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• How to specify size of output image in FFmpeg command ?

  30 juillet 2023, par saladguy

  I'm extracting frame images from an MP4 video using ffmpeg in terminal.

  



  I used the command :

  



  ffmpeg -i Video.MP4 Pictures%d.bmp


  



  Problem is that the extracted images have a size of 4.5-5MB ! I want smaller images, say around 1-2 MB. How do I limit the size of output images ?

  


• fate/gif : Remove nonsense requirement

  28 avril 2022, par Andreas Rheinhardt

  fate/gif : Remove nonsense requirement
  It seems as if it was intended to declare fate-gif-color as prerequisite
  
  of the fate-gifenc% tests. Yet the latter do not need anything from
  
  the former, so this would be unnecessary. Furthermore, given that this
  
  line has no associated recipe, it actually cancels implicit rules for
  
  fate-gifenc% instead of adding a prerequisite.
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
  

  • [DH] tests/fate/gif.mak

• HEVC/H.265 interlaced format support in ffmpeg or VLC

  30 décembre 2020, par Ernestas Gruodis

  "Music Box Russia" channel over satellite transmits in HEVC 1920x1080 25fps interlaced - and after recording VLC recognizes file as 50 fps, and resolution 1920x540 - half a height. But on satellite tuner the player works fine - it plays a file as 1920x1080 25fps... When we can expect support for HEVC/H.265 interlaced ? Here is recorded file (Garry Grey & Eva Miller - wtf). Also - a lot of lost frames in VLC player statistics..

  


  EDIT :

  


  I found some interesting info how in HEVC the interlace video content can be indicated here :

  


  


  Unlike to H.264/AVC, interlace-dedicated coding in HEVC is not exist :

  


  

  • No mixed frame-field interaction (like PAFF in H.264/AVC)

  


  • No interlace scanning of transform coefficients

  


  • No correction MVX[1] (or y-component of MV) if current and reference pictures are in different polarity (top-bottom or
bottom-top).

  


  


  However, in HEVC the interlace video content can be indicated
(signaled in VPS/SPS and pic_timing SEI messages the latter are
transmitted for every picture in the sequence). Interlace-related
setting :

  


  


  • in VPS/SPS set general_interlaced_source_flag=1 and general_progressive_source_flag=0. Indeed, the HEVC standard says :

    


    if general_progressive_source_flag is equal to 0 and
general_interlaced_source_flag is equal to 1, the source scan type of
the pictures in the CVS should be interpreted as interlaced only.

    


  


  • in VPS/SPS set general_frame_only_constraint_flag=0

    


  


  • in SPS VUI set field_seq_flag=1 and frame_field_info_present_flag=1. Notice that if these flags are ON
then picture timing SEIs shall be present for each picture.

    


  


  • transmission of Picture Timing SEI per picture with the following parameters :

    


    source_scan_type = 0 to indicate interlace mode
for top field picture signal pict_struct=1 and for bottom field picture pict_struct=2

    


  


  


  


  Perhaps it is possible to pass these parameters to ffmpeg/vlc before playing a file ?