ffmpeg player

ffmpeg_sample_player.c

/**
 * FFmpeg sample player
 * Related to the article at http://habrahabr.ru/blogs/video/137793/
 */
#include <stdio.h>

#include <SDL.h>

#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libswscale/swscale.h>

int main(int argc, char* argv[]) {
	if (argc < 2) {
		printf("Usage: %s filename\n", argv[0]);
		return 0;
	}
	
	// Register all available file formats and codecs
	av_register_all();
	
	int err;
	// Init SDL with video support
	err = SDL_Init(SDL_INIT_VIDEO);
	if (err < 0) {
		fprintf(stderr, "Unable to init SDL: %s\n", SDL_GetError());
		return -1;
	}
	
	// Open video file
	const char* filename = argv[1];
	AVFormatContext* format_context = NULL;
	err = avformat_open_input(&format_context, filename, NULL, NULL);
	if (err < 0) {
		fprintf(stderr, "ffmpeg: Unable to open input file\n");
		return -1;
	}
	
	// Retrieve stream information
	err = avformat_find_stream_info(format_context, NULL);
	if (err < 0) {
		fprintf(stderr, "ffmpeg: Unable to find stream info\n");
		return -1;
	}
	
	// Dump information about file onto standard error
	av_dump_format(format_context, 0, argv[1], 0);
	
	// Find the first video stream
	int video_stream;
	for (video_stream = 0; video_stream < format_context->nb_streams; ++video_stream) {
		if (format_context->streams[video_stream]->codec->codec_type == AVMEDIA_TYPE_VIDEO) {
			break;
		}
	}
	if (video_stream == format_context->nb_streams) {
		fprintf(stderr, "ffmpeg: Unable to find video stream\n");
		return -1;
	}
	
	AVCodecContext* codec_context = format_context->streams[video_stream]->codec;
	AVCodec* codec = avcodec_find_decoder(codec_context->codec_id);
	err = avcodec_open2(codec_context, codec, NULL);
	if (err < 0) {
		fprintf(stderr, "ffmpeg: Unable to open codec\n");
		return -1;
	}
	
	SDL_Surface* screen = SDL_SetVideoMode(codec_context->width, codec_context->height, 0, 0);
	if (screen == NULL) {
		fprintf(stderr, "Couldn't set video mode\n");
		return -1;
	}
	
	SDL_Overlay* bmp = SDL_CreateYUVOverlay(codec_context->width, codec_context->height,
											SDL_YV12_OVERLAY, screen);

	struct SwsContext* img_convert_context;
	img_convert_context = sws_getCachedContext(NULL,
								            	codec_context->width, codec_context->height,
												codec_context->pix_fmt,
												codec_context->width, codec_context->height,
												PIX_FMT_YUV420P, SWS_BICUBIC,
												NULL, NULL, NULL);
	if (img_convert_context == NULL) {
		fprintf(stderr, "Cannot initialize the conversion context\n");
		return -1;
	}

	AVFrame* frame = avcodec_alloc_frame();
	AVPacket packet;
	while (av_read_frame(format_context, &packet) >= 0) {
		if (packet.stream_index == video_stream) {
			// Video stream packet
			int frame_finished;
			avcodec_decode_video2(codec_context, frame, &frame_finished, &packet);
			
			if (frame_finished) {
				SDL_LockYUVOverlay(bmp);
				
				// Convert frame to YV12 pixel format for display in SDL overlay
				
				AVPicture pict;
				pict.data[0] = bmp->pixels[0];
				pict.data[1] = bmp->pixels[2];  // it's because YV12
				pict.data[2] = bmp->pixels[1];
				
				pict.linesize[0] = bmp->pitches[0];
				pict.linesize[1] = bmp->pitches[2];
				pict.linesize[2] = bmp->pitches[1];
				
				sws_scale(img_convert_context,
							frame->data, frame->linesize,
							0, codec_context->height,
							pict.data, pict.linesize);
				
				SDL_UnlockYUVOverlay(bmp);
				
