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authorMax Kellermann <max@duempel.org>2012-03-20 01:01:12 +0100
committerMax Kellermann <max@duempel.org>2012-03-22 01:14:51 +0100
commit81208d78acb260c7c2e6debc765042dd5e98f862 (patch)
tree32993048254599ac9d5dfb26a0ac182863d5db73 /src/pcm_convert.c
parentda8b01771ff425dd30dca1cb8a8fe943d2ecc90b (diff)
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pcm_dsd: implement DSD to 24 bit USB conversion
Implements the dCS suggested standard: http://www.dcsltd.co.uk/page/assets/DSDoverUSB.pdf
Diffstat (limited to 'src/pcm_convert.c')
-rw-r--r--src/pcm_convert.c35
1 files changed, 35 insertions, 0 deletions
diff --git a/src/pcm_convert.c b/src/pcm_convert.c
index 03172b613..f19a95223 100644
--- a/src/pcm_convert.c
+++ b/src/pcm_convert.c
@@ -22,6 +22,7 @@
#include "pcm_channels.h"
#include "pcm_format.h"
#include "pcm_pack.h"
+#include "pcm_dsd_usb.h"
#include "audio_format.h"
#include "glib_compat.h"
@@ -325,6 +326,40 @@ pcm_convert(struct pcm_convert_state *state,
size_t *dest_size_r,
GError **error_r)
{
+ struct audio_format usb_format;
+
+ if (src_format->format == SAMPLE_FORMAT_DSD &&
+ dest_format->format == SAMPLE_FORMAT_DSD_OVER_USB) {
+ size_t u_size;
+ const uint32_t *u = pcm_dsd_to_usb(&state->dsd.buffer,
+ src_format->channels,
+ src, src_size,
+ &u_size);
+ if (u == NULL) {
+ g_set_error_literal(error_r, pcm_convert_quark(), 0,
+ "DSD to USB conversion failed");
+ return NULL;
+ }
+
+ usb_format = *src_format;
+ usb_format.format = SAMPLE_FORMAT_DSD_OVER_USB;
+
+ /* each DSD-over-USB sample contains 2 DSD bytes (16
+ DSD bits), which means the sample rate must be
+ halved; this is not the real 1 bit sample rate, but
+ MPD's point of view */
+ usb_format.sample_rate = usb_format.sample_rate / 2;
+
+ if (audio_format_equals(&usb_format, dest_format)) {
+ *dest_size_r = u_size;
+ return u;
+ }
+
+ src_format = &usb_format;
+ src = u;
+ src_size = u_size;
+ }
+
struct audio_format float_format;
if (src_format->format == SAMPLE_FORMAT_DSD) {
size_t f_size;