Features of using Bluetooth headsets with Android smartphones. How to understand Bluetooth versions

Mobile devices today serve not only for their intended purpose - making calls, but also as multimedia entertainment centers. On smartphones and communicators you can watch movies, create photo albums, play games, surf the Internet, and listen to music. They listened to music and will always listen to it. But today we will find out what mobile devices need, or rather, what functions and accessories a phone should support for such musical pleasure.

The first accessory with which you can listen to music on your smartphone is headphones.

- (from English hands-free) a system that allows you to talk and control the phone without using your hands. Most often used in cars. Essentially, these are devices that provide the ability to carry on a conversation without holding a mobile phone or communicator in your hand. Consists of an earpiece and a microphone. There are wired and wireless Hands free.

Wired headsets are connected to a mobile device using a cord. They, in turn, are divided into mono and stereo headsets. There are also multimedia Handsfree, which allow you to control the player of your mobile device.

The wireless headset connects to the mobile device using . It is capable of picking up a mobile phone signal at a distance of up to 10 m.

Bluetooth wireless technology has for some time been indispensable for equipping mobile phones with various external devices such as handsfree, external memory or wireless modems. Recently, Bluetooth headsets and headphones () have become increasingly popular. Some of them have the ability to work not only with mobile phones and PDAs, but also with other devices that do not have the Stereo Bluetooth protocol through adapters.

The advent of phones that support the ability to use wireless Bluetooth stereo headphones to listen to music has allowed their owners to feel the real joy of the complete absence of wires. However, the cost of such phones and Bluetooth headphones themselves does not allow us to talk about the widespread nature of this phenomenon.

Stereo bluetooth headphones cannot work with a mobile device if the latter does not support the profile.

Any sound starts from a source. Today there are a lot of wireless protocols for transmitting sound. Some of them are much more interesting than Bluetooth, but have not yet received proper distribution. Today, almost all smartphones, laptops and tablets are equipped with Bluetooth, and equipping a device with its support if it has a USB output is a matter of five minutes.

Therefore, today we will limit ourselves to sound-reproducing devices using “blue tooth” (the guide is quite suitable for choosing a Bluetooth speaker). This technology has quite a long history and a lot of pitfalls, the existence of which is not always known to users.

The presence of a Bluetooth transmitter does not mean that the device can be used as a sound source for wireless audio equipment. Not every Bluetooth will allow you to listen to high-quality music without distortion. Not everyone is suitable for listening to files with high bitrates and lossless formats.

What to pay attention to in order to listen to music wirelessly - be it just an MP3 or a high-quality rip from a vinyl record, we will tell you in this article.

Let's start with the most important thing: this parameter directly indicates whether you can listen to music using the device.

VersionBluetooth

IN modern devices Most often you can find support for Bluetooth 3.0 or 4.0, in some top smartphones and other gadgets - 4.1. In this case, it may well turn out that the purchased headset supports connection only via protocol version 2.1. The adapters are backwards compatible, but when connected, the slowest protocol of the two works.

The differences between protocol versions for the average user are minimal due to backward compatibility. The main thing that catches your eye is with each new version The power consumption of devices is reduced, and starting with 3.0 a second module has been added for high-speed data transfer at a speed of 24 Mbit/s.

Version 2.1 + EDR transmits data at a speed of no more than 2.1 Mbit/s. This is enough to play a low bitrate audio stream. To play audio and video streams, it is recommended to use Bluetooth version no lower than 3.0.

It is necessary to take into account that in order to fully use the device as a player, it is highly desirable to have Bluetooth version 4.0 and higher, or better yet, with reduced power consumption.

You can identify such an adapter thanks to the following categories.

ProfilesBluetooth

Profiles are a set of specific functions supported by devices. Of all the ones used in Bluetooth for listening to music, the following are interesting:

1. Headset Profile (HSP) necessary for connecting a headset and a smartphone and wirelessly transmitting mono audio with a bitrate of 64 kbit/s.
2. Hands-Free Profile (HFP) also provides only mono transmission, but with higher quality.
3. Advanced Audio Distribution Profile (A2DP) necessary for transmitting a two-channel audio stream.
4. Audio/Video Remote Control Profile (AVRCP) provides control over the functions of playback devices (without it, even changing the music volume is impossible).

To fully listen to music, A2DP is required. It not only ensures the transmission of the audio stream, but also manages the compression of the data before transmission.

