Wireless sound. From the computer and almost throughout the apartment



How I really wanted to do everything on WI-FI ...

Of course, one could start this article with a lyrical digression about the “smart” houses of the future (or apartments), in which there are miniature (or not) speakers that delight the owners with music everywhere. Probably in the near future this will happen when every device in our home will be equipped with a penny WI-FI adapter. But for some reason, at the present time, such technical solutions related to wireless sound distribution via WI-FI may cost some unwise money. Here, for example, a multi-room system from the company "SONOS", where only one! wireless WI-FI column, will cost the buyer in excess of twenty thousand rubles.


In general, a good article in 2016 about WI-FI audio distribution is called “Wireless audio systems: crooked, expensive, very interesting” [1], where the last two words of the title reflect the author’s hope that in the future, at least something This will change for the better.

So, as long as the Chinese do not overwhelm us with cheap audio speakers with their famous ESP8266 microcircuit (which allows us to establish a full WI-FI data exchange with the target device and which enthusiasts shove anywhere up to light bulbs and coffee makers and), we can only turn to the proven time technical solutions.

1. Wires. (which is already dissonant with the title of our article)
2. Bluepup.
3. FM radio.

Specifically, in my case, I wanted to listen to music played on a computer in the whole apartment, so that the sound came from wherever possible and not. For this purpose, initially served 12 active speakers arranged in a whimsical manner on the window sills, cabinets and bookshelves under the ceiling. Also present was the TV responsible for the whole wall. I also wanted to use his sound-reproducing system in parallel, since I already had a wireless HDMI transmitter installed (you turn on the movie on your computer, and you watch with sound on TV and you don’t have brake dongles or media players with ever-obsolete video formats).

So part 1. Can it be done simply? ..

Initially, I laid a lot of things with wires. In principle, along the windows and at a distance of up to 10 meters, everything turned out to be quite civilized and unnoticed, and as it turned out, the output of the computer's sound card pulls even a dozen active speakers in parallel (two years already, by the way, pulls).


But with the other walls and doorways, and even in other rooms, everything was not so cloudless. Clearly required to transmit sound through the air. Yes, and I also wanted to include the TV in the general network (in vain, perhaps, is the Japanese quality lost there?). Then I decided to use the technology of Blueupup ...

But as they say, everything has been stolen long before it was invented before us. Back in 2006, the well-known company LOGITECH released the so-called Logitech Wireless Music System for PC with a quite reasonable value from $ 75. You got into the hands of a Bluetooth transmitter interfaced with your computer, and already he was distributing sound to the same bluetooth receiver up to four, which was well suited to my requests.


The only major drawback of this device was that it was taken out of production for about five years, if not more. In principle, you can now buy this device on eBay, if you have the desire. But in Russia you will not find him with fire already in the afternoon. I found only one set in Moscow. But there was only one receiver when I needed, well, at least two. Searches for similar devices from other manufacturers did not bring any success either, the only thing I constantly stumbled on was either just ordinary Bluetooth speakers or another device from the already mentioned company, the so-called Bluetooth Audio Receiver (which is a benefit, has not yet been removed from sale ).


In general, this is the same Bluetooth receiver to which you can connect active speakers, but without the possibility of networking, as long as you do not have a transmitter. And we do not have it. Or is there? Maybe you can somehow distribute to several such devices the sound directly from our computer, which will be the Bluetooth transmitter?

I tried to try. In the presence were: Bluetooth speaker, Bluetooth headphones and the above-mentioned Bluetooth Audio Receiver (it can still be called the Logitech BT Adapter Stereo), with the usual active speakers connected to it.

The connection to the list of playback devices on the computer (hereinafter, the default will be about the Windows family) was trivial (standard for all bluetooth devices) and does not deserve separate consideration.

It turns out in the end, something similar to the following picture.


Now you can try to listen to all connected audio devices. As it is easy to figure out in the end, we can only listen to one device, namely, the one on which there is a green check mark (which means the device by default). The remaining audio devices are silent, like fish, until they get the coveted check mark. On the one hand, this is understandable, but on the other, it is a little surprising if we conduct a simple experiment.

