Adding upstream version 1.4.3+ds.upstream/1.4.3+dsupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 669 insertions, 0 deletions

diff --git a/src/share/grabbag/replaygain.c b/src/share/grabbag/replaygain.c
new file mode 100644
index 0000000..32c9603
--- /dev/null
+++ b/src/share/grabbag/replaygain.c
@@ -0,0 +1,669 @@
+/* grabbag - Convenience lib for various routines common to several tools
+ * Copyright (C) 2002-2009  Josh Coalson
+ * Copyright (C) 2011-2023  Xiph.Org Foundation
+ *
+ * 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
+ */
+
+#ifdef HAVE_CONFIG_H
+#  include <config.h>
+#endif
+
+#include <locale.h>
+#include <math.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#if defined _MSC_VER || defined __MINGW32__
+#include <io.h> /* for chmod() */
+#endif
+#include <sys/stat.h> /* for stat(), maybe chmod() */
+
+#include "FLAC/assert.h"
+#include "FLAC/metadata.h"
+#include "FLAC/stream_decoder.h"
+#include "share/grabbag.h"
+#include "share/replaygain_analysis.h"
+#include "share/safe_str.h"
+
+#ifdef local_min
+#undef local_min
+#endif
+#define local_min(a,b) ((a)<(b)?(a):(b))
+
+#ifdef local_max
+#undef local_max
+#endif
+#define local_max(a,b) ((a)>(b)?(a):(b))
+
+#ifdef abs32
+#undef abs32
+#endif
+#define abs32(a) (((a)==INT32_MIN)?INT32_MAX:abs(a))
+
+static const char *reference_format_ = "%s=%2.1f dB";
+static const char *gain_format_ = "%s=%+2.2f dB";
+static const char *peak_format_ = "%s=%1.8f";
+
+static double album_peak_, title_peak_;
+
+const uint32_t GRABBAG__REPLAYGAIN_MAX_TAG_SPACE_REQUIRED = 190;
+/*
+	FLAC__STREAM_METADATA_VORBIS_COMMENT_ENTRY_LENGTH_LEN/8 + 29 + 1 + 8 +
+	FLAC__STREAM_METADATA_VORBIS_COMMENT_ENTRY_LENGTH_LEN/8 + 21 + 1 + 10 +
+	FLAC__STREAM_METADATA_VORBIS_COMMENT_ENTRY_LENGTH_LEN/8 + 21 + 1 + 12 +
+	FLAC__STREAM_METADATA_VORBIS_COMMENT_ENTRY_LENGTH_LEN/8 + 21 + 1 + 10 +
+	FLAC__STREAM_METADATA_VORBIS_COMMENT_ENTRY_LENGTH_LEN/8 + 21 + 1 + 12
+*/
+
+const FLAC__byte * const GRABBAG__REPLAYGAIN_TAG_REFERENCE_LOUDNESS = (const FLAC__byte * const)"REPLAYGAIN_REFERENCE_LOUDNESS";
+const FLAC__byte * const GRABBAG__REPLAYGAIN_TAG_TITLE_GAIN = (const FLAC__byte * const)"REPLAYGAIN_TRACK_GAIN";
+const FLAC__byte * const GRABBAG__REPLAYGAIN_TAG_TITLE_PEAK = (const FLAC__byte * const)"REPLAYGAIN_TRACK_PEAK";
+const FLAC__byte * const GRABBAG__REPLAYGAIN_TAG_ALBUM_GAIN = (const FLAC__byte * const)"REPLAYGAIN_ALBUM_GAIN";
+const FLAC__byte * const GRABBAG__REPLAYGAIN_TAG_ALBUM_PEAK = (const FLAC__byte * const)"REPLAYGAIN_ALBUM_PEAK";
+
+
+static FLAC__bool get_file_stats_(const char *filename, struct flac_stat_s *stats)
+{
+	FLAC__ASSERT(0 != filename);
+	FLAC__ASSERT(0 != stats);
+	return (0 == flac_stat(filename, stats));
+}
+
+static void set_file_stats_(const char *filename, struct flac_stat_s *stats)
+{
+	FLAC__ASSERT(0 != filename);
+	FLAC__ASSERT(0 != stats);
+
+	(void)flac_chmod(filename, stats->st_mode);
+}
+
+static FLAC__bool append_tag_(FLAC__StreamMetadata *block, const char *format, const FLAC__byte *name, float value)
+{
+	char buffer[256];
+	char *saved_locale;
+	FLAC__StreamMetadata_VorbisComment_Entry entry;
+
+	FLAC__ASSERT(0 != block);
+	FLAC__ASSERT(block->type == FLAC__METADATA_TYPE_VORBIS_COMMENT);
+	FLAC__ASSERT(0 != format);
+	FLAC__ASSERT(0 != name);
+
+	buffer[sizeof(buffer)-1] = '\0';
+	/*
+	 * We need to save the old locale and switch to "C" because the locale
+	 * influences the formatting of %f and we want it a certain way.
