2023-07-18 16:48:30
Bluetooth audio codecs are used to transmit audio from a mobile phone, tablet or notebook via Bluetooth to a wireless headset that supports the same transmission technology. Currently there are several codecs created for this purpose, and some of them have appeared in recent years and are not much commented on by the media, as they are still very new. Understand the difference between the codecs in terms of proposal and the bitrate that each one of them is capable of transmitting.
What is an audio codec?
What are Bluetooth audio codecs, how they work and what bitrate each one has. In the photo, the Huawei FreeBuds 5 headset. Source: Vitor Valeri
Audio codecs were created to allow the transmission of data with the best possible quality using a certain bit stream (binary digit composed of the values 0 and 1). Through their algorithms, codecs may or may not be able to maintain the audio quality of mastering a music album. When developing a codec, think regarding the goal you want to achieve according to the transmission method and the desire to maintain audio quality.
There are two types of codecs, those for local reproduction, which do not suffer so much from the compression of audio data, and those for wireless reproduction (Bluetooth). Every codec uses the encoding and decoding process, but the level of compression varies and Bluetooth audio codecs are the ones that suffer the most loss of quality due to the need to quickly compress and decompress the audio data. The faster the encoding and decoding process, the lower the latency, but this comes at the sacrifice of data transfer capability (bitrate).
Examples of local playback audio codecs:
Examples of Bluetooth audio codecs:
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How does the Bluetooth audio codec work?
Bluetooth is a wireless transmission standard that can be used to send audio data from one device to another. When using this form of transmission for audio, there is concern regarding latency and stability. To do this, it is necessary to apply a more aggressive, faster compression and decompression that ends up with occasional loss of quality, as the data transmission flow is limited in order to obtain a stable connection.
What are the Bluetooth audio codecs used in the market?
There are currently several Bluetooth audio codecs that are used by Bluetooth headphones and Bluetooth speakers. Each of them has a purpose, a goal to be achieved. The higher the bitrate, the tendency is for the user to achieve better sound quality, but this will generate a high consumption of the wireless headphone battery.
Due to concerns regarding battery consumption and audio quality, developers have sought to create codecs that offer a compromise between good data flow (bitrate), to provide a good listening experience, and good battery life, where one tries to determine which would be the best point to not have a great degradation of the reproduced sound. This is the case of codecs with aptX Adaptive, which have the ability to vary the bitrate in real time according to the need at the time. Check the table below with all Bluetooth audio codecs and their bitrates.
Codec
Bitrate
SBC
240 kbps a 345 kbps
AAC
up to 250 kbps
LC3
163 kbps a 345 kbps
aptX
up to 352 kbps
aptX HD
up to 576 kbps
aptX Low Latency
up to 420 kbps
aptX Adaptive
up to 420 kbps (variable)
aptX Lossless
up to 1000 kbps
LDAC
up to 990 kbps
LHDC LL (LLAC)
400 kbps a 600 kbps
LHDC
900 kbps
L2HC HD
up to 960 kbps
UAT
up to 1200 kbps
As you can see above, there is a codec called LHDC LL (LLAC). It was developed by Huawei and like Qualcomm’s aptX Adaptive, the codec is capable of maintaining a variable data flow (bitrate) according to demand. In the case of other codecs, the bitrate varies as the distance between the headset and the cell phone changes for whom the connection remains stable. The further away you are from the smartphone, the lower the bitrate.
The bitrate of a codec can also vary according to the radio wave pollution in the location. Due to interference, audio transmission may fail due to the sudden drop in data flow, which occurs when the Bluetooth signal from the user’s device is interfered with by other radio waves.
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