Merge "Add function to derive a channel mask from a channel count" (f1b244c3) · Commits · e / os / android_system_core

include/system/audio.h

+35 −1

Original line number	Diff line number	Diff line
		@@ -250,7 +250,9 @@ typedef enum {
		AUDIO_CHANNEL_IN_Z_AXIS \|
		AUDIO_CHANNEL_IN_VOICE_UPLINK \|
		AUDIO_CHANNEL_IN_VOICE_DNLINK),
		} audio_channels_t;
		};

		typedef uint32_t audio_channel_mask_t;

		typedef enum {
		AUDIO_MODE_INVALID = -2,
		@@ -382,6 +384,38 @@ static inline bool audio_is_output_channel(uint32_t channel)
		return false;
		}

		/* Derive a channel mask from a channel count.
		* This is to be used when the content channel mask is unknown. The 1, 2, 4, 5, 6, 7 and 8 channel
		* cases are mapped to the standard game/home-theater layouts, but note that 4 is mapped to quad,
		* and not stereo + FC + mono surround. A channel count of 3 is arbitrarily mapped to stereo + FC
		* for continuity with stereo.
		* Returns the matching channel mask, or 0 if the number of channels exceeds that of the
		* configurations for which a default channel mask is defined.
		*/
		static inline audio_channel_mask_t audio_channel_mask_from_count(uint32_t channel_count)
		{
		switch(channel_count) {
		case 1:
		return AUDIO_CHANNEL_OUT_MONO;
		case 2:
		return AUDIO_CHANNEL_OUT_STEREO;
		case 3:
		return (AUDIO_CHANNEL_OUT_STEREO \| AUDIO_CHANNEL_OUT_FRONT_CENTER);
		case 4: // 4.0
		return AUDIO_CHANNEL_OUT_QUAD;
		case 5: // 5.0
		return (AUDIO_CHANNEL_OUT_QUAD \| AUDIO_CHANNEL_OUT_FRONT_CENTER);
		case 6: // 5.1
		return AUDIO_CHANNEL_OUT_5POINT1;
		case 7: // 6.1
		return (AUDIO_CHANNEL_OUT_5POINT1 \| AUDIO_CHANNEL_OUT_BACK_CENTER);
		case 8:
		return AUDIO_CHANNEL_OUT_7POINT1;
		default:
		return 0;
		}
		}

		static inline bool audio_is_valid_format(audio_format_t format)
		{
		switch (format & AUDIO_FORMAT_MAIN_MASK) {