+	 */
+	saved_locale = strdup(setlocale(LC_ALL, 0));
+	if (0 == saved_locale)
+		return false;
+	setlocale(LC_ALL, "C");
+	flac_snprintf(buffer, sizeof(buffer), format, name, value);
+	setlocale(LC_ALL, saved_locale);
+	free(saved_locale);
+
+	entry.entry = (FLAC__byte *)buffer;
+	entry.length = strlen(buffer);
+
+	return FLAC__metadata_object_vorbiscomment_append_comment(block, entry, /*copy=*/true);
+}
+
+FLAC__bool grabbag__replaygain_is_valid_sample_frequency(uint32_t sample_frequency)
+{
+	return ValidGainFrequency( sample_frequency );
+}
+
+FLAC__bool grabbag__replaygain_init(uint32_t sample_frequency)
+{
+	title_peak_ = album_peak_ = 0.0;
+	return InitGainAnalysis((long)sample_frequency) == INIT_GAIN_ANALYSIS_OK;
+}
+
+FLAC__bool grabbag__replaygain_analyze(const FLAC__int32 * const input[], FLAC__bool is_stereo, uint32_t bps, uint32_t samples)
+{
+	/* using a small buffer improves data locality; we'd like it to fit easily in the dcache */
+	static flac_float_t lbuffer[2048], rbuffer[2048];
+	static const uint32_t nbuffer = sizeof(lbuffer) / sizeof(lbuffer[0]);
+	FLAC__int32 block_peak = 0, s;
+	uint32_t i, j;
+
+	FLAC__ASSERT(bps >= FLAC__MIN_BITS_PER_SAMPLE && bps <= FLAC__MAX_BITS_PER_SAMPLE);
+	FLAC__ASSERT(FLAC__MIN_BITS_PER_SAMPLE == 4 && FLAC__MAX_BITS_PER_SAMPLE == 32);
+
+	if(bps == 16) {
+		if(is_stereo) {
+			j = 0;
+			while(samples > 0) {
+				const uint32_t n = local_min(samples, nbuffer);
+				for(i = 0; i < n; i++, j++) {
+					s = input[0][j];
+					lbuffer[i] = (flac_float_t)s;
+					s = abs(s);
+					block_peak = local_max(block_peak, s);
+
+					s = input[1][j];
+					rbuffer[i] = (flac_float_t)s;
+					s = abs(s);
+					block_peak = local_max(block_peak, s);
+				}
+				samples -= n;
+				if(AnalyzeSamples(lbuffer, rbuffer, n, 2) != GAIN_ANALYSIS_OK)
+					return false;
+			}
+		}
+		else {
+			j = 0;
+			while(samples > 0) {
+				const uint32_t n = local_min(samples, nbuffer);
+				for(i = 0; i < n; i++, j++) {
+					s = input[0][j];
+					lbuffer[i] = (flac_float_t)s;
+					s = abs(s);
+					block_peak = local_max(block_peak, s);
+				}
+				samples -= n;
+				if(AnalyzeSamples(lbuffer, 0, n, 1) != GAIN_ANALYSIS_OK)
+					return false;
+			}
+		}
+	}
+	else {
+		const double scale = (
+			(bps > 16)?
