scrcpy/app/src/video_buffer.c

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#include "video_buffer.h"
#include <assert.h>
#include <libavutil/avutil.h>
#include <libavformat/avformat.h>
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#include "util/log.h"
bool
video_buffer_init(struct video_buffer *vb, bool wait_consumer) {
vb->producer_frame = av_frame_alloc();
if (!vb->producer_frame) {
goto error_0;
}
vb->pending_frame = av_frame_alloc();
if (!vb->pending_frame) {
goto error_1;
}
vb->consumer_frame = av_frame_alloc();
if (!vb->consumer_frame) {
goto error_2;
}
bool ok = sc_mutex_init(&vb->mutex);
if (!ok) {
goto error_3;
}
vb->wait_consumer = wait_consumer;
if (wait_consumer) {
ok = sc_cond_init(&vb->pending_frame_consumed_cond);
if (!ok) {
sc_mutex_destroy(&vb->mutex);
goto error_2;
}
// interrupted is not used if wait_consumer is disabled since offering
// a frame will never block
vb->interrupted = false;
}
// there is initially no frame, so consider it has already been consumed
vb->pending_frame_consumed = true;
// The callbacks must be set by the consumer via
// video_buffer_set_consumer_callbacks()
vb->cbs = NULL;
return true;
error_3:
av_frame_free(&vb->consumer_frame);
error_2:
av_frame_free(&vb->pending_frame);
error_1:
av_frame_free(&vb->producer_frame);
error_0:
return false;
}
void
video_buffer_destroy(struct video_buffer *vb) {
if (vb->wait_consumer) {
sc_cond_destroy(&vb->pending_frame_consumed_cond);
}
sc_mutex_destroy(&vb->mutex);
av_frame_free(&vb->consumer_frame);
av_frame_free(&vb->pending_frame);
av_frame_free(&vb->producer_frame);
}
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static inline void
swap_frames(AVFrame **lhs, AVFrame **rhs) {
AVFrame *tmp = *lhs;
*lhs = *rhs;
*rhs = tmp;
}
void
video_buffer_set_consumer_callbacks(struct video_buffer *vb,
const struct video_buffer_callbacks *cbs,
void *cbs_userdata) {
assert(!vb->cbs); // must be set only once
assert(cbs);
assert(cbs->on_frame_available);
vb->cbs = cbs;
vb->cbs_userdata = cbs_userdata;
}
void
video_buffer_producer_offer_frame(struct video_buffer *vb) {
assert(vb->cbs);
sc_mutex_lock(&vb->mutex);
if (vb->wait_consumer) {
// wait for the current (expired) frame to be consumed
while (!vb->pending_frame_consumed && !vb->interrupted) {
sc_cond_wait(&vb->pending_frame_consumed_cond, &vb->mutex);
}
}
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swap_frames(&vb->producer_frame, &vb->pending_frame);
bool skipped = !vb->pending_frame_consumed;
vb->pending_frame_consumed = false;
sc_mutex_unlock(&vb->mutex);
if (skipped) {
if (vb->cbs->on_frame_skipped)
vb->cbs->on_frame_skipped(vb, vb->cbs_userdata);
} else {
vb->cbs->on_frame_available(vb, vb->cbs_userdata);
}
}
const AVFrame *
video_buffer_consumer_take_frame(struct video_buffer *vb) {
sc_mutex_lock(&vb->mutex);
assert(!vb->pending_frame_consumed);
vb->pending_frame_consumed = true;
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swap_frames(&vb->consumer_frame, &vb->pending_frame);
if (vb->wait_consumer) {
// unblock video_buffer_offer_decoded_frame()
sc_cond_signal(&vb->pending_frame_consumed_cond);
}
sc_mutex_unlock(&vb->mutex);
// consumer_frame is only written from this thread, no need to lock
return vb->consumer_frame;
}
void
video_buffer_interrupt(struct video_buffer *vb) {
if (vb->wait_consumer) {
sc_mutex_lock(&vb->mutex);
vb->interrupted = true;
sc_mutex_unlock(&vb->mutex);
// wake up blocking wait
sc_cond_signal(&vb->pending_frame_consumed_cond);
}
}