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• Stream video from mobile camera to ffmpeg with NDK

  19 juillet 2013, par user2598307

  I need to create an application that captures video from a camera phone and send it to ffmpeg. Everything should be done only NDK level without SDK and Java
   The phone can be Root

  I am trying to open camera on my android device with this function "avformat_open_input()". I give this function a reference to device folder "/dev/msm_camera/" or "/dev/video0".

  I try like this :

        void Java_com_example_camera_MainActivity_testVideo(JNIEnv *env, jclass jc, jstring *filename)
  
  {
  
          av_register_all();
  
          avcodec_register_all();
  
          avformat_network_init();
  
          AVFormatContext* context = avformat_alloc_context();
  
          int video_stream_index,ret,i;
  
          AVInputFormat *input_format = NULL;
  
          const char formatName[] = "mpeg"; //for example mpeg
  
          const jbyte *str;
  
          str = (*env)->GetStringUTFChars(env, filename, NULL); //filename = "/dev/msm_camera"
  
          input_format = av_find_input_format(formatName);
  
          ret = avformat_open_input(&context, str, input_format, NULL);
  
          if (ret < 0){
  
             LOGE("Not open");
  
          }else{
  
             LOGI("camera was open");
  
          }
  
          if(avformat_find_stream_info(context,NULL) < 0){
  
             LOGE("No stream");
  
          }
  
          for(i =0;inb_streams;i++){
  
             if(context->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO)
  
                 video_stream_index = i;
  
          }
  
          AVPacket packet;
  
          AVFrame *pFrame;
  
          av_init_packet(&packet);
  
          pFrame = avcodec_alloc_frame();
  
  
  
                  //open output file
  
          AVOutputFormat* fmt = av_guess_format("avi", NULL, NULL);
  
          AVFormatContext* outputContext = avformat_alloc_context();
  
          outputContext->oformat = fmt;
  
          avio_open2(&outputContext->pb, "/sdcard/test.avi", AVIO_FLAG_WRITE,NULL,NULL);
  
          AVStream* stream=NULL;
  
          AVFrame * frame;
  
          frame = avcodec_alloc_frame();
  
          int cnt = 0, frameDecoded;
  
  
  
                  //start reading packets from stream and write them to file
  
          av_read_play(context);
  
          while(av_read_frame(context,&packet)>=0 && cnt <300){ //Here function return -1
  
            if(packet.stream_index == video_stream_index)
  
            {//packet is video
  
              if(stream == NULL){
  
                 //create stream in file
  
                       stream = avformat_new_stream(outputContext,context->streams[video_stream_index]->codec->codec);
  
                       avcodec_copy_context(stream->codec,context->streams[video_stream_index]->codec);
  
                       stream->sample_aspect_ratio = context->streams[video_stream_index]->codec->sample_aspect_ratio;
  
                       avformat_write_header(outputContext,NULL);
  
               }
  
               packet.stream_index = stream->id;
  
               av_write_frame(outputContext,&packet);
  
               cnt++;
  
             }
  
             av_free_packet(&packet);
  
             av_init_packet(&packet);
  
          }
  
          av_read_pause(context);
  
          av_write_trailer(outputContext);
  
          avio_close(outputContext->pb);
  
          avformat_free_context(outputContext);         
  
   }

  As I know, we cannot get access to camera because my program has not root permission. So how I can give my program root permission ? Or how I can go around this problem ?

  I also tried to interact with the device driver using ioctl commands on C\C++, but I did not succeed because I have no experience and examples in Google.

  Thank you !!!

• FFmpeg : avcodec_open2 returns "Permission denied" (-13)

  24 avril 2019, par maxest

  I wanted to open an encoder, H264, C++, Android. This :

  encoderH264 = avcodec_find_encoder(AV_CODEC_ID_H264);

  works. This one :

  codecContext = avcodec_alloc_context3(encoderH264);

  also works. But I get error "Permission denied" (-13) on that :

  avcodec_open2(codecContext, encoderH264, NULL);

  I’d suppose that my FFmpeg lib does support H264 encoding as avcodec_find_encoder returns valid value (when I used some other FFmpeg lib this function returned null).

  Any ideas ?