+				(double)1. / (double)(1u << (bps - 16)) :
+				(double)(1u << (16 - bps))
+		);
+
+		if(is_stereo) {
+			j = 0;
+			while(samples > 0) {
+				const uint32_t n = local_min(samples, nbuffer);
+				for(i = 0; i < n; i++, j++) {
+					s = input[0][j];
+					lbuffer[i] = (flac_float_t)(scale * (double)s);
+					s = abs32(s);
+					block_peak = local_max(block_peak, s);
+
+					s = input[1][j];
+					rbuffer[i] = (flac_float_t)(scale * (double)s);
+					s = abs32(s);
+					block_peak = local_max(block_peak, s);
+				}
+				samples -= n;
+				if(AnalyzeSamples(lbuffer, rbuffer, n, 2) != GAIN_ANALYSIS_OK)
+					return false;
+			}
+		}
+		else {
+			j = 0;
+			while(samples > 0) {
+				const uint32_t n = local_min(samples, nbuffer);
+				for(i = 0; i < n; i++, j++) {
+					s = input[0][j];
+					lbuffer[i] = (flac_float_t)(scale * (double)s);
+					s = abs32(s);
+					block_peak = local_max(block_peak, s);
+				}
+				samples -= n;
+				if(AnalyzeSamples(lbuffer, 0, n, 1) != GAIN_ANALYSIS_OK)
+					return false;
+			}
+		}
+	}
+
+	{
+		const double peak_scale = (double)(1u << (bps - 1));
+		double peak = (double)block_peak / peak_scale;
+		if(peak > title_peak_)
+			title_peak_ = peak;
+		if(peak > album_peak_)
+			album_peak_ = peak;
+	}
+
+	return true;
+}
+
+void grabbag__replaygain_get_album(float *gain, float *peak)
+{
+	*gain = (float)GetAlbumGain();
+	*peak = (float)album_peak_;
+	album_peak_ = 0.0;
+}
+
+void grabbag__replaygain_get_title(float *gain, float *peak)
+{
+	*gain = (float)GetTitleGain();
+	*peak = (float)title_peak_;
+	title_peak_ = 0.0;
+}
+
+
+typedef struct {
+	uint32_t channels;
+	uint32_t bits_per_sample;
+	uint32_t sample_rate;
+	FLAC__bool error;
+} DecoderInstance;
+
+static FLAC__StreamDecoderWriteStatus write_callback_(const FLAC__StreamDecoder *decoder, const FLAC__Frame *frame, const FLAC__int32 * const buffer[], void *client_data)
+{
+	DecoderInstance *instance = (DecoderInstance*)client_data;
+	const uint32_t bits_per_sample = frame->header.bits_per_sample;
+	const uint32_t channels = frame->header.channels;
+	const uint32_t sample_rate = frame->header.sample_rate;
+	const uint32_t samples = frame->header.blocksize;
+
+	(void)decoder;
+
+	if(
+		!instance->error &&
+		(channels == 2 || channels == 1) &&
+		bits_per_sample == instance->bits_per_sample &&
+		channels == instance->channels &&
+		sample_rate == instance->sample_rate
+	) {
+		instance->error = !grabbag__replaygain_analyze(buffer, channels==2, bits_per_sample, samples);
+	}
+	else {
+		instance->error = true;
+	}
+
+	if(!instance->error)
+		return FLAC__STREAM_DECODER_WRITE_STATUS_CONTINUE;
+	else
+		return FLAC__STREAM_DECODER_WRITE_STATUS_ABORT;
+}
+
+static void metadata_callback_(const FLAC__StreamDecoder *decoder, const FLAC__StreamMetadata *metadata, void *client_data)
+{
+	DecoderInstance *instance = (DecoderInstance*)client_data;
+
+	(void)decoder;
+
+	if(metadata->type == FLAC__METADATA_TYPE_STREAMINFO) {
+		instance->bits_per_sample = metadata->data.stream_info.bits_per_sample;
