aboutsummaryrefslogtreecommitdiffstats
path: root/src/CrossFade.cxx
diff options
context:
space:
mode:
Diffstat (limited to 'src/CrossFade.cxx')
-rw-r--r--src/CrossFade.cxx136
1 files changed, 136 insertions, 0 deletions
diff --git a/src/CrossFade.cxx b/src/CrossFade.cxx
new file mode 100644
index 000000000..fe937e4ca
--- /dev/null
+++ b/src/CrossFade.cxx
@@ -0,0 +1,136 @@
+/*
+ * Copyright (C) 2003-2013 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 "MusicChunk.hxx"
+#include "audio_format.h"
+#include "tag.h"
+
+#include <assert.h>
+#include <string.h>
+#include <stdlib.h>
+#include <glib.h>
+
+#undef G_LOG_DOMAIN
+#define G_LOG_DOMAIN "crossfade"
+
+#ifdef G_OS_WIN32
+static char *
+strtok_r(char *str, const char *delim, G_GNUC_UNUSED char **saveptr)
+{
+ return strtok(str, delim);
+}
+#endif
+
+static float mixramp_interpolate(char *ramp_list, float required_db)
+{
+ float db, secs, last_db = nan(""), last_secs = 0;
+ char *ramp_str, *save_str = NULL;
+
+ /* 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 tokens out of the input string. */
+ ramp_str = strtok_r(ramp_list, " ", &save_str);
+
+ /* Tell strtok to continue next time round. */
+ ramp_list = NULL;
+
+ /* Parse the dB value. */
+ if (NULL == ramp_str) {
+ return nan("");
+ }
+ db = (float)atof(ramp_str);
+
+ /* Parse the time. */
+ ramp_str = strtok_r(NULL, ";", &save_str);
+ if (NULL == ramp_str) {
+ return nan("");
+ }
+ secs = (float)atof(ramp_str);
+
+ /* Check for exact match. */
+ if (db == required_db) {
+ return secs;
+ }
+
+ /* Save if too quiet. */
+ if (db < required_db) {
+ last_db = db;
+ last_secs = secs;
+ continue;
+ }
+
+ /* If required db < any stored value, use the least. */
+ if (isnan(last_db)) {
+ return secs;
+ }
+
+ /* Finally, interpolate linearly. */
+ secs = last_secs + (required_db - last_db) * (secs - last_secs) / (db - last_db);
+ return secs;
+ }
+}
+
+unsigned cross_fade_calc(float duration, float total_time,
+ float mixramp_db, float mixramp_delay,
+ float replay_gain_db, float replay_gain_prev_db,
+ char *mixramp_start, char *mixramp_prev_end,
+ const struct audio_format *af,
+ const struct audio_format *old_format,
+ unsigned max_chunks)
+{
+ unsigned int chunks = 0;
+ float chunks_f;
+ float mixramp_overlap;
+
+ if (duration < 0 || duration >= total_time ||
+ /* we can't crossfade when the audio formats are different */
+ !audio_format_equals(af, old_format))
+ return 0;
+
+ assert(duration >= 0);
+ assert(audio_format_valid(af));
+
+ chunks_f = (float)audio_format_time_to_size(af) / (float)CHUNK_SIZE;
+
+ if (isnan(mixramp_delay) || !(mixramp_start) || !(mixramp_prev_end)) {
+ chunks = (chunks_f * duration + 0.5);
+ } else {
+ /* Calculate mixramp overlap. */
+ mixramp_overlap = mixramp_interpolate(mixramp_start, mixramp_db - replay_gain_db)
+ + mixramp_interpolate(mixramp_prev_end, mixramp_db - replay_gain_prev_db);
+ if (!isnan(mixramp_overlap) && (mixramp_delay <= mixramp_overlap)) {
+ chunks = (chunks_f * (mixramp_overlap - mixramp_delay));
+ g_debug("will overlap %d chunks, %fs", chunks,
+ mixramp_overlap - mixramp_delay);
+ }
+ }
+
+ if (chunks > max_chunks) {
+ chunks = max_chunks;
+ g_warning("audio_buffer_size too small for computed MixRamp overlap");
+ }
+
+ return chunks;
+}