Recherche avancée

Sur d’autres sites (9502)

• Size of files was increased after splitting by Ffmpeg

  29 avril 2014, par user3584205

  I use this code to split file to multiple parts :

  @echo off
  
  for %%i in (*.mp4) do ( 
  
    ffmpeg -i "%%~i" -vcodec copy -acodec copy -ss 00:00:00 -t 00:00:05 "D:\Ebook\%%~ni_1.mp4"
  
    ffmpeg -i "%%~i" -vcodec copy -acodec copy -ss 00:00:05 -t 00:00:10 "D:\Ebook\%%~ni_2.mp4"
  
    ffmpeg -i "%%~i" -vcodec copy -acodec copy -ss 00:00:10 "D:\Ebook\%%~ni_3.mp4"
  
    )
  
  pause

  It worked but I have a problem. It is total size of parts is larger than original file.

  Original : 700 MB and after splitting :

  Part 1: 225
  
  Part 1: 500
  
  Part 2: 250

  Why ? And how to keep same quality and size of files after splitting ? Thank you very much !

• Problems encoding to .MP4 using ffmpeg

  30 novembre 2013, par Erik Swansson

  So I'm kind of new to this, I'm writing a WIN32 app that records video to .AVI, then I planned to use ffmpeg to encode to .MP4. Based on a sample I found, I got this far. It compiles and says that it encoded and wrote the file but the output file can't be opened and played. I tried using MPEG1 encoding like the original sample was using but it only gives me weird colors for a few seconds.

  Am I missing something that should be done with the file ?

  Anyone with experience in encoding/ffmpeg, some pointers, advice or help would make me outmost grateful. Thanks in advance !

  int _tmain(int argc, _TCHAR* argv[])
  
  {
  
  
  
      AVFormatContext *pFormatCtx;
  
      int codec_id = CODEC_ID_MPEG4;
  
      char filename [] ="C:\\wav\\test2.flv";
  
  // Open video file
  
       AVCodec *codec;
  
       AVCodecContext *c= NULL;
  
       int i, out_size, x, y, outbuf_size;
  
      FILE *f;
  
       AVFrame *picture;
  
      uint8_t *outbuf;
  
       int had_output=0;
  
  
  
      av_register_all();
  
     printf("Encode video file %s\n", filename);
  
  
  
      codec = avcodec_find_encoder(CODEC_ID_H264);
  
      if (!codec) {
  
           fprintf(stderr, "codec not found\n");
  
          exit(1);
  
      }
  
  
  
      c = avcodec_alloc_context3(codec);
  
      picture= avcodec_alloc_frame();
  
  
  
     /* put sample parameters */
  
     c->bit_rate = 40000;
  
     //c->bit_rate_tolerance=30;
  
       /* resolution must be a multiple of two */
  
      c->width = 352;
  
      c->height = 288;
  
      /* frames per second */
  
  
  
      c->time_base.den=  25;
  
      c->time_base.num= 1;
  
       c->gop_size = 10; /* emit one intra frame every ten frames */
  
     c->max_b_frames=1;
  
       c->pix_fmt = PIX_FMT_YUV420P;
  
  
  
      if(codec_id == CODEC_ID_H264)
  
          av_opt_set(c->priv_data, "preset", "slow", 0);
  
  /* open it */
  
      if (avcodec_open2(c, codec, NULL) < 0) {
  
          fprintf(stderr, "could not open codec\n");
  
         exit(1);
  
      }
  
  
  
  
  
       f = fopen(filename, "wb");
  
       if (!f) {
  
          fprintf(stderr, "could not open %s\n", filename);
  
           exit(1);
  
       }
  
  
  
      /* alloc image and output buffer */
  
      outbuf_size = 100000 + 12*c->width*c->height;
  
       outbuf = (uint8_t*)malloc(outbuf_size); //CHANGED
  
  
  
