Add support for DSF files to DSDIFF decoder - v4

Version 4 of my patch to add DSF support to the DSDIFF
decoder plugin.

This time I have taken a different approach and created a new
read_metadata function specific for reading DSF files. This saves an
indent (and for me a lot of indent nightmares) and also useful for
splitting the DSF and DFF decoders later on.

There are still a few lines which exceed the 80 character width limit by
a few chars. I was not able to stay within the limit and create (for me)
readable code.

Jurgen

doc/user.xml

@@ -782,7 +782,7 @@ systemctl start mpd.socket</programlisting>
         <title><varname>dsdiff</varname></title>
 
         <para>
-          Decodes DFF files containing DSDIFF data (e.g. SACD rips).
+          Decodes DFF and DSF files containing DSDIFF data (e.g. SACD rips).
         </para>
 
         <informaltable>

src/decoder/dsdiff_decoder_plugin.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2003-2011 The Music Player Daemon Project
+ * 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
@@ -19,9 +19,12 @@
 
 /* \file
  *
- * This plugin decodes DSDIFF data (SACD) embedded in DFF files.  It
+ * This plugin decodes DSDIFF data (SACD) embedded in DFF and DSF files.
- * was modeled after the specification found here:
+ * The DFF code was modeled after the specification found here:
  * http://www.sonicstudio.com/pdf/dsd/DSDIFF_1.5_Spec.pdf
+ *
+ * The DSF code was created using the specification found here:
+ * http://dsd-guide.com/sonys-dsf-file-format-spec
  */
 
 #include "config.h"
@@ -53,10 +56,57 @@ struct dsdiff_chunk_header {
 
 struct dsdiff_metadata {
 	unsigned sample_rate, channels;
+	bool fileisdff;
+	bool bitreverse;
+	uint64_t chunk_size;
 };
 
 static bool lsbitfirst;
 
+
+struct dsf_header {
+	/** DSF header id: "DSD " */
+	struct dsdiff_id id;
+	/** DSD chunk size, including id = 28 */
+	uint32_t size_low, size_high;
+	/** Total file size */
+	uint32_t fsize_low, fsize_high;
+	/** Pointer to id3v2 metadata, should be at the end of the file */
+	uint32_t pmeta_low, pmeta_high;
+};
+/** DSF file fmt chunk */
+struct dsf_fmt_chunk {
+
+	/** id: "fmt " */
+	struct dsdiff_id id;
+	/** fmt chunk size, including id, normally 52 */
+	uint32_t size_low, size_high;
+	/** Version of this format = 1 */
+	uint32_t version;
+	/** 0: DSD raw */
+	uint32_t formatid;
+	/** Channel Type, 1 = mono, 2 = stereo, 3 = 3 channels, etc */
+	uint32_t channeltype;
+	/** Channel number, 1 = mono, 2 = stereo, ... 6 = 6 channels */
+	uint32_t channelnum;
+	/** Sample frequency: 2822400, 5644800 */
+	uint32_t sample_freq;
+	/** Bits per sample 1 or 8 */
+	uint32_t bitssample;
+	/** Sample count per channel in bytes */
+	uint32_t scnt_low, scnt_high;
+	/** Block size per channel = 4096 */
+	uint32_t block_size;
+	/** Reserved, should be all zero */
+	uint32_t reserved;
+};
+
+struct dsf_data_chunk {
+	struct dsdiff_id id;
+	/** "data" chunk size, includes header (id+size) */
+	uint32_t size_low, size_high;
+};
+
 static bool
 dsdiff_init(const struct config_param *param)
 {
@@ -224,7 +274,7 @@ dsdiff_read_prop_snd(struct decoder *decoder, struct input_stream *is,
 				return false;
 
 			if (!dsdiff_id_equals(&type, "DSD "))
-				/* only uincompressed DSD audio data
+				/* only uncompressed DSD audio data
 				   is implemented */
 				return false;
 		} else {
@@ -278,7 +328,8 @@ dsdiff_read_metadata(struct decoder *decoder, struct input_stream *is,
 		return false;
 
 	while (true) {
-		if (!dsdiff_read_chunk_header(decoder, is, chunk_header))
+		if (!dsdiff_read_chunk_header(decoder, is,
+					      chunk_header))
 			return false;
 
 		if (dsdiff_id_equals(&chunk_header->id, "PROP")) {
@@ -286,20 +337,98 @@ dsdiff_read_metadata(struct decoder *decoder, struct input_stream *is,
 					      chunk_header))
 					return false;
 		} else if (dsdiff_id_equals(&chunk_header->id, "DSD ")) {
-			/* done with metadata */
+			/* done with metadata, mark as DFF */
+			metadata->fileisdff = true;
 			return true;
 		} else {
 			/* ignore unknown chunk */
-
+			uint64_t chunk_size;
-			uint64_t chunk_size = dsdiff_chunk_size(chunk_header);
+			chunk_size = dsdiff_chunk_size(chunk_header);
 			goffset chunk_end_offset = is->offset + chunk_size;
 