+		instance->channels = metadata->data.stream_info.channels;
+		instance->sample_rate = metadata->data.stream_info.sample_rate;
+
+		if(instance->channels != 1 && instance->channels != 2) {
+			instance->error = true;
+			return;
+		}
+
+		if(!grabbag__replaygain_is_valid_sample_frequency(instance->sample_rate)) {
+			instance->error = true;
+			return;
+		}
+	}
+}
+
+static void error_callback_(const FLAC__StreamDecoder *decoder, FLAC__StreamDecoderErrorStatus status, void *client_data)
+{
+	DecoderInstance *instance = (DecoderInstance*)client_data;
+
+	(void)decoder, (void)status;
+
+	instance->error = true;
+}
+
+const char *grabbag__replaygain_analyze_file(const char *filename, float *title_gain, float *title_peak)
+{
+	DecoderInstance instance;
+	FLAC__StreamDecoder *decoder = FLAC__stream_decoder_new();
+
+	if(0 == decoder)
+		return "memory allocation error";
+
+	instance.error = false;
+
+	/* It does these three by default but lets be explicit: */
+	FLAC__stream_decoder_set_md5_checking(decoder, false);
+	FLAC__stream_decoder_set_metadata_ignore_all(decoder);
+	FLAC__stream_decoder_set_metadata_respond(decoder, FLAC__METADATA_TYPE_STREAMINFO);
+
+	if(FLAC__stream_decoder_init_file(decoder, filename, write_callback_, metadata_callback_, error_callback_, &instance) != FLAC__STREAM_DECODER_INIT_STATUS_OK) {
+		FLAC__stream_decoder_delete(decoder);
+		return "initializing decoder";
+	}
+
+	if(!FLAC__stream_decoder_process_until_end_of_stream(decoder) || instance.error) {
+		FLAC__stream_decoder_delete(decoder);
+		return "decoding file";
+	}
+
+	FLAC__stream_decoder_delete(decoder);
+
+	grabbag__replaygain_get_title(title_gain, title_peak);
+
+	return 0;
+}
+
+const char *grabbag__replaygain_store_to_vorbiscomment(FLAC__StreamMetadata *block, float album_gain, float album_peak, float title_gain, float title_peak)
+{
+	const char *error;
+
+	if(0 != (error = grabbag__replaygain_store_to_vorbiscomment_reference(block)))
+		return error;
+
+	if(0 != (error = grabbag__replaygain_store_to_vorbiscomment_title(block, title_gain, title_peak)))
+		return error;
+
+	if(0 != (error = grabbag__replaygain_store_to_vorbiscomment_album(block, album_gain, album_peak)))
+		return error;
+
+	return 0;
+}
+
+const char *grabbag__replaygain_store_to_vorbiscomment_reference(FLAC__StreamMetadata *block)
+{
+	FLAC__ASSERT(0 != block);
+	FLAC__ASSERT(block->type == FLAC__METADATA_TYPE_VORBIS_COMMENT);
+
+	if(FLAC__metadata_object_vorbiscomment_remove_entries_matching(block, (const char *)GRABBAG__REPLAYGAIN_TAG_REFERENCE_LOUDNESS) < 0)
+		return "memory allocation error";
+
+	if(!append_tag_(block, reference_format_, GRABBAG__REPLAYGAIN_TAG_REFERENCE_LOUDNESS, ReplayGainReferenceLoudness))
+		return "memory allocation error";
+
+	return 0;
+}
+
+const char *grabbag__replaygain_store_to_vorbiscomment_album(FLAC__StreamMetadata *block, float album_gain, float album_peak)
+{
+	FLAC__ASSERT(0 != block);
+	FLAC__ASSERT(block->type == FLAC__METADATA_TYPE_VORBIS_COMMENT);
+
+	if(
