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• Could you please explain what the ffmpeg script does ?

  18 juin 2022, par Stariy

  There is this script :

  


  ffmpeg.exe -t 1 -i "D:\input\3.mp4" -ss 1 -i "D:\input\3.mp4"  -i "D:\input\3.mp4" -filter_complex "[1]zoompan=z='if(lte(mod(time,2),1),2,1)':d=1:x='iw/2-(iw/zoom/2)':y='ih/2-(ih/zoom/2):s=1920x1070:fps=25/1'[s0];[0][s0]concat=n=2 [outv]" -map [outv] -map 2:a -b:v 500k -s 1920x1070 -c:v h264 -vsync 2 "D:\output\3.mp4" -y

  


  I need to understand what he is doing, comment on each step so that I understand. Why are the three input files the same, what's going on at all ? I really hope for you.

  


• Decode H264 video using libavcodec, C

  10 janvier 2015, par deadman

  I’m trying to decode a raw h264 file with ffmpeg/libavcodec, but can’t get it to work properly. Output should be a raw YUV-File for now. It’s possible to compile the code with GCC

  gcc -o decoder decoder.c -L./lib/ -llibavcodec -llibavutil

  avcodec.dll, avutil.dll and swresample.dll must be placed in the directory for the .exe to start. Output in the CMD looks like this (only part of it, but its always like this) :

  [h264 @ 00a80f20] reference picture missing during reorder
  
  [h264 @ 00a80f20] Missing reference picture, default is 65562
  
  [h264 @ 00a80f20] error while decoding MB 80 54, bytestream -10
  
  [h264 @ 00a80f20] concealing 1649 DC, 1649 AC, 1649 MV errors in B frame
  
  [h264 @ 00a80f20] reference picture missing during reorder
  
  [h264 @ 00a80f20] reference picture missing during reorder
  
  [h264 @ 00a80f20] reference picture missing during reorder
  
  [h264 @ 00a80f20] Missing reference picture, default is 65566
  
  [h264 @ 00a80f20] Missing reference picture, default is 65566
  
  [h264 @ 00a80f20] Missing reference picture, default is 65566
  
  [h264 @ 00a80f20] reference picture missing during reorder
  
  [h264 @ 00a80f20] Missing reference picture, default is 65568
  
  [h264 @ 00a80f20] reference picture missing during reorder
  
  [h264 @ 00a80f20] Missing reference picture, default is 65570
  
  [h264 @ 00a80f20] reference picture missing during reorder

  Heres my code

  #include 
  
  #include 
  
  
  
  #ifdef HAVE_AV_CONFIG_H
  
  #undef HAVE_AV_CONFIG_H
  
  #endif
  
  
  
  #include "libavcodec/avcodec.h"
  
  //#include "libavcodec/libavutil/mathematics.h"
  
  
  
  #define INBUF_SIZE 4096
  
  
  
  void video_decode(char *outfilename, char *filename)
  
  {
  
      AVCodec *codec;
  
      AVCodecContext *c= NULL;
  
      int frame, got_picture, len;
  
      FILE *f, *outf;
  
      AVFrame *picture;
  
      uint8_t inbuf[INBUF_SIZE + FF_INPUT_BUFFER_PADDING_SIZE];
  
      AVPacket avpkt;
  
      int i;
  
  
  
      av_init_packet(&avpkt);
  
  
  
      memset(inbuf + INBUF_SIZE, 0, FF_INPUT_BUFFER_PADDING_SIZE);
  
  
  
      codec = avcodec_find_decoder(AV_CODEC_ID_H264);
  
      if (!codec) {
  
          fprintf(stderr, "codec not found\n");
  
          exit(1);
  
      }
  
  
  
      c = avcodec_alloc_context3(codec);
  
      picture = av_frame_alloc();
  
  
  
      if((codec->capabilities)&CODEC_CAP_TRUNCATED)
  
          (c->flags) |= CODEC_FLAG_TRUNCATED;
  
