I have several mkv files in monoral

[RBCC]

Originally Gilligan's Island in 1964 was in monaural, Is there a piece of free software that could make this in 5.1 surround Sound?? John

[Cornucopia]

Not with even any hint of believability. Neither is there a costly software. You can't make a silk purse out of a sow's ear without buying a lot of extra silk (aka do it all over again).

You'd have a better chance getting your surround receiver to "synthesize" a fake/quasi-5.1 version directly during playback, though personally, I hate that sound. What's wrong with letting it sound like how it was created?

Scott

[smrpix]

Be aware that those shows were optimally mixed for mono, and that they would have a very limited dynamic and tonal range compared to what we are used to today. Even if you got lucky and your sources were created from the 35mm fullcoat, there will be a lot of top and bottom end rolloff.

To echo Scott: What you're trying to do is the audio equivalent of colorizing an old B&W film -- appreciate it for what it is.

[redwudz]

The OP didn't mention if the problem was that the audio was just coming out of one stereo channel.
If so, an audio editor like Audacity can 'clone' the existing audio to a second stereo channel.

But still can't create real 5.1 audio.

[Clockwork]

You'd have a better chance getting your surround receiver to "synthesize" a fake/quasi-5.1 version directly during playback...

Yeah, that's about the best you could hope for...

...little buddy.

[johns0]

Audacity can create 5.1 from a mono sources,it just won't sound right unless you know how to adjust the audio in all the channels. It's better to keep as mono.

[RBCC]

How do i extract the sound from a mkv ?

[redwudz]

Just drop the MKV into Audacity and edit the audio. Then save it out and Mux it back with the video when finished. AVIDemux can probably do that.

[jagabo]

Just drop the MKV into Audacity

To do that you'll need the ffmpeg source filter for audacity:
http://manual.audacityteam.org/index.php?title=FAQ%3AInstallation_and_Plug-Ins#How_do_...ort_Library.3F

But any fake 5.1 expansion of mono audio is going to sound like crap. Don't waste your time.

[redwudz]

Sorry, I forgot about ffmpeg. I already had it installed.

I would still advise the OP to just convert to dual audio with the same audio on the two stereo channels, just to balance out the speakers.
Audacity can do that easily.

[johns0]

Audacity can create 5.1 from a mono sources,it just won't sound right unless you know how to adjust the audio in all the channels.It's better to keep as mono.

It's better to keep as mono.The misspelling on that line is above not there when i posted it.It's a forum coding issue.

[Hoser Rob]

As mentioned unless you're just getting sound from one channel (which is easy to fix), just leave it.

Old TV broadcasts are not only mono, the audio quality is about the same as AM radio. I.e. there ain't much audio there above 3-5KHz or so. Truly a sow's ear.