/* the Music Player Daemon (MPD) * Copyright (C) 2003-2007 by Warren Dukes (warren.dukes@gmail.com) * Copyright (C) 2008 Max Kellermann <max@duempel.org> * This project's homepage is: 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */ #include "crossfade.h" #include "pcm_mix.h" #include "pipe.h" #include "audio_format.h" #include "tag.h" #include <assert.h> #include <string.h> unsigned cross_fade_calc(float duration, float total_time, const struct audio_format *af, const struct audio_format *old_format, unsigned max_chunks) { unsigned int chunks; 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(af->bits > 0); assert(af->channels > 0); assert(af->sample_rate > 0); chunks = audio_format_time_to_size(af) / CHUNK_SIZE; chunks = (chunks * duration + 0.5); if (chunks > max_chunks) chunks = max_chunks; return chunks; } void cross_fade_apply(struct music_chunk *a, const struct music_chunk *b, const struct audio_format *format, unsigned int current_chunk, unsigned int num_chunks) { size_t size; assert(current_chunk <= num_chunks); if (a->tag == NULL && b->tag != NULL) /* merge the tag into the destination chunk */ a->tag = tag_dup(b->tag); size = b->length > a->length ? a->length : b->length; pcm_mix(a->data, b->data, size, format, ((float)current_chunk) / num_chunks); if (b->length > a->length) { /* the second buffer is larger than the first one: there is unmixed rest at the end. Copy it over. The output buffer API guarantees that there is enough room in a->data. */ memcpy(a->data + a->length, b->data + a->length, b->length - a->length); a->length = b->length; } }