Listening to true lossless audio with Bluetooth headphones is not possible for most users today. Realme Buds Air 8 has LHDC and Hi-Res Audio logos on the box, and its price is only 43 dollars. But these logos do not mean that the music arrived without loss.
Why does lossless audio get stuck in the codec?
The FLAC file is compressed, but does not discard any data. Opens the file to its original state while the phone is ringing. Bluetooth can't carry that much data directly, so the phone recompresses the audio with a Bluetooth codec. Data loss also happens here.
CD quality audio requires 1,411 kbps. The best of Bluetooth codecs throttle at 1,000 kbps. Moreover, the "Hi-Res Audio" badge on the box indicates that the codec can carry high-resolution audio at high bitrates. It does not guarantee that it is lossless.
Three HD options on OnePlus 13R
When you open the Buds Air 8 in the OnePlus 13R's Bluetooth list, HD (AAC) and Standard (SBC) options appear for Media Audio. The real high definition codec is in the headset's own application. Once enabled, Realme issues a warning: high-definition audio may shorten listening time, introduce lag due to interference, and works best at home. Also Spatial Audio turns off.
Developer options show what the phone is actually sending. When HD is on, it says Streaming: AAC on the screen. The sampling rate remains locked at 44.1 kHz, with bit depth at 16.
The codec list ranges from SBC to LDAC, LHDC, aptX Adaptive and aptX TWS+. But this is what the phone can talk about. Buds Air 8 only responds to LHDC 5.0, AAC and SBC.
When high definition audio is turned on, the screen shows Streaming: LHDC and 96 kHz and 24 bit are turned on. Still, LHDC 5.0 provides a maximum of 1,000 kbps, which drops when the signal gets weaker. Even at its best, it carries about 71% of the CD sound. Savitech, the developer of the LHDC, offers a 1-1.4 Mbps LHDC Lossless mode, but it's not in the feature lists of this pair.
No difference heard in lossless audio test
A free album in 16-bit FLAC format was downloaded from Bandcamp for testing. Three tracks were converted to 320 kbps MP3 with ffmpeg on a MacBook Air M2. In each round, the FLAC and MP3 versions were played in VLC with LHDC open, and one was listened to again and asked which one it was.
Only 13 of 30 rounds were predicted correctly via LHDC. The score was 18 in 30 rounds with wired headphones. Seven of these points came from a single track because there was a single element in that track that significantly changed the clarity.
In other words, LHDC and FLAC and MP3 could not be distinguished from each other. This result remained the same even though MP3 was compressed twice and FLAC once. Therefore, in this test, the difference in lossless sound was not reflected in the ear.
Lossless audio solution in 2027 hardware
Qualcomm's aptX Lossless works today, but Snapdragon Sound on the phone and in the headset is a must. There is no aptX Lossless in the 13R's menu, there is aptX Adaptive. Pixel, Galaxy and iPhone users are completely excluded from the codec.
At its meeting in Tokyo on October 15, the Bluetooth SIG announced that High Data Throughput (HDT) will be added to the Bluetooth specification in November. HDT increases the maximum data rate of Bluetooth LE from 2 Mbps to 7.5 Mbps, paving the way for standard lossless wireless audio in 2027. OnePlus 13R or Realme Buds Air 8 will not receive this support with the software update as they require new radio hardware.
