Every once in a while I'll come across a video that I want to watch (whether it be youtube or otherwise), and the sound, for whatever reason, will be only coming out one speaker. It's not a problem with my hardware, or any kind of configuration; it's because whoever encoded the video, messed up the audio. If I used speakers this wouldn't be a problem, but 100% of my listening is done with headphones. This makes for a very annoying experience. You'd think something like this hardly ever happens, but it seems I come across this more than most people, and it;s really annoying.

One easy fix is to pull out the earphone plug a little, which causes one channel to be send through both ear speakers. This works, but the slightest tug of the wire sends the plug out completely. Also, sometimes if it's the left channel that's only playing, the "half way out" method will not work because it'll just send the right side (the quiet side) through both speakers.

There has to be some kind of program that sits between the sound system and the output jack that can make all sound mono?

  • Mono implies one channel. It sounds like these sound files are already mono. But, yes, you want both channels the same. Would it be a function of the sound mixer in Ubuntu? I'm using Ubuntu 9.10 and I just noticed it only supports stereo output! I wonder if there's a different mixer you could try. – pavium Feb 1 '10 at 10:03
  • Misuse of mono tag. – kmarsh Feb 1 '10 at 13:22
  • agree with pavium, i think your files are already mono and you're wanting to "upmix mono to stereo" or "duplicate channel" or something similar. (if it helps, PulseAudio and/or ALSA should be capable of this directly, tho it might be an advanced config.) – quack quixote Feb 6 '10 at 5:31

Updated for VLC 2.2.1:

  1. Tools > Preferences > Audio > Output. Select ALSA Audio Output.
  2. Tools > Preferences. Select the "all" radio button at the bottom.
    • Audio > Output modules > ALSA. Select the mono option from the Audio output channels dropdown menu.
  3. Restart VLC

Original answer:

You can use VLC to do this. But I had trouble getting the mono to actually work. Here's what ended up working for me:

  1. Tools > Preferences > Audio > Output. Select ALSA Audio Output.
  2. Tools > Preferences. Select the "all" radio button at the bottom.
    • Audio > Filters. Select the mono option ("audio filter for stereo to mono")
  3. Restart VLC

VLC can do it. When playing the video just go Audio ⇨ Audio Channels ⇨ Right/Left.


Not exactly a solution for you, but the 'ecasound' package will, at the command line, fake stereo from a mono sound file. That is, it will create a second sound channel on a .wav file which is in mono.

Sometimes I save an internet video to disk and then turn it into an MP3. If it's mono this fixes it.

I understand that you want something that will fix a streaming video file while it is playing: I honestly don't know of a practical way of doing that. I suppose you could put the Jack package in your sound queue and add some sort of real-time filter, but, honestly, I think the pain of trying to get that to work wouldn't be worth it. Sorry.

  • good tip on ecasound (sox can probably do this too). i too think Jack could do it live, but i expect either PulseAudio or ALSA is capable of this too, and more likely to already be installed. – quack quixote Feb 6 '10 at 5:39

In the gnome sound mixer, you can just mute one channel if you click the unlink button so the sliders don't move together.

  • This is not what the asker wants to achieve, though. He has mono sound source, and wants it on both speakers. – Gnoupi Feb 1 '10 at 14:10
  • Oh right, in that case I think they might want to look into players that can do it, or get a set of headphones that have a switch to play either stereo or one channel through both speakers. – Jonno_FTW Feb 2 '10 at 10:12

Well, i found one way that works...when playing the video on vlc Go to Audio->Audio Device->Mono....this will recognize audio input as Mono & divide the audio in both your speakers

  • While this would work for videos already on the hard drive, this would not work for YouTube videos (as stated in the question). – Cfinley Jul 16 '14 at 19:39

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