[Musicpd-dev-team] [PATCH] Add support for DSD-over-USB version 1.0, remove pre-v1 support

[Jurgen Kramer]

Hi,

Attached patch adds support for DSD-over-USB version 1.0 and removes
support for the old pre-v1 standard. Patch is against current git.

---
 src/pcm_dsd_usb.c |   33 -
 1 files changed, 28 insertions(+), 5 deletions(-)

Jurgen

diff --git a/src/pcm_dsd_usb.c b/src/pcm_dsd_usb.c
index 976420c..4b5e39f 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 0xffaa | (a  8) | b;
+	return 0xff05 | (a  8) | b;
 }
 
+G_GNUC_CONST
+static inline uint32_t
+pcm_two_dsd_to_usb_marker2(uint8_t a, uint8_t b)
+{
+	return 0xfffa | (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 */
-- 
1.7.6.5

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Re: [Musicpd-dev-team] DSD over USB

[Bobby Beever]

Max,

Sorry I've been on a holiday and totally missed out on anything digital. 
Although I didn't finish my implementation, I see you picked up the DSD 
development yourself which I'm happy about. 

You probably don't care, and probably too late.. but I do not agree with the 
addition of the added DSD sample type. I've attached my patch to give you an 
idea where I was heading to with the added FRAME_TYPE which in my opinion is 
the cleanest.

Cheers

mpd_dsd.patch
Description: Binary data
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