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• Android video encoding with fr and resolution manipulation

  24 février 2017, par apSTRK

  I want to be able to take a video recorded with an Android device and encode it to a new Resolution and Frame Rate using my app. The purpose is to upload a much smaller version of the original video (in size), since this will be videos 30 min long or more.

  So far, I’ve read of people saying FFmpeg is they way to go. However, the documentation seems to be lacking.

  I have also considered using http opencv http://opencv.org/platforms/android.html

  Considering I need to manipulate the video resolution and frame rate, which tool do you think can do such things better ? Are there any other technologies to consider ?

  An important question is, since this will be long videos, is it reasonable to do the encoding in an android device (Consider power resources, time, etc.)

  Thanks in advance !

• How I can receive MJPEG stream via RTSP with resolution more than 1080p

  21 septembre 2018, par chuchuchu

  There is a problem :
  When I get a video stream with a resolution of 1080 and below - everything is fine.
  But if I select a stream with a resolution higher than 1080 on the camera, an error occurs.
  FFMPEG :

  [mjpeg @ 0x7f5488003e40] [IMGUTILS @ 0x7f5494acb4f0] Picture size 0x0 is invalid

  If I open a stream in the player I get a disparate image :

  [mjpeg @ 0x7fd9f8043b20] error y=91 x=16
  
  [mjpeg @ 0x7fd9f8043b20] error dc

  I repeatedly recompiled and reinstalled various versions of the ffmpeg, the problem is not solved.

  I suspect that there is a restriction for video stream over 1080p, but I can not find any description or solution.
  And I found next string in rfc "RTP Payload Format for JPEG" :

  The maximum width is 2040 pixels.

  but it is dated 1998. I know for certain that this stream on the RTSP receives in the resolution I need, but I can not understand how.

  Please, tell me the way to the solution. I’m using Ubuntu 16.04 amd64.
  Perhaps there is an alternative way to receive a rtsp-stream without using a ffmpeg ?? Since all ways known to me are using ffmpeg.

• FFmpeg - Change resolution of the video with aspect ratio

  18 septembre 2024, par Arthur

  all.

  



  How to change resolution of the video with aspect ratio with FFmpeg ?

  



  There are options 
http://manpages.ubuntu.com/manpages/oneiric/man1/ffmpeg.1.html

  



         -s size
       Set frame size. The format is wxh (ffserver default = 160x128,
       ffmpeg default = same as source).  The following abbreviations are
       recognized:


  



  and

  



         -aspect aspect
       Set the video display aspect ratio specified by aspect.

       aspect can be a floating point number string, or a string of the
       form num:den, where num and den are the numerator and denominator
       of the aspect ratio. For example "4:3", "16:9", "1.3333", and
       "1.7777" are valid argument values.


  



  For example, I have two input videos :

  



  

  • with 200*400 resolution

  


  • with 400*700 resolution

  


  



  I need to make output video with 100*200 resolution.

  



  If I will run ffmpeg with -s 100x200, then second video will have bad aspect ratio.

  



  How can I limit output video by width, with auto aspect ratio by height ?

  



  For example, I want specify for the output video only width 100px and ffmpeg must automatically calculate height with right aspect ratio.

  



  For first video it will be :

  



  200/100=2

  



  400/2=200

  



  Ie 100x200

  



  For second video it will be :

  



  400/100=4

  



  700/4=75

  



  Ie 100x75

  



  Is it possible ?