// tutorial07.c
// A pedagogical video player that really works!
//
// Code based on FFplay, Copyright (c) 2003 Fabrice Bellard,
// and a tutorial by Martin Bohme (boehme@inb.uni-luebeckREMOVETHIS.de)
// and another tutorial by Stephen Dranger (dranger at gmail dot com)
// Tested on Gentoo, CVS version 5/01/07 compiled with GCC 4.1.1
// Use
//
// gcc -o tutorial07 tutorial07.c -lavformat -lavcodec -lswscale -lz -lm `sdl-config --cflags --libs`
// to build (assuming libavformat and libavcodec and libswscale are correctly installed,
// and assuming you have sdl-config. Please refer to SDL docs for your installation.)
//
// Run using
// tutorial07 myvideofile.mpg
//
// to play the video.

#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libavformat/avio.h>
#include <libswscale/swscale.h>
#include <libavutil/avstring.h>
#include <libavutil/mathematics.h>

#include <SDL/SDL.h>
#include <SDL/SDL_thread.h>

#ifdef __MINGW32__
#undef main /* Prevents SDL from overriding main() */
#endif

#include <stdio.h>
#include <math.h>

#define SDL_AUDIO_BUFFER_SIZE 1024

#define MAX_AUDIOQ_SIZE (5 * 16 * 1024)
#define MAX_VIDEOQ_SIZE (5 * 256 * 1024)

#define AV_SYNC_THRESHOLD 0.01
#define AV_NOSYNC_THRESHOLD 10.0

#define SAMPLE_CORRECTION_PERCENT_MAX 10
#define AUDIO_DIFF_AVG_NB 20

#define FF_ALLOC_EVENT   (SDL_USEREVENT)
#define FF_REFRESH_EVENT (SDL_USEREVENT + 1)
#define FF_QUIT_EVENT (SDL_USEREVENT + 2)

#define VIDEO_PICTURE_QUEUE_SIZE 1

#define DEFAULT_AV_SYNC_TYPE AV_SYNC_VIDEO_MASTER

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

typedef struct VideoPicture {
	SDL_Overlay *bmp;
	int width, height; /* source height & width */
	int allocated;
	double pts;
} VideoPicture;

typedef struct VideoState {

	AVFormatContext *pFormatCtx; /*格式化上下文*/
	int videoStream, audioStream;

	int av_sync_type;
	double external_clock; /* external clock base */
	int64_t external_clock_time;

	int seek_req;
	int seek_flags;
	int64_t seek_pos;

	double audio_clock;
	AVStream *audio_st;
	PacketQueue audioq;
	uint8_t audio_buf[(AVCODEC_MAX_AUDIO_FRAME_SIZE * 3) / 2];
	unsigned int audio_buf_size;
	unsigned int audio_buf_index;
	AVPacket audio_pkt;
	uint8_t *audio_pkt_data;
	int audio_pkt_size;
	AVFrame audio_frame;
	AVStream *video_st;
	PacketQueue videoq;
	int audio_hw_buf_size;
	double audio_diff_cum; /* used for AV difference average computation */
	double audio_diff_avg_coef;
	double audio_diff_threshold;
	int audio_diff_avg_count;
	double frame_timer;
	double frame_last_pts;
	double frame_last_delay;

	double video_current_pts; ///<current displayed pts (different from video_clock if frame fifos are used)
	int64_t video_current_pts_time; ///<time (av_gettime) at which we updated video_current_pts - used to have running video pts

	double video_clock; ///<pts of last decoded frame / predicted pts of next decoded frame

	VideoPicture pictq[VIDEO_PICTURE_QUEUE_SIZE];
	int pictq_size, pictq_rindex, pictq_windex;
	SDL_mutex *pictq_mutex;
	SDL_cond *pictq_cond;

	SDL_Thread *parse_tid;
	SDL_Thread *video_tid;

	AVIOContext *io_ctx;
	struct SwsContext *sws_ctx;

	char filename[1024];
	int quit;
} VideoState;

enum {
	AV_SYNC_AUDIO_MASTER, AV_SYNC_VIDEO_MASTER, AV_SYNC_EXTERNAL_MASTER,
};

SDL_Surface *screen;