+		FLAC__metadata_object_vorbiscomment_remove_entries_matching(block, (const char *)GRABBAG__REPLAYGAIN_TAG_ALBUM_GAIN) < 0 ||
+		FLAC__metadata_object_vorbiscomment_remove_entries_matching(block, (const char *)GRABBAG__REPLAYGAIN_TAG_ALBUM_PEAK) < 0
+	)
+		return "memory allocation error";
+
+	if(
+		!append_tag_(block, gain_format_, GRABBAG__REPLAYGAIN_TAG_ALBUM_GAIN, album_gain) ||
+		!append_tag_(block, peak_format_, GRABBAG__REPLAYGAIN_TAG_ALBUM_PEAK, album_peak)
+	)
+		return "memory allocation error";
+
+	return 0;
+}
+
+const char *grabbag__replaygain_store_to_vorbiscomment_title(FLAC__StreamMetadata *block, float title_gain, float title_peak)
+{
+	FLAC__ASSERT(0 != block);
+	FLAC__ASSERT(block->type == FLAC__METADATA_TYPE_VORBIS_COMMENT);
+
+	if(
+		FLAC__metadata_object_vorbiscomment_remove_entries_matching(block, (const char *)GRABBAG__REPLAYGAIN_TAG_TITLE_GAIN) < 0 ||
+		FLAC__metadata_object_vorbiscomment_remove_entries_matching(block, (const char *)GRABBAG__REPLAYGAIN_TAG_TITLE_PEAK) < 0
+	)
+		return "memory allocation error";
+
+	if(
+		!append_tag_(block, gain_format_, GRABBAG__REPLAYGAIN_TAG_TITLE_GAIN, title_gain) ||
+		!append_tag_(block, peak_format_, GRABBAG__REPLAYGAIN_TAG_TITLE_PEAK, title_peak)
+	)
+		return "memory allocation error";
+
+	return 0;
+}
+
+static const char *store_to_file_pre_(const char *filename, FLAC__Metadata_Chain **chain, FLAC__StreamMetadata **block)
+{
+	FLAC__Metadata_Iterator *iterator;
+	const char *error;
+	FLAC__bool found_vc_block = false;
+
+	if(0 == (*chain = FLAC__metadata_chain_new()))
+		return "memory allocation error";
+
+	if(!FLAC__metadata_chain_read(*chain, filename)) {
+		error = FLAC__Metadata_ChainStatusString[FLAC__metadata_chain_status(*chain)];
+		FLAC__metadata_chain_delete(*chain);
+		return error;
+	}
+
+	if(0 == (iterator = FLAC__metadata_iterator_new())) {
+		FLAC__metadata_chain_delete(*chain);
+		return "memory allocation error";
+	}
+
+	FLAC__metadata_iterator_init(iterator, *chain);
+
+	do {
+		*block = FLAC__metadata_iterator_get_block(iterator);
+		if((*block)->type == FLAC__METADATA_TYPE_VORBIS_COMMENT)
+			found_vc_block = true;
+	} while(!found_vc_block && FLAC__metadata_iterator_next(iterator));
+
+	if(!found_vc_block) {
+		/* create a new block */
+		*block = FLAC__metadata_object_new(FLAC__METADATA_TYPE_VORBIS_COMMENT);
+		if(0 == *block) {
+			FLAC__metadata_chain_delete(*chain);
+			FLAC__metadata_iterator_delete(iterator);
+			return "memory allocation error";
+		}
+		while(FLAC__metadata_iterator_next(iterator))
+			;
+		if(!FLAC__metadata_iterator_insert_block_after(iterator, *block)) {
+			error = FLAC__Metadata_ChainStatusString[FLAC__metadata_chain_status(*chain)];
+			FLAC__metadata_chain_delete(*chain);
+			FLAC__metadata_iterator_delete(iterator);
+			return error;
+		}
+		/* iterator is left pointing to new block */
+		FLAC__ASSERT(FLAC__metadata_iterator_get_block(iterator) == *block);
+	}
+
+	FLAC__metadata_iterator_delete(iterator);
+
+	FLAC__ASSERT(0 != *block);
+	FLAC__ASSERT((*block)->type == FLAC__METADATA_TYPE_VORBIS_COMMENT);