Let, while by default the sound output Real High Definition Audio works. This is the usual line-out of a computer sound card. By attaching the usual wired headphones to it, we will immediately see this. They reproduce the sound at the moment. But now, if we right-click on wireless headphones that are silent for now (in my case, this is the MDR-ZX330BT Hands-Free), and select the “Advanced” property and the “Check” in it, then we will hear alternately blinks. That is, they are normally connected, they can broadcast the sound (test), but here's the music, like working now wired, shish with oil.

That is, theoretically, Windows can shove sound to all devices at the same time (taking into account, of course, computer performance), but does not want to do this. You can only choose one thing (actually two).

The only possible trick to listen to two audio devices simultaneously in Windows is to use a regular stereo mixer.

One of the devices should be a linear audio output of the computer (the one to which you connect wired headphones and speakers). I have it designated as Real High Definition Audio. It must be in the “Device Default” state. Now select the second audio device.
Moving from the Playback tab to Record, Stereo Mixer, Properties, Listen. In the drop-down list, select the audio device we need.


I chose my Logitech BT Adapter Stereo. Now you can play music simultaneously on these two audio devices. And they will really play at the same time.

True, this scheme has two drawbacks. The first is that the limitation of two devices can still be experienced. The second drawback, crossing out the entire circuit - is that the sound sounds out of sync. Music on the bluetooth channel (as well as on the HDMI television), lags behind the music playing through the audio line out. The difference is about 0.2-0.3 seconds, but because of this, it is simply impossible to listen to 99% of the soundtracks, because in the end you hear a sound porridge. In rare cases (the sounds of nature there or all kinds of bells), such out-of-sync is even funny in its own way, it creates a sort of depth and presence effect. But just to listen to music, especially songs, is simply unbearable.

Probably, the problem here is in buffering digital data for wireless transmission, due to which the signal lags. But this eventually destroys everything. If it were possible to somehow adjust the signal delay for the audio line output, then the situation with the desynchronization could be corrected by setting, for example, manually the duration of this delay. But unfortunately, the standard Windows tools do not seem to represent this feature.

It would seem, then you can not use the standard audio output, and take for example, the default one Bluetooth device, and the second to pass through the above-mentioned stereo mixer Windows. Then the buffering delay will be the same, there will be no desync, and we will still get two simultaneously playing devices. But again, unfortunately, nothing will work out for us, since this circuit with a stereo mixer only works if one of its participants is a linear audio output.

It turns out just like in the book “Three in a boat, not counting a dog” with one of its characters:
“Then Harris began telling us stories about how he crossed the English Channel in such a storm that passengers had to be tied to beds, and only two people on board — he and the captain of the ship — stood against seasickness. Sometimes those who resisted seasickness turned out to be himself and a second assistant, but invariably it was himself and someone else. If it was not he himself plus someone else, then it was he alone. ”

As the saying goes, add nothing and not take away. Linear output is Harris. Still, after that, I was not disappointed. After that I tried my luck with the FM program ...

Part Two. FM transmitter. Help ultrashort waves.

After reading the relevant article on Habré [2], in my imagination I immediately had a plan to build a radio network, where there is a small FM transmitter in the center connected to the computer’s audio output, and around it throughout the apartment is located from five FM receivers, from which already broadcast active speakers. Implementing the idea was easy.

A car FM transmitter with a linear input was purchased for 500 rubles; in the documentation, it runs as an AUX input (by the way, not all transmitters have it! Everyone has USB inputs, everyone has a memory card, but half of these devices already have no simple line input!).


It was necessary, however, to modify it a bit, since twelve-volt power outside the car is rare. Therefore, I connected a USB cable to the transmitter, from which I took the wires of the five-volt power supply and soldered them to the input of a 3.3 volt voltage regulator already inside the transmitter itself (everything on the printed circuit board is indicated, it is difficult to make a mistake). I connected the audio output of the computer to the transmitter's AUX input and, when turned on, it began to consistently broadcast radio waves on the air at the default frequency (its value can then be set up with buttons if desired).

