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authorThom Johansen <thomj@rockbox.org>2007-08-29 14:32:52 +0000
committerThom Johansen <thomj@rockbox.org>2007-08-29 14:32:52 +0000
commitc668de30852552a275b809a24648aa5a887eac65 (patch)
tree785f4423564a37743fe111eede84c58e034e3468
parent8f5f690760bbf9c8dbb3d142b12cbab236e79d26 (diff)
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FS #7286. Do correct rounding of final 16 bit samples before sending to DAC, for you golden-eared people.
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@14514 a1c6a512-1295-4272-9138-f99709370657
-rw-r--r--apps/dsp.c8
-rw-r--r--apps/dsp_cf.S40
-rw-r--r--apps/plugins/test_codec.c13
3 files changed, 42 insertions, 19 deletions
diff --git a/apps/dsp.c b/apps/dsp.c
index f05c6f14ce..699b0c5c67 100644
--- a/apps/dsp.c
+++ b/apps/dsp.c
@@ -414,10 +414,11 @@ static void sample_output_mono(int count, struct dsp_data *data,
{
const int32_t *s0 = src[0];
const int scale = data->output_scale;
+ const int dc_bias = 1 << (scale - 1);
do
{
- int32_t lr = clip_sample_16(*s0++ >> scale);
+ int32_t lr = clip_sample_16((*s0++ + dc_bias) >> scale);
*dst++ = lr;
*dst++ = lr;
}
@@ -433,11 +434,12 @@ static void sample_output_stereo(int count, struct dsp_data *data,
const int32_t *s0 = src[0];
const int32_t *s1 = src[1];
const int scale = data->output_scale;
+ const int dc_bias = 1 << (scale - 1);
do
{
- *dst++ = clip_sample_16(*s0++ >> scale);
- *dst++ = clip_sample_16(*s1++ >> scale);
+ *dst++ = clip_sample_16((*s0++ + dc_bias) >> scale);
+ *dst++ = clip_sample_16((*s1++ + dc_bias) >> scale);
}
while (--count > 0);
}
diff --git a/apps/dsp_cf.S b/apps/dsp_cf.S
index e4869b7c9a..fec00020b5 100644
--- a/apps/dsp_cf.S
+++ b/apps/dsp_cf.S
@@ -415,11 +415,11 @@ channels_process_sound_chan_karaoke:
.align 2
.global sample_output_stereo
sample_output_stereo:
- lea.l -44(%sp), %sp | save registers
+ lea.l -48(%sp), %sp | save registers
move.l %macsr, %d1 | do it now as at many lines will
- movem.l %d1-%d7/%a2-%a5, (%sp) | be the far more common condition
+ movem.l %d1-%d7/%a2-%a6, (%sp) | be the far more common condition
move.l #0x80, %macsr | put emac unit in signed int mode
- movem.l 48(%sp), %a0-%a2/%a4 |
+ movem.l 52(%sp), %a0-%a2/%a4 |
lea.l (%a4, %a0.l*4), %a0 | %a0 = end address
move.l (%a1), %d1 | %a1 = multiplier: (1 << (16 - scale))
sub.l #16, %d1 |
@@ -427,6 +427,7 @@ sample_output_stereo:
moveq.l #1, %d0 |
asl.l %d1, %d0 |
move.l %d0, %a1 |
+ move.l #0x8000, %a6 | %a6 = rounding term
movem.l (%a2), %a2-%a3 | get L/R channel pointers
moveq.l #28, %d0 | %d0 = second line bound
add.l %a4, %d0 |
@@ -438,6 +439,8 @@ sample_output_stereo:
bls.b 20f | line loop start | no? start line loop
10: | long loop 0 |
move.l (%a2)+, %d1 | read longword from L and R
+ move.l %a6, %acc0 |
+ move.l %acc0, %acc1 |
mac.l %d1, %a1, (%a3)+, %d2, %acc0 | shift L to high word
mac.l %d2, %a1, %acc1 | shift R to high word
movclr.l %acc0, %d1 | get possibly saturated results
@@ -451,6 +454,10 @@ sample_output_stereo:
lea.l -12(%a0), %a5 | %a5 = at or just before last line bound
30: | line loop |
move.l (%a3)+, %d4 | get next 4 R samples and scale
+ move.l %a6, %acc0 |
+ move.l %acc0, %acc1 |
+ move.l %acc1, %acc2 |
+ move.l %acc2, %acc3 |
mac.l %d4, %a1, (%a3)+, %d5, %acc0 | with saturation
mac.l %d5, %a1, (%a3)+, %d6, %acc1 |
mac.l %d6, %a1, (%a3)+, %d7, %acc2 |
@@ -460,6 +467,10 @@ sample_output_stereo:
movclr.l %acc1, %d5 |
movclr.l %acc2, %d6 |
movclr.l %acc3, %d7 |
+ move.l %a6, %acc0 |
+ move.l %acc0, %acc1 |
+ move.l %acc1, %acc2 |
+ move.l %acc2, %acc3 |
mac.l %d0, %a1, (%a2)+, %d1, %acc0 | get next 4 L samples and scale
mac.l %d1, %a1, (%a2)+, %d2, %acc1 | with saturation
mac.l %d2, %a1, (%a2)+, %d3, %acc2 |
@@ -484,6 +495,8 @@ sample_output_stereo:
bls.b 60f | output end | no? stop
50: | long loop 1 |
move.l (%a2)+, %d1 | handle trailing longwords
+ move.l %a6, %acc0 |
+ move.l %acc0, %acc1 |
mac.l %d1, %a1, (%a3)+, %d2, %acc0 | the same way as leading ones