+
+	return 0;
+}
+
+static const char *store_to_file_post_(const char *filename, FLAC__Metadata_Chain *chain, FLAC__bool preserve_modtime)
+{
+	struct flac_stat_s stats;
+	const FLAC__bool have_stats = get_file_stats_(filename, &stats);
+
+	(void)grabbag__file_change_stats(filename, /*read_only=*/false);
+
+	FLAC__metadata_chain_sort_padding(chain);
+	if(!FLAC__metadata_chain_write(chain, /*use_padding=*/true, preserve_modtime)) {
+		const char *error;
+		error = FLAC__Metadata_ChainStatusString[FLAC__metadata_chain_status(chain)];
+		FLAC__metadata_chain_delete(chain);
+		return error;
+	}
+
+	FLAC__metadata_chain_delete(chain);
+
+	if(have_stats)
+		set_file_stats_(filename, &stats);
+
+	return 0;
+}
+
+const char *grabbag__replaygain_store_to_file(const char *filename, float album_gain, float album_peak, float title_gain, float title_peak, FLAC__bool preserve_modtime)
+{
+	FLAC__Metadata_Chain *chain;
+	FLAC__StreamMetadata *block = NULL;
+	const char *error;
+
+	if(0 != (error = store_to_file_pre_(filename, &chain, &block)))
+		return error;
+
+	if(0 != (error = grabbag__replaygain_store_to_vorbiscomment(block, album_gain, album_peak, title_gain, title_peak))) {
+		FLAC__metadata_chain_delete(chain);
+		return error;
+	}
+
+	if(0 != (error = store_to_file_post_(filename, chain, preserve_modtime)))
+		return error;
+
+	return 0;
+}
+
+const char *grabbag__replaygain_store_to_file_reference(const char *filename, FLAC__bool preserve_modtime)
+{
+	FLAC__Metadata_Chain *chain;
+	FLAC__StreamMetadata *block = NULL;
+	const char *error;
+
+	if(0 != (error = store_to_file_pre_(filename, &chain, &block)))
+		return error;
+
+	if(0 != (error = grabbag__replaygain_store_to_vorbiscomment_reference(block))) {
+		FLAC__metadata_chain_delete(chain);
+		return error;
+	}
+
+	if(0 != (error = store_to_file_post_(filename, chain, preserve_modtime)))
+		return error;
+
+	return 0;
+}
+
+const char *grabbag__replaygain_store_to_file_album(const char *filename, float album_gain, float album_peak, FLAC__bool preserve_modtime)
+{
+	FLAC__Metadata_Chain *chain;
+	FLAC__StreamMetadata *block = NULL;
+	const char *error;
+
+	if(0 != (error = store_to_file_pre_(filename, &chain, &block)))
+		return error;
+
+	if(0 != (error = grabbag__replaygain_store_to_vorbiscomment_album(block, album_gain, album_peak))) {
+		FLAC__metadata_chain_delete(chain);
+		return error;
+	}
+
+	if(0 != (error = store_to_file_post_(filename, chain, preserve_modtime)))
+		return error;
+
+	return 0;
+}
+
+const char *grabbag__replaygain_store_to_file_title(const char *filename, float title_gain, float title_peak, FLAC__bool preserve_modtime)
+{
+	FLAC__Metadata_Chain *chain;
+	FLAC__StreamMetadata *block = NULL;
+	const char *error;
+
+	if(0 != (error = store_to_file_pre_(filename, &chain, &block)))
+		return error;
+
+	if(0 != (error = grabbag__replaygain_store_to_vorbiscomment_title(block, title_gain, title_peak))) {
+		FLAC__metadata_chain_delete(chain);
+		return error;
+	}
+
+	if(0 != (error = store_to_file_post_(filename, chain, preserve_modtime)))
