Peter Cao. Apple did its part in moving the world to wireless headphones. With the removal of the headphone jack with iPhone 7the company made it clear that the future of audio is wireless. However, the company had already noted its vision well before the iPhone 7 with the original Apple Watch. Years later, the company continues removing the jack in more devices such as iPad Pro. Specifically, the different Bluetooth audio codecs and why they play an important role in the future of audio.
Earlier this year we broke down Bluetooth 5. Learn more about that here. Compression is an algorithm in which certain audio frequencies get removed compressed to reduce file size. Modern compression algorithms are typically really good at this and remove frequencies that are inaudible to the majority of humans. Next are the murky waters of lossless versus lossy which, despite sounding the same, are two completely different methods of compression. Lossy is what most music streaming services use.
LDAC vs aptX vs SBC vs AAC: Which Bluetooth codec to choose?
Lossless is where things gets slightly controversial. By definition, lossless audio means that nothing is lost and all artifacts and details are retained from the original recording.
This is important as Bluetooth audio compression varies by codec. Some codecs allow for lossy, and others allow for completely lossless audio streaming. At the baseline, every set of Bluetooth headphones or speakers uses the low-complexity subband codec, better known as SBC.
However, manufacturers typically set a maximum bitrate of Kbps.
SBC is free for manufacturers to use and was the very first audio codec to get certified for Bluetooth. Next is advanced audio coding, better known as AAC. This codec is commonly found in Apple devices, with Android recently supporting the codec in later versions of the operating system.When the two devices are combined by detection or grazing when an NFC chip is presentthey present themselves to each other and list their respective capabilities. As far as audio transmission is concerned, no less than 5 compression modes are possible.
Their choice is almost never left to the user and it is the Bluetooth chips that determine the transmission mode to be used. If the radio frequency conditions allow it low interference, proximity of the two devices, possible Bluetooth keyboards or mice connected to the sourcethe most qualitative mode is automatically chosen.
When conditions deteriorate in public transport, for example, due to the proximity of other smartphones and Bluetooth headsetstransmitters and receivers adapt and change their communication methods seamlessly. The apt-X HD codec is then switched to the next lower quality codec.
Namely: when you listen to Spotify, Deezer, Qobuz, Google Music or Apple Music, the stream is automatically recompressed according to the codec chosen by the transmitter and receiver. These codecs make it easy to identify the maximum rate allowed when transmitting the Bluetooth signal and therefore the resulting audio quality.
Here are the features of each of these Bluetooth codecs. Its operation is based on the Bluetooth 4. For a long time remained the exclusive technology of the Japanese brand, only Sony devices could use it with each other.
Fortunately, this codec has now been used by other brands for a few years. Now widely used, apt-X codecs offer high transmission quality, with a throughput of about Kbits for apt-X HD and Kbits for apt-X. The sound compression method is deteriorating information is deletedbut the playback remains very good. Listening, we notice a rather pleasant ventilation and a wide frequency response. If you own an iPhone, iPod touch or iPad, you will not be able to take advantage of the apt-X codec, Apple having chosen another Bluetooth controller supplier for its devices than Qualcomm the only manufacturer to market apt-X chips.
As a result, the impasse has so far been made on the apt-X. The qualitative differences with apt-X are very small, especially since if you listen to music with iTunes in AAC format, no re-compression is performed. On the other hand, when the rate drops to Kbps, audio artifacts are audible in the high frequencies. If you have ever had the impression that your Bluetooth headset was crackling, you didn't dream and the SBC codec is to blame.
If you are looking for a Bluetooth lossless transmission without loss of informationyou will need to choose LDAC-compatible devices such as an audiophile or Sony smartphone, as well as a Bluetooth headset, Bluetooth speaker or any other LDAC-compatible receiver device.
If you want to broaden the choice of compatible equipment, it is better to choose an apt-X or apt-X HD compatible source and broadcaster. Many smartphones are Samsung, Motorola, etc. You may also want to read:. Does GoPro Hero 8 suitable for taking picture or as vlog camera?The AAC audio format supports audio quality up to bit 96kHz, but in the Bluetooth space we are limited slightly below CD quality at best.
The graph above is a little bit of a headache to read because the results we obtained for AAC are so varied. Before we zoom in on the graphs to highlight these differences more closely, you need to know a few things.
The bulk of what you hear appears well below 10kHz. Human hearing is also limited to somewhere between 10kHz to 20kHz depending on age, so bear that in mind on the following graphs. It may be high-frequency sound, but these drop-outs will be audible to younger ears. Frequency cutoff varies widely from device to device with AAC.