/* Since we only have one decoding thread, the Big Struct
 can be global in case we need it. */
VideoState *global_video_state;

AVPacket flush_pkt;

void packet_queue_init(PacketQueue *q) {
	memset(q, 0, sizeof(PacketQueue));
	q->mutex = SDL_CreateMutex();
	q->cond = SDL_CreateCond();
}
int packet_queue_put(PacketQueue *q, AVPacket *pkt) {

	AVPacketList *pkt1;
	if (pkt != &flush_pkt && av_dup_packet(pkt) < 0) {
		return -1;
	}
	pkt1 = av_malloc(sizeof(AVPacketList));
	if (!pkt1)
		return -1;
	pkt1->pkt = *pkt;
	pkt1->next = NULL;

	SDL_LockMutex(q->mutex);

	if (!q->last_pkt)
		q->first_pkt = pkt1;
	else
		q->last_pkt->next = pkt1;
	q->last_pkt = pkt1;
	q->nb_packets++;
	q->size += pkt1->pkt.size;
	SDL_CondSignal(q->cond);

	SDL_UnlockMutex(q->mutex);
	return 0;
}
static int packet_queue_get(PacketQueue *q, AVPacket *pkt, int block) {
	AVPacketList *pkt1;
	int ret;

	SDL_LockMutex(q->mutex);

	for (;;) {

		if (global_video_state->quit) {
			ret = -1;
			break;
		}

		pkt1 = q->first_pkt;
		if (pkt1) {
			q->first_pkt = pkt1->next;
			if (!q->first_pkt)
				q->last_pkt = NULL;
			q->nb_packets--;
			q->size -= pkt1->pkt.size;
			*pkt = pkt1->pkt;
			av_free(pkt1);
			ret = 1;
			break;
		} else if (!block) {
			ret = 0;
			break;
		} else {
			SDL_CondWait(q->cond, q->mutex);
		}
	}
	SDL_UnlockMutex(q->mutex);
	return ret;
}

static void packet_queue_flush(PacketQueue *q) {
	AVPacketList *pkt, *pkt1;

	SDL_LockMutex(q->mutex);
	for (pkt = q->first_pkt; pkt != NULL; pkt = pkt1) {
		pkt1 = pkt->next;
		av_free_packet(&pkt->pkt);
		av_freep(&pkt);
	}
	q->last_pkt = NULL;
	q->first_pkt = NULL;
	q->nb_packets = 0;
	q->size = 0;
	SDL_UnlockMutex(q->mutex);
}

double get_audio_clock(VideoState *is) {
	double pts;
	int hw_buf_size, bytes_per_sec, n;

	pts = is->audio_clock; /* maintained in the audio thread */
	hw_buf_size = is->audio_buf_size - is->audio_buf_index;
	bytes_per_sec = 0;
	n = is->audio_st->codec->channels * 2;
	if (is->audio_st) {
		bytes_per_sec = is->audio_st->codec->sample_rate * n;
	}
	if (bytes_per_sec) {
		pts -= (double) hw_buf_size / bytes_per_sec;
	}
	return pts;
}

double get_video_clock(VideoState *is) {
	double delta;

	delta = (av_gettime() - is->video_current_pts_time) / 1000000.0;
	return is->video_current_pts + delta;
}
double get_external_clock(VideoState *is) {
	return av_gettime() / 1000000.0;
}

double get_master_clock(VideoState *is) {
	if (is->av_sync_type == AV_SYNC_VIDEO_MASTER) {
		return get_video_clock(is);
	} else if (is->av_sync_type == AV_SYNC_AUDIO_MASTER) {
		return get_audio_clock(is);
	} else {
		return get_external_clock(is);
	}
}
/* Add or subtract samples to get a better sync, return new
 audio buffer size */
int synchronize_audio(VideoState *is, short *samples, int samples_size,
		double pts) {
	int n;
	double ref_clock;

	n = 2 * is->audio_st->codec->channels;

	if (is->av_sync_type != AV_SYNC_AUDIO_MASTER) {
		double diff, avg_diff;
		int wanted_size, min_size, max_size;
		//int nb_samples;

		ref_clock = get_master_clock(is);
		diff = get_audio_clock(is) - ref_clock;