				SDL_Rect rect;
				rect.x = 0;
				rect.y = 0;
				rect.w = codec_context->width;
				rect.h = codec_context->height;
				SDL_DisplayYUVOverlay(bmp, &rect);
			}
		}
		
		// Free the packet that was allocated by av_read_frame
	    av_free_packet(&packet);
	
		// Handling SDL events there
		SDL_Event event;
		if (SDL_PollEvent(&event)) {
			if (event.type == SDL_QUIT) {
				break;
			}
		}
	}
	
	sws_freeContext(img_convert_context);
	
	// Free the YUV frame
	av_free(frame);
	
	// Close the codec
	avcodec_close(codec_context);
	
	// Close the video file
	avformat_close_input(&format_context);
	
	// Quit SDL
	SDL_Quit();
	return 0;
}

ffmpeg_sample_player_2_(audio_+_sync).c

/**
 * FFmpeg sample player with audio support and syncing.
 * Compile with:
 * gcc player2.c -o player -lavutil -lavformat -lavcodec -lswscale -lz -lbz2 `/opt/SDL/bin/sdl-config --cflags --libs`
 * Related to: http://habrahabr.ru/blogs/video/138426/
 * Author: Alexey Zhuchkov (zerodivisi0n)
 * License: GPL
 */

#include <stdio.h>
#include <stdint.h>
#include <assert.h>

#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libswscale/swscale.h>

#include <SDL.h>

#define SDL_AUDIO_BUFFER_SIZE 1024
#define AUDIO_BUF_SIZE ((AVCODEC_MAX_AUDIO_FRAME_SIZE * 3) / 2)
#define MAX_AUDIO_BUF_SIZE (AVCODEC_MAX_AUDIO_FRAME_SIZE * 4)
/* no AV sync correction is done if below the AV sync threshold */
#define AV_SYNC_THRESHOLD 0.01
/* no AV correction is done if too big error */
#define AV_NOSYNC_THRESHOLD 10.0

#define FF_REFRESH_EVENT (SDL_USEREVENT + 1)

typedef struct PacketQueue {
	AVPacketList *first_pkt, *last_pkt;
	int nb_packets;
	int size;
	int eof;
	SDL_mutex* mutex;
	SDL_cond* cond;
} PacketQueue;

typedef struct RingBuffer {
	uint8_t* data;
	int size;
	int max_size;
	int rindex;  // Read position
	int windex;  // Write position
	char eof;  // EOF flag
	char lastop;  // last operation flag: 0 - read, 1 - write
	SDL_mutex* mutex;
	SDL_cond* rcond;
	SDL_cond* wcond;
} RingBuffer;

typedef struct VideoPicture {
	SDL_Surface* screen;
	SDL_Overlay* bmp;
	double pts;
	int ready;
	SDL_mutex* mutex;
	SDL_cond* cond;
} VideoPicture;

typedef struct MainContext {
	AVFormatContext *format_context;
	int quit;
	
	// Streams
	AVStream* video_stream;
	AVStream* audio_stream;
	
	// Queues
	PacketQueue videoq;
	PacketQueue audioq;
	
	struct SwsContext* sws_context;
	
	VideoPicture pict;
	RingBuffer audio_buf;
	
	double video_clock;
	double audio_clock;
	
	double frame_timer;
	double frame_last_pts;
	double frame_last_delay;
	
	// Threads
	SDL_Thread* demux_tid;
	SDL_Thread* video_decode_tid;
	SDL_Thread* audio_decode_tid;
} MainContext;

static void usage(const char* progname) {
	assert(progname != NULL);
	
	fprintf(stderr, "Usage %s movie\n", progname);
}

static void packet_queue_init(PacketQueue* q) {
	assert(q != NULL);
	
	memset(q, 0, sizeof(PacketQueue));
	q->mutex = SDL_CreateMutex();
	q->cond = SDL_CreateCond();
}

static void packet_queue_deinit(PacketQueue* q) {
	assert(q != NULL);
	assert(q->mutex != NULL);
	assert(q->cond != NULL);
	
