Traditionnal SBC frame header describe encoding parameters for each frame: nr
of blocks, subbands, allocation method, and bitpool. In mSBC, only one
combination of parameter is defined. That combination cannot be expressed using
a traditionnal SBC header. Because of this, a specific header is defined with
0xAD followed by two reserved zero bytes.
---
sbc/sbc.c | 228 +++++++++++++++++++++++++++++++++++++------------------------
1 file changed, 138 insertions(+), 90 deletions(-)
diff --git a/sbc/sbc.c b/sbc/sbc.c
index ead25da..af45e65 100644
--- a/sbc/sbc.c
+++ b/sbc/sbc.c
@@ -377,8 +377,8 @@ static void sbc_calculate_bits(const struct sbc_frame *frame, int (*bits)[8])
* -3 CRC8 incorrect
* -4 Bitpool value out of bounds
*/
-static int sbc_unpack_frame(const uint8_t *data, struct sbc_frame *frame,
- size_t len)
+static int sbc_unpack_frame_internal(const uint8_t *data,
+ struct sbc_frame *frame, size_t len)
{
unsigned int consumed;
/* Will copy the parts of the header that are relevant to crc
@@ -393,59 +393,6 @@ static int sbc_unpack_frame(const uint8_t *data, struct sbc_frame *frame,
int bits[2][8]; /* bits distribution */
uint32_t levels[2][8]; /* levels derived from that */
- if (len < 4)
- return -1;
-
- if (data[0] != SBC_SYNCWORD)
- return -2;
-
- frame->frequency = (data[1] >> 6) & 0x03;
-
- frame->block_mode = (data[1] >> 4) & 0x03;
- switch (frame->block_mode) {
- case SBC_BLK_4:
- frame->blocks = 4;
- break;
- case SBC_BLK_8:
- frame->blocks = 8;
- break;
- case SBC_BLK_12:
- frame->blocks = 12;
- break;
- case SBC_BLK_16:
- frame->blocks = 16;
- break;
- }
-
- frame->mode = (data[1] >> 2) & 0x03;
- switch (frame->mode) {
- case MONO:
- frame->channels = 1;
- break;
- case DUAL_CHANNEL: /* fall-through */
- case STEREO:
- case JOINT_STEREO:
- frame->channels = 2;
- break;
- }
-
- frame->allocation = (data[1] >> 1) & 0x01;
-
- frame->subband_mode = (data[1] & 0x01);
- frame->subbands = frame->subband_mode ? 8 : 4;
-
- frame->bitpool = data[2];
-
- if ((frame->mode == MONO || frame->mode == DUAL_CHANNEL) &&
- frame->bitpool > 16 * frame->subbands)
- return -4;
-
- if ((frame->mode == STEREO || frame->mode == JOINT_STEREO) &&
- frame->bitpool > 32 * frame->subbands)
- return -4;
-
- /* data[3] is crc, we're checking it later */
-
consumed = 32;
crc_header[0] = data[1];
@@ -546,6 +493,90 @@ static int sbc_unpack_frame(const uint8_t *data, struct sbc_frame *frame,
return consumed >> 3;
}
+static int sbc_unpack_frame(const uint8_t *data,
+ struct sbc_frame *frame, size_t len)
+{
+ if (len < 4)
+ return -1;
+
+ if (data[0] != SBC_SYNCWORD)
+ return -2;
+
+ frame->frequency = (data[1] >> 6) & 0x03;
+ frame->block_mode = (data[1] >> 4) & 0x03;
+
+ switch (frame->block_mode) {
+ case SBC_BLK_4:
+ frame->blocks = 4;
+ break;
+ case SBC_BLK_8:
+ frame->blocks = 8;
+ break;
+ case SBC_BLK_12:
+ frame->blocks = 12;
