Audio File Specification

About AAC, MP3, WMA and WAV

The playable AAC/MP3/WMA/WAV file (hereafter called Audio file) and the media format has the following limitation. The Audio file, which is not conforming to the specification, may not play normally, or the file and folder names may not display correctly.

Playable Audio file

MP3 Extension .mp3
Format MPEG 1/2 Audio Layer 3 file
Transfer bit rate 8-320 kbps / Variable Bit Rate
Sampling frequency 8/ 11.025/ 12/ 16/ 22.05/ 24/ 32/ 44.1/ 48 kHz
Joint STEREO
ID3 Tag (Ver.1) Ver1.0/ 1.1 (Title/ Artist/ Album)
ID3 Tag (Ver.2) Ver2.3 (Title/ Artist/ Album : Does not support picture display.)
WMA Extension .wma
Format The file in accordance with Windows Media Audio
(Except for the file for Windows Media Player 9 or after which applies the new functions)
Transfer bit rate 48-192 kbps / Variable Bit Rate
Sampling frequency 32/ 44.1/ 48 kHz
DRM file
Professional
Lossless
Voice
WMA Tag (Content Description) (Title/ Artist)
WMA Tag (Extended Content Description) (WM/Album Title)
AAC-LC Extension .m4a
Format ".m4a" file encoded by AAC-LC format.
Transfer bit rate 16-320 kbps
Sampling frequency 16/ 22.05/ 24/ 32/ 44.1/ 48 kHz
DRM file
2 channel
Multi channel
ID3 Tag (Ver.2)
iTunes m4a Meta-data (Song Info.) (Title/ Artist/ Album)
WAV Extension .wav
Format WAVE file (Linear-PCM)
Sampling frequency 44.1 KHz
Bit count 16 bit
Channel Stereo/Monaural

Do not attach the extensions to files other than the Audio file. If the extension is attached, the file, which is not the Audio file, will play and outputs a loud noise, causing damage to the speaker.

The files with copy protection cannot be played.

Audio files cannot be played depending on the encoding software setting, USB device type, and/or recording conditions.

The unit may not be compatible with upgrade of compression format standard and additional specifications.

There are times when play time is not displayed correctly depending on the Audio file recording conditions.

Supreme is not applied for songs that have been encoded at a variable bit rate.

Sound of WAVE file may be interrupted depending on the performance of the recording media.

Playable storage media file system

CD-R/RW File system (Windows) ISO 9660 Level 1/2
ISO 9660 Level 3
Romeo
Joliet
Long File Name
File system (Macintosh)
File system (UNIX)
Multi-Session *1
USB device File system (Windows) *2 FAT16
FAT32
File system (Macintosh)
File system (UNIX)

CD-RW discs which are quick formatted by the writing software cannot be used.

When recording to the maximum CD-R/RW media capacity at once, the writing software is set to "Disc at once".

Joliet is recommended for file system of CD-R/RW. With other file systems, the display may not be shown correctly depending on the operating conditions.

*1 For CD-DA/ audio file mixed disc, the unit plays only the playback system recorded at the first setout.

*2 Multi Partition : Not compatible (Some USB devices may have multiple partitions that will be invisible on Windows OS.)

When the CD-R/RW recorded by CD-ROM MODE 2 (XA) format cannot be played, please record again by using CD-ROM MODE 1 writing format.

Limitation of structure for the file and the folder

CD-R/RW Maximum number of directory levels 8
Maximum number of folders 100
Maximum number of files (per folder) 500
USB device Maximum number of folder layers 8
Maximum number of folders (per device) 500
Maximum number of files (per folder) 4096
Maximum number of files (per device) 15000
Internal Memory Maximum number of files 500

It may take time to start playing depending on the recording conditions such as file hierarchy and folder structure.

The maximum number of characters for display

File/Folder name 128 characters
MP3 ID3 Tag 30 characters
WMA Contents property 30 characters
AAC song information 60 characters

Number of characters is based on byte unit.

File/Folder name is the number of the characters including the extensions.

This unit can display the following versions of MP3 ID3 tag: version 1.0/ 1.1/ 2.3

AAC ID3 Tag cannot be displayed.

Playing order of the Audio file

The Audio file plays in the order which is written by CD writing software. You may be able to set the playing order by writing the play sequence numbers such as "01" to "99" at the beginning of the file name.

Audio files are played in order of file names. You can specify the order of playback by numbering files in a folder. (USB device)

Example

Folder : Folder
Audio file : Audio file

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About USB device

Notes on Use of the USB device

This unit can play audio files stored in the flash memory and digital audio player that have a USB port (these devices are referred to as USB devices in this document).
The following restrictions are placed on the types and usage of available USB devices:

Available USB Devices

USB standard USB 1.1 / USB 2.0
Transfer Speed Full speed (Max. 12 Mbps)
USB class Mass storage class (MSC device)
USB subclass SCSI
Protocol Bulk Only
Current supply Max. 500 mA

USB Mass Storage Class:
USB devices that the PC can recognize as an external storage without using any special driver or application software.

Contact the sales agent as to whether your USB device conforms to the USB mass storage class specs.

Using an unsupported USB device can result in abnormal playback or display of the audio file.
Even if you use the USB device conforming to the above specs, audio files cannot be played normally depending on the type or condition of the USB device.

Some of the functions is are limited with a certain USB device.

Normal operation and power supply is not guaranteed against every USB devices.

About the Connection of the USB device

When connecting the USB device, usage of the CA-U1EX (option) is recommended.

Normal playback is not guaranteed when a cable other than the USB compatible cable is used. Connecting a cable whose total length is longer than 5 m can result in abnormal playback.

You cannot connect a USB device via a USB hub.

Install the USB device in the place where it will not prevent you from driving your vehicle properly.

Do not leave the USB device in the vehicle for a long time. It can deform or damage due to direct sunlight, high temperature, etc.

Take backups of the audio files used with this unit. The files can be erased depending on the operating conditions of the USB device.
We shall have no compensation for any damage arising out of erasure of the stored data.

Leave the cap on when not using an USB device.

About USB device Operation

USB device operation is the same as audio file operation unless otherwise some notice is indicated.

USB source is recognized as CD source on the connected unit.

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  • KDC-X991
  • Audio File Specification
  • About AAC, MP3, WMA and WAV
  • Playable Audio file
  • Playable storage media file system
  • Limitation of structure for the file and the folder
  • The maximum number of characters for display
  • Playing order of the Audio file
  • About USB device
  • Notes on Use of the USB device
  • Available USB Devices
  • About the Connection of the USB device
  • About USB device Operation