Linux-audio-user August 2019

linux-audio-user@lists.linuxaudio.org

39 participants
50 discussions

Re: [LAU] Filtering out everything but the centre position in stereo

by James Harkins

---- On Fri, 23 Aug 2019 09:16:23 -1000 Ralf Mardorf <ralf.mardorf(a)alice-dsl.net> wrote ---- > Yes, there are pitfalls [1.1], however, if you have good luck, you might > come relatively close to the desired result. No, I don't think so. I get the reasoning: the karaoke effect works by subtracting the two channels, so that anything that is equal volume and equal phase between the two channels will cancel out. We could call this a "residual." Then you think "if I subtract the residual from the total, I should get only the center material." But the math just doesn't work. L = left channel R = right channel residual = L - R Well, here's the logical error. That's not actually a "residual" (whatever "residual" was expected to mean). It's just the Side of a M/S configuration, nothing more. So then you think, "I have an original left channel -- subtract the residual and get some sort of remainder." left_anti_residual = L - residual = L - (L - R) = L - L + R = R right_anti_residual = R - (R - L) = R - R + L = L So, hooray, you've flipped the left/right stereo image and not removed anything. "But if you sum to mono"... then you get R + L = Mid. A mono mix, with nothing removed. (You had suggested that an effect that is deliberately phase-inverted between the two channels would cancel out in this case. Of course... but that's rather special pleading, isn't it? How often does that happen in the real world?) OK, then, maybe the mistake was subtracting from the individual channels. Maybe you need to go to the total and subtract the residual. Total = L + R = Mid of a M/S configuration. Total - Residual = M - S = right channel + 6 dB Total - neg(Residual) = M + S = left channel + 6 dB Sum that to mono and you get M - S + M + S = 2M = the same mono mix, only 6 dB louder. Simple sums and differences of left and right channels will, as far as I can see, never recover the "center" material. hjh

6 years, 1 month

Re: [LAU] Filtering out everything but the centre position in stereo

by James Harkins

On Aug 22 2019, Ralf Mardorf has written: > ... >> On the quick my guess is >> >> >> Original left channel + inverted right channel = plain_left >> Original right channel + inverted left channel = plain_right >> >> >> Original left channel + inverted plain_left = middle only >> Original right channel + inverted plain_right = middle only > ... > That sounds good. Unforunately it didn't work. I went down that road once before. "Plain" channels: a = l - r ("side" in mid/side) b = r - l Then l - a = l - (l - r) = r and r - b = r - (r - l) = l, neither of which isolates the center. The idea of the karaoke effect is to cut in-phase material that is in common between the channels (e.g. often lead vocals). You'd think you can do the karaoke effect and then some subtraction would leave you with "whatever is not the karaoke effect," but in fact, variables cancel out in a way that you don't get anything useful. This might be the reason why you don't find a lot of plugins for this. hjh Sent with AquaMail for Android https://www.mobisystems.com/aqua-mail

6 years, 1 month

Mtrack-8 oddity

by Will Godfrey

I've had one of these running perfectly for near 2 years now and have always run it with a buffer size of 64 frames/48kHz. This last week I've been too busy with 'other things' to do any composition. However, yesterday when I tried to run it. Jack immediately went into a cascade of Xruns with a most peculiar error report, suggestion it couldn't find the unit. Running Yoshimi by itself under Alsa worked fine, so I was now totally perplexed. Eventually I noticed that Yoshimi was set to 128 frames. When I set it to 64, it was even stranger. It ran, but on attempting to play anything it just made a horrible noise. Further tests revealed that jack also ran correctly with 128 frames or more. For a while I couldn't think of anything that had changed during that week - no upgrades or installs. Then I remembered I'd had to repair a bad solder joint in the amplifier, and as everything is mounted in a rack, had to pull quite a bit of stuff apart to get to it. I was quite sure I'd checked everything when re-assembling it, but just to be sure did a quick 'lsusb' in a terminal window, and as I thought, audio, midi, and mouse/keyboard were all on a different internal bus, and no bus had anything else on it. Today, while playing a CD on my 'office' machine I remembered I used to have a USB CD player that wouldn't work when plugged into the front USB3 sockets, even though it was identified on an internal USB2 bus, so checking the music system, I had indeed plugged it onto one of these on the back of that machine. Once swapped into a (black) USB2 socket it once again worked fine. I've no idea why it had given the symptoms it did though! -- Will J Godfrey http://www.musically.me.uk Say you have a poem and I have a tune. Exchange them and we can both have a poem, a tune, and a song.

6 years, 1 month

Filtering out everything but the centre position in stereo

by Jeanette C.