  
  
      c->height = 1080;
  
      c->width = 1920;
  
  
  
      if (avcodec_open2(c, codec, NULL) < 0) {
  
          fprintf(stderr, "could not open codec\n");
  
          exit(1);
  
      }
  
  
  
      f = fopen(filename, "rb");
  
      if (!f) {
  
          fprintf(stderr, "could not open %s\n", filename);
  
          exit(1);
  
      }
  
  
  
      outf = fopen(outfilename,"w");
  
      if(!outf){
  
          fprintf(stderr, "could not open %s\n", filename);
  
          exit(1);
  
      }
  
      frame = 0;
  
      for(;;) {
  
          avpkt.size = fread(inbuf, 1, INBUF_SIZE, f);
  
          if (avpkt.size == 0)
  
              break;
  
  
  
          avpkt.data = inbuf;
  
          while (avpkt.size > 0) {
  
  
  
              len = avcodec_decode_video2(c, picture, &got_picture, &avpkt);
  
  
  
              if (len < 0) {
  
                  fprintf(stderr, "Error while decoding frame %d\n", frame);
  
                  exit(1);
  
              }
  
              if (got_picture) {
  
                  printf("saving frame %3d\n", frame);
  
                  fflush(stdout);
  
                  for(i=0; iheight; i++)
  
                      fwrite(picture->data[0] + i * picture->linesize[0], 1, c->width, outf  );
  
                  for(i=0; iheight/2; i++)
  
                      fwrite(picture->data[1] + i * picture->linesize[1], 1, c->width/2, outf );
  
                  for(i=0; iheight/2; i++)
  
                      fwrite(picture->data[2] + i * picture->linesize[2], 1, c->width/2, outf );
  
                  frame++;
  
              }
  
              avpkt.size -= len;
  
              avpkt.data += len;
  
          }
  
      }
  
  
  
      avpkt.data = NULL;
  
      avpkt.size = 0;
  
      len = avcodec_decode_video2(c,picture, &got_picture, &avpkt);
  
      if(got_picture) {
  
          printf("saving last frame %d\n",frame);
  
          fflush(stdout);
  
          for(i=0; iheight; i++)
  
              fwrite(picture->data[0] + i * picture->linesize[0], 1, c->width, outf );
  
          for(i=0; iheight/2; i++)
  
              fwrite(picture->data[1] + i * picture->linesize[1], 1, c->width/2, outf );
  
          for(i=0; iheight/2; i++)
  
              fwrite(picture->data[2] + i * picture->linesize[2], 1, c->width/2, outf );
  
          frame++;
  
      }
  
  
  
      fclose(f);
  
      fclose(outf);
  
  
  
      avcodec_close(c);
  
      av_free(c);
  
      av_frame_free(&picture);
  
      printf("\n");
  
  }
  
  
  
  int main(int argc, char **argv){
  
      avcodec_register_all();
  
      video_decode("test", "trailer.264");
  
  
  
      return 0;
  
  }

  I also tried different videos in different formats (of course i changed the codec in the code in this case) like MPEG1, H263, H265, but none of those was working properly either.
  I hope someone can help me with this and tell me what I’m doing wrong here. Thanks

• Android-Player-SDK's overview of available Player Frameworks

  8 janvier 2015, par user1767754

  I am completely lost with the possibilities of creating Video-Applications for Android. There is natively the MediaPlayer from Android, or the VideoView which is more convenient but at the same time, there are so many different Video-Player-SDK’s around, that someone cannot see what the benefits are between those Players and which one to use.

  For example, what are the benefits of Vitamino over native Player ?

  Let’s say :
  1) Change Appearing of Player

  2) Add Additional Buttons [E-Mail Video-Link, etc.]

  3) Add Additional Functionality [Overlay text, Drawing]

  4) Get Streaming over a Network-Protocoll

  I hope we can build up here an overview page of available Frameworks and Developer Experiences.