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Commit e60eb623 authored by Glenn Kasten's avatar Glenn Kasten Committed by Android (Google) Code Review
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Merge "Representation of channel masks for position assignment and index assignment"

parents b53af3f6 432b7c6d
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+231 −25
Original line number Diff line number Diff line
@@ -52,7 +52,9 @@ typedef enum {
    AUDIO_STREAM_ALARM            = 4,
    AUDIO_STREAM_NOTIFICATION     = 5,
    AUDIO_STREAM_BLUETOOTH_SCO    = 6,
    AUDIO_STREAM_ENFORCED_AUDIBLE = 7, /* Sounds that cannot be muted by user and must be routed to speaker */
    AUDIO_STREAM_ENFORCED_AUDIBLE = 7, /* Sounds that cannot be muted by user
                                        * and must be routed to speaker
                                        */
    AUDIO_STREAM_DTMF             = 8,
    AUDIO_STREAM_TTS              = 9,

@@ -280,8 +282,19 @@ typedef enum {
                                        AUDIO_FORMAT_AAC_SUB_ELD),
} audio_format_t;

/* For the channel mask for position assignment representation */
enum {

/* These can be a complete audio_channel_mask_t. */

    AUDIO_CHANNEL_NONE                      = 0x0,
    AUDIO_CHANNEL_INVALID                   = 0xC0000000,

/* These can be the bits portion of an audio_channel_mask_t
 * with representation AUDIO_CHANNEL_REPRESENTATION_POSITION.
 * Using these bits as a complete audio_channel_mask_t is deprecated.
 */

    /* output channels */
    AUDIO_CHANNEL_OUT_FRONT_LEFT            = 0x1,
    AUDIO_CHANNEL_OUT_FRONT_RIGHT           = 0x2,
@@ -302,6 +315,8 @@ enum {
    AUDIO_CHANNEL_OUT_TOP_BACK_CENTER       = 0x10000,
    AUDIO_CHANNEL_OUT_TOP_BACK_RIGHT        = 0x20000,

/* TODO: should these be considered complete channel masks, or only bits? */

    AUDIO_CHANNEL_OUT_MONO     = AUDIO_CHANNEL_OUT_FRONT_LEFT,
    AUDIO_CHANNEL_OUT_STEREO   = (AUDIO_CHANNEL_OUT_FRONT_LEFT |
                                  AUDIO_CHANNEL_OUT_FRONT_RIGHT),
@@ -357,6 +372,8 @@ enum {
                                  AUDIO_CHANNEL_OUT_TOP_BACK_CENTER|
                                  AUDIO_CHANNEL_OUT_TOP_BACK_RIGHT),

/* These are bits only, not complete values */

    /* input channels */
    AUDIO_CHANNEL_IN_LEFT            = 0x4,
    AUDIO_CHANNEL_IN_RIGHT           = 0x8,
@@ -373,6 +390,8 @@ enum {
    AUDIO_CHANNEL_IN_VOICE_UPLINK    = 0x4000,
    AUDIO_CHANNEL_IN_VOICE_DNLINK    = 0x8000,

/* TODO: should these be considered complete channel masks, or only bits, or deprecated? */

    AUDIO_CHANNEL_IN_MONO   = AUDIO_CHANNEL_IN_FRONT,
    AUDIO_CHANNEL_IN_STEREO = (AUDIO_CHANNEL_IN_LEFT | AUDIO_CHANNEL_IN_RIGHT),
    AUDIO_CHANNEL_IN_FRONT_BACK = (AUDIO_CHANNEL_IN_FRONT | AUDIO_CHANNEL_IN_BACK),
@@ -394,9 +413,95 @@ enum {

