 			.channels = 2,
 			.values[0] = 1.0f,
 			.values[1] = 1.0f, },