+		return error;
+
+	return 0;
+}
+
+static FLAC__bool parse_double_(const FLAC__StreamMetadata_VorbisComment_Entry *entry, double *val)
+{
+	char s[32], *end;
+	const char *p, *q;
+	double v;
+
+	FLAC__ASSERT(0 != entry);
+	FLAC__ASSERT(0 != val);
+
+	p = (const char *)entry->entry;
+	q = strchr(p, '=');
+	if(0 == q)
+		return false;
+	q++;
+	safe_strncpy(s, q, local_min(sizeof(s), (size_t) (entry->length - (q-p))));
+
+	v = strtod(s, &end);
+	if(end == s)
+		return false;
+
+	*val = v;
+	return true;
+}
+
+FLAC__bool grabbag__replaygain_load_from_vorbiscomment(const FLAC__StreamMetadata *block, FLAC__bool album_mode, FLAC__bool strict, double *reference, double *gain, double *peak)
+{
+	int reference_offset, gain_offset, peak_offset;
+	char *saved_locale;
+	FLAC__bool res = true;
+
+	FLAC__ASSERT(0 != block);
+	FLAC__ASSERT(0 != reference);
+	FLAC__ASSERT(0 != gain);
+	FLAC__ASSERT(0 != peak);
+	FLAC__ASSERT(block->type == FLAC__METADATA_TYPE_VORBIS_COMMENT);
+
+	/* Default to current level until overridden by a detected tag; this
+	 * will always be true until we change replaygain_analysis.c
+	 */
+	*reference = ReplayGainReferenceLoudness;
+
+	/*
+	 * We need to save the old locale and switch to "C" because the locale
+	 * influences the behaviour of strtod and we want it a certain way.
+	 */
+	saved_locale = strdup(setlocale(LC_ALL, 0));
+	if (0 == saved_locale)
+		return false;
+	setlocale(LC_ALL, "C");
+
+	if(0 <= (reference_offset = FLAC__metadata_object_vorbiscomment_find_entry_from(block, /*offset=*/0, (const char *)GRABBAG__REPLAYGAIN_TAG_REFERENCE_LOUDNESS)))
+		(void)parse_double_(block->data.vorbis_comment.comments + reference_offset, reference);
+
+	if(0 > (gain_offset = FLAC__metadata_object_vorbiscomment_find_entry_from(block, /*offset=*/0, (const char *)(album_mode? GRABBAG__REPLAYGAIN_TAG_ALBUM_GAIN : GRABBAG__REPLAYGAIN_TAG_TITLE_GAIN))))
+		res = false;
+	if(0 > (peak_offset = FLAC__metadata_object_vorbiscomment_find_entry_from(block, /*offset=*/0, (const char *)(album_mode? GRABBAG__REPLAYGAIN_TAG_ALBUM_PEAK : GRABBAG__REPLAYGAIN_TAG_TITLE_PEAK))))
+		res = false;
+
+	if(res && !parse_double_(block->data.vorbis_comment.comments + gain_offset, gain))
+		res = false;
+	if(res && !parse_double_(block->data.vorbis_comment.comments + peak_offset, peak))
+		res = false;
+	if(res && *peak < 0.0)
+		res = false;
+
+	setlocale(LC_ALL, saved_locale);
+	free(saved_locale);
+
+	/* something failed; retry with strict */
+	if (!res && !strict)
+		res = grabbag__replaygain_load_from_vorbiscomment(block, !album_mode, /*strict=*/true, reference, gain, peak);
+
+	return res;
+}
+
+double grabbag__replaygain_compute_scale_factor(double peak, double gain, double preamp, FLAC__bool prevent_clipping)
+{
+	double scale;
+	FLAC__ASSERT(peak >= 0.0);
+ 	gain += preamp;
+	scale = (float) pow(10.0, gain * 0.05);
+	if(prevent_clipping && peak > 0.0) {
+		const double max_scale = (float)(1.0 / peak);
+		if(scale > max_scale)
+			scale = max_scale;
+	}
+	return scale;
+}