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Add function to derive a channel mask from a channel count

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Change-Id: I22523ded9cd8e5283a285a9db21d819bbbc1b6c3
This commit is contained in:
Jean-Michel Trivi 2012-03-02 16:41:35 -08:00
parent 0afee8b668
commit 4ab051ab46
1 changed files with 35 additions and 1 deletions
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36
include/system/audio.h
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@ -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) {