// tutorial03.c

// A pedagogical video player that will stream through every video frame as fast as it can

// and play audio (out of sync).

//

// Code based on FFplay, Copyright (c) 2003 Fabrice Bellard,

// and a tutorial by Martin Bohme (boehme@inb.uni-luebeckREMOVETHIS.de)

// Tested on Gentoo, CVS version 5/01/07 compiled with GCC 4.1.1

// Use

//

// gcc -o tutorial03 tutorial03.c -lavformat -lavcodec -lz -lm -lswscale `sdl-config --cflags --libs`

// to build (assuming libavformat and libavcodec are correctly installed,

// and assuming you have sdl-config. Please refer to SDL docs for your installation.)

//

// Run using

// tutorial03 myvideofile.mpg

//

// to play the stream on your screen.

#include <libavcodec/avcodec.h>

#include <libavformat/avformat.h>

#include <libswscale/swscale.h>

#include <SDL.h>

#include <SDL_thread.h>

#ifdef __MINGW32__

#undef main /* Prevents SDL from overriding main() */

#endif

#include <stdio.h>

#define SDL_AUDIO_BUFFER_SIZE 1024

typedef struct PacketQueue {

} PacketQueue;

PacketQueue audioq;

int quit = 0;

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(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;

}

/**

* Dequeue

*

* @param p the PacketQueue

* @param pkt the head AVPacket

* @param block whether block the calling thread

*/

static int packet_queue_get(PacketQueue *q, AVPacket *pkt, int block)

{

AVPacketList *pkt1;

int ret;

SDL_LockMutex(q->mutex);

for(;;) {

if(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;

}

int audio_decode_frame(AVCodecContext *aCodecCtx, uint8_t *audio_buf, int buf_size) {

static AVPacket pkt;

static uint8_t *audio_pkt_data = NULL;

static int audio_pkt_size = 0;

// len1: number of bytes used to decompress

// data_size: out put buffer size

int len1, data_size;

for(;;) {

while(audio_pkt_size > 0) {

data_size = buf_size;

// @see http://dranger.com/ffmpeg/functions.html#avcodec_decode_audio2

len1 = avcodec_decode_audio2(aCodecCtx, (int16_t *)audio_buf, &data_size,

audio_pkt_data, audio_pkt_size);

if(len1 < 0) {

/* if error, skip frame */

audio_pkt_size = 0;

break;

}

audio_pkt_data += len1;

audio_pkt_size -= len1;

if(data_size <= 0) {

/* No data yet, get more frames */

continue;

}

/* We have data, return it and come back for more later */

return data_size;

}

if(pkt.data)

av_free_packet(&pkt);

if(quit) {

return -1;

}

if(packet_queue_get(&audioq, &pkt, 1) < 0) {

return -1;

}

audio_pkt_data = pkt.data;

audio_pkt_size = pkt.size;

}

}

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

AVCodecContext *aCodecCtx = (AVCodecContext *)userdata;

int len1, audio_size;

// 一次 audio_decode_frame 出来的 audio_buf_size 可能比 len 更大， memcpy 不完，

// 下次 audio_callback 继续 memcpy 剩下的数据，而不再调用 audio_decode_frame

static uint8_t audio_buf[(AVCODEC_MAX_AUDIO_FRAME_SIZE * 3) / 2];

static unsigned int audio_buf_size = 0;

static unsigned int audio_buf_index = 0;

while(len > 0) {

if(audio_buf_index >= audio_buf_size) {

/* We have already sent all our data; get more */

audio_size = audio_decode_frame(aCodecCtx, audio_buf, sizeof(audio_buf));

if(audio_size < 0) {

/* If error, output silence */

audio_buf_size = 1024; // arbitrary?

memset(audio_buf, 0, audio_buf_size);

} else {

audio_buf_size = audio_size;

}

audio_buf_index = 0;

}

len1 = audio_buf_size - audio_buf_index;

if(len1 > len)

len1 = len;

memcpy(stream, (uint8_t *)audio_buf + audio_buf_index, len1);

len -= len1;

stream += len1;

audio_buf_index += len1;

}

}

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

AVFormatContext *pFormatCtx;

int i, videoStream, audioStream;

AVCodecContext *pCodecCtx;

AVCodec *pCodec;

AVFrame *pFrame;

AVPacket packet;

int frameFinished;

float aspect_ratio;

struct SwsContext *img_convert_ctx;

AVCodecContext *aCodecCtx;

AVCodec *aCodec;

SDL_Overlay *bmp;

SDL_Surface *screen;

SDL_Rect rect;

SDL_Event event;

SDL_AudioSpec wanted_spec, spec;

if(argc < 2) {

fprintf(stderr, "Usage: test <file>\n");

exit(1);

}

// Register all formats and codecs

av_register_all();

if(SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER)) {

fprintf(stderr, "Could not initialize SDL - %s\n", SDL_GetError());

exit(1);

}

// Open video file

if(av_open_input_file(&pFormatCtx, argv[1], NULL, 0, NULL)!=0)

return -1; // Couldn't open file

// Retrieve stream information

if(av_find_stream_info(pFormatCtx)<0)

return -1; // Couldn't find stream information

// Dump information about file onto standard error

dump_format(pFormatCtx, 0, argv[1], 0);