/* A channel mask per se only defines the presence or absence of a channel, not the order.
 * But see AUDIO_INTERLEAVE_* below for the platform convention of order.
 *
 * audio_channel_mask_t is an opaque type and its internal layout should not
 * be assumed as it may change in the future.
 * Instead, always use the functions declared in this header to examine.
 *
 * These are the current representations:
 *
 *   AUDIO_CHANNEL_REPRESENTATION_POSITION
 *     is a channel mask representation for position assignment.
 *     Each low-order bit corresponds to the spatial position of a transducer (output),
 *     or interpretation of channel (input).
 *     The user of a channel mask needs to know the context of whether it is for output or input.
 *     The constants AUDIO_CHANNEL_OUT_* or AUDIO_CHANNEL_IN_* apply to the bits portion.
 *     It is not permitted for no bits to be set.
 *
 *   AUDIO_CHANNEL_REPRESENTATION_INDEX
 *     is a channel mask representation for index assignment.
 *     Each low-order bit corresponds to a selected channel.
 *     There is no platform interpretation of the various bits.
 *     There is no concept of output or input.
 *     It is not permitted for no bits to be set.
 *
 * All other representations are reserved for future use.
 *
 * Warning: current representation distinguishes between input and output, but this will not the be
 * case in future revisions of the platform. Wherever there is an ambiguity between input and output
 * that is currently resolved by checking the channel mask, the implementer should look for ways to
 * fix it with additional information outside of the mask.
 */
typedef uint32_t audio_channel_mask_t;

/* Maximum number of channels for all representations */
#define AUDIO_CHANNEL_COUNT_MAX             30

/* log(2) of maximum number of representations, not part of public API */
#define AUDIO_CHANNEL_REPRESENTATION_LOG2   2

/* Representations */
typedef enum {
    AUDIO_CHANNEL_REPRESENTATION_POSITION    = 0,    // must be zero for compatibility
    // 1 is reserved for future use
    AUDIO_CHANNEL_REPRESENTATION_INDEX       = 2,
    // 3 is reserved for future use
} audio_channel_representation_t;

/* The return value is undefined if the channel mask is invalid. */
static inline uint32_t audio_channel_mask_get_bits(audio_channel_mask_t channel)
{
    return channel & ((1 << AUDIO_CHANNEL_COUNT_MAX) - 1);
}

/* The return value is undefined if the channel mask is invalid. */
static inline audio_channel_representation_t audio_channel_mask_get_representation(
        audio_channel_mask_t channel)
{
    // The right shift should be sufficient, but also "and" for safety in case mask is not 32 bits
    return (audio_channel_representation_t)
            ((channel >> AUDIO_CHANNEL_COUNT_MAX) & ((1 << AUDIO_CHANNEL_REPRESENTATION_LOG2) - 1));
}

/* Returns true if the channel mask is valid,
 * or returns false for AUDIO_CHANNEL_NONE, AUDIO_CHANNEL_INVALID, and other invalid values.
 * This function is unable to determine whether a channel mask for position assignment
 * is invalid because an output mask has an invalid output bit set,
 * or because an input mask has an invalid input bit set.
 * All other APIs that take a channel mask assume that it is valid.
 */
static inline bool audio_channel_mask_is_valid(audio_channel_mask_t channel)
{
    uint32_t bits = audio_channel_mask_get_bits(channel);
    audio_channel_representation_t representation = audio_channel_mask_get_representation(channel);
    switch (representation) {
    case AUDIO_CHANNEL_REPRESENTATION_POSITION:
    case AUDIO_CHANNEL_REPRESENTATION_INDEX:
        break;
    default:
        bits = 0;
        break;
    }
    return bits != 0;
}

/* Not part of public API */
static inline audio_channel_mask_t audio_channel_mask_from_representation_and_bits(
        audio_channel_representation_t representation, uint32_t bits)
{
    return (audio_channel_mask_t) ((representation << AUDIO_CHANNEL_COUNT_MAX) | bits);
}

/* Expresses the convention when stereo audio samples are stored interleaved
 * in an array.  This should improve readability by allowing code to use
 * symbolic indices instead of hard-coded [0] and [1].
@@ -942,81 +1047,182 @@ static inline bool audio_is_remote_submix_device(audio_devices_t device)
        return false;
}

