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• Difference between 'display_aspect_ratio' and 'sample_aspect_ratio' in ffprobe [duplicate]

  18 juin 2018, par John Allard

  This question already has an answer here :

  • ffmpeg scaling not working for video
    
    1 answer
    

  I have an issue where a video is played in the correct 16:9 aspect ratio when played through VLC or quicktime player, but when I attempt to extract individual frames with ffmpeg the frames come out as 4:3 aspect ratio.

  The ffprobe output on the video in question is as follows

  $ ffprobe -v error -select_streams v:0 -show_entries stream -of default=noprint_wrappers=1 -print_format json movie.mp4
  
  
  
  {
  
  "programs": [
  
  
  
  ],
  
  "streams": [
  
      {
  
          "index": 0,
  
          "codec_name": "h264",
  
          "codec_long_name": "H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10",
  
          "profile": "Main",
  
          "codec_type": "video",
  
          "codec_time_base": "126669/6400000",
  
          "codec_tag_string": "avc1",
  
          "codec_tag": "0x31637661",
  
          "width": 2592,
  
          "height": 1944,
  
          "coded_width": 2592,
  
          "coded_height": 1944,
  
          "has_b_frames": 0,
  
          "sample_aspect_ratio": "4:3",
  
          "display_aspect_ratio": "16:9",
  
          "pix_fmt": "yuvj420p",
  
          "level": 50,
  
          "color_range": "pc",
  
          "color_space": "bt709",
  
          "color_transfer": "bt709",
  
          "color_primaries": "bt709",
  
          "chroma_location": "left",
  
          "refs": 1,
  
          "is_avc": "true",
  
          "nal_length_size": "4",
  
          "r_frame_rate": "25/1",
  
          "avg_frame_rate": "3200000/126669",
  
          "time_base": "1/12800",
  
          "start_pts": 0,
  
          "start_time": "0.000000",
  
          "duration_ts": 126682,
  
          "duration": "9.897031",
  
          "bit_rate": "4638928",
  
          "bits_per_raw_sample": "8",
  
          "nb_frames": "250",
  
          "disposition": {
  
              "default": 1,
  
              "dub": 0,
  
              "original": 0,
  
              "comment": 0,
  
              "lyrics": 0,
  
              "karaoke": 0,
  
              "forced": 0,
  
              "hearing_impaired": 0,
  
              "visual_impaired": 0,
  
              "clean_effects": 0,
  
              "attached_pic": 0,
  
              "timed_thumbnails": 0
  
          },
  
          "tags": {
  
              "language": "und",
  
              "handler_name": "VideoHandler"
  
          }
  
      }
  
  ]
  
  }

  So it says

      "width": 2592,
  
      "height": 1944,
  
      "coded_width": 2592,
  
      "coded_height": 1944,
  
      "has_b_frames": 0,
  
      "sample_aspect_ratio": "4:3",
  
      "display_aspect_ratio": "16:9",

  which seems odd to me. The width/height are in 4:3, the sample aspect ratio is 4:3, the display is 16:9 ?

  Now, when I play this through VLC/Quicktime the video looks fine (screenshot below)

  

  but now, if I run an ffmpeg command to extract individual frames from this video, they come out in 4:3

  ffmpeg -y -hide_banner -nostats -loglevel error -i movie.mp4 -vf select='eq(n\,10)+eq(n\,20)+eq(n\,30)+eq(n\,40)',scale=-1:640 -vsync 0 /tmp/ffmpeg_image_%04d.jpg

  

  So I guess my questions are as follows :

  1. what is the relation between display aspect ratio, sample aspect ratio, and the width/height ratio ?
  2. how to I get ffmpeg to output in the correct aspect ratio ?

• What is the difference between ffmpeg command with -codec and without -codec

  26 avril 2018, par Sat

  I am trying to calculate video frozen time, I created mp4 format file with 23seconds frozen.
  I am converting mp4 file into segment(.ts) file using following command

  ffmpeg -i Palivala.mp4 -codec copy -vbsf h264_mp4toannexb -map 0 palivaalaa.ts

  When i directly use video file (Palivala.mp4) or segment file(palivaalaa.ts) which generated from above command, I am getting the result as expected. i.e getting video frozen time as 23seconds.

  But when I use following command

  ffmpeg -i Palivala.mp4  -map 0 palivaalaa.ts

  I am able to see 1second frozen frames then after that 1 frame without frozen immediately next frame frozen and frozen continued for 6seconds again 1 non-frozen frame...................

  1) What is the difference between above 2 commands ?

  2) both commands chooses libx264 ?

• avcodec/vc1 : store color-difference reference field type

  23 avril 2018, par Jerome Borsboom

  avcodec/vc1 : store color-difference reference field type
  The loop filter for P interlace field pictures needs the reference field type.
  
  For luma, the reference field type was already available. Store the reference
  
  field type for color-difference as well.
  Signed-off-by : Jerome Borsboom <jerome.borsboom@carpalis.nl>
  

  • [DH] libavcodec/vc1_mc.c