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-rw-r--r--src/player/CrossFade.cxx140
1 files changed, 140 insertions, 0 deletions
diff --git a/src/player/CrossFade.cxx b/src/player/CrossFade.cxx
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+++ b/src/player/CrossFade.cxx
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+/*
+ * Copyright (C) 2003-2015 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.
+ */
+
+#include "config.h"
+#include "CrossFade.hxx"
+#include "Chrono.hxx"
+#include "MusicChunk.hxx"
+#include "AudioFormat.hxx"
+#include "util/NumberParser.hxx"
+#include "util/Domain.hxx"
+#include "Log.hxx"
+
+#include <assert.h>
+
+static constexpr Domain cross_fade_domain("cross_fade");
+
+gcc_pure
+static float
+mixramp_interpolate(const char *ramp_list, float required_db)
+{
+ float last_db = 0, last_secs = 0;
+ bool have_last = false;
+
+ /* ramp_list is a string of pairs of dBs and seconds that describe the
+ * volume profile. Delimiters are semi-colons between pairs and spaces
+ * between the dB and seconds of a pair.
+ * The dB values must be monotonically increasing for this to work. */
+
+ while (1) {
+ /* Parse the dB value. */
+ char *endptr;
+ const float db = ParseFloat(ramp_list, &endptr);
+ if (endptr == ramp_list || *endptr != ' ')
+ break;
+
+ ramp_list = endptr + 1;
+
+ /* Parse the time. */
+ float secs = ParseFloat(ramp_list, &endptr);
+ if (endptr == ramp_list || (*endptr != ';' && *endptr != 0))
+ break;
+
+ ramp_list = endptr;
+ if (*ramp_list == ';')
+ ++ramp_list;
+
+ /* Check for exact match. */
+ if (db == required_db) {
+ return secs;
+ }
+
+ /* Save if too quiet. */
+ if (db < required_db) {
+ last_db = db;
+ last_secs = secs;
+ have_last = true;
+ continue;
+ }
+
+ /* If required db < any stored value, use the least. */
+ if (!have_last)
+ return secs;
+
+ /* Finally, interpolate linearly. */
+ secs = last_secs + (required_db - last_db) * (secs - last_secs) / (db - last_db);
+ return secs;
+ }
+
+ return -1;
+}
+
+unsigned
+CrossFadeSettings::Calculate(SignedSongTime total_time,
+ float replay_gain_db, float replay_gain_prev_db,
+ const char *mixramp_start, const char *mixramp_prev_end,
+ const AudioFormat af,
+ const AudioFormat old_format,
+ unsigned max_chunks) const
+{
+ unsigned int chunks = 0;
+ float chunks_f;
+
+ if (total_time.IsNegative() ||
+ duration < 0 || duration >= total_time.ToDoubleS() ||
+ /* we can't crossfade when the audio formats are different */
+ af != old_format)
+ return 0;
+
+ assert(duration >= 0);
+ assert(af.IsValid());
+
+ chunks_f = (float)af.GetTimeToSize() / (float)CHUNK_SIZE;
+
+ if (mixramp_delay <= 0 || !mixramp_start || !mixramp_prev_end) {
+ chunks = (chunks_f * duration + 0.5);
+ } else {
+ /* Calculate mixramp overlap. */
+ const float mixramp_overlap_current =
+ mixramp_interpolate(mixramp_start,
+ mixramp_db - replay_gain_db);
+ const float mixramp_overlap_prev =
+ mixramp_interpolate(mixramp_prev_end,
+ mixramp_db - replay_gain_prev_db);
+ const float mixramp_overlap =
+ mixramp_overlap_current + mixramp_overlap_prev;
+
+ if (mixramp_overlap_current >= 0 &&
+ mixramp_overlap_prev >= 0 &&
+ mixramp_delay <= mixramp_overlap) {
+ chunks = (chunks_f * (mixramp_overlap - mixramp_delay));
+ FormatDebug(cross_fade_domain,
+ "will overlap %d chunks, %fs", chunks,
+ mixramp_overlap - mixramp_delay);
+ }
+ }
+
+ if (chunks > max_chunks) {
+ chunks = max_chunks;
+ LogWarning(cross_fade_domain,
+ "audio_buffer_size too small for computed MixRamp overlap");
+ }
+
+ return chunks;
+}