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-rw-r--r--doc/user.xml4
-rw-r--r--src/pcm_dsd_usb.c33
-rw-r--r--src/pcm_dsd_usb.h5
3 files changed, 33 insertions, 9 deletions
diff --git a/doc/user.xml b/doc/user.xml
index 6c0547f0c..cd36528d5 100644
--- a/doc/user.xml
+++ b/doc/user.xml
@@ -1127,8 +1127,8 @@ systemctl start mpd.socket</programlisting>
<entry>
If set to <parameter>yes</parameter>, then DSD over
USB according to the <ulink
- url="http://www.dcsltd.co.uk/page/assets/DSDoverUSB.pdf">dCS
- suggested standard</ulink> is enabled. This wrapsa
+ url="http://www.sonore.us/DoP_openStandard_1v1.pdf">pro
+ posed standard by dCS and others</ulink> is enabled. This wraps
DSD samples in fake 24 bit PCM, and is understood by
some DSD capable products, but may be harmful to
other hardware. Therefore, the default is
diff --git a/src/pcm_dsd_usb.c b/src/pcm_dsd_usb.c
index 976420c00..4b5e39f39 100644
--- a/src/pcm_dsd_usb.c
+++ b/src/pcm_dsd_usb.c
@@ -24,11 +24,19 @@
G_GNUC_CONST
static inline uint32_t
-pcm_two_dsd_to_usb(uint8_t a, uint8_t b)
+pcm_two_dsd_to_usb_marker1(uint8_t a, uint8_t b)
{
- return 0xffaa0000 | (a << 8) | b;
+ return 0xff050000 | (a << 8) | b;
}
+G_GNUC_CONST
+static inline uint32_t
+pcm_two_dsd_to_usb_marker2(uint8_t a, uint8_t b)
+{
+ return 0xfffa0000 | (a << 8) | b;
+}
+
+
const uint32_t *
pcm_dsd_to_usb(struct pcm_buffer *buffer, unsigned channels,
const uint8_t *src, size_t src_size,
@@ -53,12 +61,27 @@ pcm_dsd_to_usb(struct pcm_buffer *buffer, unsigned channels,
uint32_t *const dest0 = pcm_buffer_get(buffer, dest_size),
*dest = dest0;
- for (unsigned i = num_frames; i > 0; --i) {
+ for (unsigned i = num_frames / 2; i > 0; --i) {
+ for (unsigned c = channels; c > 0; --c) {
+ /* each 24 bit sample has 16 DSD sample bits
+ plus the magic 0x05 marker */
+
+ *dest++ = pcm_two_dsd_to_usb_marker1(src[0], src[channels]);
+
+ /* seek the source pointer to the next
+ channel */
+ ++src;
+ }
+
+ /* skip the second byte of each channel, because we
+ have already copied it */
+ src += channels;
+
for (unsigned c = channels; c > 0; --c) {
/* each 24 bit sample has 16 DSD sample bits
- plus the magic 0xaa marker */
+ plus the magic 0xfa marker */
- *dest++ = pcm_two_dsd_to_usb(src[0], src[channels]);
+ *dest++ = pcm_two_dsd_to_usb_marker2(src[0], src[channels]);
/* seek the source pointer to the next
channel */
diff --git a/src/pcm_dsd_usb.h b/src/pcm_dsd_usb.h
index 3e7ad8fa1..389358459 100644
--- a/src/pcm_dsd_usb.h
+++ b/src/pcm_dsd_usb.h
@@ -30,8 +30,9 @@ struct pcm_buffer;
/**
* Pack DSD 1 bit samples into (padded) 24 bit PCM samples for
- * playback over USB, according to the dCS suggested standard:
- * http://www.dcsltd.co.uk/page/assets/DSDoverUSB.pdf
+ * playback over USB, according to the proposed standard by
+ * dCS and others:
+ * http://www.sonore.us/DoP_openStandard_1v1.pdf
*/
const uint32_t *
pcm_dsd_to_usb(struct pcm_buffer *buffer, unsigned channels,