	SDL_DestroyMutex(q->mutex);
	SDL_DestroyCond(q->cond);
}

static int packet_queue_put(PacketQueue* q, AVPacket* pkt) {
	assert(q != NULL);
	assert(pkt != NULL);
	
	// Duplicate current packet
	if (av_dup_packet(pkt) < 0) {
		return -1;
	}
	
	AVPacketList* pkt_list = av_malloc(sizeof(AVPacketList));
	if (pkt_list == NULL) {
		return -1;
	}
	
	pkt_list->pkt = *pkt;
	pkt_list->next = NULL;
	
	SDL_LockMutex(q->mutex);
	
	if (!q->eof) {
		if (q->last_pkt == NULL) {
			// It's a first packet in queue
			q->first_pkt = pkt_list;
		} else {
			// Append to the end of queue
			q->last_pkt->next = pkt_list;
		}
		q->last_pkt = pkt_list;
		q->nb_packets++;
		q->size += pkt->size;
	}
	SDL_CondSignal(q->cond);
	
	SDL_UnlockMutex(q->mutex);
	return 0;
}

static int packet_queue_get(PacketQueue* q, AVPacket* pkt, int block) {
	assert(q != NULL);
	assert(pkt != NULL);
	
	SDL_LockMutex(q->mutex);
	
	AVPacketList* pkt_list = q->first_pkt;
	if (!block && (pkt_list == NULL)) {
		SDL_UnlockMutex(q->mutex);
		return -1;
	} else {
		while ((pkt_list == NULL) && !q->eof) {
			// Wait for packets
			SDL_CondWait(q->cond, q->mutex);
			pkt_list = q->first_pkt;
		}
	}
	
	if ((pkt_list == NULL) && q->eof) {
		SDL_UnlockMutex(q->mutex);
		return -1;
	}
	
	q->first_pkt = pkt_list->next;
	if (q->first_pkt == NULL) {
		// No more packets
		q->last_pkt = NULL;
	}
	*pkt = pkt_list->pkt;
	q->nb_packets--;	
	q->size -= pkt->size;
	av_free(pkt_list);
	
	SDL_UnlockMutex(q->mutex);
	return 0;
}

static void packet_queue_eof(PacketQueue* q) {
	assert(q != NULL);
	
	SDL_LockMutex(q->mutex);
	q->eof = 1;
	SDL_CondBroadcast(q->cond);
	SDL_UnlockMutex(q->mutex);
}

int ring_buffer_init(RingBuffer* rb, int initial_size, int max_size) {
	assert(rb != NULL);
	assert((max_size <= 0) || (max_size >= initial_size));
	
	memset(rb, 0, sizeof(RingBuffer));
	
	rb->data = av_malloc(initial_size);
	if (rb->data == NULL) {
		return -1;
	}
	rb->size = initial_size;
	rb->max_size = max_size;
	rb->mutex = SDL_CreateMutex();
	rb->rcond = SDL_CreateCond();
	rb->wcond = SDL_CreateCond();
	return 0;
}

void ring_buffer_deinit(RingBuffer* rb) {
	assert(rb != NULL);
	assert(rb->mutex != NULL);
	assert(rb->rcond != NULL);
	assert(rb->wcond != NULL);
	
	SDL_DestroyMutex(rb->mutex);
	SDL_DestroyCond(rb->rcond);
	SDL_DestroyCond(rb->wcond);
}

// Returns number of bytes written
int ring_buffer_write(RingBuffer* rb, void* buffer, int len, int block) {
	assert(rb != NULL);
	assert(rb != NULL);
	
	if (len == 0) {
		return 0;
	}
	
	SDL_LockMutex(rb->mutex);
	
	if (rb->eof) {
		// Buffer ended
		SDL_UnlockMutex(rb->mutex);
		return -1;
	}
	
	uint8_t* buffer_ptr = buffer;
	while (len > 0) {
		int step;
		if ((rb->rindex < rb->windex) ||  // write forward
			((rb->rindex == rb->windex) && (rb->lastop == 0))) {  // buffer must be free
			step = rb->size - rb->windex;
		} else if (rb->rindex > rb->windex) {
			step = rb->rindex - rb->windex;
		} else if (block) {
			SDL_CondWait(rb->rcond, rb->mutex);
			if (rb->eof) {
				break;
			}
			continue;
		} else {
			break;
		}
		