The iPhone 7 performed by far the best, extending its limit up to That's concerning for anyone who prizes audio quality over convenience. The Samsung Galaxy Note 8 is included as a mid-point in quality. First, this data showcases a great example of the psychoacoustic compression algorithms used by AAC. This falls just shy of bits worth of data. We can see that the noise level around our test tones seems to roughly follow the amplitude.
The reason for this is due to the way Android handles encoding for some Bluetooth codes. EAS governs how a phone prioritizes CPU clock speeds versus energy efficiency, and Bluetooth encoding can be assigned a priority like any other task. Therefore, smartphones that prioritize energy efficiency over performance will encode AAC Bluetooth to a much lower bitrate and quality.
Even our best Android phone in the mix, The Galaxy Note 8, is clearly worse than the iPhone 8 across all frequencies. It offers a reasonably consistent level of noise at around dB around all of our test tones, and an impressive background noise of dB.
Definitely nothing close to CD quality here. The iPhone 7 19kHz roll-off is also noticeable with the lower final peak. The frequency responses are identical for each phone whether playing lossless or AAC file types. We can also clearly see that none of the phones reach the same 20kHz limit as our AAC input file type.
The out-of-band noise floors are also clearly differently shaped in each instance, and none reach as low as our test file. Even so, all of these phones re-pass an AAC source file back through the encoder, degrading quality. Just like with lossless files, the difference lies in how much additional compression is applied to the files on this second pass.
AAC is one of the more intriguing Bluetooth codecs to analyze, owing to its psychoacoustic rather frequency band quantization. This makes judging its quality a little tougher, as we have to take into consideration auditory masking rather than the consistent noise floor that we see with other codecs, CD, and Hi-Res files. High-quality implementations, like that from the iPhone 7, are going to be very hard to distinguish from CD quality and other high-quality Bluetooth codecs.
However, lower bitrate implementations like those seen on some of our Android phones are nowhere near CD quality in terms of frequency response or noise.The world of Bluetooth audio is as confusing as it is convenient. These are Bluetooth codecs. Here at Major HiFi, we would like to offer some assistance to those audio purists navigating these options.
Sample rate and bit depth specs reveal more information about lossless and uncompressed audio quality. Bit depth affects the amount of dynamic information that can be taken within each of the samples.
Bit depth deals with volume, and sample rate deals with frequency information. Compression formats use different algorithms to encode a file to minimize its data size.
MP3 compression made waves pun intended in the early days of portable digital audio because it could efficiently reproduce decent quality sound while simultaneously saving massive amounts of hard drive space.
Compression serves a slightly different purpose in the context of streaming.
The ultimate guide to Bluetooth headphones: AAC only acceptable on Apple phones
When we stream, playback occurs simultaneously with data transfer. This can come in many forms such as Bluetooth, Wi-Fi, or an online service. A lower bit rate typically results in a smoother stream, at the cost of some fidelity. The s ub b and c odec has a variable bit rate that results in unpredictable quality.
AAC works a little differently than the other codecs. Despite them both being lossy, compression used in Advanced Audio Coding is more efficient than an MP3. What makes AAC Bluetooth unique is that there is very little encoding or decoding in the process of transmitting the audio data. The file would sound more or less the same through a wired or wireless connection.
It streams at a max of kbps, translating to a sample rate of 96kHz and a bit depth of LDAC swaps between fixed bit rates of, and kbps depending on available signal strength. It is also possible to select which bit rate you prefer on some devices. In order to use LDAC, both the transmitting and receiving devices need a license agreement with Sony.
Now, these codecs are developed by Qualcomm to serve a number of wireless audio needs. Once, there was only aptX previously apt-X.
AptX vs SBC – Which Codec Works Better?
It offers fixed bit rate data compression, providing steady quality in a Bluetooth audio stream. Poor audio sync can ruin the emotional impact of a film, and could be the difference between winning and losing a video game.We purchase our own headphones and put them under the same test bench, so that you can compare the results easily.
No cherry-picked units sent by brands. The efficiency of the codec will determine the quality and rate at which the audio data is sent. However, since this codec has a relatively high latency and may be a bit lossy, companies have developed their own encoding algorithms, like Samsung's UHQaudio and Sony's LDAC. It is capable of bit rates up to kbps with a sampling rate of It provides fairly good audio quality without requiring a lot of processing power to encode or decode.
However, the audio quality can be a bit inconsistent at times. This is especially noticeable with a cheap Bluetooth transmitter. This codec is mostly popular with Apple's iTunes platform and some other non-wireless applications. However, it's not very common, especially for headphones.
It's ideal for demanding audio applications since it encodes audio more efficiently and at a slightly higher rate than SBC. There are also two additional variations, aptX Low Latency and aptX HD, that either drastically reduces the latency of the connection or significantly improves its audio quality. So, for now, our comparison will focus on the differences between SBC and aptX. Learn more about Bluetooth. The default sub-band codec SBC works well for most audio applications.
