Wikipedia:Reference desk/Archives/Computing/2015 August 12

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August 12

Audio delay device ?

When cooking, I have a TV on in the living room and one on in the kitchen, so I don't miss my show when I go in to stir, etc. However, the two TVs are slightly out of synch, and the audio is hard to understand as a result, when walking between the two rooms. Both use external speakers. So, what I'd like is a device I can plug into the audio-out plug (the small, light green plug) that has a dial on it, say to adjust the audio delay from 0-1 second, before sending it out to another small, light green jack. So, does such a device exist ? What's it called ? StuRat (talk) 00:14, 12 August 2015 (UTC)

Guitarists, and other musicians, often use a delay pedal. For your application you'd want to make sure that the volume of the pedal's "bypass" (perhaps called "clean") channel (which plays the input without the delay) is zeroed. -- Finlay McWalterᚠTalk 00:31, 12 August 2015 (UTC)

But I should say that the normal use of a delay effect in music is either to "fatten" the sound (making it sound like double tracking) where the delay is only a few tens of mSec, or to give a feeling of space (much like an echo), where the delay is several hundreds of mSec, and there are often several repeats. You'd need to make sure the delay effect processor you chose could go up to the delay range you want, and can be configured for only a single repeat (the better ones will). I can't speak as to whether the impedance or signal levels that instrument effects devices expect will work well with your audio equipment. -- Finlay McWalterᚠTalk 00:43, 12 August 2015 (UTC)

Why does it happen?188.247.76.211 (talk) 05:08, 12 August 2015 (UTC)

In your case, one TV is a bit faster at processing the audio. Getting back to a fix, something like this would work, but better still would be simply running both sets of speakers from one of the TVs. --Guy Macon (talk) 07:18, 12 August 2015 (UTC)

It happens to me here in the UK, if one set is tuned to Freeview and the other to Freesat. The delay is about two seconds, so it's possible to switch to Freesat and hear again what was just said. I've often wondered if Freesat is behind owing to the 71,600km round trip for the signal. --TrogWoolley (talk) 11:18, 12 August 2015 (UTC)

Only about 1/4 of a second is the radio delay to and from the Clarke orbit. -- Finlay McWalterᚠTalk 11:49, 12 August 2015 (UTC)

It's much more likely to be differences in the decoding time due to different processors etc in the tuners. Even with two TVs tuned to the same Freeview channel there is often a noticeable difference of a second or two (as per the original question). Of course, the problem with synchronising the audio feeds is that (at least) one of them will then be out of sync with the video. AndrewWTaylor (talk) 15:00, 12 August 2015 (UTC)

I would recommend feeding both sources into a computer and make a recording of both the sorces. Then determine the exact amount of lag between them and then if the lag is below 40 milliseconds, get a program called VST Host(I don't remember the link), as well as a VST plugin called FreeHaas. For this to work, you will have to have one audio source feed into your pc and the other go to where ever its going. Once you have both of those, simply open VST host and in the File menu click new plugin(I think you can use CTRL+N as well to do the same thing). Select the FreeHaas plugin(it will be a .DLL file) and it should open the plugin. You will have to configure the audio inputs so click on the devices menu and click wave. This will bring up a box that you can select audio inputs and outputs. Once you have configured your audio devices, you can open the plugin's interface by clicking the icon on the plugin box that has a round button. Once you have the interface open, simply rotate the knob to the desired delay setting. Note: you will have to duplicate the plugin to delay the other side of the audio as well. For as this plugin is built to delay only the left or the right channel at a time. This will only work if the lag between your 2 audio sources is 40 milliseconds or under. —SGA314 I am not available on weekends (talk) 15:15, 12 August 2015 (UTC)

First: Yes - delay boxes exist. They are not cheap. If you can accept a low sampling rate and a narrow band, you can get one at a reasonable cost. For a good one (that will allow you to understand what is being said), you are basically purchasing a computer that has one and only one function: convert analog audio to digital, cache the digital audio in memory, and convert the digital to analog to send it back out later. The delay allowed is dependent on the amount of memory available.

