[PATCH] Add support for reading DSF files

[Mans Rullgard <mans@mansr.com>]

This adds support for reading DSD data from DSF files as specified by
http://dsd-guide.com/sites/default/files/white-papers/DSFFileFormatSpec_E.pdf

The 1-bit DSD samples are simply unpacked to sox_sample_t values of
maximum or minimum value.  The "rate" filter can be used directly on
this to obtain usable PCM samples.

The format also allows 8-bit DSD-wide samples.  Such files are not
supported by this patch.

DSF files may include an ID3v2 metadata tag, which is not handled here.
---
 src/Makefile.am |   2 +-
 src/dsf.c       | 209 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 src/formats.h   |   1 +
 3 files changed, 211 insertions(+), 1 deletion(-)
 create mode 100644 src/dsf.c

diff --git a/src/Makefile.am b/src/Makefile.am
index 7cceaaf..462d46d 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -121,7 +121,7 @@ libsox_la_SOURCES += raw-fmt.c s1-fmt.c s2-fmt.c s3-fmt.c \
   lu-fmt.c 8svx.c aiff-fmt.c aifc-fmt.c au.c avr.c cdr.c cvsd-fmt.c \
   dvms-fmt.c dat.c hcom.c htk.c maud.c prc.c sf.c smp.c \
   sounder.c soundtool.c sphere.c tx16w.c voc.c vox-fmt.c ima-fmt.c adpcm.c adpcm.h \
-  ima_rw.c ima_rw.h wav.c wve.c xa.c nulfile.c f4-fmt.c f8-fmt.c gsrt.c
+  ima_rw.c ima_rw.h wav.c wve.c xa.c nulfile.c f4-fmt.c f8-fmt.c gsrt.c dsf.c
 
