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Add support for DSD-over-USB version 1.0, remove pre-v1 support

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This commit is contained in:
Jurgen Kramer 2012-04-01 11:10:12 +02:00 committed by Max Kellermann
parent 4feb57e895
commit f930f37d35
3 changed files with 33 additions and 9 deletions
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4
doc/user.xml
View File

@ -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

33
src/pcm_dsd_usb.c
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@ -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 0xaa marker */
plus the magic 0x05 marker */
*dest++ = pcm_two_dsd_to_usb(src[0], src[channels]);
*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 0xfa marker */
*dest++ = pcm_two_dsd_to_usb_marker2(src[0], src[channels]);
/* seek the source pointer to the next
channel */

5
src/pcm_dsd_usb.h
View File

@ -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,