Move frame swapping logic to frame.c

Expose frames_offer_decoded_frame() and frames_consume_rendered_frame()
so that callers are not exposed to frame swapping (between the decoding
and rendering frames) details.
This commit is contained in:
Romain Vimont 2018-02-08 19:23:24 +01:00
parent 0d7f050389
commit 629c296207
4 changed files with 58 additions and 27 deletions

View file

@ -21,24 +21,11 @@ static int read_packet(void *opaque, uint8_t *buf, int buf_size) {
// set the decoded frame as ready for rendering, and notify // set the decoded frame as ready for rendering, and notify
static void push_frame(struct decoder *decoder) { static void push_frame(struct decoder *decoder) {
struct frames *frames = decoder->frames; SDL_bool previous_frame_consumed = frames_offer_decoded_frame(decoder->frames);
mutex_lock(frames->mutex); if (!previous_frame_consumed) {
#ifndef SKIP_FRAMES // the previous EVENT_NEW_FRAME will consume this frame
// if SKIP_FRAMES is disabled, then the decoder must wait for the current return;
// frame to be consumed
while (!frames->rendering_frame_consumed) {
cond_wait(frames->rendering_frame_consumed_cond, frames->mutex);
} }
#else
if (!frames->rendering_frame_consumed) {
SDL_LogInfo(SDL_LOG_CATEGORY_RENDER, "Skip frame");
}
#endif
frames_swap(frames);
frames->rendering_frame_consumed = SDL_FALSE;
mutex_unlock(frames->mutex);
static SDL_Event new_frame_event = { static SDL_Event new_frame_event = {
.type = EVENT_NEW_FRAME, .type = EVENT_NEW_FRAME,
}; };

View file

@ -1,9 +1,14 @@
#include "frames.h" #include "frames.h"
#include <SDL2/SDL_assert.h>
#include <SDL2/SDL_log.h>
#include <SDL2/SDL_mutex.h> #include <SDL2/SDL_mutex.h>
#include <libavutil/avutil.h> #include <libavutil/avutil.h>
#include <libavformat/avformat.h> #include <libavformat/avformat.h>
#include "config.h"
#include "lockutil.h"
SDL_bool frames_init(struct frames *frames) { SDL_bool frames_init(struct frames *frames) {
if (!(frames->decoding_frame = av_frame_alloc())) { if (!(frames->decoding_frame = av_frame_alloc())) {
goto error_0; goto error_0;
@ -24,6 +29,8 @@ SDL_bool frames_init(struct frames *frames) {
} }
#endif #endif
// there is initially no rendering frame, so consider it has already been
// consumed
frames->rendering_frame_consumed = SDL_TRUE; frames->rendering_frame_consumed = SDL_TRUE;
return SDL_TRUE; return SDL_TRUE;
@ -45,8 +52,43 @@ void frames_destroy(struct frames *frames) {
av_frame_free(&frames->decoding_frame); av_frame_free(&frames->decoding_frame);
} }
void frames_swap(struct frames *frames) { static void frames_swap(struct frames *frames) {
AVFrame *tmp = frames->decoding_frame; AVFrame *tmp = frames->decoding_frame;
frames->decoding_frame = frames->rendering_frame; frames->decoding_frame = frames->rendering_frame;
frames->rendering_frame = tmp; frames->rendering_frame = tmp;
} }
SDL_bool frames_offer_decoded_frame(struct frames *frames) {
mutex_lock(frames->mutex);
SDL_bool previous_frame_consumed;
#ifndef SKIP_FRAMES
// if SKIP_FRAMES is disabled, then the decoder must wait for the current
// frame to be consumed
while (!frames->rendering_frame_consumed) {
cond_wait(frames->rendering_frame_consumed_cond, frames->mutex);
}
// by definition, we are not skipping the frames
previous_frame_consumed = SDL_TRUE;
#else
previous_frame_consumed = frames->rendering_frame_consumed;
if (!previous_frame_consumed) {
SDL_LogDebug(SDL_LOG_CATEGORY_RENDER, "Skip frame");
}
#endif
frames_swap(frames);
frames->rendering_frame_consumed = SDL_FALSE;
mutex_unlock(frames->mutex);
return previous_frame_consumed;
}
const AVFrame *frames_consume_rendered_frame(struct frames *frames) {
SDL_assert(!frames->rendering_frame_consumed);
frames->rendering_frame_consumed = SDL_TRUE;
#ifndef SKIP_FRAMES
// if SKIP_FRAMES is disabled, then notify the decoder the current frame is
// consumed, so that it may push a new one
cond_signal(frames->rendering_frame_consumed_cond);
#endif
return frames->rendering_frame;
}

View file

@ -22,6 +22,15 @@ struct frames {
SDL_bool frames_init(struct frames *frames); SDL_bool frames_init(struct frames *frames);
void frames_destroy(struct frames *frames); void frames_destroy(struct frames *frames);
void frames_swap(struct frames *frames); // set the decoder frame as ready for rendering
// this function locks frames->mutex during its execution
// returns true if the previous frame had been consumed
SDL_bool frames_offer_decoded_frame(struct frames *frames);
// mark the rendering frame as consumed and return it
// MUST be called with frames->mutex locked!!!
// the caller is expected to render the returned frame to some texture before
// unlocking frames->mutex
const AVFrame *frames_consume_rendered_frame(struct frames *frames);
#endif #endif

View file

@ -48,14 +48,7 @@ static void count_frame(void) {
static SDL_bool handle_new_frame(void) { static SDL_bool handle_new_frame(void) {
mutex_lock(frames.mutex); mutex_lock(frames.mutex);
AVFrame *frame = frames.rendering_frame; const AVFrame *frame = frames_consume_rendered_frame(&frames);
frames.rendering_frame_consumed = SDL_TRUE;
#ifndef SKIP_FRAMES
// if SKIP_FRAMES is disabled, then notify the decoder the current frame is
// consumed, so that it may push a new one
cond_signal(frames.rendering_frame_consumed_cond);
#endif
if (!screen_update(&screen, frame)){ if (!screen_update(&screen, frame)){
mutex_unlock(frames.mutex); mutex_unlock(frames.mutex);
return SDL_FALSE; return SDL_FALSE;