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agittins's blog

Converting audio in a video file to mono

  • Posted on: 9 April 2023
  • By: agittins

One day I'll wish I saved this tip somewhere I could find it... so here it is.

I had a video file which had a stereo audio stream in it, but there was only audio on the left channel of that stream. I wanted to convert that mono-in-left-channel-only stream to pseudo-mono-in-both-channels (ie, copy the left channel into both the left and right channels.

This is the sort of stuff that ffmpeg does before breakfast. What we are doing is "re-mux"ing (which is to say we re multiplex the video and audio streams together into a new container).

ffmpeg -i input-video.mp4 -map 0:0 -c:v copy -af "pan=stereo|c0<c0+c1|c1<c0+c1" -map 0:1 -c:a aac output-video.mkv

GitHub error "repository not found" using ssh

  • Posted on: 22 July 2021
  • By: agittins

Yesterday (2021-07-21) I started having a problem with using git against some of my private github repositories. Trying to fetch updates would look like this:

$ git fetch upstream
ERROR: Repository not found.
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.

It turns out this was caused by my using an old 2048-bit rsa key for SSH. Perhaps github are rolling this change out across all private repos. You can create a new 4096-byte key with the command:

Zoom on Linux not remembering settings or login

  • Posted on: 5 March 2021
  • By: agittins

If you're having problems with Zoom not remembering your login or settings, check if your home directory as specified in $HOME actually points to a symlink rather than an actual directory.

Mine does, and zoom would always ask me to login (regardless of having ticked "remember me") and never retained settings between runs.

In the console output of zoom (in addition to a lot of binary guff - wtf zoom?) was:

Dynasty8 Nunc Dimittis

  • Posted on: 20 May 2020
  • By: agittins

Recorded during lockdown in 2020. I'm the hairy chap. Each performer recorded their part at home, and I combined them, using Ardour for the mixdown, ffmpeg for various processing tasks and kdenlive for the video edit. This is Paul Smith's setting of Nunc Dimittis.

Dynasty8 - REST Preview

  • Posted on: 19 August 2018
  • By: agittins

A recording and preview clip I put together for our REST Programme, an hour-long meditative exploration of some of the most soul-touching music ever written:

The audio is a live recording of a performance in Tugun, Queensland in July 2018. I am performing the tenor part.

SBR Tax Office Error code CMN.ATO.AS.EM137

  • Posted on: 28 June 2018
  • By: agittins

If you're using FreeAccountingSoftware (If you're running a fairly straight-forward operation then I'd suggest checking it out) and you get this error message when trying to retrieve SBR Activity Statements:

Error, CMN.ATO.AS.EM137, There are no activity statements matching your selection. Change your criteria.,

Then your issue might be an incorrect "Branch" code in your SBR Settings.

Creating automatic backups in Ardour

  • Posted on: 23 May 2018
  • By: agittins

Ardour is an amazing piece of software, but sometimes it still crashes. This is not entirely its own fault - plugins have to run in the same process so ultimately Ardour has no control over some of the code it ends up running. I find it pretty stable, but when you are syncing it with MuseScore and/or video things get a bit twitchy.

Of course, we all know to save early, save often - but when you're in the creative flow it's easy to lose track of time and not save for quite some time.

Synchronising Ardour and MuseScore

  • Posted on: 19 May 2018
  • By: agittins

I've had to work this out again since reinstalling my laptop so thought I might record the result here...

Typical issues found when trying to get Ardour and MuseScore to work together is that MuseScore jumps around in a BAD way when it hits tempo changes from JACK, or it locks up, spewing lovely digital detritus into your monitors.

The best method I've found thus far (although it still does that lockup thing from time to time) is: