General

.masterknecht is a powerful tool for automatically mastering audio material. By analyzing a reference audio file, it matches the characteristics of your target audio file, including loudness, frequency response, stereo imaging, and spectral balance. All processing is performed locally in your browser, ensuring that your audio data remains secure and never leaves your computer.

Unlike traditional mastering, which relies on the expertise of a mastering engineer, tools like .masterknecht provide a fast and efficient solution for audio mastering. Designed for musicians, producers, and audio engineers, it offers an accessible alternative to expensive hardware or software. While it cannot fully replicate the nuanced artistry of a professional mastering engineer, .masterknecht serves as an excellent starting point for further manual adjustments.

Additionally, .masterknecht sets itself apart from other online mastering services by eliminating the need to upload audio to a server. All processing is performed directly in your browser, safeguarding your audio's privacy and security. The use of a reference audio file allows .masterknecht to tailor the mastering process to your specific needs. This approach often produces better results than generic algorithms, presets, or AI-based solutions, which lack the context and adaptability provided by a reference track. Unlike these "black box" mastering services, which lack context about your track or preferences, .masterknecht empowers you to achieve results customized to your genre, style, and creative vision. In mastering, context matters pure math alone is not enough to produce great results.

.masterknecht does not rely on machine learning or neural networks; instead, it uses proven, efficient signal processing algorithms. The quality of the results depends on the reference audio file, the target audio file, and the settings you choose. .masterknecht analyzes the reference audio file and the target audio file and tries to match the characteristics of the reference audio file to the target audio file. The process is not always perfect, and the results may vary depending on the audio material. Experimenting with different reference files and settings is encouraged to find the optimal results for your audio. .masterknecht is optimized for 48 kHz audio files, but it can also process other sample rates. The tool is designed to be user-friendly and intuitive, with a simple drag-and-drop interface and a variety of settings to customize the mastering process.

But remember, the best mastering is the one that sounds right to you. If you're uncertain or need a polished, professional touch, a human mastering engineer might still be the best choice. However, if you're eager to experiment, .masterknecht is here to make audio mastering accessible and fun. Enjoy the process!

BPM and Tempo Calculation

BPM (Beats Per Minute) and tempo are fundamental aspects of music production, providing the rhythmic framework for musical compositions. BPM quantifies the number of beats in a minute, while tempo reflects the overall pace of the music. Accurate BPM and tempo calculations are crucial for synchronizing audio tracks, creating rhythmic patterns, and ensuring a consistent flow throughout a song.

.masterknecht calculates BPM and tempo to divide audio into precise segments, such as bars or beats. This segmentation enhances the precision of analysis and adjustments made to the audio signal. Primarily, this functionality aids in identifying the loudest segments of the audio for spectral and loudness analysis. Quieter sections are excluded unless full-spectrum analysis is explicitly enabled, ensuring more accurate results for targeted adjustments.

.masterknecht employs a Wavelet-based approach for BPM and tempo estimation. Unlike traditional methods such as pure FFT-based autocorrelation, brute-force autocorrelation, or onset detection, Wavelet analysis combines frequency and time-domain insights. By leveraging four distinct bands of the Wavelet transform, .masterknecht effectively extracts rhythmic information from audio signals. This method proves particularly robust, offering accurate BPM and tempo detection even in noisy or complex audio material. The Wavelet-based approach ensures reliability and efficiency, outperforming conventional techniques in diverse audio scenarios.

Conclusion:

BPM and tempo calculation play a pivotal role in music production, facilitating precise synchronization and rhythmic control. .masterknecht leverages a Wavelet-based technique to deliver accurate and efficient BPM and tempo analysis. This enables the identification of rhythmic patterns and tempo variations, enhancing the mastering process. By detecting BPM and tempo with precision, .masterknecht empowers producers to make refined adjustments, ensuring a polished and cohesive final audio production.

Loudness Compensation

Loudness compensation is a critical aspect of audio mastering, ensuring that the perceived loudness of the audio signal is consistent across different playback systems. This process involves adjusting the gain of the audio signal to match a target loudness level, typically measured in LUFS (Loudness Units Full Scale). Loudness compensation is essential for maintaining a balanced and cohesive listening experience, especially in the context of music production and broadcasting. Loudness normalization standards, such as EBU R128 and ATSC A/85, provide guidelines for achieving consistent loudness levels in audio content. Loudness compensation can be achieved using various methods, each with its own advantages and trade-offs.

The process includes the following submethods:

• RMS-based compensation:

  • Calculates the RMS (Root Mean Square) level of the loudest pieces of the audio signal and adjusts the gain to match a target RMS level.
  • Works in iterative steps to converge on the target loudness level, where also the limiter and clipper are applied on each step, when they are enabled, to ensure that the audio signal does not exceed the target loudness profile.
  • Simple and effective but may not account for perceptual loudness differences.

