1、清理参考帧
static void frame_queue_unref_item(Frame *vp)
{
av_frame_unref(vp->frame);
avsubtitle_free(&vp->sub);
}
2、帧队列初始化
static int frame_queue_init(FrameQueue *f, PacketQueue *pktq, int max_size, int keep_last)
{
int i;
memset(f, 0, sizeof(FrameQueue));
if (!(f->mutex = SDL_CreateMutex())) {
av_log(NULL, AV_LOG_FATAL, "SDL_CreateMutex(): %s\n", SDL_GetError());
return AVERROR(ENOMEM);
}
if (!(f->cond = SDL_CreateCond())) {
av_log(NULL, AV_LOG_FATAL, "SDL_CreateCond(): %s\n", SDL_GetError());
return AVERROR(ENOMEM);
}
f->pktq = pktq;
f->max_size = FFMIN(max_size, FRAME_QUEUE_SIZE);
f->keep_last = !!keep_last;
for (i = 0; i < f->max_size; i++)
if (!(f->queue[i].frame = av_frame_alloc()))
return AVERROR(ENOMEM);
return 0;
}
3、帧队列销毁
static void frame_queue_destory(FrameQueue *f)
{
int i;
for (i = 0; i < f->max_size; i++) {
Frame *vp = &f->queue[i];
frame_queue_unref_item(vp);
av_frame_free(&vp->frame);
}
SDL_DestroyMutex(f->mutex);
SDL_DestroyCond(f->cond);
}
4、解除SDL_CondWait()的等待
static void frame_queue_signal(FrameQueue *f)
{
SDL_LockMutex(f->mutex);
SDL_CondSignal(f->cond);
SDL_UnlockMutex(f->mutex);
}
5、获取一帧数据
static Frame *frame_queue_peek(FrameQueue *f)
{
return &f->queue[(f->rindex + f->rindex_shown) % f->max_size];
}
6、获取当前帧的下一帧数据
static Frame *frame_queue_peek_next(FrameQueue *f)
{
return &f->queue[(f->rindex + f->rindex_shown + 1) % f->max_size];
}
7、获取帧队列最后一帧数据
static Frame *frame_queue_peek_last(FrameQueue *f)
{
return &f->queue[f->rindex];
}
8、等待直到有一帧数据块可写并返回该帧数据块供调用出写数据
static Frame *frame_queue_peek_writable(FrameQueue *f)
{
/* wait until we have space to put a new frame */
SDL_LockMutex(f->mutex);
while (f->size >= f->max_size &&
!f->pktq->abort_request) {
SDL_CondWait(f->cond, f->mutex);
}
SDL_UnlockMutex(f->mutex);
if (f->pktq->abort_request)
return NULL;
return &f->queue[f->windex];
}
9、等待直到有一帧数据可读取并返回该帧数据
static Frame *frame_queue_peek_readable(FrameQueue *f)
{
/* wait until we have a readable a new frame */
SDL_LockMutex(f->mutex);
while (f->size - f->rindex_shown <= 0 &&
!f->pktq->abort_request) {
SDL_CondWait(f->cond, f->mutex);
}
SDL_UnlockMutex(f->mutex);
if (f->pktq->abort_request)
return NULL;
return &f->queue[(f->rindex + f->rindex_shown) % f->max_size];
}
10、向队列添加新的帧后更新帧队列数量
static void frame_queue_push(FrameQueue *f)
{
if (++f->windex == f->max_size)
f->windex = 0;
SDL_LockMutex(f->mutex);
f->size++;
SDL_CondSignal(f->cond);
SDL_UnlockMutex(f->mutex);
}
11、跳到下一帧
static void frame_queue_next(FrameQueue *f)
{
if (f->keep_last && !f->rindex_shown) {
f->rindex_shown = 1;
return;
}
frame_queue_unref_item(&f->queue[f->rindex]);
if (++f->rindex == f->max_size)
f->rindex = 0;
SDL_LockMutex(f->mutex);
f->size--;
SDL_CondSignal(f->cond);
SDL_UnlockMutex(f->mutex);
}
12、返回帧队列中未显示的帧数
/* return the number of undisplayed frames in the queue */
static int frame_queue_nb_remaining(FrameQueue *f)
{
return f->size - f->rindex_shown;
}
13、返回最后一帧的显示位置
/* return last shown position */
static int64_t frame_queue_last_pos(FrameQueue *f)
{
Frame *fp = &f->queue[f->rindex];
if (f->rindex_shown && fp->serial == f->pktq->serial)
return fp->pos;
else
return -1;
}