pcm_dsd: implement DSD to 24 bit USB conversion

Implements the dCS suggested standard:

 http://www.dcsltd.co.uk/page/assets/DSDoverUSB.pdf

1 files changed, 41 insertions, 0 deletions

diff --git a/src/pcm_dsd_usb.h b/src/pcm_dsd_usb.h
new file mode 100644
index 000000000..3e7ad8fa1
--- /dev/null
+++ b/src/pcm_dsd_usb.h
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2003-2012 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef MPD_PCM_DSD_USB_H
+#define MPD_PCM_DSD_USB_H
+
+#include "check.h"
+
+#include <stdbool.h>
+#include <stdint.h>
+#include <stddef.h>
+
+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
+ */
+const uint32_t *
+pcm_dsd_to_usb(struct pcm_buffer *buffer, unsigned channels,
+	       const uint8_t *src, size_t src_size,
+	       size_t *dest_size_r);
+
+#endif