• LUFS-based compensation:

  • Measures the integrated loudness of the entire audio signal using the LUFS scale and adjusts the gain to match a target LUFS level.
  • The EBU R128 standard is used to measure the loudness of the audio signal.
  • Works also in iterative steps to converge on the target loudness level, where also the limiter and clipper are applied on each step, when they are enabled, to ensure that the audio signal does not exceed the target loudness profile.
  • Accounts for perceptual loudness differences and provides a standardized loudness reference for audio content.
  • More complex but offers a more accurate and perceptually relevant loudness compensation.

Conclusion:

Loudness compensation is a crucial step in audio mastering to ensure that the audio signal has a consistent loudness level across different playback systems. The choice of loudness compensation method depends on the desired loudness target, the complexity of the audio material, and the desired balance between simplicity and accuracy. Both RMS-based and LUFS-based compensation methods offer effective loudness normalization, with LUFS-based compensation providing a more perceptually relevant and standardized approach.

Spectrum Compensation

Spectrum compensation is a method used to equalize the frequency response of an audio signal to match a reference frequency response, by applying gain adjustments to specific frequency bands to compensate for deviations in the spectrum. This process is essential in mastering to ensure that the audio signal has a balanced and consistent frequency spectrum. Spectrum compensation can be achieved using various methods, each with its own advantages and trade-offs.

The process includes the following submethods:

• Time-domain-based compensation:

  • Utilizes IIR biquad filters (low shelf, high shelf, peaking) implemented in direct form I.
  • Efficient but may introduce phase distortion artifacts, as is typical for IIR filters.

• Frequency-domain-based compensation with Biquad filters:

  • Applies STFT-like FFT convolution and overlap-add processing using a Hann window.
  • Transforms the frequency response of the biquad filters into an FFT multiplication kernel, applied in the frequency domain.
  • Performs convolution with the impulse response of the biquad filters in the frequency domain, preserving the phase.
  • Avoids phase distortion but is computationally slower than the time-domain approach.

• Frequency-domain-based compensation with direct spectrum gain envelope:

  • Uses STFT-like FFT convolution and overlap-add processing with a Hann window.
  • Transforms the spectrum gain envelope directly into an FFT multiplication kernel using Catmull-Rom interpolation.
  • Applies the interpolated spectrum gains to the audio signal in the frequency domain, offering a direct and intuitive method.

Conclusion:

Depending on the requirements such as real-time processing constraints, phase linearity, and computational resources different methods of spectrum compensation can be employed, each with its own trade-offs in terms of efficiency, accuracy, and complexity.

Limiter

A limiter is a critical tool in audio mastering, designed to prevent audio signals from exceeding a specified threshold. By applying gain reduction to signals that surpass the threshold, limiters ensure the audio stays within a defined dynamic range. This is essential for controlling peaks, avoiding clipping, distortion, or overloading in audio signals. Two primary types of limiters are commonly used: Peak Limiters and True Peak Limiters, each tailored for specific needs. .masterknecht supports both modes, allowing users to choose the best approach for their mastering requirements.

The limiter in .masterknecht operates in two distinct modes:

• Peak Limiter:

  • Reduces gain for audio signals exceeding the specified threshold.
  • Attenuates signal peaks to limit the maximum amplitude effectively.
  • Provides fast, efficient control to prevent clipping and distortion in audio signals.
  • While brick-wall limiting is not fully guaranteed in this mode, the implementation in .masterknecht offers near-perfect results.
  • Simple and efficient, this mode is commonly used for ensuring signals do not exceed desired peak levels. However, it may not account for inter-sample peaks.

• True Peak Limiter:

  • Accounts for inter-sample peaks by oversampling the audio signal by a factor of four using a SINC FIR filter.
  • Ensures the audio signal does not exceed the specified true peak level, preventing clipping and distortion during digital-to-analog conversion.
  • Provides more accurate peak control by considering the maximum peak levels between samples.
  • Uses a brick-wall limiter in .masterknecht, guaranteeing that true peak levels stay within the defined threshold.
  • Ideal for digital audio processing to safeguard against inter-sample peaks exceeding the maximum amplitude.
  • Though more computationally intensive than a peak limiter, it offers superior accuracy and protection against clipping.

Conclusion:

Limiters are indispensable in audio mastering, offering precise control over peak levels to prevent clipping, distortion, or dynamic range issues. .masterknecht provides both Peak and True Peak limiting modes, each tailored to specific needs. The Peak Limiter offers fast, efficient peak control for most general use cases, while the True Peak Limiter ensures superior accuracy by addressing inter-sample peaks, making it ideal for high-fidelity digital audio processing. By choosing the appropriate limiter mode, audio professionals and enthusiasts can effectively manage dynamics, safeguard audio quality, and achieve polished, distortion-free results in their mastering projects.

Dithering

Dithering is an essential technique in digital audio processing used to minimize quantization errors and enhance the quality of low-bit-depth audio signals. During the conversion of high-resolution audio to lower bit depths, quantization noise can introduce distortion and artifacts, particularly in quieter passages. By adding low-level noise to the audio signal, dithering masks these errors and improves the overall audio quality. The two most common dithering methods are Rectangular Probability Density Function (RPDF) and Triangular Probability Density Function (TPDF), each offering distinct benefits and trade-offs depending on the desired outcome.

