Converting 2.0 stereo to 5.1 surround

Background

Over the years, I’ve recorded a number of events on my camcorder for other people. In recent months, I’ve made a 5.1 surround sound audio track available on several DVDs I’ve made. Although not as accurate as making a proper mix of material from multiple sound sources, it is possible to create a passable simulation of full surround sound from 2.0 stereo source – this relies on the two stereo channels not being identical, and making use of the differences between the two channels.

Important note: the results you get depends on the quality and nature of your source material and how much effort you are prepared to make. The following notes assume that your source material has a regular two channel stereo soundtrack, as commonly found on CDs and MP3 files. Making an acceptable 5.1 sound mix from a mono source requires a modified approach.

Software

I use Audacity as the basic framework for manipulating the soundtrack on my video files. I have the channel mixer plugin installed, to assist in the remixing process. This is available as a Nyquist Effect Plugin. Depending on the file format you export your remixed soundtrack, you might need to install the ffmpeg import/export library. – don’t forget to set Audacity to export use a custom mix instead of stereo or mono.

Basic procedure

  1. Open Audacity
  2. Import/open your video files – this should give you a two soundtracks organized as as a stereo pair
  3. Normalize your soundtrack with the Effect->Normalize
  4. Duplicate your stereo source so that you four stereo pairs of soundtracks. The first will become the front left and front right channels, the second pair will become the centre channel, the third pair will become your bass/LFE channel, and the fourth pair will become your left rear and right rear channels.
  5. [Optional] Select the first stereo pair, and select the Effect->Vocal Reduction and Isolation effect. For the action, choose remove center. Click on OK. Be patient, this can take a while for longer clips.
  6. Select the second stereo pair, and select the Effect->Vocal Reduction and Isolation effect. For the action, choose isolate center. Click on OK. Be patient, this can take a while for longer clips. Then choose mix->mix tracks to mono.
  7. Select the next stereo pair. Use mix->mix tracks to mono. Then use Effect->Low pass filter. Keep in mind that the LFE channel is commonly designed for freuencies of 120Hz and lower, so you might want to check the setting before clicking OK.
  8. Select the last stereo pair. Lately I’ve been using the channel mixer plugin for this stage of processing. The decoding matrixes described on Wikipedia might be a useful starting place for choosing the values to use. Because Audacity’s plugin uses percentages, you’ll have to multiply the figures on Wikipedia by 100.
  9. You should now have the following: 1 stereo pair, 2 mono tracks, and 1 stereo pair.
  10. Export the resultant mix into your preferred format.

 

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D’oh!

My ISP seems to be having a hard time understanding why I’m complaining to them that their spam filter is allowing spam into my inbox but blocking my efforts to report it to places like Spamcop and New Zealand’s Department of Internal Affairs. They also seem to be having a hard time accepting that I am unable to forward copies of legitimate email that has been rejected by their spam filter – I don’t have copies of email that never arrived. My sister and I have pretty much given up trying to communicate by email – she’s a customer of the same provider, and, like me, has discovered that family chit-chat is also being blocked for allegedly being spam.

I am thankful the amount of unwanted emails coming my way has dropped significantly in recent months. I am also thankful that I still have ways of forwarding samples of what I receive to interested parties without resorting to major technical trickery or serious deviousness. I have noticed on the provider’s Facbook page that other customers are being bothered by significantly more spam than myself.

One way of reporting spam when your provider blocks the outgoing spam reports is to have multiple accounts with multiple providers loaded up into your email software, and to send the reports from an account where outgoing reports aren’t blocked, this is easily done with Thunderbird. (Don’t ask me how to do it with the Outlook email client – I haven’t used it regularly for several years.)

Further reading can be found on another blog here: voogdnz.wordpress.com/2017/11/02/what-is-spam/ – while you’re there, you might want to do keyword searches for Spark and SMX.

Coding

The term “Coding” and “computer code” can mean different things to different people. Here are some examples:

  • Source code is a description of how a computer should do a task,  in a form that suits being read by people. It usually cannot be directly used by the computer or device, but will normally need to be translated into a form that the computer can use.
  • Escape codes are, in effect, signals sent to a device, such as a screen or printer, to control the device’s settings.

Something that is typed in to the computer isn’t necessarily a code, even though it might seem to be written in code. If you’re typing it on the command line (via cmd.exe on Windows systems, through the terminal on linux machines), it is a command, not a code.

Microcode is another beast altogether. Sometimes the term corresponds to what used to be referred to as BIOS, sometimes it corresponds to device drivers, sometimes it refers to some machine-level stuff that allows a computer’s processor to process machine language stuff properly. In short, the meaning can vary according to context.

Some tech-support forums ask you to use Code Tags around portions of what you submit. This is usually because the forum software will format the information better that way. It does not automatically follow that what you’re submitting is code, it’s more of an aesthetic thing.

Spam spam spam spammity spam…..

It is with some relief that I am pleased to report that Spark has responded to customer complaints and organized a “mark as spam” option for their webmail users. The incarnation I have seen seems to be available only for individual emails that are opened in their webmail, which is a start. Some other ideas for dealing with unwanted email can be found elsewhere.

A word in the ear of email providers

If you’re an email provider, try to reject unwanted mail during the SMTP exchange where possible. Once you accept a message for delivery, then decide that it shouldn’t be delivered, you are faced with the unenviable task of where to send the non-delivery report. You can’t rely on the validity of the “From:” and “Reply-to:” headers, and sometimes even the “Envelope Sender” or “Retrun path” details, because sender credentials are commonly forged in order to divert attention away from the real sender. A misdirected bounce only adds to the spam problem. Even the “Received:” headers can be tampered with.

The IP address of the system wanting to deliver email to your system is one of the more reliable pieces of information available to system admins – the internet relies on accurate IP addresses in order to work properly.  DNSBL technology is a well established method of quickly and efficiently learning about the reputation of a particular IP address. Both Spamcop and Spamhaus are well established providers of DNSBL services. Using one (or both) should help you stop spam in its tracks. Be sure to read their terms of use. Take the time to read AND understand what they do and how they work.

There are several websites available to help you do your research. The resources provided by WhatIsMyIpAddress and multirbl.valli.org can be of immense help.

Don’t be fooled by claims that you are obliged to pay for removal from one of the UCEPROTECT and Backscaterer lists. If you fix the problem that resulted in the listing, the removal will happen automatically. The payment is only required if you can’t wait a week (or more) after fixing the problem.

Spam is NOT welcome

For some reason, several Chinese spammers have attempted to contact my Lisati persona with Chinese language messages – click here for an example. Any such messages which make it to my inbox WILL be reported as spam, even if the subject tries to claim that it is NOT spam. For anything that has no connection with Ubuntu, Launchpad, or the contents of this blog, please visit my other blog.