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#ifndef OUTPUT_BUFFER_XFADE_H
#define OUTPUT_BUFFER_XFADE_H
#include "os_compat.h"
#include "audio.h"
#include "pcm_utils.h"
static struct ob_chunk *get_chunk(struct iovec vec[2], size_t i);
static size_t calculate_xfade_chunks(struct iovec vec[2])
{
size_t chunks;
struct ob_chunk *c;
size_t nr;
AudioFormat *af = &ob.audio_format;
assert(pthread_equal(ob.thread, pthread_self()));
if (!ob.total_time ||
(ob.elapsed_time + ob.xfade_time) < ob.total_time ||
!isCurrentAudioFormat(af))
return ob.bpp_cur; /* too early, don't enable xfade yet */
assert(af->bits > 0);
assert(af->channels > 0);
assert(af->sampleRate > 0);
chunks = af->sampleRate * af->bits * af->channels / 8.0 / CHUNK_SIZE;
chunks = chunks * (ob.xfade_time + 0.5);
assert(chunks);
assert(ob.index->size >= ob.bpp_cur);
if (chunks > (ob.index->size - ob.bpp_cur))
chunks = ob.index->size - ob.bpp_cur;
DEBUG("calculated xfade chunks: %d\n", chunks);
nr = vec[0].iov_len + vec[1].iov_len;
if (chunks <= nr) {
c = get_chunk(vec, chunks);
assert(c);
if (c->seq != ob.seq_player) {
do {
c = get_chunk(vec, --chunks);
assert(c);
} while (chunks && c->seq == ob.seq_decoder);
assert((c = get_chunk(vec, chunks)));
assert(c->seq != ob.seq_decoder);
++chunks;
assert((c = get_chunk(vec, chunks)));
assert(c->seq == ob.seq_decoder);
}
DEBUG("adjusted xfade chunks: %d\n", chunks);
}
ob.xfade_cur = chunks;
ob.xfade_max = chunks;
assert(ob.xfade_state == XFADE_DISABLED);
ob.xfade_state = XFADE_ENABLED;
return chunks;
}
static size_t xfade_chunks_needed(struct iovec vec[2])
{
assert(pthread_equal(ob.thread, pthread_self()));
if (ob.xfade_state == XFADE_DISABLED)
return calculate_xfade_chunks(vec);
assert(ob.xfade_state == XFADE_ENABLED);
return ob.xfade_max;
}
static void xfade_mix(struct ob_chunk *a, struct ob_chunk *b)
{
assert(pthread_equal(ob.thread, pthread_self()));
assert(ob.xfade_state == XFADE_ENABLED);
assert(ob.xfade_cur <= ob.xfade_max);
assert(b);
assert(a != b);
assert(a->len <= CHUNK_SIZE);
assert(b->len <= CHUNK_SIZE);
if (b->seq == a->seq) {
/* deal with small rounding errors */
DEBUG("seq_match: %d == %d\n", a->seq, b->seq);
return;
}
/* as xfade_cur increases, b is scaled more and a is scaled less */
pcm_mix(a->data, b->data, a->len, b->len,
&ob.audio_format, ((float)ob.xfade_cur) / ob.xfade_max);
/* next time we fade more until we have nothing to fade */
if (ob.xfade_cur)
--ob.xfade_cur;
if (b->len > a->len) {
DEBUG("reassign len: %d => %d\n", a->len, b->len);
a->len = b->len;
}
b->len = 0; /* invalidate the chunk we already mixed in */
}
#endif /* OUTPUT_BUFFER_XFADE_H */
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