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• Node js fluent-ffmpeg silencedetect info to CSV

  6 août 2023, par Eugene

  I am trying get timestamps of in and out points of silent parts of an audio file. The duration of the silent part is 5-7sec, sometimes the part have some random single noises.
Ideally as a final result I want get JSON or csv file with all info

  


  I am new to nodeJS and I am not sure how to access the outputs of the ffmpeg 'silencedetect' filter. I have been trying to console.log output of the code below but it didn't work


  


  


  var ffmpeg = require('fluent-ffmpeg');
ffmpeg(audioPath)
  .audioFilters('silencedetect=n=-50dB:d=5');

  


  


  



  

  


• Does Facebook multicast or unicast the live videos to its viewers ?

  14 avril 2018, par Kamran Zahoor

  This is how a live stream goes from one broadcaster to millions of viewers :

  1. A broadcaster starts a live video on their phone.
  2. The phone sends a RTMP stream to a Live Stream server.
  3. The Live Stream server decodes the video and transcodes to multiple bit rates.
  4. For each bit rate a set of one-second MPEG-DASH segments is continuously produced.
  5. Segments are stored in a datacenter cache.
  6. From the datacenter cache segments are sent to caches located in the points of presence (a PoP cache).
  7. On the view side the viewer receives a Live Story.
  8. The player on their device starts fetching segments from a PoP cache at a rate of one per second.

  My question is simple. After the step 6, does PoP cache/Edge cache/eNB (edge layer node) multicast a live video content to multiple viewers or unicast each user separately (opening up seperate streams for each user) ?

• Scenecut detection and consistent GOP size - adaptive streaming

  24 mars 2014, par Tarun

  Sample Command :

  -map 0:0 -f mp4 -vcodec libx264 -preset slow -profile:v main -vf scale="640:trunc(ow/a/2)*2" -vb 700k -minrate 650k -maxrate 750k -bufsize 10000k -an -g 48 -x264opts keyint=48:min-keyint=10:scenecut=40 -flags +cgop -sc_threshold 40 -pix_fmt yuv420p -threads 0 -y

  There is as such no error in encoding, But I wanted to understand following points-

  1) the above command will ensure that range of GOP size is 10,48, and if any scene change value (frame1 to fame2) is >40%, then a keyframe is introduced there ?

  2) So that means in a 3 hours of source video, there is no guarantee that GOP size will remain same

  3) No consider, I am creating 7 MP4 files each with different bitrate and resolution. (These Mp4s will be encoded to smooth in later stage). Hence i am targeting adaptive streaming. But when I did that, I found that if GOP sizes were not consistent across each bitrates. What I mean by this is, for ex : if in Bitrate1 - GOP size is like 10, 20, 48 and so on, in other bitrates it wasnt in the same sequence. I hope my question makes sense.

  So is there a way to ensure that GOP size may vary across one single output. But it should be consistent across each bitrate provided that the source is same ?

  Also for adaptive streaming Is scenecut detection advisable ?