-			if (!dsdiff_skip_to(decoder, is, chunk_end_offset))
+			if (!dsdiff_skip_to(decoder, is,
+					    chunk_end_offset))
 				return false;
 		}
 	}
 }
 
+/**
+ * Read and parse all needed metadata chunks for DSF files.
+ */
+static bool
+dsf_read_metadata(struct decoder *decoder, struct input_stream *is,
+		  struct dsdiff_metadata *metadata)
+{
+	/* Reset to beginning of the stream */
+	if (!dsdiff_skip_to(decoder, is, 0))
+		return false;
+
+	uint64_t chunk_size;
+	struct dsf_header dsf_header;
+	if (!dsdiff_read(decoder, is, &dsf_header, sizeof(dsf_header)) ||
+	    !dsdiff_id_equals(&dsf_header.id, "DSD "))
+		return false;
+
+	chunk_size = (((uint64_t)GUINT32_FROM_LE(dsf_header.size_high)) << 32) |
+		((uint64_t)GUINT32_FROM_LE(dsf_header.size_low));
+
+	if (sizeof(dsf_header) != chunk_size)
+		return false;
+
+	/* Read the 'fmt ' chunk of the DSF file */
+	struct dsf_fmt_chunk dsf_fmt_chunk;
+	if (!dsdiff_read(decoder, is, &dsf_fmt_chunk, sizeof(dsf_fmt_chunk)) ||
+	    !dsdiff_id_equals(&dsf_fmt_chunk.id, "fmt "))
+		return false;
+
+	uint64_t fmt_chunk_size;
+	fmt_chunk_size = (((uint64_t)GUINT32_FROM_LE(dsf_fmt_chunk.size_high)) << 32) |
+		((uint64_t)GUINT32_FROM_LE(dsf_fmt_chunk.size_low));
+
+	if (fmt_chunk_size != sizeof(dsf_fmt_chunk))
+		return false;
+
+	uint32_t samplefreq = (uint32_t)GUINT32_FROM_LE(dsf_fmt_chunk.sample_freq);
+
+	/* For now, only support version 1 of the standard, DSD raw stereo
+	   files with a sample freq of 2822400 Hz */
+
+	if (dsf_fmt_chunk.version != 1 || dsf_fmt_chunk.formatid != 0
+	    || dsf_fmt_chunk.channeltype != 2
+	    || dsf_fmt_chunk.channelnum != 2
+	    || samplefreq != 2822400)
+		return false;
+
+	uint32_t chblksize = (uint32_t)GUINT32_FROM_LE(dsf_fmt_chunk.block_size);
+	/* According to the spec block size should always be 4096 */
+	if (chblksize != 4096)
+		return false;
+
+	/* Read the 'data' chunk of the DSF file */
+	struct dsf_data_chunk data_chunk;
+	if (!dsdiff_read(decoder, is, &data_chunk, sizeof(data_chunk)) ||
+	    !dsdiff_id_equals(&data_chunk.id, "data"))
+		return false;
+
+	/* Data size of DSF files are padded to multiple of 4096,
+	   we use the actual data size as chunk size */
+
+	uint64_t data_size;
+	data_size = (((uint64_t)GUINT32_FROM_LE(data_chunk.size_high)) << 32) |
+		((uint64_t)GUINT32_FROM_LE(data_chunk.size_low));
+	data_size -= sizeof(data_chunk);
+
+	metadata->chunk_size = data_size;
+	metadata->channels = (unsigned) dsf_fmt_chunk.channelnum;
+	metadata->sample_rate = samplefreq;
+
+	/* Check bits per sample format, determine if bitreverse is needed */
+	metadata->bitreverse = dsf_fmt_chunk.bitssample == 1 ?  true : false;
+	metadata->fileisdff = false;
+	return true;
+}
+
 static void
 bit_reverse_buffer(uint8_t *p, uint8_t *end)
 {
@@ -307,15 +436,47 @@ bit_reverse_buffer(uint8_t *p, uint8_t *end)
 		*p = bit_reverse(*p);
 }
 