Hey hey, is there an effect or a method to filter out everything from a stereo file but the "centre"? A sort of reverse karaoke effect. In theory I'd know what to do, just not how to achieve it. i.e. find all the differences between the channels and subtract the respective difference from each channel. Any good tool/plugin or method to implement in something like Csound is appreciated. Best wishes and thanks, jeanette -- * Website: http://juliencoder.de - for summer is a state of sound * Youtube: https://www.youtube.com/channel/UCMS4rfGrTwz8W7jhC1Jnv7g * SoundCloud: https://soundcloud.com/jeanette_c * Twitter: https://twitter.com/jeanette_c_s * Audiobombs: https://www.audiobombs.com/users/jeanette_c * GitHub: https://github.com/jeanette-c She's so lucky, she's a star But she cry, cry, cries in her lonely heart... <3 (Britney Spears)

6 years, 1 month

A cardboard audio control panel

by david

https://www.rhythmo.io/ Suitable for beginners or cheap folk? -- David W. Jones gnome(a)hawaii.rr.com authenticity, honesty, community http://dancingtreefrog.com

6 years, 1 month

Creative Sound Blaster X-Fi HD occasionally drops out of ALSA.

by crocket

It drops out especially when I boot. This drop-out happens occasionally. I thought my mainboard was dying, but other USB devices weren't dropping out. Do I need to get a replacement for my USB soundcard? Or, is it a software issue?

6 years, 2 months

Re: [LAU] Creative Sound Blaster X-Fi HD occasionally drops out of ALSA.

by crocket

You seem to think that my mainboard doesn't supply enough power to X-Fi HD. through a USB cable. I just plugged it into a USB 3.0 port. But, I have to test it for a while. On Tue, Aug 20, 2019 at 9:55 AM Ralf Mardorf <ralf.mardorf(a)alice-dsl.net> wrote: > On Tue, 20 Aug 2019 09:35:09 +0900, crocket wrote: > >It drops out especially when I boot. This drop-out happens > >occasionally. > > > >I thought my mainboard was dying, but other USB devices weren't > >dropping out. > > > >Do I need to get a replacement for my USB soundcard? > >Or, is it a software issue? > > It seems to be bus powered, if so, then for testing purpose use a very > short USB cable and test different USB ports, if possible test with an > active USB hub, too. >

6 years, 2 months

[MUSIC] Synth Prelude n. 2

by Lorenzo Sutton

After ca. 10 months, a new prelude for synth. As usual it took long but is relatively short. Hope you enjoy Archive.org: https://archive.org/details/synth_prelude_02 (includes direct download links) Soundcloud: https://soundcloud.com/lorenzosu/synth-prelude-n-2 Made with Yoshimi and Rosegarden. Customary thanks to all the developers of these two music applications as well as all those contributing to the Linux Audio ecosystem for their work and dedication :) For the interested and/or curious, I have also set-up a Git repository with the Rosegarden (.rg) and Yoshimi state (.state) 'source' files for the Synth Preludes: https://gitlab.com/lorenzosu/synth-preludes Lorenzo.

6 years, 2 months

Linux MIDI resources

by Brian Hagen

Hello: I have some good audio resources up and running on Ubuntu Studio 18.04. When I searched for MIDI utilities, what I have found so far is a bunch of them that can be downloaded and compiled (supposedly). When I attempt that, so many of them have such cryptic error streams that it appears that only a highly skilled Linux programmer could get them to configure, compile, and install properly. Does anyone know why these resources seem so difficult to get going? Please comment. Brian

6 years, 2 months

[Music] A short orchestral piece

by Jeanette C.

Hey hey, "The apprentice - hard studies" was composed for an audio game - and not chosen :) -, the title says it all in terms of intent. I tried to include one of Diana Duetsch's acoustic illusions in the xylophone/marimba like pattern as a point of interest and something mildly magical. :) youtube.be/Tjw9VjUoKrI On the Linux side LinuxSampler with some free orchestral samples was involved as well as loads of plugins for processing. The orchestral samples were mixed with a hardware synth to get something a little more realistic. The strings were also layered with a simple sine sound to give a little more girth and resonance" to the instruments. Hope you enjoy it, comments are welcome. Best wishes, Jeanette -- * Website: http://juliencoder.de - for summer is a state of sound * SoundCloud: https://soundcloud.com/jeanette_c * Youtube: https://www.youtube.com/channel/UCMS4rfGrTwz8W7jhC1Jnv7g * GitHub: https://github.com/jeanette-c * Twitter: https://twitter.com/jeanette_c_s Just call out my name, and I will be there... <3 (Britney Spears)

6 years, 2 months

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Linux-audio-user August 2019