本文共 6018 字，大约阅读时间需要 20 分钟。
1.命令方式
ffmpeg -f gdigrab -i desktop -vcodec libx264 -s 1280x720 -r 30 -b 1m -f flv rtmp://192.168.20.50:1935/live/desktop 2.代码方式int video_capture()
{ AVFormatContext* m_fmt_ctx = NULL; AVInputFormat* m_input_fmt = NULL; int video_stream = -1; avdevice_register_all(); avcodec_register_all(); const char* deviceName = “desktop”; const char* inputformat = “gdigrab”; int FPS = 15; m_fmt_ctx = avformat_alloc_context(); m_input_fmt = av_find_input_format(inputformat); AVDictionary* deoptions = NULL; av_dict_set_int(&deoptions, “framerate”, FPS, AV_DICT_MATCH_CASE); av_dict_set_int(&deoptions, “rtbufsize”, 3041280 * 100 *5, 0); int ret = avformat_open_input(&m_fmt_ctx, deviceName, m_input_fmt, &deoptions); if (ret != 0) { return XError(ret); } av_dict_free(&deoptions); ret = avformat_find_stream_info(m_fmt_ctx, NULL); if (ret < 0) { return XError(ret); } av_dump_format(m_fmt_ctx, 0, deviceName, 0); video_stream = av_find_best_stream(m_fmt_ctx, AVMEDIA_TYPE_VIDEO, -1, -1, NULL, 0); if (video_stream < 0) { return -1; }AVCodecContext * _codec_ctx = m_fmt_ctx->streams[video_stream]->codec;
AVCodec* _codec = avcodec_find_decoder(_codec_ctx->codec_id); if (_codec == NULL) { return -1; } ret = avcodec_open2(_codec_ctx, _codec, NULL); if (ret != 0) { return -1; } int width = m_fmt_ctx->streams[video_stream]->codec->width; int height = m_fmt_ctx->streams[video_stream]->codec->height; int fps = m_fmt_ctx->streams[video_stream]->codec->framerate.num > 0 ? m_fmt_ctx->streams[video_stream]->codec->framerate.num : 25; AVPixelFormat videoType = m_fmt_ctx->streams[video_stream]->codec->pix_fmt; std::cout << “avstream timebase : " << m_fmt_ctx->streams[video_stream]->time_base.num << " / " << m_fmt_ctx->streams[video_stream]->time_base.den << endl; AVDictionary* enoptions = 0; av_dict_set(&enoptions, “preset”, “superfast”, 0); av_dict_set(&enoptions, “tune”, “zerolatency”, 0); AVCodec* codec = avcodec_find_encoder(AV_CODEC_ID_H264); if (!codec) { std::cout << “avcodec_find_encoder failed!” << endl; return NULL; } AVCodecContext* vc = avcodec_alloc_context3(codec); if (!vc) { std::cout << “avcodec_alloc_context3 failed!” << endl; return NULL; } std::cout << “avcodec_alloc_context3 success!” << endl; vc->flags |= AV_CODEC_FLAG_GLOBAL_HEADER; vc->codec_id = AV_CODEC_ID_H264; vc->codec_type = AVMEDIA_TYPE_VIDEO; vc->pix_fmt = AV_PIX_FMT_YUV420P; vc->width = width; vc->height = height; vc->time_base.num = 1; vc->time_base.den = FPS; vc->framerate = { FPS,1 }; vc->bit_rate = 10241000; vc->gop_size = 120; vc->qmin = 10; vc->qmax = 51; vc->max_b_frames = 0; vc->profile = FF_PROFILE_H264_MAIN; ret = avcodec_open2(vc, codec, &enoptions); if (ret != 0) { return XError(ret); } std::cout << “avcodec_open2 success!” << endl; av_dict_free(&enoptions); SwsContext vsc = NULL; vsc = sws_getCachedContext(vsc, width, height, (AVPixelFormat)videoType, //源宽、高、像素格式 width, height, AV_PIX_FMT_YUV420P,//目标宽、高、像素格式 SWS_BICUBIC, // 尺寸变化使用算法 0, 0, 0 ); if (!vsc) { cout << “sws_getCachedContext failed!”; return