138 lines
3.8 KiB
C
138 lines
3.8 KiB
C
/*
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* Copyright (C) 2003-2011 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.h"
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#include "pcm_mix.h"
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#include "chunk.h"
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#include "audio_format.h"
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#include "tag.h"
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#include <assert.h>
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#include <string.h>
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#include <stdlib.h>
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#include <glib.h>
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#undef G_LOG_DOMAIN
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#define G_LOG_DOMAIN "crossfade"
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#ifdef G_OS_WIN32
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static char *
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strtok_r(char *str, const char *delim, G_GNUC_UNUSED char **saveptr)
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{
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return strtok(str, delim);
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}
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#endif
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static float mixramp_interpolate(char *ramp_list, float required_db)
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{
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float db, secs, last_db = nan(""), last_secs = 0;
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char *ramp_str, *save_str = NULL;
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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 tokens out of the input string. */
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ramp_str = strtok_r(ramp_list, " ", &save_str);
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/* Tell strtok to continue next time round. */
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ramp_list = NULL;
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/* Parse the dB value. */
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if (NULL == ramp_str) {
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return nan("");
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}
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db = (float)atof(ramp_str);
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/* Parse the time. */
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ramp_str = strtok_r(NULL, ";", &save_str);
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if (NULL == ramp_str) {
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return nan("");
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}
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secs = (float)atof(ramp_str);
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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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continue;
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}
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/* If required db < any stored value, use the least. */
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if (isnan(last_db)) {
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return secs;
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}
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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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}
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unsigned cross_fade_calc(float duration, float total_time,
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float mixramp_db, float mixramp_delay,
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float replay_gain_db, float replay_gain_prev_db,
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char *mixramp_start, char *mixramp_prev_end,
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const struct audio_format *af,
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const struct audio_format *old_format,
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unsigned max_chunks)
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{
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unsigned int chunks = 0;
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float chunks_f;
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float mixramp_overlap;
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if (duration < 0 || duration >= total_time ||
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/* we can't crossfade when the audio formats are different */
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!audio_format_equals(af, old_format))
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return 0;
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assert(duration >= 0);
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assert(audio_format_valid(af));
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chunks_f = (float)audio_format_time_to_size(af) / (float)CHUNK_SIZE;
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if (isnan(mixramp_delay) || !(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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mixramp_overlap = mixramp_interpolate(mixramp_start, mixramp_db - replay_gain_db)
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+ mixramp_interpolate(mixramp_prev_end, mixramp_db - replay_gain_prev_db);
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if (!isnan(mixramp_overlap) && (mixramp_delay <= mixramp_overlap)) {
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chunks = (chunks_f * (mixramp_overlap - mixramp_delay));
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g_debug("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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g_warning("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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