Google Releases Fourth Beta of Android 14 with Lossless USB Audio Function

Google has recently released the highly anticipated fourth beta version of Android 14, bringing the operating system one step closer to its official release. According to the Android Developers Blog, this version is claimed to be almost final, with the official version expected to arrive sometime later this month.

One of the major highlights in Android 14 is the introduction of a groundbreaking feature called “lossless USB audio.” This innovation aims to provide a lossless format for wired digital headphones that connect via USB. By bypassing the Android audio mixer processing and output, USB headphones can deliver bit-perfect output, ensuring that the sound remains pristine without any compromises. Similar to what other operating systems refer to as “unique output,” this function ensures a seamless audio experience for users.

In conventional Android systems, a mixer module recalculates various audio sources into a single sample rate before outputting to the DAC. However, this process often results in a decline in sound quality. The beauty of the lossless USB audio feature lies in its ability to avoid interference from the mixer, enabling the transmission of digital data without loss or distortion. This represents a significant advancement in the Android audio space.

Although Android devices already boast impressive audio capabilities, it is often up to individual vendors to support such features. The inclusion of lossless USB audio as a standardized function ensures that users can enjoy high-quality output as a standard feature, regardless of their device brand or model.

Taking a closer look at the technical aspects, Android 14 introduces a new class called “AudioMixerAttributes” to the audio mixer. Of particular interest is the addition of the constant “MIXER_BEHAVIOR_BIT_PERFECT,” which signifies the audio mixer’s enhanced performance. When this flag is set, no mixing occurs, allowing the audio data to be sent without any alterations directly to the HAL controlling the device driver.

Notably, the documentation states that this feature was added in API level 34, coinciding with Android 14. This suggests that the necessary code for lossless USB audio may already be implemented in the Android 14 system.

While Google has historically paid relatively less attention to audio functionality, the inclusion of lossless audio as a standard feature marks a significant shift. This move could possibly be tied to the upcoming release of the highly anticipated “Pixel 8” smartphone in the upcoming autumn season. Overall, these advancements are expected to significantly enhance the overall audio experience on Android devices, solidifying the platform’s position as a leader in the industry.

In conclusion, Google’s latest beta version of Android 14 showcases the company’s commitment to delivering exceptional audio capabilities to its users. By introducing lossless USB audio as a standard function, Android devices now offer a remarkable sound experience that rivals even the most high-end systems. With each new release, Google continues to make substantial strides in improving the audio capabilities of its operating system, setting the stage for a future where audio quality remains at the forefront of the Android user experience.

Updated at 09:00 on 6 August 2023

Google has released the fourth beta version of Android 14, which is said to be almost final. It is said that the official version will be released within this month.

Lossless USB audio bypasses standard OS mixers

In terms of audio, the highlight is the inclusion of a function called “lossless USB audio”. According to the Android Developers Blog, it can provide a lossless format for wired digital headphones that connect via USB. More specifically, it appears to be a function that bypasses Android’s audio mixer processing and output. When connecting USB headphones to an Android smartphone, bit-perfect output can be performed as lossless data without recalculation in the mixer. It is considered similar to what is called unique output in other OSes.

Android Audio Mechanism_Mixer is in the media server

A mixer is a module that recalculates the various audio sources being handled on the OS (sometimes 48kHz, sometimes 32kHz) into a single sample rate. It is a necessary function to output to the DAC, but as a result the sound is bad or less than perfect. In conventional Android, the mixer always interfered during playback, but it can be avoided. It is also important to be able to output various information contained in digital data without destruction, as it can be transmitted without missing bits.

Android audio features may seem advanced compared to iOS devices, but that feature is often supported by vendors. Lossless USB audio allows you to benefit from lossless output as standard.

By becoming a standard function, I would like to strengthen the sound function

Digging a little deeper, a class called “AudioMixerAttributes” is added to the audio mixer. Currently, the constant “MIXER_BEHAVIOR_BIT_PERFECT (mixer bit perfection related behavior)” is added (content is 1 in hexadecimal). This MIXER_BEHAVIOR_BIT_PERFECT is a constant indicating that the audio mixer’s behavior is somewhat perfect. When the flag is set, mixing does not occur and the audio data is sent as is to the HAL that controls the device driver.

There is also a description “Added in API level 34”. Android 14 is simply API level 34, so it’s likely that Android 14 code is already implemented.

Until now, Google has been relatively indifferent to audio functions, and the implementation of the standard USB audio driver was installed last on the application, after which problems continued. It’s interesting that Google has added lossless audio as a standard. It may be because “Pixel 8” is coming in the fall. We hope these additions will further boost Android’s use of audio.

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