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authorSiarhei Siamashka <siarhei.siamashka@nokia.com>2008-12-11 21:21:28 +0200
committerMarcel Holtmann <marcel@holtmann.org>2008-12-18 23:45:36 +0100
commit037a47214cf85251ea61c611b1aaf1d73b772ce3 (patch)
tree3d06a920f264d01497ad8e344bdd12ee39025894
parent8e1872f93d867af16bccd8839752a05422bdbc25 (diff)
Bitstream writing optimization for SBC encoder
SBC encoder performance improvement up to 1.5x for ARM11 and almost twice faster for Intel Core2 in some cases.
-rw-r--r--sbc/sbc.c65
1 files changed, 37 insertions, 28 deletions
diff --git a/sbc/sbc.c b/sbc/sbc.c
index 7072673e..c495a75c 100644
--- a/sbc/sbc.c
+++ b/sbc/sbc.c
@@ -909,6 +909,29 @@ static int sbc_analyze_audio(struct sbc_encoder_state *state,
}
}
+/* Supplementary bitstream writing macros for 'sbc_pack_frame' */
+
+#define PUT_BITS(v, n)\
+ {\
+ bits_cache = (v) | (bits_cache << (n));\
+ bits_count += (n);\
+ if (bits_count >= 16) {\
+ bits_count -= 8;\
+ *data_ptr++ = (uint8_t)(bits_cache >> bits_count);\
+ bits_count -= 8;\
+ *data_ptr++ = (uint8_t)(bits_cache >> bits_count);\
+ }\
+ } while (0);\
+
+#define FLUSH_BITS()\
+ while (bits_count >= 8) {\
+ bits_count -= 8;\
+ *data_ptr++ = (uint8_t)(bits_cache >> bits_count);\
+ }\
+ if (bits_count > 0) {\
+ *data_ptr++ = (uint8_t)(bits_cache << (8 - bits_count));\
+ }\
+
/*
* Packs the SBC frame from frame into the memory at data. At most len
* bytes will be used, should more memory be needed an appropriate
@@ -926,14 +949,18 @@ static int sbc_analyze_audio(struct sbc_encoder_state *state,
static int sbc_pack_frame(uint8_t *data, struct sbc_frame *frame, size_t len)
{
- int produced;
+ /* Bitstream writer starts from the fourth byte */
+ uint8_t *data_ptr = data + 4;
+ uint32_t bits_cache = 0;
+ uint32_t bits_count = 0;
+
/* Will copy the header parts for CRC-8 calculation here */
uint8_t crc_header[11] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
int crc_pos = 0;
uint16_t audio_sample;
- int ch, sb, blk, bit; /* channel, subband, block and bit counters */
+ int ch, sb, blk; /* channel, subband, block and bit counters */
int bits[2][8]; /* bits distribution */
int levels[2][8]; /* levels are derived from that */
@@ -973,8 +1000,6 @@ static int sbc_pack_frame(uint8_t *data, struct sbc_frame *frame, size_t len)
/* Can't fill in crc yet */
- produced = 32;
-
crc_header[0] = data[1];
crc_header[1] = data[2];
crc_pos = 16;
@@ -999,6 +1024,7 @@ static int sbc_pack_frame(uint8_t *data, struct sbc_frame *frame, size_t len)
u_int32_t scalefactor_j[2];
uint8_t scale_factor_j[2];
+ uint8_t joint = 0;
frame->joint = 0;
for (sb = 0; sb < frame->subbands - 1; sb++) {
@@ -1031,6 +1057,7 @@ static int sbc_pack_frame(uint8_t *data, struct sbc_frame *frame, size_t len)
if ((scalefactor[0][sb] + scalefactor[1][sb]) >
(scalefactor_j[0] + scalefactor_j[1]) ) {
/* use joint stereo for this subband */
+ joint |= 1 << (frame->subbands - 1 - sb);
frame->joint |= 1 << sb;
frame->scale_factor[0][sb] = scale_factor_j[0];
frame->scale_factor[1][sb] = scale_factor_j[1];
@@ -1045,24 +1072,16 @@ static int sbc_pack_frame(uint8_t *data, struct sbc_frame *frame, size_t len)
}
}
- data[4] = 0;
- for (sb = 0; sb < frame->subbands - 1; sb++)
- data[4] |= ((frame->joint >> sb) & 0x01) << (frame->subbands - 1 - sb);
-
- crc_header[crc_pos >> 3] = data[4];
-
- produced += frame->subbands;
+ PUT_BITS(joint, frame->subbands);
+ crc_header[crc_pos >> 3] = joint;
crc_pos += frame->subbands;
}
for (ch = 0; ch < frame->channels; ch++) {
for (sb = 0; sb < frame->subbands; sb++) {
- data[produced >> 3] <<= 4;
+ PUT_BITS(frame->scale_factor[ch][sb] & 0x0F, 4);
crc_header[crc_pos >> 3] <<= 4;
- data[produced >> 3] |= frame->scale_factor[ch][sb] & 0x0F;
crc_header[crc_pos >> 3] |= frame->scale_factor[ch][sb] & 0x0F;
-
- produced += 4;
crc_pos += 4;
}
}
@@ -1088,25 +1107,15 @@ static int sbc_pack_frame(uint8_t *data, struct sbc_frame *frame, size_t len)
(uint16_t) ((((frame->sb_sample_f[blk][ch][sb]*levels[ch][sb]) >>
(frame->scale_factor[ch][sb] + 1)) +
levels[ch][sb]) >> 1);
- audio_sample <<= 16 - bits[ch][sb];
- for (bit = 0; bit < bits[ch][sb]; bit++) {
- data[produced >> 3] <<= 1;
- if (audio_sample & 0x8000)
- data[produced >> 3] |= 0x1;
- audio_sample <<= 1;
- produced++;
- }
+ PUT_BITS(audio_sample & levels[ch][sb], bits[ch][sb]);
}
}
}
}
- /* align the last byte */
- if (produced % 8) {
- data[produced >> 3] <<= 8 - (produced % 8);
- }
+ FLUSH_BITS();
- return (produced + 7) >> 3;
+ return data_ptr - data;
}
struct sbc_priv {