Audio Decoding With a Dac in Android (How to)
Audio quality is an important consideration for many smartphone users today. Smartphones are equipped with audio decoding capabilities and digital-to-analog converters (DACs) to convert digital audio files into analog signals that can be played through headphones or speakers. This allows you to listen to music, watch videos, and make calls with decent audio quality. However, the built-in audio decoders and DACs in smartphones may not provide the best listening experience, especially for audiophiles. Using an external DAC connected to your Android device can significantly improve audio quality and allow you to get the most out of your music library.
In this guide, we will provide an overview of how audio decoding works in Android devices and the role of the built-in DAC. We will go through the steps to enable usage of an external DAC, how to bypass Android’s audio processing, and choose the right DAC for optimal performance. With the right setup, you can experience studio-quality audio from your Android smartphone.
Audio Decoding Basics
Digital audio is encoded into different file formats for storage and transmission. Common formats include MP3, FLAC, AAC, WAV, AIFF, etc. Each format uses different encoding algorithms that compress or alter the original raw audio data to optimize for size, quality, or streaming.
MP3 is the most popular lossy format that compresses audio by discarding less audible data. It reduces file size for easy sharing while retaining reasonable quality. FLAC is a lossless format that compresses audio without data loss for higher fidelity. WAV and AIFF are uncompressed formats that store raw PCM audio data.
During playback, the encoded audio must be decoded back into raw PCM data for conversion into an analog signal. This decoding is done by software or dedicated audio decoding hardware before the signal reaches your headphones or speakers.
High quality audio requires starting with a lossless or uncompressed source file, capable decoding hardware, and quality headphones or speakers. Compressed formats like MP3 sacrifice quality for smaller files. Decoding them requires extra processing that can introduce audible artifacts.
Role of a DAC
A DAC, or digital-to-analog converter, plays a crucial role in converting digital audio signals to analog so they can be sent to headphones or speakers. In the digital domain, audio is represented by zeros and ones. However, headphones and speakers require an analog signal to produce audible sound waves.
The DAC takes the digital data and converts it into an analog signal that represents the original audio waveform. This conversion is done by assigning voltage values that correspond to the digital bits at a very high sampling rate. The DAC outputs a continuous analog signal that is then amplified and sent to your headphones or speakers (Source).
Without a DAC, you would not be able to listen to music from your smartphone, computer, or any digital device. The DAC plays an essential role in allowing digital audio to become audible sound.
Android Audio Architecture
The Android audio architecture consists of several components that work together to handle audio input, output, and processing on a device.
At the application framework level is the Android media framework, which contains APIs like MediaPlayer and AudioRecord for apps to play and record audio. The media framework interacts with the audio system through the Audio HAL.
The audio HAL is the hardware abstraction layer that allows the higher-level framework to communicate with the lower-level audio drivers and hardware. It defines a standard interface that audio drivers must implement to handle playback, recording, device configuration, and more.
At the bottom level are audio codecs that encode and decode audio data. Common codecs used on Android include AAC, MP3, FLAC, Vorbis, and more. The audio HAL handles routing encoded audio data to and from the codecs.
This layered architecture provides apps a consistent API for audio functionality while allowing device manufacturers flexibility in their audio driver and hardware implementations through the audio HAL.
Enabling External DAC
To enable the use of an external DAC with your Android device, you will need an OTG (On-The-Go) cable and a compatible audio app like USB Audio Player Pro. The OTG cable allows you to connect USB accessories like a DAC to your Android device. Without the OTG cable, the Android device will not recognize the DAC.
Once you have the OTG cable, simply connect one end to your Android device and the other end to your external DAC. Launch the USB Audio Player Pro app, which has native support for external DACs. Within the app settings, you can select the connected DAC as the audio output device rather than relying on the built-in Android audio.
This bypassing of the internal Android audio means the external DAC handles the digital-to-analog conversion and amplification, which should result in improved audio quality compared to the basic onboard DAC and amp built into most smartphones. The USB Audio Player Pro app has additional features like equalizers and audio format support that can further enhance your listening experience.