Accordingly, the following FM receiver was acquired for the receiving part:


A nice feature of this device was the presence of a headphone jack for headphones, where the plug-in from active speakers went perfectly. If you tune the receiver to the desired frequency, and it is also very conveniently tuned with the buttons, and not as a vernier or wheel in the old fashioned way, then you will hear exactly what your FM transmitter transmits - THIS is a wonderful warm radio sound. Immediately I remember childhood, when among the cod and whistle you catch illegal songs from the BBC. This is not some kind of cool clean computer sound!

In short, no matter how I changed the frequencies on the transmitter and, respectively, on the receiver, I never managed to achieve a normal clear sound. Actually, when the music itself is playing, the interference is not heard much yet, but as soon as there is a pause, you will hear all possible radio broadcast turbulences within a radius of ten kilometers. I'm not even talking about the case when you are NOT listening to music, but just let’s say you are sitting at a computer; but even then you also hear a solid crash and police talks - the receiver is working, it is catching something.
Therefore, plans to transmit sound via FM channels also had to be abandoned.

Part 3. Everything is a program ...

At the beginning, I was looking for mixers. I was not left hope by some programmatic way of organizing a signal delay on the computer’s audio output in order to listen to at least two audio devices simultaneously without desynchronization. And digital mixers, in theory, should do such things. But as it turned out, most of these programs are able to reduce the sound tracks from different sources into one final one, but they are somehow not very good to separate from one to different playback devices, that is, this is definitely not their main function. And even if this function exists, it is buried somewhere deep in the depths of the settings, from where it still needs to be dug up. In addition, we must somehow manage to integrate these mixers into the audio stream of the same browser, the music from which, for example, you are listening to.

But, going through all these mixers and audio editors, I leaned into an interesting program Virtual Audio Cable, with which I finally solved all my tasks.

Quote:
The program creates several audio devices in the system, which are called “virtual cables”, each of which contains an input and output device for sound supply. Any application can send its audio stream to the “output” part of the cable, while any other application can receive sound from the “input” part of this virtual cable. Transmission occurs entirely in digital form, due to this, the sound quality is not reduced.

The program seems to be initially paid, but you will also have no difficulty finding it for free. And once you have made your choice, you just have to run it and apply it to our connected audio devices. In my case these were: the TV "SHARP" connected to the computer via wireless HDMI channel.


Two pieces of Bluetooth Audio Receiver with active speakers attached to them. On one adapter, four columns, on the second, as many as eight.


Bluetooth headphones «SONY MDR-ZX330BT


Bluetooth speaker BoomBot 2


Now we will try to make all these devices function in parallel and without noticeable delays. We check for starters in the list of equipment that all these devices are already connected and ready to work (this is important, connecting on the fly, is fraught with glitches). Looking ahead, I’ll say, the only thing we don’t use is the line audio output of the computer, since, like the hero from the book, he always pulls the blanket over himself (yes, Harris was different too). To completely neutralize it, we plug the cheapest wired headphones into it, such as these:


We put Real High Definition Audio (Line Out) in the device list, as the default device, set in “Stereo Mixer” (see above) playback from it, throw the headphones over the system unit and forget about it now forever.

Now we will install the program Virtual Audio Cable. In the folder of the program itself and the x64 subfolder (for those with Windows 64-bit) there are two files that we need to execute: vcctlpan.exe and audiorepeater.exe (which we will simply call “audio editor” in the future).
We first run the first:


In it, we actually set the number of virtual cables - one, and the sources of the signal "Line". We close the program, we will not need it anymore. Now we launch the browser, and in it is some kind of Youtube song. If everything is in order, then we will hear a barely audible sound from somewhere because of the system unit. It earned wired headphones.

But from the second file „audiorepeater.exe“ we do a shortcut directly to the desktop, we will need it regularly.

