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/*
* Copyright 2003-2017 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 <cmath>
#include <assert.h>
static constexpr Domain cross_fade_domain("cross_fade");
gcc_pure
static FloatDuration
mixramp_interpolate(const char *ramp_list, float required_db) noexcept
{
float last_db = 0;
FloatDuration last_duration = FloatDuration::zero();
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. */
FloatDuration duration{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 duration;
}
/* Save if too quiet. */
if (db < required_db) {
last_db = db;
last_duration = duration;
have_last = true;
continue;
}
/* If required db < any stored value, use the least. */
if (!have_last)
return duration;
/* Finally, interpolate linearly. */
duration = last_duration + (required_db - last_db) * (duration - last_duration) / (db - last_db);
return duration;
}
return FloatDuration(-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 noexcept
{
unsigned int chunks = 0;
if (total_time.IsNegative() ||
duration <= FloatDuration::zero() ||
duration >= std::chrono::duration_cast<FloatDuration>(total_time) ||
/* we can't crossfade when the audio formats are different */
af != old_format)
return 0;
assert(duration > FloatDuration::zero());
assert(af.IsValid());
const auto chunk_duration =
af.SizeToTime<FloatDuration>(sizeof(MusicChunk::data));
if (mixramp_delay <= FloatDuration::zero() ||
!mixramp_start || !mixramp_prev_end) {
chunks = std::lround(duration / chunk_duration);
} else {
/* Calculate mixramp overlap. */
const auto mixramp_overlap_current =
mixramp_interpolate(mixramp_start,
mixramp_db - replay_gain_db);
const auto mixramp_overlap_prev =
mixramp_interpolate(mixramp_prev_end,
mixramp_db - replay_gain_prev_db);
const auto mixramp_overlap =
mixramp_overlap_current + mixramp_overlap_prev;
if (mixramp_overlap_current >= FloatDuration::zero() &&
mixramp_overlap_prev >= FloatDuration::zero() &&
mixramp_delay <= mixramp_overlap) {
chunks = lround((mixramp_overlap - mixramp_delay)
/ chunk_duration);
FormatDebug(cross_fade_domain,
"will overlap %d chunks, %fs", chunks,
(mixramp_overlap - mixramp_delay).count());
}
}
if (chunks > max_chunks) {
chunks = max_chunks;
LogWarning(cross_fade_domain,
"audio_buffer_size too small for computed MixRamp overlap");
}
return chunks;
}
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