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• TCP connection failed - python stream view

  18 avril 2022, par knottyextinct

  simple question :

  


  I'm getting the following error message :

  


  [tcp @ 000001fe4c283680] Connection to tcp://raspcam:8000 failed: Error number -138 occurred


  


  My code looks like this :

  


  import cv2

url = 'http://raspcam:8000/stream.mjpg'

try:
    video = cv2.VideoCapture(url)
except Exception as e:
    print(e)

while True:
    _, img = video.read()
    cv2.imshow("stream", img)

    if cv2.waitKey(1) == ord('q'):
        break

video.release()


  


  I know why I'm getting this message, my stream is currently down. My question here is now, how can I handle this exception if the default try except method is not working ?

  


• av_read_frame function in ffmpeg in android always returning packet.stream_index as 0

  31 juillet 2013, par droidmad

  I am using the following standard code pasted below (ref : http://dranger.com/ffmpeg/) to use ffmpeg in android using ndk. My code is working fine in ubuntu 10.04 using gcc compiler. But I am facing an issue in android.The issue is av_read_frame(pFormatCtx, &packet) is always returning packet.stream_index=0. I have tested my code with various rtsp urls and I have the same behaviour in all cases. I do not have any linking or compiling issues as everything seems to be working fine except this issue. I am trying to solve this from last 2 days but I am stuck badly.Please point me in right direction.

  #include 
  
  #include <android></android>log.h>
  
  
  
  #include <libavcodec></libavcodec>avcodec.h>
  
  #include <libavformat></libavformat>avformat.h>
  
  #include <libswscale></libswscale>swscale.h>
  
  
  
  #include 
  
  #define DEBUG_TAG "mydebug_ndk"
  
  
  
  jint Java_com_example_tut2_MainActivity_myfunc(JNIEnv * env, jobject this,jstring myjurl) {
  
    AVFormatContext *pFormatCtx = NULL;
  
    int             i, videoStream;
  
    AVCodecContext  *pCodecCtx = NULL;
  
    AVCodec         *pCodec = NULL;
  
    AVFrame         *pFrame = NULL;
  
    AVPacket        packet;
  
    int             frameFinished;
  
  
  
    AVDictionary    *optionsDict = NULL;
  
    struct SwsContext *sws_ctx = NULL;
  
  
  
    jboolean isCopy;
  
    const char * mycurl = (*env)->GetStringUTFChars(env, myjurl, &amp;isCopy);
  
    __android_log_print(ANDROID_LOG_DEBUG, DEBUG_TAG, "NDK:p2: [%s]", mycurl);
  
  
  
    // Register all formats and codecs
  
    av_register_all();
  
    avformat_network_init();
  
    // Open video file
  
    __android_log_print(ANDROID_LOG_DEBUG, DEBUG_TAG, "NDK:before_open");
  
  
  
    if(avformat_open_input(&amp;pFormatCtx, mycurl, NULL, NULL)!=0)
  
        return -1;
  
    __android_log_print(ANDROID_LOG_DEBUG, DEBUG_TAG, "start: %d\t%d\n",pFormatCtx->raw_packet_buffer_remaining_size,pFormatCtx->max_index_size);
  
  
  
    (*env)->ReleaseStringUTFChars(env, myjurl, mycurl);
  
    __android_log_print(ANDROID_LOG_DEBUG, DEBUG_TAG, "NDK:before_stream");
  
    // Retrieve stream information
  
    if(avformat_find_stream_info(pFormatCtx, NULL)&lt;0)
  
        return -1;
  
    __android_log_print(ANDROID_LOG_DEBUG, DEBUG_TAG, "NDK:after_stream");
  
    // Find the first video stream
  
    videoStream=-1;
  
    for(i=0; inb_streams; i++)
  
        if(pFormatCtx->streams[i]->codec->codec_type==AVMEDIA_TYPE_VIDEO) {
  
          videoStream=i;
  
          break;
  
        }
  
    if(videoStream==-1)
  
        return -1; // Didn&#39;t find a video stream
  
    __android_log_print(ANDROID_LOG_DEBUG, DEBUG_TAG, "NDK:after_videostream");
  
    // Get a pointer to the codec context for the video stream
  
    pCodecCtx=pFormatCtx->streams[videoStream]->codec;
  
    __android_log_print(ANDROID_LOG_DEBUG, DEBUG_TAG, "NDK:after_codec_context");
  
  
  