// Find the first video stream

videoStream=-1;

audioStream=-1;

for(i=0; i<pFormatCtx->nb_streams; i++) {

if(pFormatCtx->streams[i]->codec->codec_type==CODEC_TYPE_VIDEO &&

videoStream < 0) {

videoStream=i;

}

if(pFormatCtx->streams[i]->codec->codec_type==CODEC_TYPE_AUDIO &&

audioStream < 0) {

audioStream=i;

}

}

if(videoStream==-1)

return -1; // Didn't find a video stream

if(audioStream==-1)

return -1;

aCodecCtx=pFormatCtx->streams[audioStream]->codec;

// Set audio settings from codec info

wanted_spec.freq = aCodecCtx->sample_rate;

wanted_spec.format = AUDIO_S16SYS;

wanted_spec.channels = aCodecCtx->channels;

wanted_spec.silence = 0;

wanted_spec.samples = SDL_AUDIO_BUFFER_SIZE;

wanted_spec.callback = audio_callback;

wanted_spec.userdata = aCodecCtx;

if(SDL_OpenAudio(&wanted_spec, &spec) < 0) {

fprintf(stderr, "SDL_OpenAudio: %s\n", SDL_GetError());

return -1;

}

aCodec = avcodec_find_decoder(aCodecCtx->codec_id);

if(!aCodec) {

fprintf(stderr, "Unsupported codec!\n");

return -1;

}

if (avcodec_open(aCodecCtx, aCodec) < 0) {

fprintf(stderr, "Cannot open audio codec!\n");

return -1;

}

// audio_st = pFormatCtx->streams[index]

packet_queue_init(&audioq);

SDL_PauseAudio(0);

// Get a pointer to the codec context for the video stream

pCodecCtx=pFormatCtx->streams[videoStream]->codec;

// Find the decoder for the video stream

pCodec=avcodec_find_decoder(pCodecCtx->codec_id);

if(pCodec==NULL) {

fprintf(stderr, "Unsupported codec!\n");

return -1; // Codec not found

}

// Open codec

if(avcodec_open(pCodecCtx, pCodec)<0) {

fprintf(stderr, "Cannot open video codec!\n");

return -1; // Could not open codec

}

// construct the scale context, conversing to PIX_FMT_YUV420P

img_convert_ctx = sws_getContext(pCodecCtx->width, pCodecCtx->height,pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height, PIX_FMT_YUV420P, SWS_BICUBIC, NULL, NULL, NULL);// other codes

if (img_convert_ctx == NULL) {

fprintf(stderr, "Cannot initialize the conversion context!\n");

return -1;

}

// Allocate video frame

pFrame=avcodec_alloc_frame();

// Make a screen to put our video

#ifndef __DARWIN__

screen = SDL_SetVideoMode(pCodecCtx->width, pCodecCtx->height, 0, 0);

#else

screen = SDL_SetVideoMode(pCodecCtx->width, pCodecCtx->height, 24, 0);

#endif

if(!screen) {

fprintf(stderr, "SDL: could not set video mode - exiting\n");

exit(1);

}

// Allocate a place to put our YUV image on that screen

bmp = SDL_CreateYUVOverlay(pCodecCtx->width,

pCodecCtx->height,

SDL_YV12_OVERLAY,

screen);

// Read frames and save first five frames to disk

i=0;

while(av_read_frame(pFormatCtx, &packet)>=0) {

// Is this a packet from the video stream?

if(packet.stream_index==videoStream) {

// Decode video frame

avcodec_decode_video(pCodecCtx, pFrame, &frameFinished,

packet.data, packet.size);

// Did we get a video frame?

if(frameFinished) {

SDL_LockYUVOverlay(bmp);

AVPicture pict;

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

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

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

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

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

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

// Convert the image into YUV format that SDL uses

/*

img_convert(&pict, PIX_FMT_YUV420P,

(AVPicture *)pFrame, pCodecCtx->pix_fmt,

pCodecCtx->width, pCodecCtx->height);

*/

sws_scale(img_convert_ctx, (const uint8_t * const*)pFrame->data, pFrame->linesize, 0, pCodecCtx->height, pict.data, pict.linesize);

SDL_UnlockYUVOverlay(bmp);

rect.x = 0;

rect.y = 0;

rect.w = pCodecCtx->width;

rect.h = pCodecCtx->height;

SDL_DisplayYUVOverlay(bmp, &rect);

av_free_packet(&packet);

}

} else if(packet.stream_index==audioStream) {

packet_queue_put(&audioq, &packet);

} else {

av_free_packet(&packet);

}

// Free the packet that was allocated by av_read_frame

SDL_PollEvent(&event);

switch(event.type) {

case SDL_QUIT:

quit = 1;

SDL_Quit();

exit(0);

break;

default:

break;

}

}

sws_freeContext(img_convert_ctx);

// Free the YUV frame

av_free(pFrame);

// Close the codec

avcodec_close(pCodecCtx);

// Close the video file

av_close_input_file(pFormatCtx);

return 0;

}