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• Video from VFR Image Sequence

  12 octobre 2014, par Stryker33

  I am using ffmpeg to create video from an image sequence that is taken from the Android Camera’s PreviewCallback method onPreviewFrame...

  The images are written to a pipe that is connected to ffmpeg’s stdin using the command :

  ffmpeg -f image2pipe -vcodec mjpeg -i - -f flv -vcodec libx264

  The problem that’s arising is that the output video is very short as compared to the actual recording time and all of the frames are shown very rapidly...

  But when the frame size is set to the lowest supported preview size, the video appears to be in sync with the actual recording time...

  As far as I reckon this seems to be an issue related to the frame rate of the input image sequence and that of the output video...

  But the main problem is that the frames that are generated from onPreviewFrame are of variable rates...

  Is there any way to construct a smooth video from an image sequence having variable frame rate...?

  Also, the image sequence is muxed with audio from the microphone which also appears to be out of sync with the video...

  Could the video generated using the above process and audio from the microphone be muxed in perfect synchronization...?

• How to draw a waveform from an RTSP audio using ffmpeg and Python

  9 mars 2023, par S Andrew

  I have a Hikvision camera. Using ffmpeg, I can extract the audio from it and save it in wav file using below code :

  


  import os
os.system("ffmpeg -i rtsp://admin:password@192.168.0.27:554/Streaming/Channels/101/ -q:a 0 -map a -t 10 file.wav")


  


  It creates file.wav file and when played I can hear the audio recorded from camera. Now I am planning to draw the waveform of these audio's. For this I have below code :

  


  os.system("ffmpeg -i rtsp://admin:password@192.168.0.27:554/Streaming/Channels/101/ -filter_complex showwavespic -frames:v 1 output.png")


  


  and below is the output I get after pressing q

  


  [q] command received. Exiting.

Finishing stream 0:0 without any data written to it.
Output #0, image2, to 'output.png':
  Metadata:
    title           : Media Presentation
    encoder         : Lavf59.26.100
  Stream #0:0: Video: png, rgba, 600x240 [SAR 1:1 DAR 5:2], q=2-31, 200 kb/s, 1 fps, 1 tbn
    Metadata:
      encoder         : Lavc59.36.100 png
frame=    0 fps=0.0 q=0.0 Lsize=N/A time=00:00:00.00 bitrate=N/A speed=   0x    
video:0kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown
Output file is empty, nothing was encoded (check -ss / -t / -frames parameters if used)


  


  and there is no file generated. I tried the above code with and mp3 file and it generated the output.png with waveform. How can I resolve the issue ?

  


• YUV Raw frames to video stream

  30 septembre 2014, par Ahmed Nassar

  Im trying to stream raw YUV frames in an array generated in a C++ program to video using FFPEG. Can anyone point me to the right direction ?