		if (len < step) {
			step = len;
		}
		memcpy(rb->data + rb->windex, buffer_ptr, step);
		
		rb->windex += step;
		assert(rb->windex <= rb->size);
		if (rb->windex == rb->size) {
			rb->windex = 0;
		}
		rb->lastop = 1;
		SDL_CondSignal(rb->wcond);
		
		buffer_ptr += step;
		len -= step;
	}
	
	SDL_UnlockMutex(rb->mutex);
	return buffer_ptr - (uint8_t*)buffer;
}

// Returns number of bytes read
int ring_buffer_read(RingBuffer* rb, void* buffer, int len, int block) {
	assert(rb != NULL);
	assert(buffer != NULL);
	
	if (len == 0) {
		return 0;
	}
	
	SDL_LockMutex(rb->mutex);
	
	uint8_t* buffer_ptr = buffer;
	while (len > 0) {
		int step;
		if (rb->rindex < rb->windex) {  // write forward
			step = rb->windex - rb->rindex;
		} else if ((rb->rindex > rb->windex) ||  // read forward
				   ((rb->rindex == rb->windex) && (rb->lastop == 1))) {  // buffer must be full
			step = rb->size - rb->rindex;
		} else if (block && !rb->eof) {
			SDL_CondWait(rb->wcond, rb->mutex);
			continue;
		} else {
			break;
		}
		
		if (len < step) {
			step = len;
		}
		memcpy(buffer_ptr, rb->data + rb->rindex, step);
		
		rb->rindex += step;
		assert(rb->rindex <= rb->size);
		if (rb->rindex == rb->size) {
			rb->rindex = 0;
		}
		rb->lastop = 0;
		SDL_CondSignal(rb->rcond);
		
		buffer_ptr += step;
		len -= step;
	}
	
	int count = buffer_ptr - (uint8_t*)buffer;
	if ((count == 0) && rb->eof) {
		count = -1;
	}
	
	SDL_UnlockMutex(rb->mutex);
	return count;
}

int ring_buffer_size(RingBuffer* rb) {
	assert(rb != NULL);
	
	int size;
	SDL_LockMutex(rb->mutex);
	if (rb->rindex < rb->windex) {
		size = rb->windex - rb->rindex;
	} else {
		size = rb->size - rb->rindex + rb->windex;
	}
	SDL_UnlockMutex(rb->mutex);
	return size;
}

void ring_buffer_eof(RingBuffer* rb) {
	assert(rb != NULL);
	
	SDL_LockMutex(rb->mutex);
	rb->eof = 1;
	SDL_CondBroadcast(rb->wcond);
	SDL_UnlockMutex(rb->mutex);
}

static AVStream* open_stream(AVFormatContext* format_context, int type) {
	assert(format_context != NULL);
	
	int index;
	AVStream* stream = NULL;
	// Find stream index
	for (index = 0; index < format_context->nb_streams; ++index) {
		if (format_context->streams[index]->codec->codec_type == type) {
			stream = format_context->streams[index];
			break;
		}
	}
	if (stream == NULL) {
		// Stream index not found
		return NULL;
	}
	
	AVCodecContext* codec_context = stream->codec;
	
	// Find suitable codec
	AVCodec* codec = avcodec_find_decoder(codec_context->codec_id);
	if (codec == NULL) {
		// Codec not found
		return NULL;
	}
	if (avcodec_open2(codec_context, codec, NULL) < 0) {
		// Failed to open codec
		return NULL;
	}
	
	return stream;
}

static void close_stream(AVStream* stream) {
	assert(stream != NULL);
	
	if (stream->codec != NULL) {
		avcodec_close(stream->codec);
	}
}

static void audio_callback(void* userdata, uint8_t* stream, int len) {
	assert(userdata != NULL);
	
	MainContext* main_context = (MainContext*)userdata;
	ring_buffer_read(&main_context->audio_buf, stream, len, 1);
}

static int configure_audio(MainContext* main_context) {
	assert(main_context != NULL);
	
