71f0ed8b74
This eliminates some overhead, because the compiler doesn't need to consider these functions throwing.
141 lines
3.9 KiB
C++
141 lines
3.9 KiB
C++
/*
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* Copyright 2003-2017 The Music Player Daemon Project
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* http://www.musicpd.org
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#include "config.h"
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#include "CrossFade.hxx"
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#include "Chrono.hxx"
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#include "MusicChunk.hxx"
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#include "AudioFormat.hxx"
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#include "util/NumberParser.hxx"
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#include "util/Domain.hxx"
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#include "Log.hxx"
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#include <assert.h>
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static constexpr Domain cross_fade_domain("cross_fade");
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gcc_pure
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static float
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mixramp_interpolate(const char *ramp_list, float required_db) noexcept
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{
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float last_db = 0, last_secs = 0;
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bool have_last = false;
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/* ramp_list is a string of pairs of dBs and seconds that describe the
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* volume profile. Delimiters are semi-colons between pairs and spaces
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* between the dB and seconds of a pair.
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* The dB values must be monotonically increasing for this to work. */
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while (1) {
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/* Parse the dB value. */
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char *endptr;
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const float db = ParseFloat(ramp_list, &endptr);
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if (endptr == ramp_list || *endptr != ' ')
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break;
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ramp_list = endptr + 1;
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/* Parse the time. */
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float secs = ParseFloat(ramp_list, &endptr);
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if (endptr == ramp_list || (*endptr != ';' && *endptr != 0))
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break;
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ramp_list = endptr;
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if (*ramp_list == ';')
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++ramp_list;
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/* Check for exact match. */
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if (db == required_db) {
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return secs;
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}
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/* Save if too quiet. */
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if (db < required_db) {
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last_db = db;
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last_secs = secs;
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have_last = true;
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continue;
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}
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/* If required db < any stored value, use the least. */
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if (!have_last)
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return secs;
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/* Finally, interpolate linearly. */
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secs = last_secs + (required_db - last_db) * (secs - last_secs) / (db - last_db);
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return secs;
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}
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return -1;
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}
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unsigned
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CrossFadeSettings::Calculate(SignedSongTime total_time,
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float replay_gain_db, float replay_gain_prev_db,
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const char *mixramp_start, const char *mixramp_prev_end,
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const AudioFormat af,
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const AudioFormat old_format,
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unsigned max_chunks) const noexcept
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{
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unsigned int chunks = 0;
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float chunks_f;
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if (total_time.IsNegative() ||
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duration < 0 || duration >= total_time.ToDoubleS() ||
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/* we can't crossfade when the audio formats are different */
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af != old_format)
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return 0;
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assert(duration >= 0);
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assert(af.IsValid());
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chunks_f = (float)af.GetTimeToSize() / (float)CHUNK_SIZE;
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if (mixramp_delay <= 0 || !mixramp_start || !mixramp_prev_end) {
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chunks = (chunks_f * duration + 0.5);
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} else {
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/* Calculate mixramp overlap. */
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const float mixramp_overlap_current =
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mixramp_interpolate(mixramp_start,
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mixramp_db - replay_gain_db);
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const float mixramp_overlap_prev =
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mixramp_interpolate(mixramp_prev_end,
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mixramp_db - replay_gain_prev_db);
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const float mixramp_overlap =
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mixramp_overlap_current + mixramp_overlap_prev;
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if (mixramp_overlap_current >= 0 &&
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mixramp_overlap_prev >= 0 &&
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mixramp_delay <= mixramp_overlap) {
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chunks = (chunks_f * (mixramp_overlap - mixramp_delay));
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FormatDebug(cross_fade_domain,
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"will overlap %d chunks, %fs", chunks,
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mixramp_overlap - mixramp_delay);
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}
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}
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if (chunks > max_chunks) {
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chunks = max_chunks;
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LogWarning(cross_fade_domain,
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"audio_buffer_size too small for computed MixRamp overlap");
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}
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return chunks;
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}
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