/* Returns true if:
 *  representation is valid, and
 *  there is at least one channel bit set which _could_ correspond to an input channel, and
 *  there are no channel bits set which could _not_ correspond to an input channel.
 * Otherwise returns false.
 */
static inline bool audio_is_input_channel(audio_channel_mask_t channel)
{
    if ((channel & ~AUDIO_CHANNEL_IN_ALL) == 0)
        return channel != 0;
    else
    uint32_t bits = audio_channel_mask_get_bits(channel);
    switch (audio_channel_mask_get_representation(channel)) {
    case AUDIO_CHANNEL_REPRESENTATION_POSITION:
        if (bits & ~AUDIO_CHANNEL_IN_ALL) {
            bits = 0;
        }
        // fall through
    case AUDIO_CHANNEL_REPRESENTATION_INDEX:
        return bits != 0;
    default:
        return false;
    }
}

/* Returns true if:
 *  representation is valid, and
 *  there is at least one channel bit set which _could_ correspond to an output channel, and
 *  there are no channel bits set which could _not_ correspond to an output channel.
 * Otherwise returns false.
 */
static inline bool audio_is_output_channel(audio_channel_mask_t channel)
{
    if ((channel & ~AUDIO_CHANNEL_OUT_ALL) == 0)
        return channel != 0;
    else
    uint32_t bits = audio_channel_mask_get_bits(channel);
    switch (audio_channel_mask_get_representation(channel)) {
    case AUDIO_CHANNEL_REPRESENTATION_POSITION:
        if (bits & ~AUDIO_CHANNEL_OUT_ALL) {
            bits = 0;
        }
        // fall through
    case AUDIO_CHANNEL_REPRESENTATION_INDEX:
        return bits != 0;
    default:
        return false;
    }
}

/* Returns the number of channels from an input channel mask,
 * used in the context of audio input or recording.
 * If a channel bit is set which could _not_ correspond to an input channel,
 * it is excluded from the count.
 * Returns zero if the representation is invalid.
 */
static inline uint32_t audio_channel_count_from_in_mask(audio_channel_mask_t channel)
{
    return popcount(channel & AUDIO_CHANNEL_IN_ALL);
    uint32_t bits = audio_channel_mask_get_bits(channel);
    switch (audio_channel_mask_get_representation(channel)) {
    case AUDIO_CHANNEL_REPRESENTATION_POSITION:
        // TODO: We can now merge with from_out_mask and remove anding
        bits &= AUDIO_CHANNEL_IN_ALL;
        // fall through
    case AUDIO_CHANNEL_REPRESENTATION_INDEX:
        return popcount(bits);
    default:
        return 0;
    }
}

/* Returns the number of channels from an output channel mask,
 * used in the context of audio output or playback.
 * If a channel bit is set which could _not_ correspond to an output channel,
 * it is excluded from the count.
 * Returns zero if the representation is invalid.
 */
static inline uint32_t audio_channel_count_from_out_mask(audio_channel_mask_t channel)
{
    return popcount(channel & AUDIO_CHANNEL_OUT_ALL);
    uint32_t bits = audio_channel_mask_get_bits(channel);
    switch (audio_channel_mask_get_representation(channel)) {
    case AUDIO_CHANNEL_REPRESENTATION_POSITION:
        // TODO: We can now merge with from_in_mask and remove anding
        bits &= AUDIO_CHANNEL_OUT_ALL;
        // fall through
    case AUDIO_CHANNEL_REPRESENTATION_INDEX:
        return popcount(bits);
    default:
        return 0;
    }
}

