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• Issues implementing video Steganography using C# and ffmpeg [closed]

  25 juin 2012, par RAZER

  I'm trying to implement video steganography using c# and ffmpeg.
  The logic is as follows :

  -get bitmap frames from a video using ffmpeg argument
  (" -i d :\video.avi -r 25 d :\images\image-%5d.bmp")

  -hide data within lsb of bitmap data, starting from the first frames.

  -get video from the encode bitmap frames using ffmpeg argument
  (" -r 25 -i d :\images\image-%5d.bmp d :\out.avi")

  -now to decode hidden data, again get bitmap frames from above created video and perform decoding by
  extracting data from lsb of bitmap data.

  But the problem is the last step i cannot get the exact data that was hidden.
  I don't know what's go'in on, can anybody help me with the issue.

• v4l2 Repeating headers causing issues with FFmpeg

  11 septembre 2019, par AlexVestin

  I’m trying to stream from a raspberry pi using the python library aiortc with some modification to allow use the hardware encoding the rpi provides.

  The issue is if I the use v4l2 control repeat_sequence_header=0, the server is never sent any PPS or SPS at all, and is just sent nal unit types 1 and 5. So this makes the decoder on the server gives this error on every frame :

  failed to decode, skipping package: [Errno 1094995529] Invalid data found when processing input (16: h264)
  
  non-existing PPS 0 referenced
  
  decode_slice_header error
  
  no frame!

  However with repeat_sequence_header enabled the decoder complains on sending the SPS and PPS that the frame_num is resetting with

  Frame num change from 199 to 0
  
  decode_slice_header error

  So is there any way to tell the decoder that the frame_nums will be repeating, or to tell v4l2 to keep counting the frames up ?

• Problems getting real width and height of videos

  1er mai 2022, par Eduardo

  I'm having a problem when I upload videos. The thing is that I record my videos with my cellphone in vertical way and when I download them to my computer or pass them through whatsapp they still look vertical, I can still watch them in vertical way as I recorded them, but when I try to upload them on my website using PHP and FFMPEG I always get horizontal resolutions.

  


  I use this command to get the width of my videos :

  


  $width = $video_attributes['width'] ;

  


  The variable $video_attributes is an array that comes from a FFMPEG function that returns an array with the data related to the video.

  


  Somebody could help me out with some ideas about what I'm doing wrong ?

  


  I need to get the vertical resolution so my videos will be displayed in vertical containers in my website.

  


  Thanks in advance :)