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/*
* 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 "AudioFormat.hxx"
#include "Tag.hxx"
#include <cmath>
#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 (std::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 AudioFormat af,
const AudioFormat 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 */
af != old_format)
return 0;
assert(duration >= 0);
assert(af.IsValid());
chunks_f = (float)af.GetTimeToSize() / (float)CHUNK_SIZE;
if (std::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 (!std::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;
}
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