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• Reload scrolling drawtext filter in ffmpeg only while off screen

  3 janvier 2021, par J45p3r

  I have a drawtext filter in ffmpeg that scrolls right to left on the bottom of the screen showing current weather data. The problem I have is the text file containing the weather data updates every 2 seconds and when the weather readings change the length of the text also changes. This causes the looping text to jump around. I tried using a conditional statement to set reload to 1 only if x was greater than the screen width but it seems reload doesn't evaluate conditional statements. Can anyone think of a way around this problem so that the text will only update once per loop, while off screen ?

  


  My command :

  


  ffmpeg -thread_queue_size 512 -re -rtsp_transport tcp -i "rtsp://192.168.x.x:7447" -i /YouTubeStream/CupolaCam/logo.png -f lavfi -i anullsrc -filter_complex "[0:v][1:v]overlay=20:925","drawbox=x=0:y=ih-35:w=iw:h=35:color=black@0.75:t=fill","drawtext=fontsize=30:fontcolor=white@.8:line_spacing=10:fontfile=/usr/share/fonts/truetype/Courier_Prime/CourierPrime-Regular.ttf:textfile=/YouTubeStream/CupolaCam/weatherdata/curtempformatted:y=h-line_h-5:x='if(gt(x\,-tw),w-mod(4*n\,w+tw)\,w)':reload=1" -c:v libx264 -profile:v high -bf 2 -g 15 -crf 18 -pix_fmt yuv420p -c:a aac -profile:a aac_low -b:a 128k -movflags faststart -f flv "rtmp://a.rtmp.youtube.com/live2/stream_key"


  


  The video on youtube : https://www.youtube.com/watch?v=Av6k8bf_2Zc

  


• capture video conference between 1:1 user and broadcast to an rtmp url

  20 octobre 2020, par Asif Alamgir

  I am currently working on nodejs and socket app that is currently doing 1:1 video conference that is using webrtc. Videos are two separate element in the html and i would like to merge them together so that i can broadcast to rtmp url for public view (2:many). Is this possible

  


  For webrtc, i followed this tutorial https://www.youtube.com/watch?v=DvlyzDZDEq4, and for broadcasting i am using ffmpeg which current does 1 video stream.

  


  Please confirm if this is doable

  


  Update

  


  I was able to merge the video using
https://www.npmjs.com/package/video-stream-merger

  


  And now the final issue

  


  i am receiving merger.result which is merged stream and I tried to create a mediaRecorder object. Callback method for MediaRecorder ondataavailable is called only once but not every 250ms which i need to broadcast to youtube. How can i do this ?

  


  var merger = new VideoStreamMerger(v_opts);
...
...
merger.start()
myMediaRecorder = new MediaRecorder(merger.result);
myMediaRecorder.start(250);
myMediaRecorder.ondataavailable = function (e) {
    console.log("DataAvailable")
    //socket.emit("binarystream", e.data);
    state = "start";
    //chunks.push(e.data);
}


  


• Poor video quality in first few frames using video output options in gganimate

  27 janvier 2021, par Nautica

  I'm trying to export some animations I've made using gganimate through video format as the gifs I'm creating are quite large.

  


  Sample code :

  


  library(gganimate)

p <- ggplot(mtcars, aes(factor(cyl), mpg)) +
  theme_dark() +
  theme(panel.grid = element_line(colour = "white")) +
  geom_boxplot() +
  transition_states(
    gear,
    transition_length = 2,
    state_length = 1
  ) +
  enter_fade() +
  exit_shrink() +
  ease_aes('sine-in-out')

anim_save("example.mp4",
          animate(
            p,
            nframes = 450,
            fps = 25,
            width = 1280,
            height = 720,
            type = "cairo",
            start_pause = 50,
            end_pause = 50,
            renderer = av_renderer()
          ))


  


  Produces the video seen here : https://vimeo.com/505019987

  


  With the standard ggplot2 theme : https://vimeo.com/505020822

  


  This is another example of something I made using gganimate : https://www.youtube.com/watch?v=fHzjl_z_sSo

  


  You can see that the video quality in the first few frames are very bad. In the video with the standard ggplot2 theme and the YouTube video, the gridlines and watermark text are not visible at the start but fade in much later. I don't know much about video codecs but I assume it has something to do with the ffmpeg library the av package/av_renderer() is using. Has anyone experienced something like this ?