CRI ADX  Last Updated: 2025-05-07 13:34 p
Audio Compression Codec

Supported Audio Compression Codecs

The following audio compression codecs are supported in this system.

Original Audio Compression Codec
Codec Description
ADX compression High-quality, low-load codec with a compression ratio of about 1/4
HCA compression High-quality, high-compression codec with a maximum compression ratio of 1/16
HCA-MX compression HCA data subjected to special encoding for HCA-MX playback


Codec-specific features

About ADX

ADX is an audio compression codec with super-low load.
Although compression rate is not good compared with HCA etc., since the decoding process is very lightweight, it can play a lot of sound with low load.

About HCA

HCA was developed for the purpose of low load, high-quality, and high compression ratio.
Compression ratio comparable to the general-purpose audio codecs such as mp3 or AAC is achieved.
Since the algorithm of HCA is simple, it needs low-load and uses less memory compared to the general-purpose audio codecs.
Moreover, since it is designed so that rapid load fluctuation may not occur, it will not adversely affect the application at a specific timing.
When performing HCA encoding, sound quality (compression ratio) can be specified by the five-level value.
Relationship between the encode setting and the compression ratio is described in the ' Compression Ratio of HCA '.

About HCA-MX

HCA-MA is a name of playback method that decodes after mixing HCA data.
In ordinary audio compression codecs, CPU load rises ten times when ten sounds are played, but in HCA-MX, load rises as low as two times.
Its audio data format is the same as HCA codec's, but it is encoded for HCA-MX playback while changing sample rates and loop regions.
If audio data that does not match the HCA-MX playback condition, sample rate or playback pitch may be changed.
In HCA-MX playback, audio data is decoded after mixing.
Therefore, functions such as filtering or pitch change by sounds or seamless concatenated playback cannot be used in HCA-MX.

Available Functions

Functions which can be used for each codec are as follows.
Comparison of Functions In Each\Codec
Function ADX HCA HCA-MX Note
Loop playback Yes Yes Partial In order to use loop playback in HCA-MX, the number of samples in loop interval must be the multiples of 128.
Seek playback Partial Yes Partial In seek playback in ADX, noise may occur depending on the starting position or loop position.
In seek playback in HCA-MX, sound may be distorted at the starting position.
Seamless concatenated playback Yes Yes No
Filter callback Yes Yes No
Volume change Yes Yes Yes
Pan change Yes Yes Yes
Pitch change Yes Yes No
Envelope setting Partial Partial No Whether envelope setting is possible or not depends on the target.
Biquad filter Yes Yes No
Band-pass filter Yes Yes Partial Band-pass filter in HCA-MX only allows the sound to be changed by 1/256th of the sampling rate.
Bus send level setting Yes Yes No
Bass Effects Yes Yes No