    // Find the decoder for the video stream
  
    pCodec=avcodec_find_decoder(pCodecCtx->codec_id);
  
    __android_log_print(ANDROID_LOG_DEBUG, DEBUG_TAG, "NDK:after_decoder");
  
  
  
    if(pCodec==NULL)
  
        return -1;
  
    __android_log_print(ANDROID_LOG_DEBUG, DEBUG_TAG, "NDK:found_decoder");
  
  
  
    // Open codec
  
    if(avcodec_open2(pCodecCtx, pCodec, &amp;optionsDict)&lt;0)
  
        return -1;
  
    // Allocate video frame
  
    pFrame=avcodec_alloc_frame();
  
    sws_ctx = sws_getContext(pCodecCtx->width,pCodecCtx->height,pCodecCtx->pix_fmt,pCodecCtx->width,
  
          pCodecCtx->height,PIX_FMT_YUV420P,SWS_BILINEAR,NULL,NULL,NULL);
  
    __android_log_print(ANDROID_LOG_DEBUG, DEBUG_TAG, "NDK:before_while");
  
  
  
    int count=0;
  
    while(av_read_frame(pFormatCtx, &amp;packet)>=0) {
  
          __android_log_print(ANDROID_LOG_DEBUG, DEBUG_TAG, "entered while: %d   %d   %d\n", packet.duration,packet.stream_index,packet.size);
  
  
  
        if(packet.stream_index==videoStream) {
  
            // Decode video frame
  
            //break;
  
            avcodec_decode_video2(pCodecCtx, pFrame, &amp;frameFinished,&amp;packet);
  
            __android_log_print(ANDROID_LOG_DEBUG, DEBUG_TAG, "NDK:in_while");
  
            if(frameFinished) {
  
                __android_log_print(ANDROID_LOG_DEBUG, DEBUG_TAG, "NDK:gng_out_of_while");
  
                  break;
  
            }
  
        }
  
  
  
        // Free the packet that was allocated by av_read_frame
  
        av_free_packet(&amp;packet);
  
        if(++count>1000)
  
           return -2; //infinite while loop
  
    }
  
    __android_log_print(ANDROID_LOG_DEBUG, DEBUG_TAG, "NDK:after_while");
  
  
  
    // Free the YUV frame
  
    av_free(pFrame);
  
    // Close the codec
  
    avcodec_close(pCodecCtx);
  
    // Close the video file
  
    avformat_close_input(&amp;pFormatCtx);
  
  
  
    return 0;
  
  
  
  }

• how to read data using ffmpeg in c ?

  24 octobre 2018, par Dilchun Dev

  I have followed this tutorial :http://dranger.com/ffmpeg/tutorial01.html for using ffmpeg in android studio using android NDK.
  I have made some minor correction as some functions used here are depreciated now.Here’s my code can anyone point out whats wrong with my code as i am getting errorand couldn’t find out what’s wrong

  #include 
  
  #include 
  
  #include <libavcodec></libavcodec>avcodec.h>
  
  #include <libavformat></libavformat>avformat.h>
  
  #include <libswscale></libswscale>swscale.h>
  
  #include <libavutil></libavutil>imgutils.h>
  
  void SaveFrame(AVFrame *pFrame, int width, int height, int iFrame);
  
  JNICALL
  
  JNIEXPORT jstring
  
  Java_com_viralsam_root_tester_MainActivity_trtest(JNIEnv *env, jobject obj , jint argc,
  
                                                    jstring argv_){
  
      const char *name;
  
      int i,videostream;
  
      name= (*env)->GetStringUTFChars(env, argv_,0);
  
      AVFormatContext *pFormatctx=NULL;
  
      if (avformat_open_input(&amp;pFormatctx,name,NULL,NULL)!=0){
  
          return (*env)->NewStringUTF(env,"a");
  
      }
  
      if(pFormatctx==NULL){
  
          return (*env)->NewStringUTF(env,"b");
  
      }
  
      if(avformat_find_stream_info(pFormatctx,NULL)&lt;0){
  
          return (*env)->NewStringUTF(env,"c");
  
      }
  
      av_dump_format(pFormatctx, 0, name, 0);
  
      videostream=-1;
  
      AVCodecContext *pCodecCtxOrig = NULL;
  
      AVCodecContext *pCodecCtx = NULL;
  
      for (i=0;inb_streams;i++){
  
          if((pFormatctx->streams[i]->codecpar->codec_type)==AVMEDIA_TYPE_VIDEO){
  
              videostream=i;
  
              break;
  