Bypassing Android Audio
By default, Android resamples audio to 48kHz before sending it to an external DAC through USB Audio. This resample process degrades audio quality and prevents bit-perfect playback. To bypass Android’s audio processing, specialized audio apps are required that support bit-perfect output. Some popular options include:
USB Audio Player Pro (UAPP) is one of the most commonly used audio players on Android for bit-perfect playback. According to a Reddit thread, UAPP includes an option to bypass Android SRC, allowing the original sample rate and bit depth to pass through unaltered.
HibyMusic is another audiophile player that supports bit-perfect output at high sample rates like DSD256 and 768kHz PCM. As discussed on the Roon community forums, HibyMusic can integrate with Roon and bypass Android audio processing for improved quality.
These specialized audio apps tap into USB audio drivers to output pure digital audio, bypassing Android’s default audio pipeline. Proper setup in the app along with compatible hardware is required, but they enable Android devices to achieve bit-perfect playback when using an external DAC.
Choosing a DAC
When choosing a DAC for your Android device, there are several key factors to consider:
Budget – DACs range widely in price from under $100 to over $1,000. Determine how much you want to spend based on the audio quality improvements you are seeking.
Connectivity – Make sure the DAC matches the connection type on your Android device, typically USB-C or micro USB. Some DACs also offer wireless Bluetooth connectivity.
Power – More powerful DACs with their own battery supply tend to provide better audio quality. But they are larger and more expensive. Passive DACs without a battery draw power from your phone.
Size and portability – If you want to pair a DAC with your phone on the go, smaller USB stick-style DACs offer the most portability. Larger DACs offer more power but less portability.
Resolution – A DAC’s bitrate and sampling frequency determine resolution and audio quality. Aim for 24-bit/96kHz or better for a noticeable jump in quality.
Headphone amp – Some DACs include a built-in headphone amp for driving high-impedance headphones, allowing them to reach full audio potential.
Features – Consider if you need a line out to connect to speakers, balanced output, EQ controls, or other useful features for your setup.
Brands like Chord, iFi Audio, Fiio, and others consistently produce quality portable DAC options for Android devices across various budgets.
DAC Setup
Setting up a DAC with an Android device requires a few steps. First, you’ll need to physically connect the DAC to your Android phone or tablet. Most DACs connect via USB-C or micro USB. Use the appropriate cable to connect your DAC to your device. According to Nuprime, it’s best to connect the cable to your phone first before connecting it to the DAC [1].
Once connected, your Android device should automatically detect the DAC and switch the audio output to it after a few seconds. However, sometimes you may need to install drivers or enable USB audio in your device settings for the DAC to be recognized. If your DAC isn’t being detected, try downloading the manufacturer’s drivers and installing them on your device [2].
Finally, in your device settings, you can select the sample rate for the DAC output. 44.1kHz is standard, but some DACs support higher sample rates like 96kHz for increased audio resolution. Set this to match the capabilities of your DAC. Once these steps are complete, audio playback from your device should route through the external DAC.
Audio Quality Improvements
Using an external DAC can significantly improve the audio quality compared to the built-in DAC in your device. Some of the key improvements include:
Better Dynamics
A high quality external DAC like the iFi Audio xDSD can produce a wider dynamic range. This means you get punchier bass, clearer vocals, and more sparkly treble. The sound will have better impact and liveliness.
Improved Imaging
With an external DAC, the stereo imaging will be more precise and holographic. You can pinpoint the exact location of instruments. The soundstage will have more width and depth.
Increased Detail
Because of lower noise and distortion, an external DAC reveals more micro-details in the music. You’ll hear subtle textures, decays and spacial cues that get lost with lesser DACs. This adds realism and immersion.
Overall, upgrading to a quality external DAC hugely elevates audio quality, making music more engaging and enjoyable.
Conclusion
In summary, using an external DAC is a great way to improve audio quality on Android devices. By bypassing the built-in DAC and amplifiers, you can tap into the power of high-quality audio components designed specifically for music listening.
While connecting and configuring an external DAC takes some extra effort, the sound quality improvements are worthwhile for audio enthusiasts. With the right setup, you can experience studio-quality audio right from your Android smartphone or tablet.
DAC technology will likely continue advancing in the future. We may see even more compact DACs with lower power consumption and noise, designed specifically for mobile use. Additionally, improved USB and Bluetooth audio standards will make external DAC connectivity easier and more robust.
For now, with a bit of research and shopping around, you can find excellent external DAC options to dramatically upgrade your Android audio experience.
