scrcpy/app/src/frame_buffer.c

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#include "frame_buffer.h"
#include <assert.h>
#include <libavutil/avutil.h>
#include <libavformat/avformat.h>
#include "util/log.h"
bool
sc_frame_buffer_init(struct sc_frame_buffer *fb) {
fb->pending_frame = av_frame_alloc();
if (!fb->pending_frame) {
LOG_OOM();
return false;
}
fb->tmp_frame = av_frame_alloc();
if (!fb->tmp_frame) {
LOG_OOM();
av_frame_free(&fb->pending_frame);
return false;
}
bool ok = sc_mutex_init(&fb->mutex);
if (!ok) {
av_frame_free(&fb->pending_frame);
av_frame_free(&fb->tmp_frame);
return false;
}
// there is initially no frame, so consider it has already been consumed
fb->pending_frame_consumed = true;
return true;
}
void
sc_frame_buffer_destroy(struct sc_frame_buffer *fb) {
sc_mutex_destroy(&fb->mutex);
av_frame_free(&fb->pending_frame);
av_frame_free(&fb->tmp_frame);
}
static inline void
swap_frames(AVFrame **lhs, AVFrame **rhs) {
AVFrame *tmp = *lhs;
*lhs = *rhs;
*rhs = tmp;
}
bool
sc_frame_buffer_push(struct sc_frame_buffer *fb, const AVFrame *frame,
bool *previous_frame_skipped) {
// Use a temporary frame to preserve pending_frame in case of error.
// tmp_frame is an empty frame, no need to call av_frame_unref() beforehand.
int r = av_frame_ref(fb->tmp_frame, frame);
if (r) {
LOGE("Could not ref frame: %d", r);
return false;
}
sc_mutex_lock(&fb->mutex);
// Now that av_frame_ref() succeeded, we can replace the previous
// pending_frame
swap_frames(&fb->pending_frame, &fb->tmp_frame);
av_frame_unref(fb->tmp_frame);
if (previous_frame_skipped) {
*previous_frame_skipped = !fb->pending_frame_consumed;
}
fb->pending_frame_consumed = false;
sc_mutex_unlock(&fb->mutex);
return true;
}
void
sc_frame_buffer_consume(struct sc_frame_buffer *fb, AVFrame *dst) {
sc_mutex_lock(&fb->mutex);
assert(!fb->pending_frame_consumed);
fb->pending_frame_consumed = true;
av_frame_move_ref(dst, fb->pending_frame);
// av_frame_move_ref() resets its source frame, so no need to call
// av_frame_unref()
sc_mutex_unlock(&fb->mutex);
}