David Bourgeois wrote:
> Or can I imagine patching dmix to add support for 8 bits
Please try this patch.
Index: alsa/alsa-lib/src/pcm/pcm_dmix.c
===================================================================
--- alsa.orig/alsa-lib/src/pcm/pcm_dmix.c 2007-07-07 11:07:05.000000000 +0200
+++ alsa/alsa-lib/src/pcm/pcm_dmix.c 2007-09-23 12:32:44.000000000 +0200
@@ -219,7 +219,7 @@ static void mix_areas(snd_pcm_direct_t *
sum = dmix->u.dmix.sum_buffer + channels * dst_ofs + chn;
dmix->u.dmix.mix_areas2(size, dst, src, sum, dst_step, src_step, channels * sizeof(signed int));
}
- } else { /* SND_PCM_FORMAT_S24_3LE */
+ } else if (dmix->shmptr->s.format == SND_PCM_FORMAT_S24_3LE) {
unsigned char *src;
volatile unsigned char *dst;
if (dmix->interleaved) {
@@ -245,6 +245,32 @@ static void mix_areas(snd_pcm_direct_t *
sum = dmix->u.dmix.sum_buffer + channels * dst_ofs + chn;
dmix->u.dmix.mix_areas3(size, dst, src, sum, dst_step, src_step, channels * sizeof(signed int));
}
+ } else { /* SND_PCM_FORMAT_U8 */
+ unsigned char *src;
+ volatile unsigned char *dst;
+ if (dmix->interleaved) {
+ /*
+ * process all areas in one loop
+ * it optimizes the memory accesses for this case
+ */
+ dmix->u.dmix.mix_areas_u8(size * channels,
+ ((unsigned char *)dst_areas[0].addr) + dst_ofs * channels,
+ ((unsigned char *)src_areas[0].addr) + src_ofs * channels,
+ dmix->u.dmix.sum_buffer + (dst_ofs * channels),
+ 1, 1, sizeof(signed int));
+ return;
+ }
+ for (chn = 0; chn < channels; chn++) {
+ dchn = dmix->bindings ? dmix->bindings[chn] : chn;
+ if (dchn >= dmix->shmptr->s.channels)
+ continue;
+ src_step = src_areas[chn].step / 8;
+ dst_step = dst_areas[dchn].step / 8;
+ src = (unsigned char *)(((char *)src_areas[chn].addr + src_areas[chn].first / 8) + (src_ofs * src_step));
+ dst = (unsigned char *)(((char *)dst_areas[dchn].addr + dst_areas[dchn].first / 8) + (dst_ofs * dst_step));
+ sum = dmix->u.dmix.sum_buffer + channels * dst_ofs + chn;
+ dmix->u.dmix.mix_areas_u8(size, dst, src, sum, dst_step, src_step, channels * sizeof(signed int));
+ }
}
}
Index: alsa/alsa-lib/src/pcm/pcm_direct.c
===================================================================
--- alsa.orig/alsa-lib/src/pcm/pcm_direct.c 2007-05-24 20:41:40.000000000 +0200
+++ alsa/alsa-lib/src/pcm/pcm_direct.c 2007-09-23 12:34:10.000000000 +0200
@@ -883,6 +883,7 @@ int snd_pcm_direct_initialize_slave(snd_
SND_PCM_FORMAT_S16,
SND_PCM_FORMAT_S16 ^ SND_PCM_FORMAT_S16_LE ^ SND_PCM_FORMAT_S16_BE,
SND_PCM_FORMAT_S24_3LE,
+ SND_PCM_FORMAT_U8,
};
snd_pcm_format_t format;
unsigned int i;
Index: alsa/alsa-lib/src/pcm/pcm_direct.h
===================================================================
--- alsa.orig/alsa-lib/src/pcm/pcm_direct.h 2007-04-07 09:19:48.000000000 +0200
+++ alsa/alsa-lib/src/pcm/pcm_direct.h 2007-09-23 12:26:17.000000000 +0200
@@ -39,6 +39,11 @@ typedef void (mix_areas3_t)(unsigned int
volatile signed int *sum, size_t dst_step,
size_t src_step, size_t sum_step);
+typedef void (mix_areas_u8_t)(unsigned int size,
+ volatile unsigned char *dst, unsigned char *src,
+ volatile signed int *sum, size_t dst_step,
+ size_t src_step, size_t sum_step);
+
struct slave_params {
snd_pcm_format_t format;
int rate;
@@ -151,6 +156,7 @@ struct snd_pcm_direct {
mix_areas1_t *mix_areas1;
mix_areas2_t *mix_areas2;
mix_areas3_t *mix_areas3;
+ mix_areas_u8_t *mix_areas_u8;
} dmix;
struct {
} dsnoop;
Index: alsa/alsa-lib/src/pcm/pcm_dmix_generic.c
===================================================================
--- alsa.orig/alsa-lib/src/pcm/pcm_dmix_generic.c 2007-07-07 11:07:05.000000000 +0200
+++ alsa/alsa-lib/src/pcm/pcm_dmix_generic.c 2007-09-23 12:40:52.000000000 +0200
@@ -277,6 +277,32 @@ static void generic_mix_areas3(unsigned
}
}
+static void generic_mix_areas_u8(unsigned int size,
+ volatile unsigned char *dst, unsigned char *src,
+ volatile signed int *sum, size_t dst_step,
+ size_t src_step, size_t sum_step)
+{
+ for (;;) {
+ register int sample = *src - 0x80;
+ if (!*dst) {
+ *sum = sample;
+ } else {
+ sample += *sum;
+ *sum = sample;
+ if (sample > 0x7f)
+ sample = 0x7f;
+ else if (sample < -0x80)
+ sample = -0x80;
+ }
+ *dst = sample + 0x80;
+ if (!--size)
+ return;
+ dst += dst_step;
+ src += src_step;
+ sum = (signed int *) ((char *)sum + sum_step);
+ }
+}
+
static void generic_mix_select_callbacks(snd_pcm_direct_t *dmix)
{
@@ -288,6 +314,7 @@ static void generic_mix_select_callbacks
dmix->u.dmix.mix_areas2 = generic_mix_areas2_swap;
}
dmix->u.dmix.mix_areas3 = generic_mix_areas3;
+ dmix->u.dmix.mix_areas_u8 = generic_mix_areas_u8;
}
#endif
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