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• Fast and Precise Video Clip Extraction using FFmpeg [closed]

  30 octobre 2023, par smjadeja

  I'm currently using FFmpeg to extract a specific segment from a video. My goal is to get a precise extraction that is also done quickly.

  


  My current command, which aims for precision, is as follows :

  


  command_2 = ['ffmpeg','-y','-i', input_video_path, "-ss", "00:00:03.567", "-to", "00:00:14.678", "-async", "1", "-strict", "-2", "with_sync.webm"]


  


  However, this takes a significant amount of time to extract the desired clip.

  


  Previously, I utilized the command below, which is much faster but occasionally results in a video that stutters or isn't as precise :

  


  command_1 = ["ffmpeg", "-i", input_video_path, "-ss", "00:00:03.567", "-to", "00:00:14.678", "-c:v", "copy", "-c:a", "copy", "without_sync.webm"]


  


  


  1. Why is there a drastic difference in the extraction time between the two commands ?

     


  


  2. How can I achieve both speed and precision in my video clip extraction ?

     


  


  


• fastest ways of cropping a fixed size image into 9 fixed size crops

  18 septembre 2022, par bit_scientist

  I have thousands of images in a folder and I need to crop each image(3840x2160) into 9 crops (1280x720) with the fastest way possible. The cropped images should preserve all the details of the original image as it may contain small objects of interest. I found that image_slicer does the job, but not sure about its speed.

  


  from image_slicer import slice
slice('cake.png', 9)


  


  I also looked at PIL (image_slicer uses it), Imagemagick and some other similar libraries, but was not able to evaluate their speed. Maybe ffmpeg has some line command to achieve my goal.

  


  Eventually, I need a Windows executable file where a user inserts a full path to images and gets cropped images for each image in the new folder.

  


• How to use ffmpeg to record audio from a video for first 10seconds in Python

  2 novembre 2022, par S Andrew

  I have rtsp stream coming from a camera which also has audio. My goal is to save the audio. To do this, I have below code :

  


  import ffmpeg&#xA;ffmpeg.input("rtsp://john:<pwd>@192.168.10.111:5545/Streaming/Channels/291/").output("test.wav", map="0:a:0").run&#xA;</pwd>

  


  When I terminate the python script, it saves the test.wav file which has just the audio from the rtsp stream. Now I am trying to save the first 10sec from the stream into 1 file and then the next 10sec in another file and then it keeps on goining untill terminated.

  


  To do this, I have thought of putting the ffmpeg stream in a seprate thread and to schedule that thread to run every 10 sec. This way a new stream will create which will save the audio for 10sec and will exit, and then this keeps on going. But to achieve this, I need to know how can we just save the intial 10 sec from the stream. Please help thanks.