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• vdpau : add av_vdpau_bind_context()

  4 octobre 2014, par Rémi Denis-Courmont

  vdpau : add av_vdpau_bind_context()
  This function provides an explicit VDPAU device and VDPAU driver to
  
  libavcodec, so that the application is relieved from codec specifics
  
  and VdpDevice life cycle management.
  A stub flags parameter is added for future extension. For instance, it
  
  could be used to ignore codec level capabilities (if someone feels
  
  dangerous).
  Signed-off-by : Anton Khirnov <anton@khirnov.net>
  

  • [DBH] doc/APIchanges
  • [DBH] libavcodec/vdpau.c
  • [DBH] libavcodec/vdpau.h
  • [DBH] libavcodec/vdpau_internal.h
  • [DBH] libavcodec/version.h

• accurate cutting of video (+ audio) with ffmpeg [migrated]

  4 novembre 2012, par Pete Oakey

  I want my website to allow users to accurately create their own clips from a source video I provide.

  I have a source video file that I first want to convert to something suitable for a website :

  Input #0, matroska,webm, from 'source.mkv': 
  
  Duration: 00:28:18.57, start: 0.000000, bitrate: 10183 kb/s 
  
  Stream #0:0: Video: h264 (Constrained Baseline), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], 23.98 fps, 23.98 tbr, 1k tbn, 48 tbc (default)
  
  Stream #0:1: Audio: mp3, 44100 Hz, stereo, s16, 128 kb/s (default)

  So I use ffmpeg to convert it like so :

  ffmpeg -i source.mkv -c:v libx264 -c:a aac -strict experimental -vf scale="960:-1" source.mp4

  Watching this video back it is good enough quality and small enough file size for my needs, and loads/plays on my website.

  So I have a webpage that lets users select a start and endpoint on this video - and create a clip. Here's an example of the ffmpeg command that I use for that :

  -ss 577.920 -i source.mp4 -t 011.980 -codec:v copy -codec:a copy -vf scale="960:-1" clip1.mp4

  The problem is the clip is not always time-accurate enough. Usually the audio is accurate enough but the video stops half a second early or something.

  Is there any way to make this accurate and in-sync to say, 0.2 of a second ?

  EDIT :
  Adding -force_key_frames 00:00:00.2 didn't help.

• How to use delogo with ffmpeg when logo starts at y=0

  22 avril 2021, par Valentin

  I have a 1920x800 video, all content, no black bars. At the top of the frame (y=0) there is a station logo I want to remove (presumably the original capture was cropped, leaving a half of a station logo inside the usable frame). Since the logo I'm trying to remove starts at the very top of the frame and because the default band=1 option that cannot be changed anymore (the option was seemingly removed from the API), the command needs to take it into account and make y=1 :

  


  ffmpeg -i video.mp4 -vf "delogo=x=1696:y=1:w=113:h=32:show=1" output.mp4


  


  but this breaks the interpolation, since that 1px on top is completely dirtying the box :
Logo with show=1 so we see the problem

  


  Tries with y=0 fail with or without trying to specify the band width (with band=0 or the alias t=0) :

  


  ffmpeg -i video.mp4 -vf "delogo=x=1696:y=0:w=113:h=33:band=0" output.mp4
[Parsed_delogo_0 @ 0000020528a7cf00] Option 'band' not found
ffmpeg -i video.mp4 -vf "delogo=x=1696:y=0:w=113:h=33:t=0" output.mp4
[Parsed_delogo_0 @ 000002b9b87acf40] Option 't' not found
ffmpeg -i video.mp4 -vf "delogo=x=1696:y=0:w=113:h=33" output.mp4
[delogo @ 0000023d971cd000] Logo area is outside of the frame.


  


  Is there a solution to this ?