		if (diff < AV_NOSYNC_THRESHOLD) {
			// accumulate the diffs
			is->audio_diff_cum = diff
					+ is->audio_diff_avg_coef * is->audio_diff_cum;
			if (is->audio_diff_avg_count < AUDIO_DIFF_AVG_NB) {
				is->audio_diff_avg_count++;
			} else {
				avg_diff = is->audio_diff_cum * (1.0 - is->audio_diff_avg_coef);
				if (fabs(avg_diff) >= is->audio_diff_threshold) {
					wanted_size = samples_size
							+ ((int) (diff * is->audio_st->codec->sample_rate)
									* n);
					min_size = samples_size
							* ((100 - SAMPLE_CORRECTION_PERCENT_MAX) / 100);
					max_size = samples_size
							* ((100 + SAMPLE_CORRECTION_PERCENT_MAX) / 100);
					if (wanted_size < min_size) {
						wanted_size = min_size;
					} else if (wanted_size > max_size) {
						wanted_size = max_size;
					}
					if (wanted_size < samples_size) {
						/* remove samples */
						samples_size = wanted_size;
					} else if (wanted_size > samples_size) {
						uint8_t *samples_end, *q;
						int nb;

						/* add samples by copying final sample*/
						nb = (samples_size - wanted_size);
						samples_end = (uint8_t *) samples + samples_size - n;
						q = samples_end + n;
						while (nb > 0) {
							memcpy(q, samples_end, n);
							q += n;
							nb -= n;
						}
						samples_size = wanted_size;
					}
				}
			}
		} else {
			/* difference is TOO big; reset diff stuff */
			is->audio_diff_avg_count = 0;
			is->audio_diff_cum = 0;
		}
	}
	return samples_size;
}

int audio_decode_frame(VideoState *is, double *pts_ptr) {

	int len1, data_size = 0, n;
	AVPacket *pkt = &is->audio_pkt;
	double pts;

	for (;;) {
		while (is->audio_pkt_size > 0) {
			int got_frame = 0;
			len1 = avcodec_decode_audio4(is->audio_st->codec, &is->audio_frame,
					&got_frame, pkt);
			if (len1 < 0) {
				/* if error, skip frame */
				is->audio_pkt_size = 0;
				break;
			}

			if (got_frame) {
				data_size = is->audio_frame.linesize[0];
				/*av_samples_get_buffer_size(NULL,
				 is->audio_st->codec->channels,
				 is->audio_frame.nb_samples,
				 is->audio_st->codec->sample_fmt, 1);*/
				memcpy(is->audio_buf, is->audio_frame.data[0], data_size);
			}

			is->audio_pkt_data += len1;
			is->audio_pkt_size -= len1;
			if (data_size <= 0) {
				/* No data yet, get more frames */
				continue;
			}

			pts = is->audio_clock;
			*pts_ptr = pts;
			n = 2 * is->audio_st->codec->channels;
			is->audio_clock += (double) data_size
					/ (double) (n * is->audio_st->codec->sample_rate);

			/* We have data, return it and come back for more later */
			return data_size;
		}
		if (pkt->data)
			av_free_packet(pkt);

		if (is->quit) {
			return -1;
		}
		/* next packet */
		if (packet_queue_get(&is->audioq, pkt, 1) < 0) {
			return -1;
		}

		if (pkt->data == flush_pkt.data) {
			avcodec_flush_buffers(is->audio_st->codec);
			continue;
		}

		is->audio_pkt_data = pkt->data;
		is->audio_pkt_size = pkt->size;

		/* if update, update the audio clock w/pts */
		if (pkt->pts != AV_NOPTS_VALUE) {
			is->audio_clock = av_q2d(is->audio_st->time_base) * pkt->pts;
		}
	}

	return 0;
}

void audio_callback(void *userdata, Uint8 *stream, int len) {

	VideoState *is = (VideoState *) userdata;
	int len1, audio_size;
	double pts;