       /* the image can be allocated by any means and av_image_alloc() is
  
        * just the most convenient way if av_malloc() is to be used */
  
      av_image_alloc(picture->data, picture->linesize,
  
                     c->width, c->height, c->pix_fmt, 1);
  
  
  
       /* encode 1 second of video */
  
       for(i=0;i<25;i++) {
  
           fflush(stdout);
  
           /* prepare a dummy image */
  
          /* Y */
  
           for(y=0;yheight;y++) {
  
              for(x=0;xwidth;x++) {
  
                  picture->data[0][y * picture->linesize[0] + x] = x + y + i * 3;
  
              }
  
           }
  
  
  
          /* Cb and Cr */
  
          for(y=0;yheight/2;y++) {
  
              for(x=0;xwidth/2;x++) {
  
                  picture->data[1][y * picture->linesize[1] + x] = 128 + y + i * 2;
  
                  picture->data[2][y * picture->linesize[2] + x] = 64 + x + i * 5;
  
              }
  
          }
  
  
  
           /* encode the image */
  
          out_size = avcodec_encode_video(c, outbuf, outbuf_size, picture);
  
           had_output |= out_size;
  
          printf("encoding frame %3d (size=%5d)\n", i, out_size);
  
          fwrite(outbuf, 1, out_size, f);
  
       }
  
  
  
       /* get the delayed frames */
  
       for(; out_size || !had_output; i++) {
  
           fflush(stdout);
  
  
  
          out_size = avcodec_encode_video(c, outbuf, outbuf_size, NULL);
  
          had_output |= out_size;
  
           printf("write frame %3d (size=%5d)\n", i, out_size);
  
         fwrite(outbuf, 1, out_size, f);
  
       }
  
  
  
       /* add sequence end code to have a real mpeg file */
  
       outbuf[0] = 0x00;
  
       outbuf[1] = 0x00;
  
       outbuf[2] = 0x01;
  
     outbuf[3] = 0xb7;
  
       fwrite(outbuf, 1, 4, f);
  
       fclose(f);
  
          fclose(p);
  
      free(outbuf);
  
  
  
       avcodec_close(c);
  
       av_free(c);
  
       av_free(picture->data[0]);
  
      av_free(picture);
  
       printf("\n");
  
  
  
      return 0;
  
  }

• Size Discrepany in the ‘du’ Command

  22 juin 2012, par Multimedia Mike — General

  I had a problem today while using the common Unix command ’du’. As a refresher, ’du’ stands for disk usage and is a handy tool for understanding how much disk space is being occupied.

  I think ’du’ is probably doing the right thing. The problem might be that I’m getting strange (read : 1/2 the expected number) when running the tool against directories on vmhgfs, the VMware filesystem.

  Science Project
  On an Ubuntu Linux VMware session, my home directory is on the main file system, which is ext4. The directory /mnt/hgfs is reported by ’mount’ to be of type vmhgfs and is shared with the host machine.

  Create a directory in the home directory and generate a 10 MiB file :

  mkdir /home/melanson/dir
  dd if=/dev/urandom of=/home/melanson/dir/random-file bs=1048576 count=10
  

  Create a directory on the shared drive and copy the same file :

  mkdir /mnt/hgfs/vmshare/dir
  cp /home/melanson/dir/random-file /mnt/hgfs/vmshare/dir
  

  Run ’du’ on each directory using the -k and -h options :

  du -k /home/melanson/dir /mnt/hgfs/vmshare/dir
  10244   /home/melanson/dir
  5120    /mnt/hgfs/vmshare/dir
  du -h /home/melanson/dir /mnt/hgfs/vmshare/dir
  
  11M    /home/melanson/directory
  
  5.0M   /mnt/hgfs/vmshare/directory
  

  I noticed this discrepancy when I was trying to pack a set of files (akin to ’tar’-ing) living in a directory in the shared location. I was going mad trying to understand why the original directory was only 2 MB as reported by ’du’ but the final packed file was 4 MB.

  To be fair, the man page for ’du’ succinctly states that the tool’s purpose is merely to "estimate file space usage".