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• How to extract orientation information from videos ?

  23 décembre 2016, par Sid

  After surfing through tons of documentation on the web it seems that the iPhone always shoots the video at a 480x360 aspect ratio and applies a transformation matrix on the video track. (480x360 may change but its always the same for a given device)

  Here is a way of modifying the ffmpeg source within a iOS project and accessing the matrix http://www.seqoy.com/correct-orientation-for-iphone-recorded-movies-with-ffmpeg/

  Here is a cleaner way of finding the transformation matrix in iOS-4
  how to detect (iphone sdk) if a video file was recorded in portrait orientation, or landscape

  How can the orientation of the video be extracted in either of the options below -
  
   iOS 3.2
  
   ffmpeg (through the command line server side)
  
   ruby
  

  Any help will be appreciated.

• ffprobe not showing language tag for ASS files in Ubuntu

  9 juillet 2023, par Efraín

  This is something that has me totally lost, because I'm not sure what could I have done, but from one week to another, "language" stopped appearing in the tags of an ASS track on a MKV. I know this just started to appear, because just last week I ended working on an script to detect the language of tracks, and today that I decided to test it again, I noted that it started to fail, and from my debug it's because ffprobe is now printing this

  


  {
    "index": 2,
    "codec_name": "ass",
    "codec_long_name": "ASS (Advanced SSA) subtitle",
    "codec_type": "subtitle",
    "codec_tag_string": "[0][0][0][0]",
    "codec_tag": "0x0000",
    "r_frame_rate": "0/0",
    "avg_frame_rate": "0/0",
    "time_base": "1/1000",
    "start_pts": 0,
    "start_time": "0.000000",
    "duration_ts": 1430816,
    "duration": "1430.816000",
    "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": {
        "BPS-eng": "85",
        "DURATION-eng": "00:23:34.830000000",
        "NUMBER_OF_FRAMES-eng": "262",
        "NUMBER_OF_BYTES-eng": "15128",
        "_STATISTICS_WRITING_APP-eng": "mkvmerge v40.0.0 ('Old Town Road + Pony') 32-bit",
        "_STATISTICS_WRITING_DATE_UTC-eng": "2023-07-02 11:29:54",
        "_STATISTICS_TAGS-eng": "BPS DURATION NUMBER_OF_FRAMES NUMBER_OF_BYTES"
    }
}


  


  Where it should be a field called "language" in the "tags", like this(Note that other file types, like SRT, or audio tracks show it correctly)

  


  "tags": {
    "language": "eng",
    "BPS-eng": "128000",
    "DURATION-eng": "00:23:50.813000000",
    "NUMBER_OF_FRAMES-eng": "61620",
    "NUMBER_OF_BYTES-eng": "22893018",
    "_STATISTICS_WRITING_APP-eng": "mkvmerge v40.0.0 ('Old Town Road + Pony') 32-bit",
    "_STATISTICS_WRITING_DATE_UTC-eng": "2023-07-02 11:29:54",
    "_STATISTICS_TAGS-eng": "BPS DURATION NUMBER_OF_FRAMES NUMBER_OF_BYTES"
}


  


  The weird part is that is the same file I used for testing(And it worked), and I haven't edited it, so I'm not sure why is this happening, Does someone knows if I might have messed up something installing a library for another thing that might have caused it ?

  


  Just in case is necessary, this is the command I use : ffprobe -v quiet -print_format json -show_streams <file></file>

  


• aviobuf : Increase the default SHORT_SEEK_THRESHOLD to 32 KB

  30 octobre 2020, par Martin Storsjö

  aviobuf : Increase the default SHORT_SEEK_THRESHOLD to 32 KB
  The previous threshold, 4 KB, maybe was reasonable when it was set
  
  (in 2010), but in today's settings and with typical network speeds
  
  and data sizes, it's pretty small. 32 KB probably is a more reasonable
  
  default now, regardless of input.
  This changes the test references for two seek tests.
  When using the normal seek function, which boils down to the lseek(2)
  
  function, a seek to an out of bounds position doesn't return an error,
  
  but that condition is only reported when doing the subsequent read
  
  (which returns EOF). When doing more seeks by fast forwarding, the
  
  fact that the seeked to destination is out of bounds is noticed and
  
  reported sooner in these cases.
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DH] libavformat/aviobuf.c
  • [DH] tests/ref/seek/lavf-al
  • [DH] tests/ref/seek/lavf-ul