Sur d’autres sites (17848)

• What is the commmand line to add watermark while screen recording using ffmpeg ? [duplicate]

  11 septembre 2020, par Yong Ju

  I tried to record screen using ffmpeg commmand line. So, I have complete it using this commmand.
ffmpeg.exe -rtbufsize 1500M -f -y -rtbufsize 100M -f gdigrab -t 00:02:00 -framerate 30 0 0 -probesize 10M 1920 1080 -draw_mouse 1 -i desktop -c:v libx264 -r 30 -preset ultrafast -tune zerolatency -crf 30 -pix_fmt yuv420p output.avi".

  


  Now, I want to add watermark while recording video.
If you have good experience this field, Please give me good advice.
Thanks for your attention.
Sincerely.

  


• FFmpeg command to apply multiple filters and limit the final file size

  16 mars 2016, par Konrad — ffmpeg

  I’m using ffmpeg command below to convert video to a format of the defined scale and in order to hardcode the subtitles

  Original syntax

  ffmpeg -i "Original File.mov"  -vf subtitles=Subtitles.srt -vf scale=1920:1080 \
  
         -crf 12 "Final File".mov

  Problem

  I would like to expand this command further and :

  • ensure that the produce file is under 2GB
  • I would like to include additional parameters with advanced subtitle options, like setting the canvas size and fixing the potential delay

  Side notes

  I reckon that in case of predefining the file size the -crf 12 paramater will be redundant ?

• H264 decoding using ffmpeg

  14 juillet 2016, par Kindermann

  I’m trying to decode a video stream with ffmpeg library, that’s how I do it basically :

  void video_decode(const char *filename)
  
  {
  
      AVCodec *codec;
  
      AVCodecContext *c= NULL;
  
      int frame_count=0;
  
      FILE *f;
  
      AVFrame *frame;
  
      uint8_t inbuf[INBUF_SIZE + AV_INPUT_BUFFER_PADDING_SIZE];
  
      AVPacket avpkt;
  
      av_init_packet(&avpkt);
  
      memset(inbuf + INBUF_SIZE, 0, AV_INPUT_BUFFER_PADDING_SIZE);
  
      printf("Decoding video file...\n");
  
      /* find the h264 video decoder */
  
      codec = avcodec_find_decoder(AV_CODEC_ID_H264);
  
      c = avcodec_alloc_context3(codec);
  
      c->bit_rate = 400000;
  
      c->width = 1920;
  
      c->height = 1080;
  
  
  
      if (avcodec_open2(c, codec, NULL) < 0) {
  
          fprintf(stderr, "Could not open codec\n");
  
          exit(1);
  
      }
  
      frame = av_frame_alloc();
  
      for (;;) {
  
          avpkt.size = fread(inbuf, 1, INBUF_SIZE, f);         
  
      if (avpkt.size == 0)
  
              break;
  
          avpkt.data = inbuf;
  
          while(avpkt.size > 0){
  
  
  
          int len, got_frame;
  
              len = avcodec_decode_video2(c, frame, &got_frame, &avpkt);          
  
          if (len < 0) {
  
                  fprintf(stderr, "Errr while decding frame %d\n", frame_count);
  
                  exit (1);
  
              }
  
              if (got_frame) {
  
                  //Print out frame information..
  
          }
  
              if (avpkt.data) {
  
                  avpkt.size -= len;
  
                  avpkt.data += len;
  
              }
  
      }               
  
      }  
  
  }

  But I got the following outputs :

  Decoding video file...
  
  [h264 @ 0x303c040] decode_slice_header error
  
  [h264 @ 0x303c040] decode_slice_header error
  
  [h264 @ 0x303c040] decode_slice_header error
  
  [h264 @ 0x303c040] no frame!
  
  Errr while decding frame 0

  Obviously the initiation of codec was incomplete. Do you have experience with h264 api ? Any help would be appreciated.