/* Derive an output channel mask from a channel count.
/* Derive an output channel mask for position assignment 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.
 * Returns the matching channel mask,
 * or AUDIO_CHANNEL_NONE if the channel count is zero,
 * or AUDIO_CHANNEL_INVALID if the channel count exceeds that of the
 * configurations for which a default output channel mask is defined.
 */
static inline audio_channel_mask_t audio_channel_out_mask_from_count(uint32_t channel_count)
{
    uint32_t bits;
    switch (channel_count) {
    case 0:
        return AUDIO_CHANNEL_NONE;
    case 1:
        return AUDIO_CHANNEL_OUT_MONO;
        bits = AUDIO_CHANNEL_OUT_MONO;
        break;
    case 2:
        return AUDIO_CHANNEL_OUT_STEREO;
        bits = AUDIO_CHANNEL_OUT_STEREO;
        break;
    case 3:
        return (AUDIO_CHANNEL_OUT_STEREO | AUDIO_CHANNEL_OUT_FRONT_CENTER);
        bits = AUDIO_CHANNEL_OUT_STEREO | AUDIO_CHANNEL_OUT_FRONT_CENTER;
        break;
    case 4: // 4.0
        return AUDIO_CHANNEL_OUT_QUAD;
        bits = AUDIO_CHANNEL_OUT_QUAD;
        break;
    case 5: // 5.0
        return (AUDIO_CHANNEL_OUT_QUAD | AUDIO_CHANNEL_OUT_FRONT_CENTER);
        bits = AUDIO_CHANNEL_OUT_QUAD | AUDIO_CHANNEL_OUT_FRONT_CENTER;
        break;
    case 6: // 5.1
        return AUDIO_CHANNEL_OUT_5POINT1;
        bits = AUDIO_CHANNEL_OUT_5POINT1;
        break;
    case 7: // 6.1
        return (AUDIO_CHANNEL_OUT_5POINT1 | AUDIO_CHANNEL_OUT_BACK_CENTER);
        bits = AUDIO_CHANNEL_OUT_5POINT1 | AUDIO_CHANNEL_OUT_BACK_CENTER;
        break;
    case 8:
        return AUDIO_CHANNEL_OUT_7POINT1;
        bits = AUDIO_CHANNEL_OUT_7POINT1;
        break;
    default:
        return 0;
        return AUDIO_CHANNEL_INVALID;
    }
    return audio_channel_mask_from_representation_and_bits(
            AUDIO_CHANNEL_REPRESENTATION_POSITION, bits);
}

/* Similar to above, but for input.  Currently handles only mono and stereo. */
/* Derive an input channel mask for position assignment from a channel count.
 * Currently handles only mono and stereo.
 * Returns the matching channel mask,
 * or AUDIO_CHANNEL_NONE if the channel count is zero,
 * or AUDIO_CHANNEL_INVALID if the channel count exceeds that of the
 * configurations for which a default input channel mask is defined.
 */
static inline audio_channel_mask_t audio_channel_in_mask_from_count(uint32_t channel_count)
{
    uint32_t bits;
    switch (channel_count) {
    case 0:
        return AUDIO_CHANNEL_NONE;
    case 1:
        return AUDIO_CHANNEL_IN_MONO;
        bits = AUDIO_CHANNEL_IN_MONO;
        break;
    case 2:
        return AUDIO_CHANNEL_IN_STEREO;
        bits = AUDIO_CHANNEL_IN_STEREO;
        break;
    default:
        return 0;
        return AUDIO_CHANNEL_INVALID;
    }
    return audio_channel_mask_from_representation_and_bits(
            AUDIO_CHANNEL_REPRESENTATION_POSITION, bits);
}

/* Derive a channel mask for index assignment from a channel count.
 * Returns the matching channel mask,
 * or AUDIO_CHANNEL_NONE if the channel count is zero,
 * or AUDIO_CHANNEL_INVALID if the channel count exceeds AUDIO_CHANNEL_COUNT_MAX.
 */
static inline audio_channel_mask_t audio_channel_mask_for_index_assignment_from_count(
        uint32_t channel_count)
{
    if (channel_count == 0) {
        return AUDIO_CHANNEL_NONE;
    }
    if (channel_count > AUDIO_CHANNEL_COUNT_MAX) {
        return AUDIO_CHANNEL_INVALID;
    }
    uint32_t bits = (1 << channel_count) - 1;
    return audio_channel_mask_from_representation_and_bits(
            AUDIO_CHANNEL_REPRESENTATION_INDEX, bits);
}

static inline bool audio_is_valid_format(audio_format_t format)