	while (len > 0) {
		if (is->audio_buf_index >= is->audio_buf_size) {
			/* We have already sent all our data; get more */
			audio_size = audio_decode_frame(is, &pts);
			if (audio_size < 0) {
				/* If error, output silence */
				is->audio_buf_size = 1024;
				memset(is->audio_buf, 0, is->audio_buf_size);
			} else {
				audio_size = synchronize_audio(is, (int16_t *) is->audio_buf,
						audio_size, pts);
				is->audio_buf_size = audio_size;
			}
			is->audio_buf_index = 0;
		}
		len1 = is->audio_buf_size - is->audio_buf_index;
		if (len1 > len)
			len1 = len;
		memcpy(stream, (uint8_t *) is->audio_buf + is->audio_buf_index, len1);
		len -= len1;
		stream += len1;
		is->audio_buf_index += len1;
	}
}

static Uint32 sdl_refresh_timer_cb(Uint32 interval, void *opaque) {
	SDL_Event event;
	event.type = FF_REFRESH_EVENT;
	event.user.data1 = opaque;
	SDL_PushEvent(&event);
	return 0; /* 0 means stop timer */
}

/* schedule a video refresh in 'delay' ms */
static void schedule_refresh(VideoState *is, int delay) {
	SDL_AddTimer(delay, sdl_refresh_timer_cb, is);
}

void video_display(VideoState *is) {

	SDL_Rect rect;
	VideoPicture *vp;
	float aspect_ratio;
	int w, h, x, y;

	vp = &is->pictq[is->pictq_rindex];
	if (vp->bmp) {
		if (is->video_st->codec->sample_aspect_ratio.num == 0) {
			aspect_ratio = 0;
		} else {
			aspect_ratio = av_q2d(is->video_st->codec->sample_aspect_ratio)
					* is->video_st->codec->width / is->video_st->codec->height;
		}
		if (aspect_ratio <= 0.0) {
			aspect_ratio = (float) is->video_st->codec->width
					/ (float) is->video_st->codec->height;
		}
		h = screen->h;
		w = ((int) rint(h * aspect_ratio)) & -3;
		if (w > screen->w) {
			w = screen->w;
			h = ((int) rint(w / aspect_ratio)) & -3;
		}
		x = (screen->w - w) / 2;
		y = (screen->h - h) / 2;

		rect.x = x;
		rect.y = y;
		rect.w = w;
		rect.h = h;
		SDL_DisplayYUVOverlay(vp->bmp, &rect);
	}
}

void video_refresh_timer(void *userdata) {

	VideoState *is = (VideoState *) userdata;
	VideoPicture *vp;
	double actual_delay, delay, sync_threshold, ref_clock, diff;

	if (is->video_st) {
		if (is->pictq_size == 0) {
			schedule_refresh(is, 1);
		} else {

			vp = &is->pictq[is->pictq_rindex];

			is->video_current_pts = vp->pts;
			is->video_current_pts_time = av_gettime();

			delay = vp->pts - is->frame_last_pts; /* the pts from last time */
			if (delay <= 0 || delay >= 1.0) {
				/* if incorrect delay, use previous one */
				delay = is->frame_last_delay;
			}
			/* save for next time */
			is->frame_last_delay = delay;
			is->frame_last_pts = vp->pts;

			/* update delay to sync to audio */
			ref_clock = get_audio_clock(is);
			diff = vp->pts - ref_clock;

			/* update delay to sync to audio if not master source */
			if (is->av_sync_type != AV_SYNC_VIDEO_MASTER) {
				ref_clock = get_master_clock(is);
				diff = vp->pts - ref_clock;

				/* Skip or repeat the frame. Take delay into account
				 FFPlay still doesn't "know if this is the best guess." */
				sync_threshold =
						(delay > AV_SYNC_THRESHOLD) ? delay : AV_SYNC_THRESHOLD;
				if (fabs(diff) < AV_NOSYNC_THRESHOLD) {
					if (diff <= -sync_threshold) {
						delay = 0;
					} else if (diff >= sync_threshold) {
						delay = 2 * delay;
					}
				}
			}
			is->frame_timer += delay;
			/* computer the REAL delay */
			actual_delay = is->frame_timer - (av_gettime() / 1000000.0);
			if (actual_delay < 0.010) {
				/* Really it should skip the picture instead */
				actual_delay = 0.010;
			}
			schedule_refresh(is, (int) (actual_delay * 1000 + 0.5));

			/* show the picture! */
			video_display(is);