+/**
+ * DSF data is build up of alternating 4096 blocks of DSD samples for left and
+ * right. Convert the buffer holding 1 block of 4096 DSD left samples and 1
+ * block of 4096 DSD right samples to 8k of samples in normal PCM left/right
+ * order.
+ */
+static void
+dsf_to_pcm_order(uint8_t *dest, uint8_t *scratch, size_t nrbytes)
+{
+	for (unsigned i = 0, j = 0; i < (unsigned)nrbytes; i += 2) {
+		scratch[i] = *(dest+j);
+		j++;
+	}
+
+	for (unsigned i = 1, j = 0; i < (unsigned) nrbytes; i += 2) {
+		scratch[i] = *(dest+4096+j);
+		j++;
+	}
+
+	for (unsigned i = 0; i < (unsigned)nrbytes; i++) {
+		*dest = scratch[i];
+		dest++;
+	}
+}
+
 /**
  * Decode one "DSD" chunk.
  */
 static bool
 dsdiff_decode_chunk(struct decoder *decoder, struct input_stream *is,
 		    unsigned channels,
-		    uint64_t chunk_size)
+		    uint64_t chunk_size,
+		    bool fileisdff,
+		    bool bitreverse)
 {
 	uint8_t buffer[8192];
+
+	/* Scratch buffer for DSF samples to convert to the needed
+	   normal Left/Right regime of samples */
+	uint8_t dsf_scratch_buffer[8192];
+
 	const size_t sample_size = sizeof(buffer[0]);
 	const size_t frame_size = channels * sample_size;
 	const unsigned buffer_frames = sizeof(buffer) / frame_size;
@@ -338,9 +499,12 @@ dsdiff_decode_chunk(struct decoder *decoder, struct input_stream *is,
 
 		chunk_size -= nbytes;
 
-		if (lsbitfirst)
+		if (lsbitfirst || bitreverse)
 			bit_reverse_buffer(buffer, buffer + nbytes);
 
+		if (!fileisdff)
+			dsf_to_pcm_order(buffer, dsf_scratch_buffer, nbytes);
+
 		enum decoder_command cmd =
 			decoder_data(decoder, is, buffer, nbytes, 0);
 		switch (cmd) {
@@ -370,8 +534,13 @@ dsdiff_stream_decode(struct decoder *decoder, struct input_stream *is)
 	};
 
 	struct dsdiff_chunk_header chunk_header;
+	/* First see if it is is a DFF file */
 	if (!dsdiff_read_metadata(decoder, is, &metadata, &chunk_header))
+	{
+		/* It was not a DFF file, now check if it is a DSF file */
+		if (!dsf_read_metadata(decoder, is, &metadata))
 			return;
+	}
 
 	GError *error = NULL;
 	struct audio_format audio_format;
@@ -384,19 +553,34 @@ dsdiff_stream_decode(struct decoder *decoder, struct input_stream *is)
 	}
 
 	/* success: file was recognized */
-
 	decoder_initialized(decoder, &audio_format, false, -1);
 
+	if (!metadata.fileisdff) {
+		uint64_t chunk_size = metadata.chunk_size;
+		if (!dsdiff_decode_chunk(decoder, is,
+					 metadata.channels,
+					 chunk_size,
+					 metadata.fileisdff,
+					 metadata.bitreverse))
+			return;
+
+	} else {
+
 		/* every iteration of the following loop decodes one "DSD"
-	   chunk */
+		   chunk from a DFF file */
 
 		while (true) {
+
 			uint64_t chunk_size = dsdiff_chunk_size(&chunk_header);
 
 			if (dsdiff_id_equals(&chunk_header.id, "DSD ")) {
 				if (!dsdiff_decode_chunk(decoder, is,
 							 metadata.channels,
-						 chunk_size))
+							 chunk_size,
+							 metadata.fileisdff,
+						/* Set bitreverse to
+						   false for DFF files */
+							false))
 					break;
 			} else {
 				/* ignore other chunks */
@@ -408,9 +592,11 @@ dsdiff_stream_decode(struct decoder *decoder, struct input_stream *is)
 			/* read next chunk header; the first one was read by
 			   dsdiff_read_metadata() */
 
-		if (!dsdiff_read_chunk_header(decoder, is, &chunk_header))
+			if (!dsdiff_read_chunk_header(decoder,
+						      is, &chunk_header))
 				break;
 		}
+	}
 }
 
 static bool
@@ -424,8 +610,13 @@ dsdiff_scan_stream(struct input_stream *is,
 	};
 
 	struct dsdiff_chunk_header chunk_header;
+	/* First check for DFF metadata */
 	if (!dsdiff_read_metadata(NULL, is, &metadata, &chunk_header))
+	{
+		/* It was not an DFF file, now check for DSF metadata */
+		if (!dsf_read_metadata(NULL, is, &metadata))
 			return false;
+	}
 
 	struct audio_format audio_format;
 	if (!audio_format_init_checked(&audio_format, metadata.sample_rate / 8,
@@ -440,11 +631,13 @@ dsdiff_scan_stream(struct input_stream *is,
 
 static const char *const dsdiff_suffixes[] = {
 	"dff",
+	"dsf",
 	NULL
 };
 
 static const char *const dsdiff_mime_types[] = {
 	"application/x-dff",
+	"application/x-dsf",
 	NULL
 };