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• Video Concat using ffmpeg [closed]

  17 juin 2022, par Milan K Jain

  ffmpeg -i url1 -i url2 -i url3 -i url4 -filter_complex "[0:v:0]scale=1920:1080[c1] ; [1:v:0]scale=1920:1080[c2] ; [2:v:0]scale=1920:1080[c3] ; [3:v:0]scale=1920:1080[c4], [c1] [0:a:0] [c2] [1:a:0] [c3] [2:a:0] [c4] [3:a:0] concat=n=4:v=1:a=1 [v] [a]" -map "[v]" -map "[a]" /Users/myname/Downloads/f1-2017-07-12.mp4 -y

  


  In Place of url I want to give link U get from after storing my video in amazon s3 bucket
Someone pls help

  


• ffmpeg FPS information mismatch with the video

  8 décembre 2017, par Adorn

  I have a bunch of videos with some statistics of what is happening inside a video. One such piece of information is given in terms of time of the video in seconds up to one decimal point.

  To get the FPS of a video, I am using ffmpeg -i

  But when I manually compute one particular frame’s time using given FPS, it does not match.

  For example, ffmpeg outputs FPS = 30.

  I look at the video statistics, the frame at the 156.8 = 2.368 has to be
  4704'th frame. I open the video using ’skvideo’, read all the frames, and view the 4704'th frame. It is some frame around time 2.12 ?. I checked multiple such instances in multiple videos and this is a common behavior.

  I do not understand why this is so and how can I get around the problem ?

  As such I am not bounded by ffmpeg. Skvideo is being used to read the videos. I tried opencv, as of now it does not work with VideoCapture, and reinstalling it is costly for me time wise. But I guess ’opencv/skvideo’ should not matter, one can count the frames manually as well.

  So, in the solution, I am looking out for -

  1. Given timestamps of inside of a video, how can I find a frame of that particular time location ?

  2. In case someone might have already worked on this, this is related to THUMOS dataset. I am on Ubuntu 16.04

  EDIT_1

  Actually I can be more specific as it is a publicly available data. The time bounds are of an important activity. For example, in a video, when does basketball dunk occurs ? It is given in pairs - [start end]. Some videos have multiple activities, some have only one.

  Here is a sample video, and following are the activity times.

  [[  16.5, 20.8],
  
  [  26.6, 32.2],
  
  [  34.8, 42.1],
  
  [  47.8, 50.0],
  
  [  58.1, 62.9],
  
  [  65.6, 67.2],
  
  [  68.5, 74.0],
  
  [  76.4, 78.3],
  
  [  78.7, 79.8],
  
  [  80.8, 82.1],
  
  [  85.0, 87.3],
  
  [  90.1, 91.4],
  
  [  98.5, 100.3]]

  I also tried checking manually, 32.87 FPS "almost" works for few videos but not for all. and almost means it is off by 10 frames. This is a huge difference for my task, and I need exact frame.

  Also, there has to be some way, because it can be visually observed with multiple video players that times in the dataset are correct.

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

  13 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 10 sec from the stream into 1 file and then the next 10sec in another file and then it keeps on going until terminated.

  


  To do this, I have thought of putting the ffmpeg stream in a separate 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 initial 10 sec from the stream.