			/* update queue for next picture! */
			if (++is->pictq_rindex == VIDEO_PICTURE_QUEUE_SIZE) {
				is->pictq_rindex = 0;
			}
			SDL_LockMutex(is->pictq_mutex);
			is->pictq_size--;
			SDL_CondSignal(is->pictq_cond);
			SDL_UnlockMutex(is->pictq_mutex);
		}
	} else {
		schedule_refresh(is, 100);
	}
}

void alloc_picture(void *userdata) {

	VideoState *is = (VideoState *) userdata;
	VideoPicture *vp;

	vp = &is->pictq[is->pictq_windex];
	if (vp->bmp) {
		// we already have one make another, bigger/smaller
		SDL_FreeYUVOverlay(vp->bmp);
	}
	// Allocate a place to put our YUV image on that screen
	vp->bmp = SDL_CreateYUVOverlay(is->video_st->codec->width,
			is->video_st->codec->height, SDL_YV12_OVERLAY, screen);
	vp->width = is->video_st->codec->width;
	vp->height = is->video_st->codec->height;

	SDL_LockMutex(is->pictq_mutex);
	vp->allocated = 1;
	SDL_CondSignal(is->pictq_cond);
	SDL_UnlockMutex(is->pictq_mutex);

}

int queue_picture(VideoState *is, AVFrame *pFrame, double pts) {

	VideoPicture *vp;
	//int dst_pix_fmt;
	AVPicture pict;

	/* wait until we have space for a new pic */
	SDL_LockMutex(is->pictq_mutex);
	while (is->pictq_size >= VIDEO_PICTURE_QUEUE_SIZE && !is->quit) {
		SDL_CondWait(is->pictq_cond, is->pictq_mutex);
	}
	SDL_UnlockMutex(is->pictq_mutex);

	if (is->quit)
		return -1;

	// windex is set to 0 initially
	vp = &is->pictq[is->pictq_windex];

	/* allocate or resize the buffer! */
	if (!vp->bmp || vp->width != is->video_st->codec->width
			|| vp->height != is->video_st->codec->height) {
		SDL_Event event;

		vp->allocated = 0;
		/* we have to do it in the main thread */
		event.type = FF_ALLOC_EVENT;
		event.user.data1 = is;
		SDL_PushEvent(&event);

		/* wait until we have a picture allocated */
		SDL_LockMutex(is->pictq_mutex);
		while (!vp->allocated && !is->quit) {
			SDL_CondWait(is->pictq_cond, is->pictq_mutex);
		}
		SDL_UnlockMutex(is->pictq_mutex);
		if (is->quit) {
			return -1;
		}
	}
	/* We have a place to put our picture on the queue */
	/* If we are skipping a frame, do we set this to null
	 but still return vp->allocated = 1? */

	if (vp->bmp) {

		SDL_LockYUVOverlay(vp->bmp);

		//dst_pix_fmt = PIX_FMT_YUV420P;
		/* point pict at the queue */

		pict.data[0] = vp->bmp->pixels[0];
		pict.data[1] = vp->bmp->pixels[2];
		pict.data[2] = vp->bmp->pixels[1];

		pict.linesize[0] = vp->bmp->pitches[0];
		pict.linesize[1] = vp->bmp->pitches[2];
		pict.linesize[2] = vp->bmp->pitches[1];

		// Convert the image into YUV format that SDL uses
		sws_scale(is->sws_ctx, (const uint8_t * const *) pFrame->data,
				pFrame->linesize, 0, is->video_st->codec->height, pict.data,
				pict.linesize);

		SDL_UnlockYUVOverlay(vp->bmp);
		vp->pts = pts;

		/* now we inform our display thread that we have a pic ready */
		if (++is->pictq_windex == VIDEO_PICTURE_QUEUE_SIZE) {
			is->pictq_windex = 0;
		}
		SDL_LockMutex(is->pictq_mutex);
		is->pictq_size++;
		SDL_UnlockMutex(is->pictq_mutex);
	}
	return 0;
}

double synchronize_video(VideoState *is, AVFrame *src_frame, double pts) {

	double frame_delay;

	if (pts != 0) {
		/* if we have pts, set video clock to it */
		is->video_clock = pts;
	} else {
		/* if we aren't given a pts, set it to the clock */
		pts = is->video_clock;
	}
	/* update the video clock */
	frame_delay = av_q2d(is->video_st->codec->time_base);
	/* if we are repeating a frame, adjust clock accordingly */
	frame_delay += src_frame->repeat_pict * (frame_delay * 0.5);
	is->video_clock += frame_delay;
	return pts;
}
uint64_t global_video_pkt_pts = AV_NOPTS_VALUE;

