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authorMichael Sevakis <jethead71@rockbox.org>2007-02-09 18:11:11 +0000
committerMichael Sevakis <jethead71@rockbox.org>2007-02-09 18:11:11 +0000
commitd52f2e4bcaac8a70f306d3022a16ea6360108559 (patch)
tree134ae84bc188ee44f4e6cfc7706616618cedd67b /apps/codecs
parent0abfe9f8ea5cc52a17ae3ac0b4ebe9df0b27ce14 (diff)
downloadrockbox-d52f2e4bcaac8a70f306d3022a16ea6360108559.tar.gz
rockbox-d52f2e4bcaac8a70f306d3022a16ea6360108559.zip
Encoders: Add a little dithering with the fractional bit for mono mixdowns so faster shifts can be used again instead of division without introducing their own DC offset into the mixed channels.
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@12246 a1c6a512-1295-4272-9138-f99709370657
Diffstat (limited to 'apps/codecs')
-rw-r--r--apps/codecs/aiff_enc.c16
-rw-r--r--apps/codecs/mp3_enc.c7
-rw-r--r--apps/codecs/wav_enc.c16
-rw-r--r--apps/codecs/wavpack_enc.c7
4 files changed, 34 insertions, 12 deletions
diff --git a/apps/codecs/aiff_enc.c b/apps/codecs/aiff_enc.c
index f1569d20ff..5f993084c7 100644
--- a/apps/codecs/aiff_enc.c
+++ b/apps/codecs/aiff_enc.c
@@ -69,9 +69,10 @@ struct aiff_header aiff_header =
/* (*) updated when finalizing file */
-static int num_channels;
-uint32_t sample_rate;
-uint32_t enc_size;
+static int num_channels IBSS_ATTR;
+static uint32_t sample_rate;
+static uint32_t enc_size;
+static int32_t err IBSS_ATTR;
/* convert unsigned 32 bit value to 80-bit floating point number */
static void uint32_h_to_ieee754_extended_be(uint8_t f[10], uint32_t l) ICODE_ATTR;
@@ -240,10 +241,14 @@ static void chunk_to_aiff_format(uint32_t *src, uint32_t *dst)
int32_t lr1, lr2;
lr1 = *(*src)++;
- lr1 = ((int16_t)lr1 + (lr1 >> 16)) / 2;
+ lr1 = (int16_t)lr1 + (lr1 >> 16) + err;
+ err = lr1 & 1;
+ lr1 >>= 1;
lr2 = *(*src)++;
- lr2 = ((int16_t)lr2 + (lr2 >> 16)) / 2;
+ lr2 = (int16_t)lr2 + (lr2 >> 16) + err;
+ err = lr2 & 1;
+ lr2 >>= 1;
*(*dst)++ = swap_odd_even_le32((lr1 << 16) | (uint16_t)lr2);
} /* to_mono */
@@ -311,6 +316,7 @@ static bool init_encoder(void)
sample_rate = inputs.sample_rate;
num_channels = inputs.num_channels;
+ err = 0;
/* configure the buffer system */
params.afmt = AFMT_AIFF;
diff --git a/apps/codecs/mp3_enc.c b/apps/codecs/mp3_enc.c
index 64c0996dc2..70b327aef2 100644
--- a/apps/codecs/mp3_enc.c
+++ b/apps/codecs/mp3_enc.c
@@ -174,6 +174,7 @@ static unsigned samp_per_frame IBSS_ATTR;
static config_t cfg IBSS_ATTR;
static char *res_buffer;
+static int32_t err IBSS_ATTR;
static const uint8_t ht_count_const[2][2][16] =
{ { { 1, 5, 4, 5, 6, 5, 4, 4, 7, 3, 6, 0, 7, 2, 3, 1 }, /* table0 */
@@ -2055,7 +2056,9 @@ static void to_mono_mm(void)
inline void to_mono(uint32_t **samp)
{
int32_t lr = **samp;
- int32_t m = ((int16_t)lr + (lr >> 16)) / 2;
+ int32_t m = (int16_t)lr + (lr >> 16) + err;
+ err = m & 1;
+ m >>= 1;
*(*samp)++ = (m << 16) | (uint16_t)m;
} /* to_mono */
@@ -2434,6 +2437,8 @@ static bool enc_init(void)
init_mp3_encoder_engine(inputs.sample_rate, inputs.num_channels,
inputs.config);
+ err = 0;
+
/* configure the buffer system */
params.afmt = AFMT_MPA_L3;
params.chunk_size = cfg.byte_per_frame + 1;
diff --git a/apps/codecs/wav_enc.c b/apps/codecs/wav_enc.c
index 4b7b0083c8..dddca3f5c2 100644
--- a/apps/codecs/wav_enc.c
+++ b/apps/codecs/wav_enc.c
@@ -57,9 +57,10 @@ struct riff_header
#define PCM_SAMP_PER_CHUNK 2048
#define PCM_CHUNK_SIZE (PCM_SAMP_PER_CHUNK*4)
-static int num_channels;
-uint32_t sample_rate;
-uint32_t enc_size;
+static int num_channels IBSS_ATTR;
+static uint32_t sample_rate;
+static uint32_t enc_size;
+static int32_t err IBSS_ATTR;
static const struct riff_header riff_header =
{
@@ -229,10 +230,14 @@ static void chunk_to_wav_format(uint32_t *src, uint32_t *dst)
int32_t lr1, lr2;
lr1 = *(*src)++;
- lr1 = ((int16_t)lr1 + (lr1 >> 16)) / 2;
+ lr1 = (int16_t)lr1 + (lr1 >> 16) + err;
+ err = lr1 & 1;
+ lr1 >>= 1;
lr2 = *(*src)++;
- lr2 = ((int16_t)lr2 + (lr2 >> 16)) / 2;
+ lr2 = (int16_t)lr2 + (lr2 >> 16) + err;
+ err = lr2 & 1;
+ lr2 >>= 1;
*(*dst)++ = swap_odd_even_be32((lr1 << 16) | (uint16_t)lr2);
} /* to_mono */
@@ -300,6 +305,7 @@ static bool init_encoder(void)
sample_rate = inputs.sample_rate;
num_channels = inputs.num_channels;
+ err = 0;
/* configure the buffer system */
params.afmt = AFMT_PCM_WAV;
diff --git a/apps/codecs/wavpack_enc.c b/apps/codecs/wavpack_enc.c
index 208cd3bc68..71222597e0 100644
--- a/apps/codecs/wavpack_enc.c
+++ b/apps/codecs/wavpack_enc.c
@@ -69,6 +69,7 @@ static int8_t input_buffer[PCM_CHUNK_SIZE*2] IBSS_ATTR;
static WavpackConfig config IBSS_ATTR;
static WavpackContext *wpc;
static int32_t data_size, input_size, input_step IBSS_ATTR;
+static int32_t err IBSS_ATTR;
static const WavpackMetadataHeader wvpk_mdh =
{
@@ -126,7 +127,9 @@ static void chunk_to_int32(int32_t *src)
{
int32_t t = *(*src)++;
/* endianness irrelevant */
- *(*dst)++ = ((int16_t)t + (t >> 16)) / 2;
+ t = (int16_t)t + (t >> 16) + err;
+ err = t & 1;
+ *(*dst)++ = t >> 1;
} /* to_int32 */
do
@@ -364,6 +367,8 @@ static bool init_encoder(void)
if (!WavpackSetConfiguration(wpc, &config, -1))
return false;
+ err = 0;
+
/* configure the buffer system */
params.afmt = AFMT_WAVPACK;
input_size = PCM_CHUNK_SIZE*inputs.num_channels / 2;