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• setting bit rates in creating video from images in ffmpeg not working

  2 mai 2014, par mast kalandar

  I have a HQ video of one second

  Some information of this video is as below

  Dimensions : 1920 x 1080    
  
  Codec : H.264    
  
  Framerate : 30 frames per second    
  
  Size : 684.7 kB (6,84,673 bytes)
  
  Bitrates : 5458 kbps

  I have extracted frames from video

  ffmpeg -i f1.mp4 f%d.jpg

  All images are of 1920 x 1020 pixels by default 30 frames are generated (f7_1.jpg, f7_2.jpg,.....,f7_30.jpg)

  I have added some texts and objects to these images (without changing dimensions of any image, all 30 images are still of 1920 x 1020 pixels)

  Now I am trying to merge all these images to create single video (of 1 second)

  I referred this official document, I have run below command

  ffmpeg -f image2 -i f7_%d.jpg -r 30 -b:v 5458k foo_5458_2.mp4

  Video created is also of one second, thing is its bit rates are higher then the original one. New video has 6091 kbps bit rates, while I expect are 5458 kbps only.

  Because of higher bits, its gets finish very quickly compare to original video in video player.

  Is there any thing I missing ??

  And I don’t know what is exact meaning and job of -f image2 option, when I run command without this option, I am getting same video.

• How to build FFmpeg into static libs for MacOS for usage in a C++ application

  29 septembre 2017, par Programist

  How can I build static libs of FFmpeg for MacOS.

  All I need is to make a .mp4 with H264 codecs out of some images using ffmpeg. Dont need the build to be fully loaded with features.

  I built it for iOS using a script from here which was really simple and smooth. It checked out the code & smoothly built the output into include/ & lib/ folders.

  I checked the official FFmpeg site offers excutables for MacOS. But I need static libs to use in my C++ code.

  Question :
  I want to build FFmpeg into static libs for MacOS only for creating .mp4 videos. How can I do it OR
  How can I change this script to do the same for MacOS ?

  PS :
  I am Mac OS Sierra with Xcode9

• What is the best way to get duration of a video using ffprobe (ffmpeg) ?

  15 juin 2023, par promaxdev

  Most of the solutions to get duration revolves around parsing the output to get the duration. Even FFProbe official documentation here says that there is no duration stored for MKV, webm, etc.

  


  Take the below examples.

  


  ffprobe -v error -i <inputmkv> -show_entries stream=...,duration,.. -of default=noprint_wrappers=1&#xA;</inputmkv>

  


  This gives me the below output. This is not having duration.

  


  

  


  But when I run the same command differently like below, I am getting this output but having duration. Just removed '-v error' part.

  


  ffprobe -i <inputmkv> -show_entries stream=...duration,... -of default=noprint_wrappers=1 &#xA;</inputmkv>

  


  

  


  If you notice the same command shows the duration in one place and not in another place.

  


  So my question is, What is the best way to get duration in ffmpeg, especially for the video streams ?

  


  Edit : I have already explored decoding using null mux option. But that is a costly operation and also need to parse the output.