/* These are called whenever we allocate a frame
 * buffer. We use this to store the global_pts in
 * a frame at the time it is allocated.
 */
int our_get_buffer(struct AVCodecContext *c, AVFrame *pic) {
	int ret = avcodec_default_get_buffer(c, pic);
	uint64_t *pts = av_malloc(sizeof(uint64_t));
	*pts = global_video_pkt_pts;
	pic->opaque = pts;
	return ret;
}
void our_release_buffer(struct AVCodecContext *c, AVFrame *pic) {
	if (pic)
		av_freep(&pic->opaque);
	avcodec_default_release_buffer(c, pic);
}

int video_thread(void *arg) {
	VideoState *is = (VideoState *) arg;
	AVPacket pkt1, *packet = &pkt1;
	//int len1;
	int frameFinished;
	AVFrame *pFrame;
	double pts;

	pFrame = avcodec_alloc_frame();

	for (;;) {
		if (packet_queue_get(&is->videoq, packet, 1) < 0) {
			// means we quit getting packets
			break;
		}

		pts = 0;

		// Save global pts to be stored in pFrame in first call
		global_video_pkt_pts = packet->pts;

		// Decode video frame
		//len1 =
		avcodec_decode_video2(is->video_st->codec, pFrame, &frameFinished,
				packet);

		if (packet->dts == AV_NOPTS_VALUE && pFrame->opaque
				&& *(uint64_t*) pFrame->opaque != AV_NOPTS_VALUE) {
			pts = *(uint64_t *) pFrame->opaque;
		} else if (packet->dts != AV_NOPTS_VALUE) {
			pts = packet->dts;
		} else {
			pts = 0;
		}
		pts *= av_q2d(is->video_st->time_base);

		// Did we get a video frame?
		if (frameFinished) {
			pts = synchronize_video(is, pFrame, pts);
			if (queue_picture(is, pFrame, pts) < 0) {
				break;
			}
		}
		av_free_packet(packet);
	}
	av_free(pFrame);
	return 0;
}

int stream_component_open(VideoState *is, int stream_index) {

	AVFormatContext *pFormatCtx = is->pFormatCtx;
	AVCodecContext *codecCtx;
	AVCodec *codec;
	SDL_AudioSpec wanted_spec, spec;

	if (stream_index < 0 || stream_index >= pFormatCtx->nb_streams) {
		return -1;
	}

	// Get a pointer to the codec context for the video stream
	codecCtx = pFormatCtx->streams[stream_index]->codec;

	if (codecCtx->codec_type == AVMEDIA_TYPE_AUDIO) {
		// Set audio settings from codec info
		wanted_spec.freq = codecCtx->sample_rate;
		wanted_spec.format = AUDIO_S16SYS;
		wanted_spec.channels = codecCtx->channels;
		wanted_spec.silence = 0;
		wanted_spec.samples = SDL_AUDIO_BUFFER_SIZE;
		wanted_spec.callback = audio_callback;
		wanted_spec.userdata = is;

		if (SDL_OpenAudio(&wanted_spec, &spec) < 0) {
			fprintf(stderr, "SDL_OpenAudio: %s\n", SDL_GetError());
			return -1;
		}
		is->audio_hw_buf_size = spec.size;
	}
	codec = avcodec_find_decoder(codecCtx->codec_id);
	if (!codec || (avcodec_open2(codecCtx, codec, NULL) < 0)) {
		fprintf(stderr, "Unsupported codec!\n");
		return -1;
	}

	switch (codecCtx->codec_type) {
	case AVMEDIA_TYPE_AUDIO:
		is->audioStream = stream_index;
		is->audio_st = pFormatCtx->streams[stream_index];
		is->audio_buf_size = 0;
		is->audio_buf_index = 0;

