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/* 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 "chunk.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(a != NULL);
assert(b != NULL);
assert(a->length == 0 || b->length == 0 ||
audio_format_equals(&a->audio_format, &b->audio_format));
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. */
#ifndef NDEBUG
if (a->length == 0)
a->audio_format = b->audio_format;
#endif
memcpy(a->data + a->length,
b->data + a->length,
b->length - a->length);
a->length = b->length;
}
}
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