+ break;
+ case SBC_BLK_16:
+ frame->blocks = 16;
+ break;
+ }
+
+ frame->mode = (data[1] >> 2) & 0x03;
+
+ switch (frame->mode) {
+ case MONO:
+ frame->channels = 1;
+ break;
+ case DUAL_CHANNEL: /* fall-through */
+ case STEREO:
+ case JOINT_STEREO:
+ frame->channels = 2;
+ break;
+ }
+
+ frame->allocation = (data[1] >> 1) & 0x01;
+
+ frame->subband_mode = (data[1] & 0x01);
+ frame->subbands = frame->subband_mode ? 8 : 4;
+
+ frame->bitpool = data[2];
+
+ if ((frame->mode == MONO || frame->mode == DUAL_CHANNEL) &&
+ frame->bitpool > 16 * frame->subbands)
+ return -4;
+
+ if ((frame->mode == STEREO || frame->mode == JOINT_STEREO) &&
+ frame->bitpool > 32 * frame->subbands)
+ return -4;
+
+ return sbc_unpack_frame_internal(data, frame, len);
+}
+
+static int msbc_unpack_frame(const uint8_t *data,
+ struct sbc_frame *frame, size_t len)
+{
+ if (len < 4)
+ return -1;
+
+ if (data[0] != MSBC_SYNCWORD)
+ return -2;
+ if (data[1] != 0)
+ return -2;
+ if (data[2] != 0)
+ return -2;
+
+ frame->frequency = SBC_FREQ_16000;
+ frame->block_mode = SBC_BLK_4;
+ frame->blocks = MSBC_BLOCKS;
+ frame->allocation = LOUDNESS;
+ frame->mode = MONO;
+ frame->channels = 1;
+ frame->subband_mode = 1;
+ frame->subbands = 8;
+ frame->bitpool = 26;
+
+ return sbc_unpack_frame_internal(data, frame, len);
+}
+
static void sbc_decoder_init(struct sbc_decoder_state *state,
const struct sbc_frame *frame)
{
@@ -790,38 +821,6 @@ static SBC_ALWAYS_INLINE ssize_t sbc_pack_frame_internal(uint8_t *data,
uint32_t levels[2][8]; /* levels are derived from that */
uint32_t sb_sample_delta[2][8];
- data[0] = SBC_SYNCWORD;
-
- data[1] = (frame->frequency & 0x03) << 6;
-
- data[1] |= (frame->block_mode & 0x03) << 4;
-
- data[1] |= (frame->mode & 0x03) << 2;
-
- data[1] |= (frame->allocation & 0x01) << 1;
-
- switch (frame_subbands) {
- case 4:
- /* Nothing to do */
- break;
- case 8:
- data[1] |= 0x01;
- break;
- default:
- return -4;
- break;
- }
-
- data[2] = frame->bitpool;
-
- if ((frame->mode == MONO || frame->mode == DUAL_CHANNEL) &&
- frame->bitpool > frame_subbands << 4)
- return -5;
-
- if ((frame->mode == STEREO || frame->mode == JOINT_STEREO) &&
- frame->bitpool > frame_subbands << 5)
- return -5;
-
/* Can't fill in crc yet */
crc_header[0] = data[1];
@@ -889,6 +888,28 @@ static SBC_ALWAYS_INLINE ssize_t sbc_pack_frame_internal(uint8_t *data,
static ssize_t sbc_pack_frame(uint8_t *data, struct sbc_frame *frame, size_t len,
int joint)
{
+ int frame_subbands = 4;
+
+ data[0] = SBC_SYNCWORD;
+
+ data[1] = (frame->frequency & 0x03) << 6;
+ data[1] |= (frame->block_mode & 0x03) << 4;
+ data[1] |= (frame->mode & 0x03) << 2;
+ data[1] |= (frame->allocation & 0x01) << 1;
+
+ data[2] = frame->bitpool;
+
+ if (frame->subbands != 4)
+ frame_subbands = 8;
+
+ if ((frame->mode == MONO || frame->mode == DUAL_CHANNEL) &&
+ frame->bitpool > frame_subbands << 4)