		/* averaging filter for audio sync */
		is->audio_diff_avg_coef = exp(log(0.01 / AUDIO_DIFF_AVG_NB));
		is->audio_diff_avg_count = 0;
		/* Correct audio only if larger error than this */
		is->audio_diff_threshold = 2.0 * SDL_AUDIO_BUFFER_SIZE
				/ codecCtx->sample_rate;

		memset(&is->audio_pkt, 0, sizeof(is->audio_pkt));
		packet_queue_init(&is->audioq);
		SDL_PauseAudio(0);
		break;
	case AVMEDIA_TYPE_VIDEO:
		is->videoStream = stream_index;
		is->video_st = pFormatCtx->streams[stream_index];

		is->sws_ctx = sws_getContext(is->video_st->codec->width,
				is->video_st->codec->height, is->video_st->codec->pix_fmt,
				is->video_st->codec->width, is->video_st->codec->height,
				PIX_FMT_YUV420P, SWS_FAST_BILINEAR, NULL, NULL, NULL);

		is->frame_timer = (double) av_gettime() / 1000000.0;
		is->frame_last_delay = 40e-3;
		is->video_current_pts_time = av_gettime();

		packet_queue_init(&is->videoq);
		is->video_tid = SDL_CreateThread(video_thread, is);
		codecCtx->get_buffer = our_get_buffer;
		codecCtx->release_buffer = our_release_buffer;
		break;
	default:
		break;
	}

	return 0;
}

int decode_interrupt_cb(void *opaque) {
	return (global_video_state && global_video_state->quit);
}

int decode_thread(void *arg) {

	VideoState *is = (VideoState *) arg;
	AVFormatContext *pFormatCtx = NULL;
	AVPacket pkt1, *packet = &pkt1;

	int video_index = -1;
	int audio_index = -1;
	int i;

	is->videoStream = -1;
	is->audioStream = -1;

	AVIOInterruptCB interupt_cb;

	global_video_state = is;

	// will interrupt blocking functions if we quit!
	interupt_cb.callback = decode_interrupt_cb;
	interupt_cb.opaque = is;
	if (avio_open2(&is->io_ctx, is->filename, 0, &interupt_cb, NULL)) {
		fprintf(stderr, "Cannot open I/O for %s\n", is->filename);
		return -1;
	}

	// Open video file
	if (avformat_open_input(&pFormatCtx, is->filename, NULL, NULL) != 0)
		return -1; // Couldn't open file

	is->pFormatCtx = pFormatCtx;

	// Retrieve stream information
	if (avformat_find_stream_info(pFormatCtx, NULL) < 0)
		return -1; // Couldn't find stream information

	// Dump information about file onto standard error
	av_dump_format(pFormatCtx, 0, is->filename, 0);

	// Find the first video stream

	for (i = 0; i < pFormatCtx->nb_streams; i++) {
		if (pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO
				&& video_index < 0) {
			video_index = i;
		}
		if (pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_AUDIO
				&& audio_index < 0) {
			audio_index = i;
		}
	}
	if (audio_index >= 0) {
		stream_component_open(is, audio_index);
	}
	if (video_index >= 0) {
		stream_component_open(is, video_index);
	}

	if (is->videoStream < 0 || is->audioStream < 0) {
		fprintf(stderr, "%s: could not open codecs\n", is->filename);
		goto fail;
	}

	// main decode loop

	for (;;) {
		if (is->quit) {
			break;
		}

		// seek stuff goes here
		if (is->seek_req) {
			int stream_index = -1;
			int64_t seek_target = is->seek_pos;

			if (is->videoStream >= 0)
				stream_index = is->videoStream;
			else if (is->audioStream >= 0)
				stream_index = is->audioStream;

			if (stream_index >= 0) {
				seek_target = av_rescale_q(seek_target, AV_TIME_BASE_Q,
						pFormatCtx->streams[stream_index]->time_base);
			}
			if (av_seek_frame(is->pFormatCtx, stream_index, seek_target,
					is->seek_flags) < 0) {
				fprintf(stderr, "%s: error while seeking\n",
						is->pFormatCtx->filename);
			} else {
				if (is->audioStream >= 0) {
					packet_queue_flush(&is->audioq);
					packet_queue_put(&is->audioq, &flush_pkt);
				}
				if (is->videoStream >= 0) {
					packet_queue_flush(&is->videoq);
					packet_queue_put(&is->videoq, &flush_pkt);
				}
			}
			is->seek_req = 0;
		}

		if (is->audioq.size > MAX_AUDIOQ_SIZE
				|| is->videoq.size > MAX_VIDEOQ_SIZE) {
			SDL_Delay(10);
			continue;
		}
		