	AVCodecContext* codec_context = main_context->audio_stream->codec;
	
	SDL_AudioSpec wanted_spec, spec;
	// Set audio settings from codec info
    wanted_spec.freq = codec_context->sample_rate;
    wanted_spec.format = AUDIO_S16SYS;
    wanted_spec.channels = codec_context->channels;
    wanted_spec.silence = 0;
    wanted_spec.samples = SDL_AUDIO_BUFFER_SIZE;
    wanted_spec.callback = audio_callback;
    wanted_spec.userdata = main_context;
    
    if (SDL_OpenAudio(&wanted_spec, &spec) < 0) {
      fprintf(stderr, "SDL: %s\n", SDL_GetError());
      return -1;
    }

	SDL_PauseAudio(0);
	
	return 0;
}

static int open_file(MainContext* main_context, const char* filename) {
	assert(main_context != NULL);
	assert(filename != NULL);
	
	int err;

	// Open video file
	AVFormatContext* format_context = NULL;
	err = avformat_open_input(&format_context, filename, NULL, NULL);
	if (err < 0) {
		fprintf(stderr, "ffmpeg: Unable to open input file\n");
		return -1;
	}
	main_context->format_context = format_context;

	// Retrieve stream information
	err = avformat_find_stream_info(format_context, NULL);
	if (err < 0) {
		fprintf(stderr, "ffmpeg: Unable to find stream info\n");
		return -1;
	}
	
	// Dump information about file onto standard error
	av_dump_format(format_context, 0, filename, 0);
	
	// Open video and audio streams
	main_context->video_stream = open_stream(format_context, AVMEDIA_TYPE_VIDEO);
	if (main_context->video_stream == NULL) {
		fprintf(stderr, "ffmpeg: Could not open video stream\n");
		return -1;
	}
	main_context->audio_stream = open_stream(format_context, AVMEDIA_TYPE_AUDIO);
	if (main_context->audio_stream == NULL) {
		fprintf(stderr, "ffmpeg: Could not open audio stream\n");
		return -1;
	}
	
	// Create conversion context
	AVCodecContext* video_codec_context = main_context->video_stream->codec;
	main_context->sws_context = sws_getCachedContext(NULL,
													 video_codec_context->width, video_codec_context->height,
													 video_codec_context->pix_fmt,
													 video_codec_context->width, video_codec_context->height,
													 PIX_FMT_YUV420P, SWS_BICUBIC,
													 NULL, NULL, NULL);
	
	// Prepare SDL video output
	main_context->pict.screen = SDL_SetVideoMode(video_codec_context->width, video_codec_context->height, 0, 0);
	if (main_context->pict.screen == NULL) {
		fprintf(stderr, "Couldn't set video mode\n");
		return -1;
	}
	
	main_context->pict.bmp = SDL_CreateYUVOverlay(video_codec_context->width, video_codec_context->height,
												  SDL_YV12_OVERLAY, main_context->pict.screen);
	if (main_context->pict.bmp == NULL) {
		fprintf(stderr, "Couldn't create YUV overlay\n");
		return -1;
	}
	
	// Set initial timer value
	main_context->frame_timer = (double)av_gettime() / 1000000.0;
	
	return 0;
}

// Main demux loop
static int demux_thread(void* arg) {
	assert(arg != NULL);
	
	MainContext* main_context = (MainContext*)arg;
	
	int video_stream_index = main_context->video_stream->index;
	int audio_stream_index = main_context->audio_stream->index;
	AVPacket packet;
	while (av_read_frame(main_context->format_context, &packet) >= 0) {
		if (main_context->quit) {
			av_free_packet(&packet);
			break;
		}
		if (packet.stream_index == video_stream_index) {
			// Video packet
			packet_queue_put(&main_context->videoq, &packet);
		} else if (packet.stream_index == audio_stream_index) {
			// Audio packet
      		packet_queue_put(&main_context->audioq, &packet);
    	} else {
      		av_free_packet(&packet);
    	}
	}
	packet_queue_eof(&main_context->videoq);
	packet_queue_eof(&main_context->audioq);
	
	return 0;
}

double synchronize_video(MainContext* main_context, AVFrame *src_frame, double pts) {
	assert(main_context != NULL);
	assert(src_frame != NULL);
	
