基于FFmpeg的推流器 （simplest ffmpeg streamer）

基于FFmpeg的推流器 （simplest ffmpeg streamer）。推流器的作用就是将本地的视频数据推送至流媒体服务器。本文记录的推流器，可以将本地的 MOV / AVI / MKV / MP4 / FLV 等格式的媒体文件，通过流媒体协议（例如RTMP，HTTP，UDP，TCP，RTP等等）以直播流的形式推送出去。目前主要的推流器如下：TMP流媒体服务器（例如 Flash Media Server，Red5，Wowza等等），本文实现推流器后用相应的flash media server实现直播流播放

推流器代码如下：

1. #include <stdio.h>

2. #define __STDC_CONSTANT_MACROS

3. #ifdef _WIN32

4. //Windows

5. extern "C"

6. {

7. #include "libavformat/avformat.h"

8. #include "libavutil/mathematics.h"

9. #include "libavutil/time.h"

10. };

11. #else

12. //Linux...

13. #ifdef __cplusplus

14. extern "C"

15. {

16. #endif

17. #include <libavformat/avformat.h>

18. #include <libavutil/mathematics.h>

19. #include <libavutil/time.h>

20. #ifdef __cplusplus

21. };

22. #endif

23. #endif

24. int main(int argc, char* argv[])

25. {

26. AVOutputFormat *ofmt = NULL;

27. //Input AVFormatContext and Output AVFormatContext

28. AVFormatContext *ifmt_ctx = NULL, *ofmt_ctx = NULL;

29. AVPacket pkt;

30. const char *in_filename, *out_filename;

31. int ret, i;

32. int videoindex=-1;

33. int frame_index=0;

34. int64_t start_time=0;

35. in_filename = "dakongtou.mp4";//输入URL（Input file URL）

36. //in_filename = "shanghai03_p.h264";

37. out_filename = "rtmp://localhost/test/livestream";//输出 URL（Output URL）[RTMP]

38. av_register_all();

39. //Network

40. avformat_network_init();

41. //Input

42. if ((ret = avformat_open_input(&ifmt_ctx, in_filename, 0, 0)) < 0) {

43. printf( "Could not open input file.");

44. goto end;

45. }

46. if ((ret = avformat_find_stream_info(ifmt_ctx, 0)) < 0) {

47. printf( "Failed to retrieve input stream information");

48. goto end;

49. }

50. for(i=0; i<ifmt_ctx->nb_streams; i++)

51. if(ifmt_ctx->streams[i]->codec->codec_type==AVMEDIA_TYPE_VIDEO){

52. videoindex=i;

53. break;

54. }

55. av_dump_format(ifmt_ctx, 0, in_filename, 0);

56. //Output

57. avformat_alloc_output_context2(&ofmt_ctx, NULL, "flv", out_filename); //RTMP

58. //avformat_alloc_output_context2(&ofmt_ctx, NULL, "mpegts", out_filename);//UDP

59. if (!ofmt_ctx) {

60. printf( "Could not create output context\n");

61. ret = AVERROR_UNKNOWN;

62. goto end;

63. }

64. ofmt = ofmt_ctx->oformat;

65. for (i = 0; i < ifmt_ctx->nb_streams; i++) {

66. //Create output AVStream according to input AVStream

67. AVStream *in_stream = ifmt_ctx->streams[i];

68. AVStream *out_stream = avformat_new_stream(ofmt_ctx, in_stream->codec->codec);

69. if (!out_stream) {

70. printf( "Failed allocating output stream\n");

71. ret = AVERROR_UNKNOWN;

72. goto end;

73. }

74. //Copy the settings of AVCodecContext

75. ret = avcodec_copy_context(out_stream->codec, in_stream->codec);

76. if (ret < 0) {

77. printf( "Failed to copy context from input to output stream codec context\n");

78. goto end;

79. }

80. out_stream->codec->codec_tag = 0;

81. if (ofmt_ctx->oformat->flags & AVFMT_GLOBALHEADER)

