[FFmpeg-devel] how to use http proxy in ffmpeg-devel

[486179]

for example
avformat_alloc_output_context2(&putFmtCtx, NULL, "rtmp", "rtmp://1.1.1.1/live");
or 
avformat_open_input(&InputFmtCtx, "rtmp://1.1.1.1/live", 0, 0)


how to set http proxy? thanks