However, even if both the transmitting and reproducing device (for example, a smartphone and wireless headphones) are equipped with Bluetooth 3.0 or 4.0 and support the required protocol, you need to pay attention to the codec that is used.

CodecsBluetooth

The most important thing for playing music using the A2DP protocol is the codec, which compresses the audio stream transmitted to the headset. There are currently three codecs:

1. Subband Coding (SBC)- codec used by A2DP by default and created by the profile developers. Unfortunately, SBC is much rougher than MP3. And therefore, it is not suitable for listening to music.
2. Advanced Audio Coding (AAC)- a more advanced codec that uses different compression algorithms. Sounds much better than SBC.
3. AptX- here he is, right choice! At least because of the ability to transfer files to MP3 and AAC without additional manipulations and transcoding. This means no sound deterioration. However, it is worth making a reservation. There are several versions of aptX to play different bitrates. Each of them is designed for its own sound flow.

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The main features of the latest two versions of the codec are the most reduced audio playback delay and reduced processor load during encoding. The Low Latency version allows you to achieve a delay of 32 ms between the audio stream source and the playback device. This will reduce the distortion introduced by the equipment when listening to music.

Thus, with certain preferences, you can choose a specific codec. If playback of a lossless stream is not expected, and high audio latency is not critical, you should limit yourself to standard aptX and not overpay for device support for subsequent versions.

It is worth remembering that the required profile and codec must be supported by both the smartphone (or other audio stream source) and the headset itself (or Bluetooth speaker). Otherwise, the A2DP algorithm will automatically start working using SBC.

With Bluetooth, any two devices always work using the lowest version, the simplest codec and protocol. So, if one of them does not support the necessary technology, you will not be able to fully enjoy the sound quality.

To listen to music for a long time, you need support for Bluetooth version 3.0 or higher, aptX codec and A2DP profile. To listen to music with a high bitrate, you need support for the aptX Lossless codec - no other will work, since the music will be compressed when transferred to the playback device.

Bluetooth technology is named after Harald Bluetooth, an ancient Viking king. And for the sake of God, don't ask why. It’s better to figure out the really important things: how it works, what it’s capable of, why it’s interesting—and why it’s not—to a music lover. And most importantly, what happens to the audio stream when it leaves the smartphone or tablet to reach wireless headphones or speakers via Bluetooth.

Today, it is impossible to imagine a smartphone, a tablet, or any other self-respecting mobile device without Bluetooth support. However, the technology itself was born much earlier than smartphones and tablets - back in 1994, and its original purpose was to replace the wires in the filling of telecommunication stations.

Initially, the “blue tooth” had a lot of problems with the speed and reliability of communication, energy consumption and compatibility between various devices, but over time the technology has grown, becoming noticeably faster, more economical and more capable with each new version.

Some improvements - for example, simplifying the "pairing" procedure in version 2.1 and seriously reducing the load on batteries in the current version 4.0 - have made daily life music lovers are noticeably more comfortable. The appearance of NFC technology- in conjunction with it, Bluetooth does not require any ceremony at all in the mutual recognition of the receiver and transmitter; it is enough just to touch the gadgets to each other. But in general, progress has had little effect on the quality of sound transmission: in the latest edition of Bluetooth, this process is arranged in the same way as in its version before last ten years ago. But how exactly?

35 blue teeth

Like the vast majority of others wireless interfaces,Bluetooth is based on the use of radio waves. To transmit information, the “blue tooth” uses radio frequencies in the region of 2.4 GHz - Wi-Fi routers, wireless computer keyboards and mice, some DECT phones and a lot of other equipment “graze” here.

How Bluetooth differs from many others wireless technologies? On the one hand, it has a relatively low range: its range of action does not exceed ten meters, and thick walls can further reduce this figure.

On the other hand - multifunctionality. “Blue tooth” can be used for a wide variety of purposes: from transferring photos to a laptop to sending documents for printing, from controlling external devices to streaming audio. It's no wonder that Bluetooth has so many different so-called. “profiles”, each of which ensures the execution of a particular task, defining technical specifications interaction between the Bluetooth transmitter and receiver. The total number of profiles is measured in dozens (according to an article on Wikipedia, there are a basic 35), only three are responsible for sound transmission. How are they different from each other?

