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• FFmpeg delay and mix audio streams while keeping overall volume constant

  5 octobre 2020, par unstuck

  I have about 100 audio streams, all with the same intro music/sound, and in some of them the intro is delayed by a few seconds. I want to align and mix all the audio streams such that all the intros play at the same time and the output remains pretty much the same volume throughout. I know in advance how much each stream needs to be delayed by.

  


  Like this in Audacity. Each audio stream is aligned to the intro, and the duration before the intro is arbitrary. (This doesn't solve the volume problem though.)

  


  What I have so far uses adelay and amix. It looks something like this but with more audio streams.

  


  ffmpeg -i 00.oga \
       -i 01.oga \
       -i 02.oga \
       -i 03.oga -filter_complex \
"[0]adelay=delays=     123S:all=1[a0]; \
 [1]adelay=delays=    2718S:all=1[a1]; \
 [2]adelay=delays= 6283185S:all=1[a2]; \
 [3]adelay=delays=11235813S:all=1[a3]; \
 [a0][a1][a2][a3]amix=inputs=4" output.oga


  


  In this example the first stream is delayed by 123 samples, the second by 2 718, the third by 6 283 185, and the by fourth 11 235 813.

  


  This works, except at the beginning of the output it's very quiet. When fed n streams, amix makes each stream 1/nth its original volume, which is a good thing in principle. In this case it's not an entirely good thing, because at the beginning of the output 3 of the 4 audio streams are silent (adelay fills delayed streams with silence), meaning the only audible stream is 1/4 = 25% of its original volume. When the second stream becomes audible, the overall volume is 2/4, with three audible streams 3/4, and with all four streams audible it's 4/4 = 100%.

  


  Instead, I want the the first stream to be at 100% volume when it's the only audible one, 50% volume each when there are two audible streams, etc.

  


  Is there a way to make it so when there are n audio streams but m non-silent audio streams, the volume for each of the audio streams is 1/m not 1/n ? amix does this when streams end ; if one stream ends it changes the volume of the others from 1/n to 1/n-1 over a period of time (dropout_transition : https://ffmpeg.org/ffmpeg-filters.html#amix).

  


  I found a similar question where someone wanted to do something like this but only with 2 audio streams. The answer was to split, trim, and change the volume manually. This would be incredibly complicated with 100 audio streams or more, like in my situation.

  


  Is there any easy way to achieve this, even without FFmpeg ?

  


• Real Time indoor streaming and music mixing

  9 novembre 2015, par Saneet

  I am working on this project where we are doing a live performance with about 6 musicians placed away from each other in a big space. The audience will be wearing their headphones and as they move around we want them to hear different kinds of effects in different areas of the place. For calculating the position of users we are using bluetooth beacons. We’re expecting around a 100 users and we can’t have a latency of more than 2 seconds.

  Is such kind of a setup possible ?

  The current way we’re thinking of implementing this is that we’ll divide the place into about 30 different sections.
  For the server we’ll take the input from all the musicians and mix a different stream for every section and stream it on a local WLAN using the RTP protocol.
  We’ll have Android and iOS apps that will locate the users using Bluetooth beacons and switch the live streams accordingly.

  Presonus Studio One music mixer - Can have multiple channels that can be output to devices. 30 channels.
  Virtual Audio Cable - Used to create virtual devices that will get the output from the channels. 30 devices.
  FFMpeg streaming - Used to create an RTP stream for each of the devices. 30 streams.

  Is this a good idea ? Are there other ways of doing this ?
  Any help will be appreciated.

• Bot isn't playing music [closed]

  15 mai 2020, par DevTeddy

  My bot can join, but it isn't playing any music ! The code is written is Javascript, and I am using Discord.js , Node.js and FFmpeg. The prefix and token are in a seperate JSON file. There are no errors in the Console, though. Also, it says the "added song to queue" message twice, for some reason. I have already tried using VS Code's debugger and checked it for errors. Please help me !

  



  My code is at : https://github.com/Dev-Ted/ForestBot

  



  Thanks !