（转）利用ffmpeg来进行视频解码的完整示例代码（H.264）

Decode()
{
FILE * inpf;

int nWrite;
int i,p;
int nalLen;
unsigned char* Buf;
int got_picture, consumed_bytes;
unsigned char *DisplayBuf;
DisplayBuf=(unsigned char *)malloc(60000);

char outfile[] = "test.pgm";

//1.打开输入文件
inpf = fopen("test.264", "rb");

//outf = fopen("out.yuv", "wb");

if(!inpf)
{
goto Decodereturn;
}

nalLen = 0;
Buf = (unsigned char*)calloc ( 1000000, sizeof(char)); //准备解码文件缓冲

//2.注册解码器，并且找到H264解码器
avcodec_init();
avcodec_register_all();
codec = avcodec_find_decoder(CODEC_ID_H264);

if (!codec) {
return 0;
}
//allocate codec context
//分配解码器内存
c = avcodec_alloc_context();

if(!c){
return 0;
}
//open codec
//3.打开解码器
if (avcodec_open(c, codec) < 0) {
return 0;
}

//allocate frame buffer
//分配解码器用的帧缓冲
picture = avcodec_alloc_frame();
if(!picture){
return 0;
}

rgbdatanew = (unsigned char *)malloc(sizeof(unsigned char)*(3 * width * height));

while(!feof(inpf))
{

//4.获取下一个NAL的长度,并且将NAL放入Buf
nalLen = getNextNal(inpf, Buf);

//5.对改NAL解码，解码的YUV数据存在picture中
consumed_bytes= avcodec_decode_video(c, picture, &got_picture, Buf, nalLen);

if(consumed_bytes > 0)
{

//6.将picture中的YUV数据显示或者保存到文件
p=0;
for(i=0; i<c->height; i++)
{
memcpy(DisplayBuf+p,picture->data[0] + i * picture->linesize[0], c->width);
p+=c->width;
}
for(i=0; i<c->height/2; i++)
{
memcpy(DisplayBuf+p,picture->data[1] + i * picture->linesize[1], c->width/2);
p+=c->width/2;
}
for(i=0; i<c->height/2; i++)
{
memcpy(DisplayBuf+p,picture->data[2] + i * picture->linesize[2], c->width/2);
p+=c->width/2;
}
//显示画面
DisplayVideo(DisplayBuf);
}
}

//7.关闭输入文件
if(inpf)
fclose(inpf);

Decodereturn:

//8.关闭解码器,释放解码器内存
if(c) {
avcodec_close(c);
av_free(c);
c = NULL;
}
//9.释放解码画面内存
if(picture) {
av_free(picture);
picture = NULL;
}

//10.释放解码文件缓冲
if(Buf)
{
free(Buf);
Buf = NULL;
}

free(DisplayBuf);
}