Hundreds of new wireless headphones are marketed every month but Qualcomm has only closed this alliance with one brand: Xiaomi.
The new Xiaomi FlipBuds Pro are the only ones compatible with Snapdragon Sound, technology developed by Qualcomm to get the most out of audio chips and ensure optimal sound quality – which results in bitrates higher and latencies lower—- What are we talking about? Let’s unveil it right now.
Three basic concepts
Before talking about the different differences in digital audio compression or encoding protocols, we are going to review three basic concepts.
- Bitrate or bit rate (kbps): digital audio is measured in kbps, or kilobits per second. This rate tells us about the amount of data that is transmitted per second through a connection. The lower it is, the lower the definition and sharpness of the frequencies as it will equal less data transmitted within a specific frequency range. For reference, a CD is compiled and transmitted at a bit rate of 1411 kbps.
- Sampling frequency (kHz): this value measures the amount of data per second to which an audio file has been recorded. This is known as the sampling frequency and the usual standard is 40 kHz (44.1 kHz or 48 kHz), although it is common to master in the studio at frequencies much higher, at 96,000. and even 192,000Hz. It should be noted that only 44.1kHz already covers twice the frequency range that a human ear is capable of hearing.
- Bit depth: finally, this value speaks of the number of bits stored within an audio sample. The higher the bit depth, as is the case with color, the higher the precision and hues registered. Digital music for home consoles has been recorded for decades at 8-bit depth, allowing for minimal file size. A CD is recorded at 16-bit resolution, which translates to 96 decibels of dynamic range. A 24-bit DVD, which is equivalent to 144.5 dB of dynamic range. There are already standards that operate with a 32-bit depth – with floating point, not with fixed point -, which according to the IEEE-754 standard implies files a third larger and a range of up to 1500 dB. Crazy.
The main audio compression codecs
We finally have a clear map of the three figures that define the “quality” of digital sound: bitrate, sample rate and resolution. Now let’s get to know the different codecs on the market that deal with quality with a fourth value always on the rise: latency.
Latency is the time it takes for an audio signal to arrive from when it is sent by the host device (mobile) until it is received by the receiving device (headphones). And in terms of latency, the aforementioned Xiaomi FlipBuds Pro have set a historical record: its game mode is capable of going down to 69ms.
- AAC (Advanced Audio Coding): developed by a consortium of companies, this standard has existed since 1997 and is the most popular codec on the internet, being the one adopted by iTunes (Apple) and YouTube (Google). It guarantees high quality for the same bit rate as the SBC codec in exchange for a latency that is too high – between 170 and 200 ms.
- AptX (Audio Data Reduction Technology) – A standard adopted by almost all companies. Although this codec dates back to the 80s, used mainly in radio, over the years it has experienced different iterations, first after the purchase of CSR (Cambridge Silicon Radio) and then with the absorption by Qualcomm in 2015, when it presented a number of key innovations. There are currently three iterations depending on the technology. The first, aptX LL (Low Latency), where latencies lower than 35 ms are prioritized, compared to the usual 150. The second, aptX HD (High Definition), focused on offering a higher bitrate taking advantage of the bandwidth, reaching 576 kbps at 24-bit and 192 kHz; that is to say, DVD quality. Finally, the aptX Adaptive, the most advanced of the three and capable of achieving dynamic compression with a minimum bitrate of 276 Kbps and a maximum of 420 kbps.
- LDAC: the standard adopted by Sony – although it is open source, it only requires a license from Sony – has its own algorithms and can operate at three bit rates, 330 kbps, 660 kbps (normal mode) and 990 kbps (quality mode) at 24 bit / 96 kHz.
- LHDC (Low Latency High Definition Codec): this standard created by the HWA (Hi-Res Wireless Audio) is committed to a high bitrate of up to 900 kbps at 24 bit / 96 kHz and latencies below 100ms. It is one of the most used by expert audio manufacturers such as Optoma, Pioneer, Sennheiser or Audio Technica.
- LC3 (Low Complexity Communication Codec): This standard has one of the lowest bitrates – 160 kbps to 345 kbps – and has the widest sample rate, from 8 kHz to 48 kHz. He is a regular in podcasting and broadcasting audio from websites. In exchange for its limited bandwidth, it guarantees greater stability and less audio interference.
What is Snapdragon Sound
As is evident, Snapdragon Sound supports the highest quality standards. That is, with LDAC and LHDC and their ability to broadcast 24-bit / 96 kHz audio.
But it also supports external DACs and supports formats like LPCM (Linear Pulse Code Modulation), the standard used for recording in audio containers such as WAV or AIFF, or working with high-fidelity lossy compression formats, such as the Tidal standard MQA (Master Quality Authenticated)
Snapdragon Sound supports up to 384 kHz 32-bit PCM and DSD with a minimum THD + N. This concept, short for “Total Harmonic Distortion + Noise” refers to both the amount of harmonic distortion and the signal noise generated, the two Achilles heels of the sound. Lovers of Audirvana and portable DACs are in luck.
Introduced eight months ago, Snapdragon Sound pushes its chest out to become the new Qualcomm standard bringing together the latest advances in wireless connectivity and digital audio encoding. Of course, it is only compatible with the Snapdragon 888 SoC and the future Snapdragon 888+.
For now, it is the ability to amplify the sound without greater electrical excitation —that is, without consuming more battery from the mobile—, in addition to offering a stable and very low latency of only 89 milliseconds.
Hence, we are facing an important change which will mainly affect voice sampling and voice quality in long distance calls, by amplifying the bandwidth from 8 kHz to 32 kHz and that in music marks an ascending step towards that excellence, wireless and free of physical formats, that any audiophile would look for.