Bluetooth profiles HSP, HFP and A2DP

The first of the Bluetooth audio profiles is called HSP - Headset Profile. As the name suggests, it is designed to work with mobile headsets and is tailored for basic voice transmission with all the ensuing consequences: audio is allowed only in mono format and with a bitrate no higher than 64 kB/s. Compared to this sound, even compressed MP3s seem like a divine delight to the ears.

The second - HFP, Handsfree Profile - is a slightly more advanced version of the same profile. Its target audience is the same monophonic headsets, so stereo is still not supported, but the sound quality is slightly higher. However, this profile is still not suitable for listening to music.

For this purpose, a special A2DP profile is provided - Advanced Audio Distribution Profile. He is the one responsible for the connection mobile devices with wireless speakers and headphones. The A2DP profile allows the sound source to find a common language with wireless acoustics, and most importantly, it controls audio compression for sending over the “bluetooth” channel. This procedure cannot be avoided due to the low bandwidth of Bluetooth, but the level of compression, algorithms used for compression and, ultimately, losses in sound quality can vary noticeably. This is where, as they say, nuances arise.

The SBC codec squeezes rougher than MP3

As you know, sound can be compressed in different ways. With or without loss in quality, with low or high bitrate, with different settings, using different codecs. Instead of one of the ubiquitous codecs for compressing the audio stream, the A2DP profile by default uses its own Subband Coding compression algorithm - or, simply, SBC.

Sound processing using SBC methods has a lot in common with the well-known MP3 compression, but the priorities are structured somewhat differently: the main task is not so much to minimize sound losses, but to simplify calculations. Everything should be fast, simple and easy to do even for the flimsiest mobile processor.

As a result, SBC deals with sound without unnecessary ceremony - for example, frequencies above 14 kHz are simply cut off during conversion, as a result of which the frequency range is noticeably narrowed. It is not surprising that even with the same bitrate as MP3 (and SBC allows bitrates up to 320 kB/s), SBC-encoded audio sounds noticeably worse.

As a result, when using the default encoder, transmission via Bluetooth degrades the sound of not only uncompressed audio, but also regular mp3 files - after all, during wireless transportation they are first decoded and then compressed again, this time much more roughly. Fortunately, SBC is the main, but not necessarily the only, audio stream compression tool that A2DP has in its arsenal. There are other, more interesting proposals.

Advanced Audio Coding: advanced, but not perfect

The basic SBC codec with its modest musical capabilities is not the best way to attract the attention of music lovers to Bluetooth technology. That is why the developers of many blue-toothed devices, especially in the top segment, complete the A2DP profile with optional, more advanced audio compression tools. The most popular of these tools is the AAC algorithm.

Unlike the SBC codec, which is familiar only to those who like to delve deeper into the technical specifications of Bluetooth, the AAC abbreviation is well known to the general public. Still would! After all, this is the format used, for example, in iTunes. The initial goal of the algorithm developers was to surpass MP3 in sound quality at the same bitrates - it is no coincidence that its name stands for Advanced Audio Coding, “advanced audio coding.”

Due to more complex algorithms, AAC actually stores more musical information than mp3, and even more so SBC. It is not surprising that its inclusion in the set of codecs supported by the A2DP profile significantly improves the sound of Bluetooth speakers and headphones.

The main thing is to make sure that the AAC codec is supported by both “blue-toothed” devices: both the one that serves as an audio signal transmitter and the one that works to receive it. If only one of a pair of such devices can understand AAC encoding, the A2DP profile automatically rolls back to the base codec. With quite obvious consequences for the sound.

AptX codec: the best option for music lovers

Even more advanced audio compression is provided by the aptX codec, which is actively promoted by CSR in the Bluetooth wireless audio market. The creators promote it as a means for wirelessly transmitting music “in CD quality.”

In fact, this is not entirely true, although the algorithms underlying aptX, in their principle of operation, do indeed resemble lossless encoders that compress the audio stream without losing audio information. Among the advantages of aptX is the ability to Bluetooth broadcast MP3 and AAC without additional processing, and therefore without sound deterioration.

A special version of aptX Low Latency, tailored to the needs of gamers and movie buffs, also ensures minimal delay in signal delivery - which means watching a movie without the lines lagging behind the characters’ facial expressions.