Second: Another option, depending on what you have. I have an LG television. With pretty much any Android device, I can watch and hear my TV on my handheld device. So, I can just carry it with me around the house and ignore the television all together. The only drawback to LG's implementation is that I cannot turn the TV off from the handheld device. I have to return to the actual television to turn it off. 209.149.114.32 (talk) 16:07, 12 August 2015 (UTC)

In that line of thought, simply using "wireless speakers" sent to headphones from one of the TVs would work. Is there such a device ? StuRat (talk) 17:30, 12 August 2015 (UTC)

I'm a bit confused whether you want speakers or headphones, but either way the most common solution nowadays would be a bluetooth audio transmitter (something like [1]) and then Bluetooth headphones or speakers. Bear in mind some TVs will mute the audio output when something is plugged in to the headphone output, and this will also likely increase latency by a noticable margin so it's unlikely the speakers or headphones will be in sync with the output TV. You could try something using aptX and optimised for low latency like [2] along with suitable speakers or headphones, but if the problem is two different audio sources rather than audio in sync with the video, I think you'll find that the requirements are fairly stringent (at least it seemed to be from my limited experience with this). Probably your best bet is to find something which supports outputting to two different Bluetooth devices simultaenously (the earlier linked aptX device is one option), and then sending to two devices. If you want two (sets of) speakers, this is easy (well provided you don't buy two different sorts of speakers). If you want a (set of) speaker/s and headphones this may be trickier as it's possible the headphones will have different internal latency from the speakers (although I'm not certain the device latencies really vary enough to be significant even for simultaneous output sync issues provided they are using the same codec). P.S. You didn't mention what sort of TVs you're referring to. If these are cheap 32" ones, you may find your best bet is simply to sell the current TVs and buy two news TVs of exactly the same brand and model. Nil Einne (talk) 23:31, 12 August 2015 (UTC)

So spend several hundred dollars for a pair of new TVs ? I don't think so. If I can't find a cheaper solution than that I will just live with it as is. StuRat (talk) 02:02, 13 August 2015 (UTC)

Yes. There are wireless headphones. I purchased some for my father. He was going deaf and had the TV cranked up so loud I could hear it before I went inside his house. I got him wireless headphones with a volume knob on the headphones. There were many models to choose from (I chose over-the-ear noise-canceling Sony). 209.149.114.32 (talk) 13:40, 13 August 2015 (UTC)

Sounds like a good solution. StuRat (talk) 14:53, 13 August 2015 (UTC)

What is FreeVST?

What is FreeVSt? I was reading about Magnus Choir and in the Overview section it says, "Magnus Choir also is compatible with FreeVST allowing GNU/Linux users to use native Microsoft Windows VST plugins by using parts of the Wine compatibility layer." Could this be done without Wine? And what is FreeVST exactly? I ask because I have a Raspberry Pi 2 that I want to run VST plugins on and this just might do it. Also does anyone know if Wine can run on a Raspberry Pi 2(This is an arm hard float processor)? Thanks for your help in advance. —SGA314 I am not available on weekends (talk) 15:22, 12 August 2015 (UTC)

I'm sure you can get Wine working on the Raspberry Pi 2 somehow. However since it's an ARM, the vast majority of Windows software isn't going to work without binary translation or emulation. This [3] seems to confirm that (without specific reference to the Raspberry Pi) although I don't know if you can read it. The same BTW if you're trying to run most VST plugins on the Pi 2, [4] is about the original Pi but unlikely anything has changed, it's simply not going to work without birnary translation or emulation of the hardware. (Note also even if you could get hardware emulation or binary translation working, and it works for some stuff, it's fairly unlikely to be suited when you're aiming for extremely low latency like for real time audio generation.) Nil Einne (talk) 15:56, 12 August 2015 (UTC)

Ok so most likely no, I can't run Wine on the Pi. However, I can use QEMU to emulate an X86 or an X64 processor. But I don't know how to run a single program instead of a whole operating system. For instance, I want to run a program called VST Host. However, it is made for windows(I think there is a Linux distro but probably not for the arm hf processor). So if i can't run Wine on the Pi, then how would I use QEMU to run the VST Host(It is what loads VST plugins) software ONLY. I don't want to run a whole OS for this 1 app. Any idea on how to do this. Note: If there is a way to do this that doesn't involve QEMU please suggest as well. Here is another question, can FreeVST translate X86/X64 instructions into ARM-HF processor instructions? As regards to latency issues that could arise with emulation, I will tackle that bridge if/when I come to it (Although a few words like JACK ring in my mind when I think about this problem). Right now I am focused on just getting the software running. —SGA314 I am not available on weekends (talk) 16:05, 12 August 2015 (UTC)

QEMU is just a x86-32 or x86-64 emulator. If you want to run Windows programs, you will either need to run Windows on QEMU (or some other emulator), or you will need to run QEMU with Wine. The above link has some discussion of how you may be able to get the later QEMU with Wine) working at one time on one set-up, but I doubt it will be easy, it sounds like a large amount of pointless work if you're going to try something which almost definitely won't give useful results, even more so if you lack the resources most other people can use to get it working.

