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刚刚接触到FFmpeg,测试第一个例子264解码,如下。
Q1:在第4步中:4.获取下一个NAL的长度,并且将NAL放入Buf,getNextNal函数的原型在哪里可以找到,包含该函数的头文件在哪里,需要用到库文件,若需要,需要哪个库文件?
搜索了好久,都没找到关于getNextNal的信息。
运行到此处,程序报告错误信息:
test.c:76: warning: implicit declaration of function ‘getNextNal’
test.c:76: undefined reference to `getNextNal'
还请大家多多帮忙。- 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;
- //准备解码文件缓冲
- Buf = (unsigned char *)calloc(100000, sizeof(char));
- //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;
- }
- //open codec
- //3.打开解码器
- if(avcodec_open(c, codec) < 0)
- {
- return 0;
- }
- //allocate codec context
- //分配解码器内存
- 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 = avcode_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.释放解码器画面内存
- if(picture)
- {
- av_free(picture);
- picture = NULL;
- }
- //10.释放解码文件缓冲
- if(Buf)
- {
- free(Buf);
- Buf = NULL;
- }
- free(DisplayBuf);
- }
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