false; } AVFrame* yuv = av_frame_alloc(); yuv->format = AV_PIX_FMT_YUV420P; yuv->width = width; yuv->height = height; yuv->pts = 0; ret = av_frame_get_buffer(yuv, 32); if (ret != 0) { return XError(ret); } const char* rtmpurl = “rtmp://192.168.20.50:1355/live/test”; AVFormatContext* ic = NULL; ret = avformat_alloc_output_context2(&ic, 0, “flv”, rtmpurl); if (ret < 0) { return XError(ret); } AVStream* st = avformat_new_stream(ic, NULL); if (!st) { return -1; } st->codecpar->codec_tag = 0; avcodec_parameters_from_context(st->codecpar, vc); av_dump_format(ic, 0, rtmpurl, 1); ret = avio_open(&ic->pb, rtmpurl, AVIO_FLAG_WRITE); if (ret != 0) { return XError(ret); } ret = avformat_write_header(ic, NULL); if (ret != 0) { return XError(ret); } AVPacket* packet = av_packet_alloc(); AVPacket* Encodepacket = av_packet_alloc(); int frameIndex = 0; int EncodeIndex = 0; AVFrame* rgb = av_frame_alloc(); AVBitStreamFilterContext* h264bsfc = av_bitstream_filter_init(“h264_mp4toannexb”); long long startpts = m_fmt_ctx->start_time; long long lastpts = 0; long long duration = av_rescale_q(1, { 1,FPS }, { 1,AV_TIME_BASE }); int got_picture = 0; while (frameIndex < 200) { ret = av_read_frame(m_fmt_ctx, packet); if (ret < 0) { break; } if (packet->stream_index == video_stream) { ret = avcodec_decode_video2(_codec_ctx, rgb, &got_picture, packet); if (ret < 0) { printf(“Decode Error.\n”); return ret; } if (got_picture) { int h = sws_scale(vsc, rgb->data, rgb->linesize, 0, height, //源数据 yuv->data, yuv->linesize); int guesspts = frameIndex * duration; yuv->pts = guesspts; frameIndex++; ret = avcodec_encode_video2(vc, Encodepacket, yuv, &got_picture); if (ret < 0) { printf(“Failed to encode! \n”); break; } if (got_picture == 1) { Encodepacket->pts = av_rescale_q(EncodeIndex, vc->time_base, st->time_base); Encodepacket->dts = Encodepacket->pts; std::cout << “frameindex : " << EncodeIndex << " pts:” << Encodepacket->pts << " dts: " << Encodepacket->dts << " encodeSize:” << Encodepacket->size << " curtime - lasttime " << Encodepacket->pts - lastpts << endl; lastpts = Encodepacket->pts; ret = av_interleaved_write_frame(ic, Encodepacket); EncodeIndex++; av_packet_unref(Encodepacket); } } } av_packet_unref(packet); } ret = avcodec_send_frame(vc, NULL); while (ret >= 0) { ret = avcodec_receive_packet(vc, Encodepacket); if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF) { break; } if (ret < 0) { break; } ret = av_interleaved_write_frame(ic, Encodepacket); EncodeIndex++; } av_write_trailer(ic); av_packet_free(&packet); av_packet_free(&Encodepacket); av_frame_free(&rgb); av_frame_free(&yuv); av_bitstream_filter_close(h264bsfc); h264bsfc = NULL; if (vsc) { sws_freeContext(vsc); vsc = NULL; } if (_codec_ctx) avcodec_close(_codec_ctx); _codec_ctx = NULL; _codec = NULL; if (vc) avcodec_free_context(&vc); if (m_fmt_ctx) avformat_close_input(&m_fmt_ctx); if (ic && !(ic->flags & AVFMT_NOFILE)) avio_closep(&ic->pb); if (ic) { avformat_free_context(ic); ic = NULL; } m_input_fmt = NULL; return 0; }转载地址：http://mdayk.baihongyu.com/