	AVCodecContext* video_codec_context = main_context->video_stream->codec;
	if(pts != 0) {
		/* if we have pts, set video clock to it */
		main_context->video_clock = pts;
	} else {
		/* if we aren't given a pts, set it to the clock */
		pts = main_context->video_clock;
	}
	/* update the video clock */
	double frame_delay = av_q2d(video_codec_context->time_base);
	/* if we are repeating a frame, adjust clock accordingly */
	frame_delay += src_frame->repeat_pict * (frame_delay * 0.5);
	main_context->video_clock += frame_delay;
	
	return pts;
}

static int video_decode_thread(void* arg) {
	assert(arg != NULL);
	
	MainContext* main_context = (MainContext*)arg;
	AVCodecContext* video_codec_context = main_context->video_stream->codec;
	
	AVFrame frame;
	while (!main_context->quit) {
		avcodec_get_frame_defaults(&frame);
		
		// Get packet from queue
		AVPacket pkt;
		if (packet_queue_get(&main_context->videoq, &pkt, 1) < 0) {
			// eof queue
			break;
		}
		
		int got_frame;
		int len = avcodec_decode_video2(video_codec_context, &frame, &got_frame, &pkt);
		if (len < 0) {
			av_free_packet(&pkt);
			fprintf(stderr, "Failed to decode video frame\n");
			break;
		}
		
		if (got_frame) {
			// Consider sync
			double pts = frame.pkt_dts;
			if (pts == AV_NOPTS_VALUE) {
				pts = frame.pkt_pts;
			}
			if (pts == AV_NOPTS_VALUE) {
				pts = 0;
			}
			pts *= av_q2d(main_context->video_stream->time_base);
			pts = synchronize_video(main_context, &frame, pts);
			
			// Wait until picture is released
			SDL_LockMutex(main_context->pict.mutex);
			while (main_context->pict.ready && !main_context->quit) {
				SDL_CondWait(main_context->pict.cond, main_context->pict.mutex);
			}
			SDL_UnlockMutex(main_context->pict.mutex);
			
			if (main_context->quit) {
				break;
			}
			
			SDL_Overlay* bmp = main_context->pict.bmp;
			main_context->pict.pts = pts;
			
			// Convert frame to YV12 pixel format for display in SDL overlay
			SDL_LockYUVOverlay(bmp);
			
			AVPicture pict;
			pict.data[0] = bmp->pixels[0];
			pict.data[1] = bmp->pixels[2];  // it's because YV12
			pict.data[2] = bmp->pixels[1];
			
			pict.linesize[0] = bmp->pitches[0];
			pict.linesize[1] = bmp->pitches[2];
			pict.linesize[2] = bmp->pitches[1];
			
			sws_scale(main_context->sws_context,
					  frame.data, frame.linesize,
					  0, video_codec_context->height,
					  pict.data, pict.linesize);
			
			SDL_UnlockYUVOverlay(bmp);
			
			SDL_LockMutex(main_context->pict.mutex);
			main_context->pict.ready = 1;
			SDL_CondSignal(main_context->pict.cond);
			SDL_UnlockMutex(main_context->pict.mutex);
		}
	}
	
	return 0;
}

static int audio_decode_thread(void *arg) {
	assert(arg != NULL);
	
	MainContext* main_context = (MainContext*)arg;
	AVCodecContext* audio_codec_context = main_context->audio_stream->codec;
	
	AVFrame frame;
	while (!main_context->quit) {
		avcodec_get_frame_defaults(&frame);
		
		// Get packet from queue
		AVPacket pkt;
		if (packet_queue_get(&main_context->audioq, &pkt, 1) < 0) {
			// eof queue
			break;
		}
		
