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• time progress bar does not scale by sec in FFMPEG chopped mp4 in iOS and Android devices

  10 juillet 2017, par Xi Xiao

  I have used the below command to cut out a 44sec length video. The result video can be found here.

  ffmpeg -i friends.mkv -ss 00:15:30.0 -t 44 -vf scale=640:360  video.mp4

  One odd issue appears from the generated video.mp4.

  when playing it in iphone 7 and huawei honor8 android, the time progress bar does not scale by second.

  What I mean is, for example, the video can start to play either from 0 second or 6 second. But, if I drag the progress bar to time between 0 - 6, such as 4, the video player will jump to 0 and play, instead of playing from 4 second.

  When I use Javascript to setTime for 2 second for html5 video player, it does not work either, i.e. the player will play from 0 second instead of 2. Code is as below :

  var vid = document.getElementById("video1");
  
  vid.currentTime = 2;
  
  vid.play();

  screenshot made in iphone 7

  I stop the video, try set the progress bar between 0 and 6 as in screenshot. When I click play, the player will play from 0.

  

  In what devices have I tested it ?

  • This issue appears in iphone 7, huawei honor8 android phone.
  • This issue does not appear in PC browser, nor in ipad.

  At last, I suspect that the issue roots from video codec, but had no success to locate the keyword to explain my issue and google the solution.

• How can I reencode a video to match another's codec exactly ?

  24 janvier 2020, par Stephen Schrauger

  When I’m on vacation, I usually use our camcorder to record videos. Since they’re all the same format, I can use ffmpeg to concat them into one large, smooth video without re-encoding.

  However, sometimes I will use a phone or other camera to record a video (if the camcorder ran out of space/battery or was left at a hotel).

  I’d like to determine the codec, framerate, etc used by my camcorder and use those parameters to convert the phone vidoes into the same format. That way, I will be able to concatonate all the videos without re-encoding the camcorder videos.

  Using ffprobe, I found my camcorder has this encoding :

    Input #0, mpegts, from 'camcorderfile.MTS':
  
    Duration: 00:00:09.54, start: 1.936367, bitrate: 24761 kb/s
  
    Program 1 
  
      Stream #0:0[0x1011]: Video: h264 (High) (HDPR / 0x52504448), yuv420p(progressive), 1920x1080 [SAR 1:1 DAR 16:9], 59.94 fps, 59.94 tbr, 90k tbn, 119.88 tbc
  
      Stream #0:1[0x1100]: Audio: ac3 (AC-3 / 0x332D4341), 48000 Hz, stereo, fltp, 256 kb/s
  
      Stream #0:2[0x1200]: Subtitle: hdmv_pgs_subtitle ([144][0][0][0] / 0x0090), 1920x1080

  The phone (iPhone 5s) encoding is :

    Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'mov.MOV':
  
    Metadata:
  
      major_brand     : qt  
  
      minor_version   : 0
  
      compatible_brands: qt  
  
      creation_time   : 2017-01-02T03:04:05.000000Z
  
      com.apple.quicktime.location.ISO6709: +12.3456-789.0123+456.789/
  
      com.apple.quicktime.make: Apple
  
      com.apple.quicktime.model: iPhone 5s
  
      com.apple.quicktime.software: 10.2.1
  
      com.apple.quicktime.creationdate: 2017-01-02T03:04:05-0700
  
    Duration: 00:00:14.38, start: 0.000000, bitrate: 11940 kb/s
  
      Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709), 1920x1080, 11865 kb/s, 29.98 fps, 29.97 tbr, 600 tbn, 1200 tbc (default)
  
      Metadata:
  
        creation_time   : 2017-01-02T03:04:05.000000Z
  
        handler_name    : Core Media Data Handler
  
        encoder         : H.264
  
      Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, mono, fltp, 63 kb/s (default)
  
      Metadata:
  
        creation_time   : 2017-01-02T03:04:05.000000Z
  
        handler_name    : Core Media Data Handler
  
      Stream #0:2(und): Data: none (mebx / 0x7862656D), 0 kb/s (default)
  
      Metadata:
  
        creation_time   : 2017-01-02T03:04:05.000000Z
  
        handler_name    : Core Media Data Handler
  
      Stream #0:3(und): Data: none (mebx / 0x7862656D), 0 kb/s (default)
  
      Metadata:
  
        creation_time   : 2017-01-02T03:04:05.000000Z
  
        handler_name    : Core Media Data Handler

  I’m presuming that ffmpeg will automatically take any acceptable video format, and that I only need to figure out the output settings. I think I need to use -s 1920x1080 and -pix_fmt yuv420p for the output, but what other flags do I need in order to make the phone video into the same encoding as the camcorder video ?

  Can I get some pointers as to how I can translate the ffprobe output into the flags I need to give to ffmpeg ?

  Edit : Added the entire Input #0 for both media files.

• x264 Encoding use x264_picture_clean crash

  5 mai 2017, par Wong Sam

  When I use iphone encoding CMSampleBufferRef To H264, it offen crash at x264_picture_clean I dont’t know how to deal it

  enter image description here

  x264_picture_t* pPic_in; 

  here is my init about pPic_in

  pPic_in = (x264_picture_t*)malloc(sizeof(x264_picture_t));
  
  pPic_out = (x264_picture_t*)malloc(sizeof(x264_picture_t));
  
  
  
  x264_picture_init(pPic_out);
  
  
  
  x264_picture_init(pPic_in);
  
  x264_picture_alloc(pPic_in, csp, pParam->i_width, pParam->i_height);
  
  
  
  pPic_in->img.i_stride[0] = width;
  
  pPic_in->img.i_stride[1] = width / 2;
  
  pPic_in->img.i_stride[2] = width / 2;
  
  pPic_in->img.i_plane = 3;

  and i set data here

      picture_buf = yuv420_data;
  
      pPic_in->img.plane[0] = picture_buf;
  
      pPic_in->img.plane[1] = picture_buf + y_size;
  
      pPic_in->img.plane[2] = picture_buf + y_size*5/4;

  it looks well , when i run it on my iphone,but sometimes it will crash at

  x264_picture_clean

  here is more detail abuot pPic_in when crash occer
  enter image description here

  Thank u very much