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• How to correctly detect window with xdotool in bash script

  24 mai 2020, par wasd

  I'm trying to record screen and also input from my webcam. To show image from a webcam I use ffplay. However I want it to be placed in a specific location of my screen. To do so I use xdotool and following bash script :

  



   #!/bin/bash                                                                                                                                                                                                                                   
 ffplay -i /dev/video0 &                                                                                                                                                                                       
 res=$!                                                                                                                  
 echo $res                                                                                                               
 window_pid=$(xdotool search --pid $res)                                                                                       
 echo $window_pid
 xdotool windowmove $window_pid 1200 200                                                                                                       
 wait


  



  For some reason I get correct process id res but nothing for the window_pid. If I run similar commands in terminal it works correctly (I run ffplay in one terminal instance and the rest of commands in another). What am I missing here ?

  


• ffmpeg : How to add an image to the end of a video, freeze framing the last frame and using a fade

  26 novembre 2019, par Jeremy Thomerson

  (I’ve looked at a number of other similar questions, but can’t find any with an answer that actually works)

  I often need to combine a short video clip with in image. Typically, the video clip is a short explanation of a concept, followed by an image that helps the user visualize the concept. Rarely do the frame sizes / resolution of the video and image match. Typically, I need every second of the video clip to display, so even though I would like a cross-fade between the video and image, I’d like to freeze-frame the final frame of the video, and then cross-fade between that frozen frame and the following image.

  I’d like both the video and image, despite the disparity in their resolutions, to "fit to frame", such that I get an output that’s either a) the size of the larger asset, or b) some fixed size (like 720p), and in either case, both the image and video are scaled to fit into those dimensions, while maintaining their original aspect ratio.

  For example, given the following two assets (video and image), how could I accomplish what’s described above ? (Note : these assets are just ones I found that are available for examples, and not the actual type of content I’d be using ; however, they do accurately represent the disparity in resolution and aspect ratio I’d often have between video and image file).

  • https://file-examples.com/wp-content/uploads/2017/04/file_example_MP4_640_3MG.mp4
  • https://upload.wikimedia.org/wikipedia/commons/e/e8/World_blank_map_countries.PNG

  Bonus : At times, I’d like to :

  1. Reverse the order (image, and then video), or
  2. Have a video and then multiple images, one after the other, faded between each, or
  3. Video, fade to image, then more video

  Note : I’m running ffmpeg on Mac / OSX, installed via brew

  Thanks so much if you can help !

• Can't record S-Video with avconv

  16 avril 2014, par Ertain

  I've been trying to record feed from my S-Video cable using avconv. I am able to record composite video with avconv, but the quality isn't the best. To set the input, I use v4l2-ctl -i $n, where $n is either 0 for composite, or 1 for S-Video. I tried to use v4l2-ctl -i 1 to set the input, but that doesn't work. Oddly enough, when I use tvtime or qv4l2 I can view the video.

  I am able to record audio, just not the video. In tvtime I can get audio as well as video. Also, I was able to record the S-Video with ffmpeg using the -channel option. ffmpeg, btw, can't record the audio, and recording the separate audio isn't an option.

  Edit : as per Anton's request, here's the command I use to capture video with avconv.

  avconv -f video4linux2 -i /dev/video0 -f alsa -i hw:2,0 -vcodec mpeg4 -vtag xvid -b 8000k -r 30000/1001 -acodec \
  
  libmp3lame -ar 48000 -ac 2 -ab 192k -aspect 16:9 -vf yadif=0,scale=1200:800 -y test.avi

  And here's the output from this command :

  avconv version 0.8.6-6:0.8.6-0ubuntu0.12.10.1, Copyright (c) 2000-2013 the Libav developers
  
    built on Apr  2 2013 17:02:16 with gcc 4.7.2
  
  [video4linux2 @ 0x982340] Estimating duration from bitrate, this may be inaccurate
  
  Input #0, video4linux2, from '/dev/video0':
  
    Duration: N/A, start: 1368113780.210591, bitrate: 165722 kb/s
  
     Stream #0.0: Video: rawvideo, yuyv422, 720x480, 165722 kb/s, 29.97 tbr, 1000k tbn, 29.97 tbc
  
  [alsa @ 0x982ba0] Estimating duration from bitrate, this may be inaccurate
  
  Input #1, alsa, from 'hw:2,0':
  
    Duration: N/A, start: 854.715783, bitrate: N/A
  
      Stream #1.0: Audio: pcm_s16le, 48000 Hz, 2 channels, s16, 1536 kb/s
  
  Incompatible pixel format 'yuyv422' for codec 'mpeg4', auto-selecting format 'yuv420p'
  
  [buffer @ 0x9930a0] w:720 h:480 pixfmt:yuyv422
  
  [yadif @ 0x997960] mode:0 parity:-1 auto_enable:0
  
  [yadif @ 0x997960] auto-inserting filter 'auto-inserted scaler 0' between the filter 'src' and the filter 'Parsed filter 0 yadif'
  
  [scale @ 0x985a80] w:720 h:480 fmt:yuyv422 -> w:720 h:480 fmt:yuv420p flags:0x4
  
  [scale @ 0x998000] w:720 h:480 fmt:yuv420p -> w:1200 h:800 fmt:yuv420p flags:0x4
  
  Output #0, avi, to 'test.avi':
  
    Metadata:
  
      ISFT            : Lavf53.21.1
  
      Stream #0.0: Video: mpeg4, yuv420p, 1200x800 [PAR 32:27 DAR 16:9], q=2-31, 8000 kb/s, 29.97 tbn, 29.97 tbc
  
      Stream #0.1: Audio: libmp3lame, 48000 Hz, 2 channels, s16, 192 kb/s
  
  Stream mapping:
  
        Stream #0:0 -> #0:0 (rawvideo -> mpeg4)
  
        Stream #1:0 -> #0:1 (pcm_s16le -> libmp3lame)