		// The audio packet can contain several frames
		int got_frame;
		int len = avcodec_decode_audio4(audio_codec_context, &frame, &got_frame, &pkt);
		if (len < 0) {
			av_free_packet(&pkt);
			fprintf(stderr, "Failed to decode audio frame\n");
			break;
		}
		
		if (got_frame) {
			// Store frame
			// Get decoded buffer size
			int data_size = av_samples_get_buffer_size(NULL, audio_codec_context->channels,
														frame.nb_samples,
														audio_codec_context->sample_fmt, 1);
			
			// Obtain audio clock
			if (pkt.pts != AV_NOPTS_VALUE) {
				main_context->audio_clock = av_q2d(main_context->audio_stream->time_base) * pkt.pts;
			} else {
				/* if no pts, then compute it */
				main_context->audio_clock += (double)data_size /
										  				(audio_codec_context->channels *
														audio_codec_context->sample_rate *
														av_get_bytes_per_sample(audio_codec_context->sample_fmt));
			}
			ring_buffer_write(&main_context->audio_buf, frame.data[0], data_size, 1);
		}
		av_free_packet(&pkt);
	}
	ring_buffer_eof(&main_context->audio_buf);
	return 0;
}

static uint32_t sdl_refresh_timer(uint32_t interval, void *opaque) {
  SDL_Event event;
  event.type = FF_REFRESH_EVENT;
  event.user.data1 = opaque;
  SDL_PushEvent(&event);
  return 0;
}

static void schedule_refresh(MainContext* main_context, int delay) {
	assert(main_context != 0);
	assert(delay > 0.0);
	
	SDL_AddTimer(delay, sdl_refresh_timer, main_context);
}

static double get_audio_clock(MainContext* main_context) {
	assert(main_context != NULL);
	
	AVCodecContext* audio_codec_context = main_context->audio_stream->codec;
	double pts = main_context->audio_clock;
	
	int bytes_per_sec = audio_codec_context->sample_rate *
							audio_codec_context->channels *
							av_get_bytes_per_sample(audio_codec_context->sample_fmt);
	int buffer_size = ring_buffer_size(&main_context->audio_buf);
	
	if (bytes_per_sec != 0) {
		pts -= (double)buffer_size / bytes_per_sec;
	}
	
	return pts;
}

static void video_display(MainContext* main_context) {
	AVCodecContext* video_codec_context = main_context->video_stream->codec;
	SDL_Rect rect;
	rect.x = 0;
	rect.y = 0;
	rect.w = video_codec_context->width;
	rect.h = video_codec_context->height;
	SDL_DisplayYUVOverlay(main_context->pict.bmp, &rect);
}

static double compute_delay(MainContext* main_context) {
	double delay = main_context->pict.pts - main_context->frame_last_pts;
	if (delay <= 0.0 || delay >= 1.0) {
		// Delay incorrect - use previous one
		delay = main_context->frame_last_delay;
	}
	// Save for next time
	main_context->frame_last_pts = main_context->pict.pts;
	main_context->frame_last_delay = delay;

	// Update delay to sync to audio
	double ref_clock = get_audio_clock(main_context);
	double diff = main_context->pict.pts - ref_clock;
	double sync_threshold = FFMAX(AV_SYNC_THRESHOLD, delay);
	if (fabs(diff) < AV_NOSYNC_THRESHOLD) {
		if (diff <= -sync_threshold) {
			delay = 0;
		} else if (diff >= sync_threshold) {
			delay = 2 * delay;
		}
	}

	main_context->frame_timer += delay;
	
	double actual_delay = main_context->frame_timer - (av_gettime() / 1000000.0);
	if(actual_delay < 0.010) {
		/* Really it should skip the picture instead */
		actual_delay = 0.010;
	}
	return actual_delay;
}

static void video_refresh_timer(MainContext* main_context) {
	SDL_LockMutex(main_context->pict.mutex);
	while ((main_context->pict.ready == 0) && !main_context->quit) {
		SDL_CondWait(main_context->pict.cond, main_context->pict.mutex);
	}
	SDL_UnlockMutex(main_context->pict.mutex);
	
	if (main_context->quit) {
		return;
	}
	
	// Sync video to audio
	double delay = compute_delay(main_context);
	schedule_refresh(main_context, (int)(delay * 1000 + 0.5));
	