mac.l %d2, %a1, %acc1 |
movclr.l %acc0, %d1 |
@@ -494,9 +507,9 @@ sample_output_stereo:
cmp.l %a4, %a0 |
bhi.b 50b | long loop 1
60: | output end |
- movem.l (%sp), %d1-%d7/%a2-%a5 | restore registers
+ movem.l (%sp), %d1-%d7/%a2-%a6 | restore registers
move.l %d1, %macsr |
- lea.l 44(%sp), %sp | cleanup
+ lea.l 48(%sp), %sp | cleanup
rts |
.size sample_output_stereo, .-sample_output_stereo
@@ -510,17 +523,18 @@ sample_output_stereo:
.align 2
.global sample_output_mono
sample_output_mono:
- lea.l -28(%sp), %sp | save registers
+ lea.l -32(%sp), %sp | save registers
move.l %macsr, %d1 | do it now as at many lines will
- movem.l %d1-%d5/%a2-%a3, (%sp) | be the far more common condition
+ movem.l %d1-%d5/%a2-%a4, (%sp) | be the far more common condition
move.l #0x80, %macsr | put emac unit in signed int mode
- movem.l 32(%sp), %a0-%a3 |
+ movem.l 36(%sp), %a0-%a3 |
lea.l (%a3, %a0.l*4), %a0 | %a0 = end address
move.l (%a1), %d1 | %d5 = multiplier: (1 << (16 - scale))
sub.l #16, %d1 |
neg.l %d1 |
moveq.l #1, %d5 |
asl.l %d1, %d5 |
+ move.l #0x8000, %a4 | %a4 = rounding term
movem.l (%a2), %a2 | get source channel pointer
moveq.l #28, %d0 | %d0 = second line bound
add.l %a3, %d0 |
@@ -532,6 +546,7 @@ sample_output_mono:
bls.b 20f | line loop start | no? start line loop
10: | long loop 0 |
move.l (%a2)+, %d1 | read longword from L and R
+ move.l %a4, %acc0 |
mac.l %d1, %d5, %acc0 | shift L to high word
movclr.l %acc0, %d1 | get possibly saturated results
move.l %d1, %d2 |
@@ -544,6 +559,10 @@ sample_output_mono:
lea.l -12(%a0), %a1 | %a1 = at or just before last line bound
30: | line loop |
move.l (%a2)+, %d0 | get next 4 L samples and scale
+ move.l %a4, %acc0 |
+ move.l %acc0, %acc1 |
+ move.l %acc1, %acc2 |
+ move.l %acc2, %acc3 |
mac.l %d0, %d5, (%a2)+, %d1, %acc0 | with saturation
mac.l %d1, %d5, (%a2)+, %d2, %acc1 |
mac.l %d2, %d5, (%a2)+, %d3, %acc2 |
@@ -573,6 +592,7 @@ sample_output_mono:
bls.b 60f | output end | no? stop
50: | loop loop 1 |
move.l (%a2)+, %d1 | handle trailing longwords
+ move.l %a4, %acc0 |
mac.l %d1, %d5, %acc0 | the same way as leading ones
movclr.l %acc0, %d1 |
move.l %d1, %d2 |
@@ -582,8 +602,8 @@ sample_output_mono:
cmp.l %a3, %a0 |
bhi.b 50b | long loop 1 |
60: | output end |
- movem.l (%sp), %d1-%d5/%a2-%a3 | restore registers
+ movem.l (%sp), %d1-%d5/%a2-%a4 | restore registers
move.l %d1, %macsr |
- lea.l 28(%sp), %sp | cleanup
+ lea.l 32(%sp), %sp | cleanup
rts |
.size sample_output_mono, .-sample_output_mono
diff --git a/apps/plugins/test_codec.c b/apps/plugins/test_codec.c
index c29094b372..4346a23304 100644
--- a/apps/plugins/test_codec.c
+++ b/apps/plugins/test_codec.c
@@ -221,7 +221,8 @@ static bool pcmbuf_insert_wav(const void *ch1, const void *ch2, int count)
const int32_t* data1_32;
const int32_t* data2_32;
unsigned char* p = wavbuffer;
- int scale = wavinfo.sampledepth - 15;
+ const int scale = wavinfo.sampledepth - 15;
+ const int dc_bias = 1 << (scale - 1);
/* Prevent idle poweroff */
rb->reset_poweroff_timer();
@@ -266,18 +267,18 @@ static bool pcmbuf_insert_wav(const void *ch1, const void *ch2, int count)
{
case STEREO_INTERLEAVED:
while (count--) {
- int2le16(p, clip_sample((*data1_32++) >> scale));
+ int2le16(p, clip_sample((*data1_32++ + dc_bias) >> scale));
p += 2;
- int2le16(p, clip_sample((*data1_32++) >> scale));
+ int2le16(p, clip_sample((*data1_32++ + dc_bias) >> scale));
p += 2;
}
break;
case STEREO_NONINTERLEAVED:
while (count--) {
- int2le16(p, clip_sample((*data1_32++) >> scale));
+ int2le16(p, clip_sample((*data1_32++ + dc_bias) >> scale));
p += 2;
- int2le16(p, clip_sample((*data2_32++) >> scale));
+ int2le16(p, clip_sample((*data2_32++ + dc_bias) >> scale));
p += 2;
}
@@ -285,7 +286,7 @@ static bool pcmbuf_insert_wav(const void *ch1, const void *ch2, int count)
case STEREO_MONO:
while (count--) {
- int2le16(p, clip_sample((*data1_32++) >> scale));
+ int2le16(p, clip_sample((*data1_32++ + dc_bias) >> scale));
p += 2;
}
break;