Now we open it for the first time and change two lines in it: from the “Wave in” drop-down menu, select “Stereo Mixer”, since we conducted the audio channel through it, and from the “Wave out” drop-down menu, select the TV and click “Start” . TV should ring out. As before, the sound from it will lag behind the wired headphones, but we will not care anymore, we simply will not hear them.

In general, as it turned out, the “Wave” in line can be not changed, but the original “Reassignment of sound devices” should be left. It seems like the program itself understands where the desired input is by default. Therefore, we do not even touch this line in the future. Save power.


Now we launch a new copy of the audiorepiter. In it, select the first Bluetooth Audio Receiver (it is slightly different from the second in the title) and click “Start”. The speakers connected to this receiver begin to vote.


We do the same with the second Bluetooth receiver. Now speakers connected to it are voting.

Now we are accepted for the wireless speaker BoomBot 2.


And the final touch - wireless headphones MDR-ZX330BT. Play?


Please note that due to approximately the same buffering delays, there is no out-of-sync sound (by the way, it can now be adjusted by changing the value in the "Total buffer" field). Sound quality? To be honest, I'm not an audiophile, it suits me perfectly. Although, of course, professionals in this field swear at me with obscenities for the transmission of blupup and computer speakers. As for the communication range, within one room the signal passes steadily at a distance of ten meters (no longer measure, the apartment is over) and successfully overcomes one interior partition.

Of course, I would like to use a linear audio output, since it is available. But again, there is the problem of desynchronization. It would seem that the signal to it, too, can be passed through the audio recorder and adjust the delay, but alas, it will still be played in parallel with the audio output itself. That is, for some reason, it is always present in the virtual cable and in the present. Maybe someone will succeed in defeating him, but it did not work out for me.

Now about some subtleties. Not all wireless devices are enabled by default, such as TV or headphones. Therefore, when the computer is turned on, Windows assigns a default device to the device as the default. That's why we use those wired headphones in this quality so that we are guaranteed to always have the same default playback device (and since they always turn on simultaneously with the computer, the system finds them first). Accordingly, the signal in the stereomixer is also reproduced through them, but even if there are sound overlaps, we no longer care about it (we cannot hear them). But if they didn’t exist, then at startup, Windows would have assigned some remote device that was currently turned on, and would also duplicate it through a stereo mixer. You can, of course, check the list of devices each time at startup, but it seemed to me convenient to put a “stub” in the form of wired headphones and forget about these nuances. By the way, the stereo mixer cannot be turned off, nothing works without it.

And now about the fly in the ointment in our barrel of honey:

1. The number of devices connected via the Bluetooth program cannot be brought to the theoretical limit (71 pieces like?). In reality, I have absolutely stable at most three such devices at the same time. Well, plus a TV via HDMI channel (the impression is that he absolutely doesn’t care about the number of neighbors; it always works correctly). Already four blupups begin to stutter sooner or later, and the “VirtualCable” buffers overflow. There is a version that maybe this is a Bluetooth adapter and the sound card of the computer itself no longer has time to distribute its audio streams.

2. Not all Bluetooth devices are compatible with each other. When I tried to connect an additional wireless column "Defender", it suddenly began to conflict with BumBot.


In general, they tried to sing at the same time, but it turned out they only alternately. And they did not conflict with other devices. Only with each other. This question also requires its study.

In the end, I still got what I wanted, even in such a limited quantitative version. You can listen to the birds singing in the woods and in the living room and in the bedroom, or watch the fire play in the fireplace (on the TV, of course) and fire wood, and outside the window a winter wind howls or it rains or waves splash. Youtube is full of these many hours of videos. You can share the screen on a computer, children can put cartoons on TV with an additional screen and sound, and work and listen to music on the computer itself through wireless headphones (or watch a teleconference on it), while the wife in the bedroom reads a book and listens to the birds singing in the woods via wireless speakers. Well, and so on.

I would be glad if my article would be useful to someone.

[1] Wireless audio systems: crooked, expensive, very interesting
[2] FM transmitter radio headphones

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