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• Ramp- Slow Motion in IOS

  26 juin 2013, par 2vision2

  I have to do "ramp-slow motion" in a video file along with audio, in-between some frames and need to store the ramped video as a new video.

  Ref : http://www.youtube.com/watch?v=BJ3_xMGzauk (watch from 0 to 10s)

  From my analysis, I've found that AVFoundation framework can be helpful.

  Ref :
  http://developer.apple.com/library/ios/#documentation/AudioVideo/Conceptual/AVFoundationPG/Articles/00_Introduction.html

  Copy and pasted from the above link :

  "
  Editing
  AV Foundation uses compositions to create new assets from existing pieces of media (typically, one or more video and audio tracks). You use a mutable composition to add and remove tracks, and adjust their temporal orderings. You can also set the relative volumes and ramping of audio tracks ; and set the opacity, and opacity ramps, of video tracks. A composition is an assemblage of pieces of media held in memory. When you export a composition using an export session, it's collapsed to a file.
  On iOS 4.1 and later, you can also create an asset from media such as sample buffers or still images using an asset writer.

  "

  Questions :
  Can I "ramp-slow mote" the video/audio file using the AVFoundation framework ? Or Is there any other package available ? If i want to handle audio and video separately, please guide me how to do ?

• How to stream cv2.VideoWriter frames to and RTSP server

  10 juin 2022, par chasez0r

  Environment : Docker, Ubuntu 20.04, OpenCV 3.5.4, FFmpeg 4.2.4

  


  Im currently reading the output of a cv2.VideoCapture session using the CV_FFMPEG backend and successfully writing that back out in real time to a file using cv2.VideoWriter. The reason I am doing this is to drawing bounding boxes on the input and saving it to a new output.

  


  The problem is I am doing this in a headless environment (Docker container). And I’d like to view what's being written to cv2.VideoWriter in realtime.

  


  I know there are ways to pass my display through using XQuartz for example so I could use cv2.imshow. But what I really want to do is write those frames to an RTSP Server. So not only my host can "watch" but also other hosts could watch too.

  


  After the video is released I can easily stream the video to my RTSP Server using this command.

  


  ffmpeg -re -stream_loop -1 -i output.mp4 -c copy -f rtsp rtsp://rtsp_server_host:8554/stream

  


  Is there anyway to pipe the frames as they come in to the above command ? Can cv2.VideoWriter itself write frames to an RTSP Server ?

  


  Any ideas would be much appreciated ! Thank you.

  


• Line 1 : unknown keyword ' file' ffmpeg

  6 janvier 2024, par pops64

  I am trying to run a concation of multiple files using ffmpeg. Followed directions in docs and getting

  


  Line 1: unknown keyword 'file'
[in#0 @ 000001b09b25e840] Error opening input: Invalid data found when processing input
Error opening input file mylist.txt.
Error opening input files: Invalid data found when processing input


  


  I am not sure what is going wrong. The text file appears to be in the correct format.

  


  $clips = Get-ChildItem -Path Y:\****\Test -File -Filter "*.mp4"
$regex = "(?:\w+)-(?:[i]+-)?(?\d+)-(?\d+)-(?:\w+)"
$groupedScenes = $clips | Group-Object {[regex]::Match($_.Name, $regex).Groups["scene_id"].value}
foreach($scene in $groupedScenes)
{
    $sortedScene = $scene.Group | Sort-Object {[regex]::Match($_.Name, $regex).Groups["clip_id"].value -as [int]} 
    foreach($i in $sortedScene) 
    {
        "file 'Y:\*****\Test\$i'" | Out-File mylist.txt -Encoding utf8 -Append
    }
    .\ffmpeg.exe -f concat -safe 0 -i mylist.txt -map 0 -c:v hevc_amf -quality quality -rc cqp -qp_p 26 -qp_i 26 -c:a aac -b:a 128K -y Y:\*****\Test\Procssed\$sortedScene.mp4
    Remove-Item mylist.txt
}