.masterknecht supports dithering for 8-bit, 16-bit, and 24-bit integer output WAV formats, ensuring high-quality audio during bit-depth reduction. Dithering is excluded from the 32-bit float output WAV format, as it is unnecessary and could degrade audio quality due to the format's already high dynamic range. The dithering options provided in .masterknecht include:

• RPDF Dithering:

  • Uses a rectangular probability density function to add low-level noise to the audio signal.
  • Provides a straightforward method for reducing quantization errors and distortion in low-bit-depth audio.
  • Introduces noise with a flat spectral distribution, effectively masking quantization noise.
  • Commonly used in general audio processing for its simplicity and effectiveness during bit-depth reduction.

• TPDF Dithering:

  • Uses a triangular probability density function to add low-level noise to the audio signal.
  • Delivers more advanced noise-shaping characteristics compared to RPDF.
  • Introduces noise with a spectral distribution that emphasizes higher frequencies, making it less audible and masking quantization noise more effectively.
  • Offers superior audio quality, particularly for critical listening environments and high-fidelity applications.
  • Preferred for professional audio mastering and production where maintaining the highest audio fidelity is critical.

Conclusion:

Dithering plays a crucial role in digital audio processing, helping to preserve audio fidelity during bit-depth reduction by minimizing quantization errors and distortion. .masterknecht provides both RPDF and TPDF dithering methods, offering flexibility to meet various audio quality requirements. Whether applied in professional mastering or personal projects, dithering ensures enhanced audio quality and a more polished listening experience.

1. No Data Collection

.masterknecht is a tool for automatic mastering of audio material. It uses a reference audio file to match the characteristics of the target audio file, including loudness, frequency response, stereo image, and spectral balance. All processing is done locally in the browser, and no audio data is uploaded to any server. This ensures that all audio remains secure and private.

.masterknecht does not store any audio data or personal information. It does not use cookies or tracking mechanisms. The only data stored is the settings selected for the mastering process, which are kept locally in the browser. This data is not shared with third parties and is solely used to improve the functionality of the tool for individual use.

Any questions or concerns about the privacy policy of .masterknecht can be directed to the developer via email here. Ensuring privacy and security is a priority, and every effort is made to protect and handle data responsibly.

In formal terms, .masterknecht does not collect, store, or share personal information or audio data. It does not use cookies or tracking mechanisms. Only web server logs are maintained for security and maintenance purposes, and these logs contain no personal information. .masterknecht is designed to be privacy-conscious and secure, focusing on user control and data protection.

2. Web Server Logs

Like most websites, the web server hosting .masterknecht automatically logs certain non-personal data when the site is accessed. This includes:

• IP address
• Date and time of access
• Pages visited
• Browser type and version
• Operating system

These logs are used for security and maintenance purposes, such as identifying and addressing technical issues, preventing misuse, and ensuring the stability and performance of the service. They are not used for tracking or profiling users and are not shared with third parties. These logs are stored securely and are not accessible to unauthorized individuals and are deleted after two weeks.

3. No Third-Party Services

.masterknecht does not integrate with any third-party analytics, tracking, or advertising services. This ensures activity remains private and free from external tracking.

4. Cookies

.masterknecht does not use cookies or any other tracking technologies to monitor activity or preferences.

5. Data Security

While .masterknecht does not collect or store personal data, the web server is secured to prevent unauthorized access or misuse of server logs.

6. Rights Under GDPR

Under the General Data Protection Regulation (GDPR), it is possible to:

• Request access to data that might have been collected (though .masterknecht is designed not to collect such data beyond web server logs).
• Request correction or deletion of any stored data.
• Lodge a complaint with a supervisory authority if data rights appear to have been violated.

Since no personal data is collected, these rights are inherently respected.

7. Changes to the Privacy Policy

This Privacy Policy may be updated to reflect changes in practices or legal requirements. Updates will be posted on this page with a revised "Last Updated" date.

8. Contact

Questions about this Privacy Policy or privacy concerns while using .masterknecht can be directed to the developer at here.

Your Support Matters

If you find .masterknecht useful and would like to support its development, you can do so by making a donation. Your contribution helps cover the costs of maintaining and improving the tool, as well as supporting future updates and features.

Donations are greatly appreciated and help ensure that .masterknecht remains a free tool for everyone to use. So it is basically Donationware, which is based on the generosity of users like you. Your support enables me to continue working on the project and provide new features and improvements in the future.

If you'd like to make a donation, you can do so via various method, see below at the links provided. Your generosity is what keeps .masterknecht running and growing. Thank you for your support!

Donation Methods

The following donation methods are available:

• Patreon
• Ko-fi
• Buy Me a Coffee
• GitHub Sponsor
• PayPal

Or you can also contact me directly via email at here for other donation methods. Otherwise you can also support me by sharing .masterknecht with others who might find it useful.