However, the subtle audio quality differences may be noticeable to trained ears and more critical listeners. Below are a few samples of the same headphones using aptX and SBC. Can you tell the difference? As you may have noticed, it's difficult to tell the difference between SBC and aptX by ear. This shows that Frequency Response and Total Harmonic Distortion alone are not sufficient for evaluating the benefits of a better codec, as there are more subjective factors that are not reflected in the FR and THD measurements.
This should better simulate the subjective experience of most listeners when a codec is enabled. However, since both the transmitter and receiver must support aptX, you will be using the default sub-band coding more often than not. The default SBC connection typically has more than ms of latency, which is noticeable when watching videos and may be severe enough to ruin your gaming experience.
Regular aptX does somewhat improve latency due to its more efficient encoding algorithm than SBC. Regular aptX does somewhat improve the latency, but not as significantly as aptX-LL.
This makes the Backbeat Pro 2 and other headphones with the low latency codec good headphones for gaming and watching movies as long as both your Bluetooth transmitter and receiver support the aptX-LL.Audio playback on smartphones has evolved so much that some manufacturers are set on getting rid of the 3. So, how will you be able to listen to music then?
With the help of Bluetooth codecs. Bluetooth is notorious for its slow transfer speeds. However, you can now improve the transfer rate by using a Bluetooth codec.
Thanks to Bluetooth codecs, you can listen to music on your smartphone with wireless headphones. It can have a sampling rate no bigger than 48 kHz, while its bitrates can amount to anywhere between for mono streams and kbps.
This codec is very slow and usually has a latency of somewhere between and ms. This is only noticeable while interacting with video content, where the audio inside of a video happens to go out of sync.
The aptX codec took quite some time to be made compatible with Android phones, but it was well worth the wait. This codec uses the adaptive differential pulse code modulation ADPCM to compress audio signals and transmit them at kbps.
ADPCM can divide the audio file into four frequency bands that are separate. This creates a better signal-to-noise ratio, which makes the audio quality of aptX quite better than that of SBC. In addition, there is another version of this codec called aptX Low Latency. The high definition version of aptX focuses on improving sound quality as much as possible. It works great with wireless headphones and still manages not to increase the latency, making it a good choice for audiophiles on the go.
If you really want to get rid of latency, whether to play a video game or watch a live stream, aptX Low Latency is the codec for you. You should be able to change the codec at any time, but note that not every Android smartphone will have this option. For one, SBC has problems with data loss and high latency.
It manages to solve many problems that SBC has. Its Low Latency and HD versions are very useful, the latter bringing the sound quality level of wireless headphones close to that of wired models. Which of these two is your Bluetooth codec of choice? Is there some other audio codec you prefer? Share your thoughts and tell us about your favorites in the comments below.Bluetooth audio is gaining a lot of followers today.
The disappearance of the mini-jack ports for headphones on some smartphones, such as the iPhone, has led to audio companies producing high-quality wireless devices.
Among Bluetooth audio technology, the Qualcomm aptX code is in a privileged place. In other words, it is the process by which zeros and ones, of binary digital data, acquire format. It is used to transmit stereo audio through a source device, such as a telephone, a computer, television, etc …, to a receiver, such as wireless speakers or headphones.
Different codecs send the audio information using different formats, they can also introduce their own compression technologies to maintain a balance between the sound quality and the information package of the audio files.
Compression may sound negative for lovers of high-quality audio, but it is necessary if we are going to send heavy files wirelessly. This means that the variants between the Bluetooth codecs are compatible with different audio devices, in addition to providing different connections and sound qualities. To offer greater consistency to users of Bluetooth products, several companies have developed their own Bluetooth codecs, and then offer the license to other producing houses.
The codecs are coding algorithms that compress audio to handle sound packets and thus achieve fast wireless transmission. Bluetooth devices, However, this codec has relatively high latency and can be somewhat noisy. It is the code found in most wireless devices and with which all the Bluetooth headphones that feature the A2DP Advance Distribution Pro le feature. It is capable of transmitting up to kbps with sample rates of It provides very decent quality audio and does not require much processing.
However, audio may be inconsistent in some situations. This is notable, especially when using cheap Bluetooth transmitters. Similar to SBC but provides better sound quality. This codec is very popular thanks to the Apple iTunes platform.
As against, we must mention that it is not very comfortable to find it in headphones. Ideal for demanding audio applications as it encodes the audio more efficiently and accepts more information than the SBC. It has additional variations, such as aptX LL and aptX HDwhich drastically reduce latency in the wireless connection and improve sound quality. However, it is somewhat limiting because both the transmitter and the receiver must have the aptX capability for this codec to work.