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• duration change after transcode ts

  1er mai 2017, par Feilong Luo

  i have a problem about transcode with ffmpeg

  i want to cover m3u8 to mp4, so i transcode every ts file first, and then concat them to a mp4, but i found that the duration will be bigger than source file.

  source file is :
  http://oc7iy3eta.bkt.clouddn.com/src_20.ts

  after transcode, test file is :
  http://oc7iy3eta.bkt.clouddn.com/test_20.ts

  i use the command as bellow to change to 5fps, and 400k bitrate :

  sudo ffmpeg -analyzeduration 2147483647 -probesize 2147483647 -nostdin -y -v warning -i ./src_20.ts -threads 3 -movflags faststart -metadata:s:v rotate=0 -chunk_duration 520000 -video_track_timescale 25000 -pix_fmt yuv420p -copytb 1 -vcodec libx264 -b:v 400000 -minrate 400000 -maxrate 400000 -bufsize 500k -force_key_frames "expr:gte(t,n_forced*2)" -vsync 1 -r 5 -s 544*960 -acodec libfaac -async 1 ./test_20.ts

  i use ffprobe command to see video info :

  source file info :

  Duration : 00:00:01.26, start : 28.346989, bitrate : 921 kb/s
  Program 1
  Metadata :
  service_name : Service01
  service_provider : FFmpeg
  Stream #0:0[0x100] : Audio : aac ([15][0][0][0] / 0x000F), 44100 Hz, stereo, fltp, 23 kb/s
  Stream #0:1[0x101] : Video : h264 (High) ([27][0][0][0] / 0x001B), yuv420p, 544x960, 10.67 tbr, 90k tbn, 180k tbc

  test file :

  Input #0, mpegts, from ’test_20.ts’ :
  Duration : 00:00:01.62, start : 1.576778, bitrate : 447 kb/s
  Program 1
  Metadata :
  service_name : Service01
  service_provider : FFmpeg
  Stream #0:0[0x100] : Video : h264 (High) ([27][0][0][0] / 0x001B), yuv420p, 544x960, 5 fps, 5 tbr, 90k tbn, 10 tbc
  Stream #0:1[0x101] : Audio : aac ([15][0][0][0] / 0x000F), 44100 Hz, stereo, fltp, 5 kb/s

  =======================================================================

  question

  so , we can see that the duration of src file is 1.26s , but after transcode, the test file is 1.62s.

  why ? can anybody help

• Overlay Image on moving object in Video

  10 mai 2017, par Karandeep Atwal

  I am using FFmpeg to overlay image/emoji on video by this command -

  "-i "+inputfilePath+" -filter_complex "+"[0][1]overlay=enable='between(t,"+startTime+","+endTime+")'[v1]"+" -map [v0] -map 0:a "+OutputfilePath;  

  But above command only overlay image over video and stays still.

  In Instagram and Snapchat there is New pin feature . I want exactly same ,eg blur on moving faces or as in below videos -

  

  Here is link.

  Is it possible via FFmpeg ?

• Python-Opencv Write x264 video on memory buffer

  9 novembre 2016, par faxcon

  I have a problem for writing x264 video(or single frame) on memory buffer. In opencv for images, imencode and imdecode do this task. But i want save x264 video frame for lower memory usage and sending on internet. I am able to with jpeg but jpeg size bigger than x264 video frame and quality much worser. I searched but i can’t find how i write video frame on buffer.

  Here is the example code to taking frames on webcam

          import numpy as np
  
          import cv2
  
  
  
  
  
          cap = cv2.VideoCapture(0)
  
          cap.set(3,320)
  
          cap.set(4,240)
  
          cap.set(5,30)
  
          # Define the codec and create VideoWriter object
  
          fourcc = cv2.VideoWriter_fourcc(*'x264')
  
          out = cv2.VideoWriter('.....sample.avi',fourcc, 30.0, (320,240))
  
  
  
          while(cap.isOpened()):
  
              ret, frame = cap.read()
  
              if ret==True:
  
                  cv2.imshow('frame',frame)
  
                  out.write(frame) #I want to write memory not disk
  
                  if cv2.waitKey(1) & 0xFF == ord('q'):
  
                      break
  
              else:
  
                  break
  
  
  
          # Release everything if job is finished
  
          cap.release()
  
          out.release()
  
          cv2.destroyAllWindows()