82. out_stream->codec->flags |= CODEC_FLAG_GLOBAL_HEADER;

83. }

84. //Dump Format------------------

85. av_dump_format(ofmt_ctx, 0, out_filename, 1);

86. //Open output URL

87. if (!(ofmt->flags & AVFMT_NOFILE)) {

88. ret = avio_open(&ofmt_ctx->pb, out_filename, AVIO_FLAG_WRITE);

89. if (ret < 0) {

90. printf( "Could not open output URL '%s'", out_filename);

91. goto end;

92. }

93. }

94. //Write file header

95. ret = avformat_write_header(ofmt_ctx, NULL);

96. if (ret < 0) {

97. printf( "Error occurred when opening output URL\n");

98. goto end;

99. }

100. start_time=av_gettime();

101. while (1) {

102. AVStream *in_stream, *out_stream;

103. //Get an AVPacket

104. ret = av_read_frame(ifmt_ctx, &pkt);

105. if (ret < 0)

106. break;

107. //FIX：No PTS (Example: Raw H.264)

108. //Simple Write PTS

109. if(pkt.pts==AV_NOPTS_VALUE){

110. //Write PTS

111. AVRational time_base1=ifmt_ctx->streams[videoindex]->time_base;

112. //Duration between 2 frames (us)

113. int64_t calc_duration=(double)AV_TIME_BASE/av_q2d(ifmt_ctx->streams[videoindex]->r_frame_rate);

114. //Parameters

115. pkt.pts=(double)(frame_index*calc_duration)/(double)(av_q2d(time_base1)*AV_TIME_BASE);

116. pkt.dts=pkt.pts;

117. pkt.duration=(double)calc_duration/(double)(av_q2d(time_base1)*AV_TIME_BASE);

118. }

119. //Important:Delay

120. if(pkt.stream_index==videoindex){

121. AVRational time_base=ifmt_ctx->streams[videoindex]->time_base;

122. AVRational time_base_q={1,AV_TIME_BASE};

123. int64_t pts_time = av_rescale_q(pkt.dts, time_base, time_base_q);

124. int64_t now_time = av_gettime() - start_time;

125. if (pts_time > now_time)

126. av_usleep(pts_time - now_time);

127. }

128. in_stream = ifmt_ctx->streams[pkt.stream_index];

129. out_stream = ofmt_ctx->streams[pkt.stream_index];

131. //Convert PTS/DTS

132. pkt.pts = av_rescale_q_rnd(pkt.pts, in_stream->time_base, out_stream->time_base, (AVRounding)(AV_ROUND_NEAR_INF|AV_ROUND_PASS_MINMAX));

133. pkt.dts = av_rescale_q_rnd(pkt.dts, in_stream->time_base, out_stream->time_base, (AVRounding)(AV_ROUND_NEAR_INF|AV_ROUND_PASS_MINMAX));

134. pkt.duration = av_rescale_q(pkt.duration, in_stream->time_base, out_stream->time_base);

135. pkt.pos = -1;

136. //Print to Screen

137. if(pkt.stream_index==videoindex){

138. printf("Send %8d video frames to output URL\n",frame_index);

139. frame_index++;

140. }

141. //ret = av_write_frame(ofmt_ctx, &pkt);

142. ret = av_interleaved_write_frame(ofmt_ctx, &pkt);

143. if (ret < 0) {

144. printf( "Error muxing packet\n");

145. break;

146. }

147. av_free_packet(&pkt);

148. }

149. //Write file trailer

150. av_write_trailer(ofmt_ctx);

151. end:

152. avformat_close_input(&ifmt_ctx);

154. if (ofmt_ctx && !(ofmt->flags & AVFMT_NOFILE))

155. avio_close(ofmt_ctx->pb);

156. avformat_free_context(ofmt_ctx);

157. if (ret < 0 && ret != AVERROR_EOF) {

158. printf( "Error occurred.\n");

159. return -1;

160. }

161. return 0;

162. }

由代码中可以看出，视频源为dakongtou.mp4,推送出的url地址为rtmp://localhost/test/livestream