• avio_open() function returns -138

  8 avril 2024, par checkright

  When I use ffmpeg4.4.1 to push rtmp to the desktop, the program returns -138 when running avio_open().I use dshow's screen-capture-recorder on the input side. My purpose is to capture the desktop in real time and use rtmp to push the stream.

  


      avdevice_register_all();
    avformat_network_init();

    AVFormatContext* pFmtCtx_In = nullptr;
    AVFormatContext* pFmtCtx_Out = nullptr;
    AVInputFormat*   pInFmt  = nullptr;
    AVDictionary* options = nullptr;
    int nVideoIndex          = -1;
    int              ret     = 0;

    AVCodecParameters* pCodecParam = nullptr;
    AVCodecContext   * pCodecCtx   = nullptr;
    AVCodec          * pCodec      = nullptr;

    AVFrame* pFrame    = av_frame_alloc();
    AVFrame* pFrameRGB = av_frame_alloc();
    AVPacket* pkt      = nullptr;

    pFrame    = av_frame_alloc();
    pFrameRGB = av_frame_alloc();
    pkt       = nullptr;
    img_convert_ctx = nullptr;

    pFmtCtx_In = avformat_alloc_context();
    if(!pFmtCtx_In)
    {
        qDebug() << "create AVFormatContext failed." ;
        return;
    }

    QString urlString = QString("video=screen-capture-recorder");
    const char* rtmpAddress = "rtmp://192.168.0.136:8554/myapp/test";
    
    if(1){
        pInFmt = const_cast(av_find_input_format("dshow"));
        ret = avformat_open_input(&pFmtCtx_In, urlString.toStdString().c_str(), pInFmt, nullptr);
    }else{
        pInFmt = const_cast(av_find_input_format("gdigrab"));
        av_dict_set(&options, "video_device_index", "1", 0);  
        av_dict_set(&options, "offset_x", "1920", 0);
        av_dict_set(&options, "offset_y", "0", 0);
        av_dict_set(&options, "draw_mouse", "1", 0);
        av_dict_set(&options, "video_size", "1920x1080", 0);
        ret = avformat_open_input(&pFmtCtx_In, "desktop", pInFmt, &options);
    }

    if(!pInFmt)
    {
        qDebug() << "find AVInputFormat failed." ;
        return;
    }

    if(ret < 0)
    {
        qDebug() << "open camera failed."<nb_streams; i++){
        if(pFmtCtx_In->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO){
            nVideoIndex = i;
            continue;
        }
    }

    if(nVideoIndex == -1){
        qDebug() << "cannot find video stream." ;
        return;
    }


    pCodecParam = pFmtCtx_In->streams[nVideoIndex]->codecpar;
    pCodec = avcodec_find_decoder(pCodecParam->codec_id);
    if(!pCodec)
    {
        qDebug() << "cannot find codec." ;
        return;
    }

    ret = avformat_alloc_output_context2(&pFmtCtx_Out, NULL, "flv", rtmpAddress);
    //    ret = avformat_alloc_output_context2(&pFmtCtx_Out, NULL, "rtsp", rtmpAddress);
    if (ret < 0) {
        qDebug() << "cannot avformat_alloc_output_context2." ;
        return ;
    }

    for (int i = 0; i < pFmtCtx_In->nb_streams; i++) {
        AVStream *outStream = avformat_new_stream(pFmtCtx_Out, pFmtCtx_In->streams[i]->codec->codec);
        if (!outStream) {
            qDebug() << "cannot outStream." ;

            return ;
        }

        ret = avcodec_parameters_copy(outStream->codecpar, pFmtCtx_In->streams[i]->codecpar);
        if (ret < 0) {
             qDebug() << "cannot avcodec_parameters_copy." ;
            return ;
        }
        outStream->codec->codec_tag = 0;
    }
  
    av_dump_format(pFmtCtx_Out, 0, rtmpAddress, 1);

    ret = avio_open(&pFmtCtx_Out->pb, rtmpAddress, AVIO_FLAG_WRITE);
    if (ret < 0) {
        qDebug() << "cannot avio_open." <code>

  


  An error occurs here.According to the data, the problem occurs at the input end, and the input end can display the desktop normally. How can I make it run successfully ? How do I need to modify the above code ?