Recherche avancée

Sur d’autres sites (6890)

• NVENC_HEVC Encoding making my files larger

  9 novembre 2016, par Alan

  I got a new Nvidia GPU to speed up my video encoding. I am working with x264 files to x265 and wanted to go faster. Using the library libx265 I am getting about 85fps when working on a file that is 720p, but if I use the nvenc_hevc I get around 600-700fps

  My input file is 269M and when I use the nvenc_hevc it grows to 394M. Doing the exact same command with libx265 gives me a file size of only 68M. Obviously I would like to keep the low file size, but take advantage of the GPU to process it 15X faster.

  Anyone else have any experience with this video codec ?

  My command is : ffmpeg -i infile.avi -c:v nvenc_hevc -rc vbr_2pass -rc-lookahead 20 -gpu any out7.mp4

  vs

  ffmpeg -i infile.avi -c:v libx265 -rc vbr_2pass -rc-lookahead 20 -gpu any out7.mp4

• Python code for making multiple splits on silence of a video [closed]

  15 janvier 2021, par Shikhar Jaiswal

  I am trying to write a python code where I want to make multiple splits of a single mp4 file, on its silences. Basically a video should get be split into multiple sub-videos on its silence. Silence can be detected via srt file of that video or just detecting it in the video itself.

  


• Forcing global headers in LibAV

  23 septembre 2015, par Kienan Knight-Boehm

  I’m trying to write a C program using LibAV that takes input video from a webcam and saves it as an H264 MP4 file. I’m modifying a working program that saves .ppm frames from the webcam. I’m unable to convert the AVPackets so that they may be written, though—specifically, avformat_write_header() is failing, with the messages

  [mp4 @ 0050c000] Codec for stream 0 does not use global headers but container format requires global headers
  
  [mp4 @ 0050c000] Could not find tag for codec none in stream #0, codec not currently supported in container

  The call is apparently returning error -22, but I can find no place where that error code is actually explained. How can I force avformat_write_header() to add in global headers when it’s trying to write the MP4 ? Code below ; some of it is adapted from this question, but I’m trying to adapt it from an input video file to a webcam.

  int _tmain(int argc, _TCHAR* argv[])
  
  {
  
      AVInputFormat *inputFormat = NULL;
  
      AVDictionary *inputDictionary= NULL;
  
      AVFormatContext *inputFormatCtx = NULL;
  
      AVFormatContext *outputFormatCtx = NULL;
  
      AVCodecContext *inputCodecCtxOrig = NULL;
  
      AVCodecContext *inputCodecCtx = NULL;
  
      AVCodecContext *outputCodecCtx;
  
      AVCodec *inputCodec = NULL;
  
      AVCodec *outputCodec = NULL;
  
      AVStream *stream = NULL;
  
      AVIOContext *avioContext = NULL;
  
      avcodec_register_all();
  
      av_register_all();
  
      avdevice_register_all();
  
      av_dict_set(&inputDictionary, "Logitech HD Pro Webcam C920", "video", 0);
  
      avformat_alloc_output_context2(&outputFormatCtx, NULL, NULL, "output.mp4");
  
      avio_open(&avioContext, "output.mp4", AVIO_FLAG_WRITE);
  
      outputFormatCtx->pb = avioContext;
  
      stream = avformat_new_stream(outputFormatCtx, outputCodec);
  
      inputFormat = av_find_input_format("dshow");
  
      int r = avformat_open_input(&inputFormatCtx, "video=Logitech HD Pro Webcam C920", inputFormat, &inputDictionary);
  
      if (r != 0) {
  
          fprintf(stderr, "avformat_open_input() failed with error %d!\n", r);
  
          return -1; }
  
      r = avformat_find_stream_info(inputFormatCtx, NULL);
  
      if (r != 0) {
  
          fprintf(stderr, "avformat_find_stream_info() failed!\n");
  
          return -1; }
  
      av_dump_format(inputFormatCtx, 0, "video=Logitech HD Pro Webcam C920", 0);
  
      unsigned int i;
  
      int videoStream;
  
      videoStream = -1;
  
      for (i = 0; i < inputFormatCtx->nb_streams; i++) {
  
          if (inputFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO {
  
              videoStream = i;
  
              break; }
  
      }
  
      if (videoStream == -1)
  
          { return -1; }
  
      inputCodecCtxOrig = inputFormatCtx->streams[videoStream]->codec;
  
      inputCodec = avcodec_find_decoder(inputCodecCtxOrig->codec_id);
  
      if (inputCodec == NULL) {
  
          fprintf(stderr, "avcodec_find_decoder() failed!\n");
  
          return -1; }
  
      else { printf("Supported codec!\n"); }
  
      inputCodecCtx = avcodec_alloc_context3(inputCodec);
  
      if (inputCodecCtx == NULL) {
  
          fprintf(stderr, "avcodec_alloc_context3() failed!\n");
  
          return -1; }
  
      if (avcodec_copy_context(inputCodecCtx, inputCodecCtxOrig) != 0) {
  
          fprintf(stderr, "avcodec_copy_context() failed!\n");
  
          return -1; }
  
      if (avcodec_open2(inputCodecCtx,inputCodec,&inputDictionary) < 0) {
  
          fprintf(stderr, "avcodec_open2() failed!\n");
  
          return -1; }
  
      outputFormatCtx->oformat = av_guess_format(NULL, "output.mp4", NULL);
  
      outputFormatCtx->oformat->flags |= AVFMT_GLOBALHEADER;
  
      outputCodecCtx = avcodec_alloc_context3(outputCodec);
  
      avcodec_copy_context(outputCodecCtx, inputCodecCtx);
  
      outputCodec = inputCodec;
  
      avcodec_open2(outputCodecCtx, outputCodec, NULL);
  
      AVPacket packet;
  
      printf("foo\n");
  
      int errnum = avformat_write_header(outputFormatCtx, &inputDictionary);
  
      printf("bar %d\n", errnum);
  
      while(av_read_frame(inputFormatCtx, &packet)>=0) {
  
          av_interleaved_write_frame(outputFormatCtx, &packet);
  
          av_free_packet(&packet);
  
      }
  
      avcodec_close(inputCodecCtx);
  
      avcodec_close(inputCodecCtxOrig);
  
      avformat_close_input(&inputFormatCtx);
  
      return 0;
  
  }