		// 对文件进行重复读取
		if (av_read_frame(is->pFormatCtx, packet) < 0) {
			if (is->pFormatCtx->pb->error == 0) {
				SDL_Delay(100); /* no error; wait for user input */
				continue;
			} else {
				break;
			}
		}

		// Is this a packet from the video stream?
		if (packet->stream_index == is->videoStream) {
			packet_queue_put(&is->videoq, packet);
		} else if (packet->stream_index == is->audioStream) {
			packet_queue_put(&is->audioq, packet);
		} else {
			av_free_packet(packet);
		}
	}

	/* all done - wait for it */
	while (!is->quit) {
		SDL_Delay(100);
	}

	fail: {
		SDL_Event event;
		event.type = FF_QUIT_EVENT;
		event.user.data1 = is;
		SDL_PushEvent(&event);
	}
	return 0;
}

void stream_seek(VideoState *is, int64_t pos, int rel) {

	if (!is->seek_req) {
		is->seek_pos = pos;
		is->seek_flags = rel < 0 ? AVSEEK_FLAG_BACKWARD : 0;
		is->seek_req = 1;
	}
}

int main(int argc, char *argv[]) {

	SDL_Event event;
	//double pts;
	VideoState *is;

	is = av_mallocz(sizeof(VideoState));

	if (argc < 2) {
		fprintf(stderr, "Usage: test <file>\n");
		exit(1);
	}
	// Register all formats and codecs
	av_register_all();
	avformat_network_init();

	if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER)) {
		fprintf(stderr, "Could not initialize SDL - %s\n", SDL_GetError());
		exit(1);
	}

	// Make a screen to put our video
#ifndef __DARWIN__
	screen = SDL_SetVideoMode(640, 480, 0, 0);
#else
	screen = SDL_SetVideoMode(640, 480, 24, 0);
#endif
	if (!screen) {
		fprintf(stderr, "SDL: could not set video mode - exiting\n");
		exit(1);
	}

	av_strlcpy(is->filename, argv[1], sizeof(is->filename));

	is->pictq_mutex = SDL_CreateMutex();
	is->pictq_cond = SDL_CreateCond();

	schedule_refresh(is, 40);

	is->av_sync_type = DEFAULT_AV_SYNC_TYPE;

	is->parse_tid = SDL_CreateThread(decode_thread, is);
	if (!is->parse_tid) {
		av_free(is);
		return -1;
	}
	av_init_packet(&flush_pkt);
	flush_pkt.data = (unsigned char *) "FLUSH";
	for (;;) {
		double incr, pos;
		SDL_WaitEvent(&event);
		switch (event.type) {
		case SDL_KEYDOWN:
			switch (event.key.keysym.sym) {
			case SDLK_LEFT:
				incr = -10.0;
				goto do_seek;
			case SDLK_RIGHT:
				incr = 10.0;
				goto do_seek;
			case SDLK_UP:
				incr = 60.0;
				goto do_seek;
			case SDLK_DOWN:
				incr = -60.0;
				goto do_seek;
				do_seek: if (global_video_state) {
					pos = get_master_clock(global_video_state);
					pos += incr;
					stream_seek(global_video_state,
							(int64_t) (pos * AV_TIME_BASE), incr);
				}
				break;
			default:
				break;
			}
			break;
		case FF_QUIT_EVENT:
		case SDL_QUIT:
			SDL_CondSignal(is->audioq.cond);
			SDL_CondSignal(is->videoq.cond);
			is->quit = 1;
			SDL_Quit();
			exit(0);
			break;
		case FF_ALLOC_EVENT:
			alloc_picture(event.user.data1);
			break;
		case FF_REFRESH_EVENT:
			video_refresh_timer(event.user.data1);
			break;
		default:
			break;
		}
	}
	return 0;

}