Wireless audio devices, like headphones, use different types of wireless connections to transmit audio from the source (e.g., phone) to the receiver (e.g., headphones). The three main types are Infrared (IR), Radio Frequency (RF), and Bluetooth (BT). We will focus on Bluetooth, but the basic principle applies to all.
When sending audio wirelessly, the size of the audio file affects the bandwidth needed for transmission. Larger files require more bandwidth. Bluetooth has a maximum bandwidth it can handle, and if the file size exceeds this limit, the audio connection may become unstable and stutter.
To reduce file size, Bluetooth transmitters use special algorithms to compress the audio file. The compressed file is then sent to the receiver, which will decode it back into a playable audio file.
The special sauce responsible for encoding and decoding is called the audio codec. A codec is a software or algorithm that compresses and encodes the data for transmission and decodes it for playback. Both the transmitter and receiver must support the same codec for proper communication.
There are several Bluetooth audio codecs available, including SBC, AAC, aptX, aptX HD, aptX LL, LDAC, LC3, and Samsung Scalable Codec. Each codec has its own unique compression algorithm and affects the quality of wireless audio in terms of latency and fidelity.
Before diving into codecs, it’s essential to understand some basic audio terms:
- Sample Rate: The number of snapshots or samples taken per second to capture and reproduce an audio signal accurately. Common rates include 44.1kHz, 48kHz, 96kHz, and 192kHz.
- Bit Depth: Related to dynamic range, it represents the resolution within the range of the quietest to loudest sounds in a piece of music. Common bit depths are 16-bit and 24-bit.
- Bitrate: The rate at which data is transferred, measured in bits per second (bps), kilobits per second (kbps), or megabits per second (Mbps). Higher bitrate allows for better audio quality but requires more bandwidth.
- HD Audio: Lossless formats like FLAC, ALAC, WAV, and AIFF offer higher audio quality and are popular among audiophiles and music collectors.
When choosing audio equipment, consider the codec it supports to ensure the best wireless audio experience, especially if HD audio is essential to you.