	// Show the picture
	video_display(main_context);
	
	SDL_LockMutex(main_context->pict.mutex);
	main_context->pict.ready = 0;
	SDL_CondSignal(main_context->pict.cond);
	SDL_UnlockMutex(main_context->pict.mutex);
}

static MainContext* allocate_context() {
	MainContext* main_context = av_mallocz(sizeof(MainContext));
	if (main_context == NULL) {
		// memory allocation failed
		return NULL;
	}
	
	packet_queue_init(&main_context->videoq);
	packet_queue_init(&main_context->audioq);
	ring_buffer_init(&main_context->audio_buf, AUDIO_BUF_SIZE, MAX_AUDIO_BUF_SIZE);
	
	main_context->pict.mutex = SDL_CreateMutex();
	main_context->pict.cond = SDL_CreateCond();
	
	return main_context;
}

static void free_context(MainContext* main_context) {
	assert(main_context != NULL);
	
	// Close streams
	close_stream(main_context->video_stream);
	close_stream(main_context->audio_stream);
	
	packet_queue_deinit(&main_context->videoq);
	packet_queue_deinit(&main_context->audioq);
	ring_buffer_deinit(&main_context->audio_buf);
	
	// Free SDL resources
	SDL_FreeSurface(main_context->pict.screen);
	SDL_FreeYUVOverlay(main_context->pict.bmp);
	
	// Close file
	if (main_context->format_context != NULL)  {
		avformat_close_input(&main_context->format_context);
	}
}

static void quit(MainContext* main_context) {
	main_context->quit = 1;
	SDL_CondBroadcast(main_context->pict.cond);
}

static void event_loop(MainContext* main_context) {
	assert(main_context != NULL);
	
	SDL_Event event;
	while (!main_context->quit) {
		SDL_WaitEvent(&event);
		switch (event.type) {
			case SDL_QUIT:
				quit(main_context);
				break;
			case FF_REFRESH_EVENT:
				video_refresh_timer(main_context);
				break;
		}
	}
}

typedef int (SDLCALL *ThreadProc)(void *);

static SDL_Thread* thread_start(ThreadProc fn, void* userdata, const char* name) {
	assert(fn != NULL);
	
	SDL_Thread* thread = SDL_CreateThread(fn, userdata);
	if (thread == NULL) {
		fprintf(stderr, "SDL: Failed to run '%s' thread - %s\n", name, SDL_GetError());
	}
	return thread;
}

static int thread_wait(SDL_Thread* tid, const char* name) {
	int status;
	SDL_WaitThread(tid, &status);
	printf("Thread '%s' finished with status %d\n", name, status);
	return status;
}

int main(int argc, char* argv[]) {
	int err;
	// Check arguments
	if (argc < 2) {
		usage(argv[0]);
		return -1;
	}
	
	// Register all available file formats and codecs
	av_register_all();
	
	// Init SDL
	err = SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER);
	if (err < 0) {
		fprintf(stderr, "SDL: %s\n", SDL_GetError());
		return -1;
	}
	
	MainContext* main_context = allocate_context();

	const char* filename = argv[1];
	err = open_file(main_context, filename);
	if (err < 0) {
		return -1;
	}
	
	configure_audio(main_context);
	
	// Run required threads
	main_context->demux_tid = thread_start(demux_thread, main_context, "demux");
	main_context->video_decode_tid = thread_start(video_decode_thread, main_context, "video_decode");
	main_context->audio_decode_tid = thread_start(audio_decode_thread, main_context, "audio_decode");
	
	// Start video refresh
	schedule_refresh(main_context, 40);

	// Start event loop
	event_loop(main_context);
	
	// Wait until all the threads will be finished
	thread_wait(main_context->demux_tid, "demux");
	thread_wait(main_context->video_decode_tid, "video_decode");
	thread_wait(main_context->audio_decode_tid, "audio_decode");
	
	// Free resources
	free_context(main_context);
	SDL_Quit();
	
	return 0;
}