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True Gapless Conversion of Audio Files

For audio conversion of some album kinds (operas, symphonies, live concerts, musicals, shows, etc.), seamless/gapless transients between neighbor tracks are required.

True Gapless Conversion (TGC) is seamless album conversion. It allows to avoid of conversion artifacts on the borders between adjacent tracks. Keep reading...


Author: Yuri Korzunov,
Audiophile Inventory's developer with 25+ year experience in digital signal processing,
author of the articles that make audio easy for beginners



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What is True Gapless Conversion

There are albums like operas, live concerts, etc., where no pauses between neighboring tracks. Also, non-zero levels at track borders of the albums may be there.

Some ISO (1-bit audio) has a level bias (DC-bias, direct current bias) throughout a full album. At the beginning and end of tracks, DC bias (non-zero level) is present. It can be heard as a click.

Level bias (DC-bias) throughout the full album

ISO DC bias (1-bit HD audio)

In conversion may be applied audio processing:

  1. Resampling (sample rate altering)
  2. Altering 1-bit audio stuff (DSF, DFF, ISO).

In conversion without the processing, there are no artifacts at output-track borders.

But, if each album track (file) is processed separately, a non-zero level at the input file's border generates the artifact at border of output file. Because the processing is re-initialized for each track.

For seamless audio processing of the album, all its audio files are processed as a continuous audio stream without re-initializing of processing for each track (file).

Audiophile Inventory's trueG is a seamless conversion algorithm that allows seamless processing of adjacent tracks of album.

True gapless mode is switched in AuI ConverteR's main window > Parameters tab (upper left).  Turn ON (checked state) / OFF (unchecked state) for "True Gapless Mode" switch.

Management of True Gapless Conversion mode

True gapless conversion management

Here merged converted neighbor album tracks are shown

True gapless conversion spectrum


If True Gapless Conversion is turned OFF, we see the noise splash on the border of merged resampled tracks after the conversion. The splash at the spectrum shows short level increase, which is absent in source files.

The noise splash is an additional ringing artifact rising due to a rather significant non-zero level at the beginning or end of file. It happens when resampling filter gets a sharp level transient.

If True Gapless Conversion is turned ON, we see seamless transient between resampled converted tracks. Like input source files.

In this case, resampling filter gets a continuous input stream and has no additional ringing at the output.

AuI ConverteR 48x44 provides True Gapless Conversion for the following conditions:

  1. All input (source) tracks (files) must have the same sample rate and bit depth.
  2. Input tracks must be sorted in album order.


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  1. True gapless mode can't use multi-CPU capability. Because files (album tracks) should be processed sequentially. To convert the next audio file, converter state at end of the previous track is needed.
  2. Audio player (software or hardware), that playback processed files, should support gapless (seamless, without re-initialization on each file) playback. All files should be played back as a continuous stream.


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AuI ConverteR is a configurable software that lets you choose the features you need and pay only for them. A "module" is a part of AuI ConverteR's functionality that you can buy separately. You can buy new modules later to enhance your Modula-R major version (details). Each module is a license key that you get by email and enter in the software. A "major update" is a change in the first version number of the software version (for example, from 10.x to 11.x) and it is not free. However, your license is unlimited-time, which means you can use the software as long as you want without any subscription fees. (details)

IMPORTANT: The Free version of AuI ConverteR does not work with any modules. You need to buy a CORE module first, and then you can add other modules that are compatible with it (details). If you buy all the modules, you get the same features as the PROduce-RD version, which is a complete and cheaper package. You cannot exchange your Modula-R license for a PROduce-RD license.

* All prices on this page are in U.S. dollars without V.A.T. and other applicable taxes and fees. The prices are recommended. Information on this page is not a public offer.


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