The aptX codec provides audio transmission with a bitrate of up to 352 kB/s, does not cut off the upper case and expands the frequency range to a quite respectable 10 Hz - 22 kHz, but the high complexity of the algorithms used requires mobile processors Triple the processing power of a basic SBC. That is why aptX support is quite rare among blue-toothed devices, most often in the premium segment of smartphones.

However, in order to become the owner of a smartphone with aptX, you don’t have to shell out that much cash: the catalogs of Samsung, Sony, HTS and Asus contain many models that support the advanced codec, including quite affordable ones.

As with AAC, when wireless connection audio source with speakers or headphones, you should make sure that the aptX codec is supported by both devices. Only in this case can you be sure that you are really squeezing out the maximum of its musical potential from the “blue tooth”.

(If you don’t use a Bluetooth headset, you don’t have to waste your time on the text below.) I’ve been using Bluetooth for a long time, and when choosing each new phone, I always pay attention to how fully and competently it works with this accessory. Until recently, if a candidate for purchase did not meet this criterion, he was crossed off the list. The Android smartphone and tablet were exceptions to this rule - I had to sacrifice many of the convenient features that I was so used to in my previous phones. What is missing in Android to fully work with “blue-toothed ears”? And is it really so much lacking?

I'll start with a nice little thing. Even starting from version 1.5 or 1.6, for a stereo headset you can choose which connection profiles to use - “telephone” HSP/HFP, multimedia A2DP/AVRCP, or all at once. That is, the headset can be connected to a smartphone only for conversations, and music can be listened to, for example, from a computer or another smartphone. At this point, alas, Android features"impossibilities" end and begin.

As far as I know (tested on several Android smartphones of different brands), Android up to version 2.2 inclusive does not allow:

1) transmit the call melody assigned to the subscriber to the headset - both monophonic and stereo (the melody is played through the phone speaker, and a standard ringtone sounds in the headset);

2) output a call signal only into the headset when it is connected (without changing the profile in the smartphone to silent);

3) use this standard function AVRCP, like rewinding within a track (only the transition between tracks works);

4) play multimedia files through a mono headset that does not support A2DP (that is, even audiobooks and podcasts that do not require special sound quality cannot be listened to through a mono headset)

5) rename or remove previously connected (paired) Bluetooth devices from the list (if there are two identical headsets or phones in a family, this creates confusion);

6) flexibly manage access to Bluetooth devices (separately for each profile);

7) call a subscriber from address book by his name (or pre-recorded voice tag) with one press of a button on the headset;

8) control the response mode incoming call- manually or automatically.

All this would not be so offensive if before the Android smartphone I had not used Motorola E770v (2005 model) and RAZR2 V9 (2007) phones on a proprietary OS (P2K), in which all of the above can be done.

In addition, you can only use a Bluetooth headset for voice calls on Skype if it supports A2DP. And then in it you can only hear the interlocutor, but you need to speak into the microphone of the smartphone (since the HSP profile in Skype for Android for some reason not used). That is, when using a wireless headset, you are still tied to your smartphone/tablet with an invisible “leash”. Most likely, the fault of the developers here is not of Skype, but of Android, since back in Maemo 4 (IT OS 2008) the Skype client worked perfectly using the “telephone” profile.

Yes, for mono headsets in the Market there are applications like Super BT Mono, which allow you to solve problem No. 4 (but not No. 1 and No. 2), and at the same time output the incoming audio stream to the headset in Skype. But the headset microphone still doesn't work in Skype.

The conclusion is sad: modern smartphones with a fashionable OS on board, they are completely inferior to the “simple phones” of 7 years ago in terms of the ability to work with Bluetooth headsets. Even if only about 5% of mobile phone owners use Bluetooth, even if most of the functions listed above are generally needed by probably less than 1% - the fact remains a fact.

Recently, our communication with friends, colleagues, etc. has increasingly moved to social networks and instant messengers. That is, voice calls are being squeezed out and replaced by text messages, while, for example, my phone spends more time in my hands and in front of my eyes than in my pocket. This means that voice dialing is needed less and less, remote control and even personal ringtones. Apparently, this is why both users and manufacturers do not care too much about the functionality of Bluetooth headsets, and most of those who read this note will consider my claims far-fetched.

However, if:

- you still talk on the phone more than you write;

— all the features provided by the Bluetooth headset are important and useful for you;

- you do not want to change your communication style,

then I advise you to purchase another copy of your favorite Motorola model or Sony Ericsson while they can still be found.