I don't see much relevance of JACK Audio Connection Kit, it doesn't sound like it has anything to do with QEMU or Wine so there's a very good chance it's not going to help you with the fact it's fairly unlikely either QEMU or Wine are designed for such low latency access to the audio stack.

JACK Audio Connection Kit may be useful if you weren't trying to go through such a complicated set-up chain, like running something compiled for Linux on your Raspberry Pi 2 rather than something compiled for Windows on a x86 computer. Since you haven't even got this part working properly (although I'm fairly sure there is open source audio stuff targeted compatible with Linux and ARMs), it seems to me you're putting the cart before the horse. Get the audio part working first, then if you really can't find Linux substitute for whatever VST plug in you want, only explore the minute possbility of getting VST working.

Nil Einne (talk) 22:57, 12 August 2015 (UTC)

I'm really hoping that our OP makes this project work, but I can't help but observe a few things. User:SGA314 wishes to build a software device with competitive specifications to professional audio devices that sell for tens of thousands of dollars, using a Raspberry Pi. At some point you have to be wondering ... why does a bottom-of-the-barrel used Line6 POD sell for $200, and the really functional programmable ones sell for many thousands of dollars, if anyone could just program a $30 Raspberry Pi to do the same thing? Have a look at our article on project management scoping: "pick any two"! Well, you already picked "cheap." You're dead-set on making it "good" by demanding a lot of advanced features (high performance, low latency, and software compatibility with a complex and proprietary technology, VST). So... this project is going to take a very long time. You need to became much more familiar with the technology stack. From your questions, I can see that you're not an experienced Linux user; you're surely not an experienced Windows developer; and you're only barely familiar with the Raspberry Pi. You're trying to do things with software - running cross-platform, cross-architecture virtualization with proprietary, high-performance applications - that would make experienced experts tremble. You probably bit off more than you can chew, and unless you have many years to complete the project, or a large budget to draw from, there's little chance of success.

I think you need to re-scope the project. What you should do is find a book or tutorial for Raspberry Pi, and follow along with work that has already been done. Once you develop expertise, you can start to explore a more difficult technology implementation, or start tuning for better real-time performance.

Here's a starting point: Raspberry Pi 2: A Beginner's Guide with Over 20 Projects .... After you run through a few of those, you'll be in a much better place to venture out into more difficult technology areas. Nimur (talk) 14:17, 13 August 2015 (UTC)

Ok I understand. So first I should learn how to use and work with the Pi and Linux before embarking on such an ambitious project. Thanks for recommending the book. I will take a look. Thanks soo much for everyone's help on this subject. —SGA314 I am not available on weekends (talk) 18:27, 13 August 2015 (UTC)

How to list drivers as they load in Windows 7 ?

Either when booting my Windows 7 32 bit Optiplex 320 Pentium 4 PC or my Windows 7 64 bit Gateway ACPI SX2855 Celeron G460. How do I do it ?

Thanks, StuRat (talk) 17:32, 12 August 2015 (UTC)

If you need to see the system drivers loading, then just enter safe mode. Beware that this will not load drivers such as GPU drivers. —SGA314 I am not available on weekends (talk) 17:49, 12 August 2015 (UTC)

Does Windows still have msconfig.exe? If so, it used to have two boot troubleshooting options. One is to show the booting process on the screen - which means you have to read very fast. The other is to log the boot process to a file, which lets you read it at your own personal pace. 209.149.114.32 (talk) 17:50, 12 August 2015 (UTC)

Yes, I do belive Win 7 does still have msconfig.exe. Good idea. —SGA314 I am not available on weekends (talk) 18:19, 12 August 2015 (UTC)

Thanks, all. My solution was to hold the power button down to do an emergency log off. It then asked if I wanted to restart in Safe Mode. Doing so listed all the drivers as they loaded. StuRat (talk) 01:58, 13 August 2015 (UTC)

Resolved

Ethernet to wireless

My child will be living in a dorm room that has an ethernet connection but no wireless. What do I need to buy in order for her to get a wireless connection? Thanks for your help. 2601:82:C101:9BF:7018:D571:C12:B9A4 (talk) 19:02, 12 August 2015 (UTC)

One of these should do the job nicely, and is probably the cheapest option. Just check the college policy on what you may and may not plug into their Ethernet ports. Cucumber Mike (talk) 19:17, 12 August 2015 (UTC)

Thanks for the suggestion, and for the heads-up on asking for the college's policy. It turns she can use any router, just as long as the college installs it, which makes everything easier.2601:82:C101:9BF:7018:D571:C12:B9A4 (talk) 00:05, 13 August 2015 (UTC)