          }
  
      }
  
      if(videostream==-1){
  
          return (*env)->NewStringUTF(env,"d");
  
      }
  
      pCodecCtx=pFormatctx->streams[videostream]->codecpar;
  
      AVCodec *pCodec = NULL;
  
      pCodec=avcodec_find_decoder(pCodecCtx->codec_id);
  
      if(pCodec==NULL){
  
          return (*env)->NewStringUTF(env,"e");
  
      }
  
      pCodecCtx=avcodec_alloc_context3(pCodec);
  
      if(avcodec_open2(pCodecCtx,pCodec,NULL)&lt;0){
  
          return (*env)->NewStringUTF(env,"g");
  
      }
  
      AVFrame *pFrame = NULL,*pFrameRBG=NULL;
  
  
  
      pFrame=av_frame_alloc();
  
      pFrameRBG=av_frame_alloc();
  
      if(pFrameRBG==NULL){
  
          return (*env)->NewStringUTF(env,"h");
  
      }
  
      uint8_t *buffer=NULL;
  
      int numBytes;
  
      numBytes=av_image_get_buffer_size(AV_PIX_FMT_RGB24,pCodecCtx->width,pCodecCtx->height,1);
  
      buffer=(uint8_t *)av_malloc(numBytes* sizeof(uint8_t));
  
      av_image_fill_arrays(pFrameRBG->data,pFrameRBG->linesize,buffer,AV_PIX_FMT_RGB24,pCodecCtx->width,pCodecCtx->height,1);
  
      struct SwsContext *sws_ctx = NULL;
  
      int frameFinished;
  
      AVPacket *packet=av_packet_alloc();
  
      sws_ctx=sws_getContext(pCodecCtx->width,pCodecCtx->height,pCodecCtx->pix_fmt,pCodecCtx->width,pCodecCtx->height,AV_PIX_FMT_RGB24,SWS_BILINEAR,NULL,NULL,NULL);
  
      i=0;
  
      while(av_read_frame(pFormatctx,&amp;packet)>=0){
  
  
  
          if(packet->stream_index==videostream){
  
              int used=avcodec_send_packet(pCodecCtx,&amp;packet);
  
              used=avcodec_receive_frame(pCodecCtx,pFrame);
  
              if (used &lt; 0 &amp;&amp; used != AVERROR(EAGAIN) &amp;&amp; used != AVERROR_EOF){
  
                  break;
  
  
  
              } else{
  
  
  
                  if (used == AVERROR(EAGAIN) || used == AVERROR_EOF){
  
                      break;
  
                  }
  
              }
  
  
  
              sws_scale(sws_ctx,(uint8_t const * const *)pFrame->data,pFrame->linesize,0,pCodecCtx->height,pFrameRBG->data,pFrameRBG->linesize);
  
              if(++i&lt;=5){
  
                  SaveFrame(pFrameRBG,pCodecCtx->width,pCodecCtx->height,i);
  
              }
  
  
  
  
  
          }
  
          av_packet_free(&amp;packet);
  
  
  
      }
  
      char blubuk[50];
  
      sprintf(blubuk,"%d",buffer);
  
      av_free(buffer);
  
      av_frame_free(&amp;pFrameRBG);
  
      av_frame_free(&amp;pFrame);
  
      avcodec_close(pCodecCtx);
  
      avcodec_close(pCodecCtxOrig);
  
      avformat_close_input(&amp;pFormatctx);
  
  
  
      return (*env)->NewStringUTF(env,blubuk);
  
  
  
  }
  
  void SaveFrame(AVFrame *pFrame, int width, int height, int iFrame){
  
      FILE *pFile;
  
      char szFilename[32];
  
      int  y;
  
      sprintf(szFilename, "frame%d.ppm", iFrame);
  
      pFile=fopen(szFilename,"wb");
  
      if(pFile==NULL){
  
          return;
  
      }
  
      fprintf(pFile, "P6\n%d %d\n255\n", width, height);
  
      for(y=0; ydata[0]+y*pFrame->linesize[0], 1, width*3, pFile);
  
      }
  
      fclose(pFile);
  
  
  
  }

  UPDATE :
  I am getting "-22" from "int used=avcodec_send_packet(pCodecCtx,packet) ;".Can’t figure out where i went wrong.