Need Video to have 2 audio tracks

Discussion in 'General Off-Topic Chat' started by junker_man32, May 16, 2009.

May 16, 2009
  1. junker_man32
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    So the thing is on the left channel is the karoake music with no voice, and right channel is the music with the voice, but i want it to have 2 other audio channels, the voice on the right channel by itself in the middle, the left channel by itself in the middle, then finally, both of them in parallel playing. how do i do this? convert it somehow?
     
  2. FAST6191

    Reporter FAST6191 Techromancer

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    Be careful when asking that question "2 audio tracks" usually means a dub and the original (or directors commentary or something) which is container dependent (AVI has a crude hack but MKV is the chosen method here).

    I am slightly confused as to what you want and what you have, if I understand you
    your have a video file with a single audio track.
    This track is a stereo track but it is odd in that the left channel is just music (no vocals) while the right is the music and some vocals. That must sound kind of odd but that is besides the point.

    However you have a 3 channel speaker setup (left, right and middle).

    While you could encode you might be able to get away with doing it in real time at the mixer level.
    Most codec packs and playback uses FFDshow (CCCP is a good pack if you want http://www.cccp-project.net/ )
    http://mewiki.project357.com/wiki/FFDShow_reference#Mixer
    Failing that most players will have something like it.

    Simple stick a non zero number in the box you want (the number refers to the ultimate volume with 1 being full volume).
    You can however have multiple "speakers" playing through one speaker (it is how playing a 5.1 track through stereo speakers works) by simply sticking a 1 in the relevant box.

    You now have a problem, removing vocals to leave a "pleasant" track behind is notoriously difficult. You appear to have lucked out though and you have the "master" track.
    So without going into the proper audio engineering territory try placing a "-1" in the box. This will essentially invert the song and courtesy of physics it will cancel things out.
    Do this with the music + vocals track and by essentially doing a -music you are left with the vocals. This is a drastic oversimplification of course (for a "pure" audio track without the issues of encoding, decoding, post processing, the invert and less than flawless recording equipment) and you might get better results using a number less than 1 and otherwise reducing the volume to the track.
    If that does not work human vocals are usually fairly well contained frequency wise and if you are lucky your instruments will fall outside this, you then have various filters to try and kill frequency ranges:
    http://www.dspguru.com/info/faqs/index.htm Note this is how such things are usually done if you are not as lucky as you are here.

    If you do want to encode then you will essentially be doing the same thing, do yourself a favour though and encode it using something like audacity (you can dump audio to wave using virtual dub) rather than fiddling with the audio options that most video programs give*.

    *if you are using one of the uber expensive programs or something like avisynth you could probably do it but I would still avoid it when something simple like this exists.

    Good news about doing it outside of a video environment is that you can simply mux it back in and save yourself a video encode.
     
  3. junker_man32
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    ok, for example........im gonna burn it on a vcd, i want to make it so i can switch audio from both parallel, to only the karoke channel, then to only the voice channel by using the remote. so like almost switching languages, how would i go doing this, i ve seen some youtube videos do this with the right and left channel after i download them.
     
  4. FAST6191

    Reporter FAST6191 Techromancer

    pip
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    VCD?
    I have to ask why VCD when plenty of DVD authoring apps exist but even then are VCD and the related formats capable of multiple audio tracks?
    Personally I suggest merging the tracks (making a music+voices track to go with the voices and music one) and making a DVD with 3 audio tracks (trivial to do).

    What I guess the youtube videos do is to have the audio "tracks" as distinct channels (playing through different speakers) and then the PC/player ultimately makes them appear as a single track but by muting a speaker (you call it selecting a speaker via your TV remote) it appears as though multiple tracks exist.

    My reservations aside if you really want a single track though you are going to need a distinct stereo track made from each track.
    Audacity is the app of choice here.
    http://audacity.sourceforge.net/
    First you have to make each individual track a "mono" track.
    Do this by importing the track of choice (you can do both but make sure to select one).
    Under the tracks pulldown menu there is an option called stereo to mono.
    Repeat for the other track.

    Now simply slide one slider for the pan (the bottom slider option with L and R) to the left and the other to the right.
    You can test it in app using the mute button, when satisfied export it to your chosen format (I suggest wave, no need to encode it many times as a lossy format if you can avoid it).

    Use this audio track in lieu of your original, I warn you though even with both "tracks" playing (with just one track it will be even worse) on a decent or widely/noticeably spaced (this includes headphones) speaker setup it will sound very odd and possibly even confusing to people (it will be like two conversations happening at once).
     

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