（转）利用ffmpeg来进行视频解码的完整示例代码（H.264）

1. Decode()
2. {
3. FILE * inpf;
5. int nWrite;
6. int i,p;
7. int nalLen;
8. unsigned char* Buf;
9. int got_picture, consumed_bytes;
10. unsigned char *DisplayBuf;
11. DisplayBuf=(unsigned char *)malloc(60000);
13. char outfile[] = "test.pgm";
15. //1.打开输入文件
16. inpf = fopen("test.264", "rb");
18. //outf = fopen("out.yuv", "wb");
20. if(!inpf)
21. {
22. goto Decodereturn;
23. }
25. nalLen = 0;
26. Buf = (unsigned char*)calloc ( 1000000,sizeof(char));//准备解码文件缓冲
28. //2.注册解码器，并且找到H264解码器
29. avcodec_init();
30. avcodec_register_all();
31. codec = avcodec_find_decoder(CODEC_ID_H264);
33. if (!codec) {
34. return 0;
35. }
36. //allocate codec context
37. //分配解码器内存
38. c = avcodec_alloc_context();
40. if(!c){
41. return 0;
42. }
43. //open codec
44. //3.打开解码器
45. if (avcodec_open(c, codec) < 0) {
46. return 0;
47. }
49. //allocate frame buffer
50. //分配解码器用的帧缓冲
51. picture = avcodec_alloc_frame();
52. if(!picture){
53. return 0;
54. }
56. rgbdatanew = (unsigned char *)malloc(sizeof(unsignedchar)*(3 * width * height));
58. while(!feof(inpf))
59. {
61. //4.获取下一个NAL的长度,并且将NAL放入Buf
62. nalLen = getNextNal(inpf, Buf);
64. //5.对改NAL解码，解码的YUV数据存在picture中
65. consumed_bytes= avcodec_decode_video(c, picture, &got_picture, Buf, nalLen);
67. if(consumed_bytes > 0)
68. {
70. //6.将picture中的YUV数据显示或者保存到文件
71. p=0;
72. for(i=0; i<c->height; i++)
73. {
74. memcpy(DisplayBuf+p,picture->data[0] + i * picture->linesize[0], c->width);
75. p+=c->width;
76. }
77. for(i=0; i<c->height/2; i++)
78. {
79. memcpy(DisplayBuf+p,picture->data[1] + i * picture->linesize[1], c->width/2);
80. p+=c->width/2;
81. }
82. for(i=0; i<c->height/2; i++)
83. {
84. memcpy(DisplayBuf+p,picture->data[2] + i * picture->linesize[2], c->width/2);
85. p+=c->width/2;
86. }
87. //显示画面
88. DisplayVideo(DisplayBuf);
89. }
90. }
92. //7.关闭输入文件
93. if(inpf)
94. fclose(inpf);
96. Decodereturn:
98. //8.关闭解码器,释放解码器内存
99. if(c) {
100. avcodec_close(c);
101. av_free(c);
102. c = NULL;
103. }
104. //9.释放解码画面内存
105. if(picture) {
106. av_free(picture);
107. picture = NULL;
108. }
110. //10.释放解码文件缓冲
111. if(Buf)
112. {
113. free(Buf);
114. Buf = NULL;
115. }
117. free(DisplayBuf);
118. }