 libsox_la_LIBADD += @GSM_LIBS@ @LIBGSM_LIBADD@
 libsox_la_LIBADD += @LPC10_LIBS@ @LIBLPC10_LIBADD@
diff --git a/src/dsf.c b/src/dsf.c
new file mode 100644
index 0000000..04864e1
--- /dev/null
+++ b/src/dsf.c
@@ -0,0 +1,209 @@
+/* DSF file support
+ *
+ * Copyright (c) 2015 Mans Rullgard <mans@mansr.com>
+ *
+ * This library is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation; either version 2.1 of the License, or (at
+ * your option) any later version.
+ *
+ * This library 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 Lesser
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this library; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+/* File format specification available at
+ * http://dsd-guide.com/sites/default/files/white-papers/DSFFileFormatSpec_E.pdf
+ */
+
+#include <stdint.h>
+#include "sox_i.h"
+
+struct dsf {
+	uint64_t file_size;
+	uint64_t metadata;
+	uint32_t version;
+	uint32_t format_id;
+	uint32_t chan_type;
+	uint32_t chan_num;
+	uint32_t sfreq;
+	uint32_t bps;
+	uint64_t scount;
+	uint32_t block_size;
+
+	uint32_t block_pos;
+	uint8_t *block;
+	uint64_t read_samp;
+};
+
+#define TAG(a, b, c, d) ((a) | (b) << 8 | (c) << 16 | (d) << 24)
+
+#define DSF_TAG  TAG('D', 'S', 'D', ' ')
+#define FMT_TAG  TAG('f', 'm', 't', ' ')
+#define DATA_TAG TAG('d', 'a', 't', 'a')
+
+static int dsf_startread(sox_format_t *ft)
+{
+	struct dsf *dsf = ft->priv;
+	uint32_t magic;
+	uint64_t csize;
+	uint32_t v;
+
+	if (lsx_readdw(ft, &magic) || magic != DSF_TAG) {
+		lsx_fail_errno(ft, SOX_EHDR, "DSF signature not found");
+		return SOX_EHDR;
+	}
+
+	if (lsx_readqw(ft, &csize) || csize != 28) {
+		lsx_fail_errno(ft, SOX_EHDR, "invalid DSD chunk size");
+		return SOX_EHDR;
+	}
+
+	lsx_readqw(ft, &dsf->file_size);
+	lsx_readqw(ft, &dsf->metadata);
+
+	if (lsx_readdw(ft, &magic) || magic != FMT_TAG) {
+		lsx_fail_errno(ft, SOX_EHDR, "fmt chunk not found");
+		return SOX_EHDR;
+	}
+
+	if (lsx_readqw(ft, &csize) || csize != 52) {
+		lsx_fail_errno(ft, SOX_EHDR, "invalid fmt chunk size");
+		return SOX_EHDR;
+	}
+
+	if (lsx_readdw(ft, &dsf->version)   ||
+	    lsx_readdw(ft, &dsf->format_id) ||
+	    lsx_readdw(ft, &dsf->chan_type) ||
+	    lsx_readdw(ft, &dsf->chan_num)  ||
+	    lsx_readdw(ft, &dsf->sfreq)     ||
+	    lsx_readdw(ft, &dsf->bps)       ||
+	    lsx_readqw(ft, &dsf->scount)    ||
+	    lsx_readdw(ft, &dsf->block_size))
+		return SOX_EHDR;
+
+	if (lsx_readdw(ft, &v) || v) /* reserved */
+		return SOX_EHDR;
+
+	if (lsx_readdw(ft, &magic) || magic != DATA_TAG) {
+		lsx_fail_errno(ft, SOX_EHDR, "data chunk not found");
+		return SOX_EHDR;
+	}
+
+	if (lsx_readqw(ft, &csize) ||
+	    csize < 12 + dsf->block_size * dsf->chan_num) {
+		lsx_fail_errno(ft, SOX_EHDR, "invalid data chunk size");
+		return SOX_EHDR;
+	}
+
+	if (dsf->version != 1) {
+		lsx_fail_errno(ft, SOX_EHDR, "unknown format version %d",
+			       dsf->version);
+		return SOX_EHDR;
+	}
+
+	if (dsf->format_id != 0) {
+		lsx_fail_errno(ft, SOX_EFMT, "unknown format ID %d",
+			       dsf->format_id);
+		return SOX_EFMT;
+	}
+
+	if (dsf->chan_num < 1 || dsf->chan_num > 6) {
+		lsx_fail_errno(ft, SOX_EHDR, "inavlid channel count %d",
+			       dsf->chan_num);
+		return SOX_EHDR;
+	}
+
+	if (dsf->bps != 1) {
+		lsx_fail_errno(ft, SOX_EFMT, "unsupported bit depth %d",
+			       dsf->bps);
+		return SOX_EFMT;
+	}
+
+	dsf->block = lsx_calloc(dsf->chan_num, dsf->block_size);
+	if (!dsf->block)
+		return SOX_ENOMEM;
+
+	dsf->block_pos = dsf->block_size;
+
+	ft->signal.rate = dsf->sfreq;
+	ft->signal.channels = dsf->chan_num;
+	ft->signal.precision = 1;
+	ft->signal.length = dsf->scount * dsf->chan_num;
+
+	ft->encoding.encoding = SOX_ENCODING_UNSIGNED;
+	ft->encoding.bits_per_sample = 1;
+
+	return SOX_SUCCESS;
+}
+
+static size_t dsf_read(sox_format_t *ft, sox_sample_t *buf, size_t len)
+{
+	struct dsf *dsf = ft->priv;
+	uint64_t samp_left = dsf->scount - dsf->read_samp;
+	size_t rsamp = 0;
+	uint8_t *dsd;
+	unsigned i, j;
+
+	len /= dsf->chan_num;
+	len = min(len, samp_left);
+
+	while (len >= 8) {
+		if (dsf->block_pos >= dsf->block_size) {
+			size_t rlen = dsf->chan_num * dsf->block_size;
+			if (lsx_read_b_buf(ft, dsf->block, rlen) < rlen)
+				return rsamp * dsf->chan_num;
+			dsf->block_pos = 0;
+		}
+
+		dsd = dsf->block + dsf->block_pos;
+
+		for (i = 0; i < dsf->chan_num; i++) {
+			unsigned d = dsd[i * dsf->block_size];
+
+			for (j = 0; j < 8; j++) {
+				buf[i + j * dsf->chan_num] = d & 1 ?
+					SOX_SAMPLE_MAX : -SOX_SAMPLE_MAX;
+				d >>= 1;
+			}
+		}
+
+		buf += 8 * dsf->chan_num;
+
+		dsf->block_pos++;
+		rsamp += 8;
+		len -= 8;
+	}
+
+	return rsamp * dsf->chan_num;
+}
+
+static int dsf_stopread(sox_format_t *ft)
+{
+	struct dsf *dsf = ft->priv;
+
+	free(dsf->block);
+
+	return SOX_SUCCESS;
+}
+
+LSX_FORMAT_HANDLER(dsf)
+{
+	static char const * const names[] = { "dsf", NULL };
+	static unsigned const write_encodings[] = { 0 };
+	static sox_format_handler_t const handler = {
+		SOX_LIB_VERSION_CODE,
+		"Container for DSD data",
+		names, SOX_FILE_LIT_END,
+		dsf_startread, dsf_read, dsf_stopread,
+		NULL, NULL, NULL,
+		NULL, write_encodings, NULL,
+		sizeof(struct dsf)
+	};
+	return &handler;
+}
diff --git a/src/formats.h b/src/formats.h
index a42ce27..4701efd 100644
--- a/src/formats.h
+++ b/src/formats.h
@@ -26,6 +26,7 @@
   FORMAT(cvsd)
   FORMAT(cvu)
   FORMAT(dat)
+  FORMAT(dsf)
   FORMAT(dvms)
   FORMAT(f4)
   FORMAT(f8)
-- 
2.5.0


------------------------------------------------------------------------------