+ return -5;
+
+ if ((frame->mode == STEREO || frame->mode == JOINT_STEREO) &&
+ frame->bitpool > frame_subbands << 5)
+ return -5;
+
if (frame->subbands == 4) {
if (frame->channels == 1)
return sbc_pack_frame_internal(
@@ -897,6 +918,7 @@ static ssize_t sbc_pack_frame(uint8_t *data, struct sbc_frame *frame, size_t len
return sbc_pack_frame_internal(
data, frame, len, 4, 2, joint);
} else {
+ data[1] |= 0x01;
if (frame->channels == 1)
return sbc_pack_frame_internal(
data, frame, len, 8, 1, joint);
@@ -906,6 +928,16 @@ static ssize_t sbc_pack_frame(uint8_t *data, struct sbc_frame *frame, size_t len
}
}
+static ssize_t msbc_pack_frame(uint8_t *data, struct sbc_frame *frame,
+ size_t len, int joint)
+{
+ data[0] = MSBC_SYNCWORD;
+ data[1] = 0;
+ data[2] = 0;
+
+ return sbc_pack_frame_internal(data, frame, len, 8, 1, joint);
+}
+
static void sbc_encoder_init(unsigned long flags,
struct sbc_encoder_state *state, const struct sbc_frame *frame)
{
@@ -924,10 +956,24 @@ struct sbc_priv {
struct SBC_ALIGNED sbc_frame frame;
struct SBC_ALIGNED sbc_decoder_state dec_state;
struct SBC_ALIGNED sbc_encoder_state enc_state;
+ int (*unpack_frame)(const uint8_t *data, struct sbc_frame *frame,
+ size_t len);
+ ssize_t (*pack_frame)(uint8_t *data, struct sbc_frame *frame,
+ size_t len, int joint);
};
static void sbc_set_defaults(sbc_t *sbc, unsigned long flags)
{
+ struct sbc_priv *priv = sbc->priv;
+
+ if (flags & SBC_MSBC) {
+ priv->pack_frame = msbc_pack_frame;
+ priv->unpack_frame = msbc_unpack_frame;
+ } else {
+ priv->pack_frame = sbc_pack_frame;
+ priv->unpack_frame = sbc_unpack_frame;
+ }
+
sbc->flags = flags;
sbc->frequency = SBC_FREQ_44100;
sbc->mode = SBC_MODE_STEREO;
@@ -981,7 +1027,7 @@ SBC_EXPORT ssize_t sbc_decode(sbc_t *sbc, const void *input, size_t input_len,
priv = sbc->priv;
- framelen = sbc_unpack_frame(input, &priv->frame, input_len);
+ framelen = priv->unpack_frame(input, &priv->frame, input_len);
if (!priv->init) {
sbc_decoder_init(&priv->dec_state, &priv->frame);
@@ -1115,13 +1161,15 @@ SBC_EXPORT ssize_t sbc_encode(sbc_t *sbc, const void *input, size_t input_len,
int j = priv->enc_state.sbc_calc_scalefactors_j(
priv->frame.sb_sample_f, priv->frame.scale_factor,
priv->frame.blocks, priv->frame.subbands);
- framelen = sbc_pack_frame(output, &priv->frame, output_len, j);
+ framelen = priv->pack_frame(output,
+ &priv->frame, output_len, j);
} else {
priv->enc_state.sbc_calc_scalefactors(
priv->frame.sb_sample_f, priv->frame.scale_factor,
priv->frame.blocks, priv->frame.channels,
priv->frame.subbands);
- framelen = sbc_pack_frame(output, &priv->frame, output_len, 0);
+ framelen = priv->pack_frame(output,
+ &priv->frame, output_len, 0);
}
if (written)
--
1.7.9.5
--
To unsubscribe from this list: send the line "unsubscribe linux-bluetooth" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
