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• Saving Raw Uncompressed Video Files using OpenCv, Gstreamer, and/or FFMPEG ?

  20 septembre 2022, par adav0033

  I have been trying to implement the cv::VideoWriter function from OpenCV to generate a an uncompressed (raw) video file. I started this because of a statement within the OpenCV Documentation which I will link here along with the statement.

  


  cv::VideoWriter::VideoWriter    (   const String &  filename,
int     fourcc,
double  fps,
Size    frameSize,
bool    isColor = true 
)       


  


  "If FFMPEG is enabled, using codec=0 ; fps=0 ; you can create an uncompressed (raw) video file."

  


  Ref. https://docs.opencv.org/3.4/dd/d9e/classcv_1_1VideoWriter.html

  


  However whilst troubleshooting the function I came across the refuting statement,

  


  " VideoCapture and VideoWriter do not provide interface to access raw compressed video stream, except maybe MJPEG in some cases.
Make sure you actually use FFmpeg backend by setting apiPreference parameter : VideoWriter("outfile.avi", cv2.CAP_FFMPEG, ...)"

  


  Ref. https://github.com/opencv/opencv/issues/14573

  


  I am now confused about how I go about writing the cv::VideoWriter function to satisfy the requirements to create a raw uncompressed video file (.avi) and if it is even possible. If it is not possible how do I achieve the outcome of saving an raw uncompressed video file, as I assume it would use some combination of FFMPEG, OpenCV,or Gstreamer.

  


  Note : My code is implemented in c++

  


• vc1dec : redesign the intensity compensation

  24 avril 2013, par Michael Niedermayer

  vc1dec : redesign the intensity compensation
  The existing implementation had little to do with VC1.
  
  This could be implemented by adjusting the reference frames
  
  ithemselfs but that would make frame multi-threading difficult.
  Signed-off-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] libavcodec/vc1.c
  • [DH] libavcodec/vc1.h
  • [DH] libavcodec/vc1dec.c

• FFMPEG DASH - Live Streaming a Sequence of MP3 Clips

  4 décembre 2018, par Daniel

  I am attempting to create a online radio application using FFMPEG - an audio only DASH stream.

  I have a directory of mp3 clips (all of the same bitrate and sample size) which I am encoding to the AAC format and outputting to a mpd.

  This is the current command I am working with to stream a single mp3 file :

  ffmpeg -re -i <input />.mp3 -c:a aac -use_timeline 1 -use_template 1 -window_size 5 -f dash <out>.mpd
  
  </out>

  (Input and output paths have been substituted for < input >.mp3 and < output >.mpd in this snippet)

  I am running a web server and have made the mpd accessible on it. I am testing the stream using VLC player at the moment.

  The problem :
  Well, the command works, but it will only work for one clip at a time. Once the next command is run immediately proceeding the completion of the first, VLC player will halt and I need to refresh the player to continue.

  I’m aiming for an uninterrupted stream wherein the clips play in sequence.
  I imagine the problem is that a new mpd is being created with no reference to the previous one, and what I ought to be doing is appending segments to the existing mpd - but I don’t know how to do that using FFMPEG.

  The question : Is there such a command to append segments to a previously existing mpd file in FFMPEG ? or am I coming at this problem all wrong ? Perhaps I should be using FFMPEG to format the clips into these segments, but then adjusting the mpd file manually.

  Any help or suggestions would be very much appreciated !