CDA - CD Audio Track Shortcut File
What is a CDA file?
A file with the .cda extension is a small stub file generated automatically by the Microsoft Windows operating system for every track on a standard audio CD. Contrary to common belief, these CDA files do not contain the actual music data. Instead, they function as intelligent pointers, holding essential information like track timing and serving as a direct Windows shortcut to the corresponding audio data on the disc. In essence, a CDA file is a reference or a shortcut that tells the system where to find the specific music file located within the storage sectors of the CD itself.
CDA File Format
The CDA file format is used to tell a computer that which audio file to play on a CD. So, the CDA files become useless separated from a CD they represent. The CDA files are commonly considered as RIFF resources. There is only one chunk which is named “CDDA” and contain only one data block called “FMT " in current version of .cda file. This block is 24 bytes long. The identifier created by Windows is used by the Windows 95 and Windows 98 related CD drive and its player can’t connect to FreeDB or CDDB. So that it can display song title and the artist name, which you have to manually enter this information in the cdplayer.ini file.
Key Characteristics of CDA Files
| Characteristic | Description |
|---|---|
| Audio Content | None. Contains only pointer information, not audio data. |
| File Extension | .cda |
| File Size | Extremely Small (~44 bytes - 1 KB). Confirming they are not actual audio files. |
| Playback Dependency | Requires Original CD. Cannot be played without the source CD in the drive. |
| Primary Function | Navigation. Acts as a shortcut for media players to locate tracks on an audio CD. |
| Platform | Microsoft Windows. A specific feature of the Windows OS. |
Organization of a CDA file
The following table shows the information about typical offsets:
| offset | length | content |
|---|---|---|
| 0x00 | 4 | the 4 ASCII characters “RIFF” |
| 0x04 | 4 | the size of the following chunk: always 36 (44 - 8), on 4 bytes (Intel order) |
| 0x08 | 4 | chunk identifier: the 4 ASCII characters “CDDA” |
| 0x0C | 4 | the 3 ASCII characters “fmt” followed by a space |
| 0x10 | 4 | length of the chunk: always 24, on 4 bytes (Intel order) |
| 0x14 | 2 | version of the CD format, on 2 bytes (Intel order). In May 2006, always equal to 1. |
| 0x016 | 2 | number of the range, on 2 bytes (Intel order). The first track has the number 1. |
| 0x18 | 4 | identifier calculated by Windows for cdplayer.exe. |
| 0x1c | 4 | range offset, in number of frames (Intel order) |
| 0x20 | 4 | duration of the track, total number of frames (Intel order) |
| 0x24 | 1 | range position: frames |
| 0x25 | 1 | range position: seconds |
| 0x26 | 1 | range position: minutes |
| 0x27 | 1 | a null byte (binary value 0) |
| 0x28 | 1 | duration of the track: frames |
| 0x29 | 1 | duration of the track: seconds |
| 0x2a | 1 | duration of the track: minutes |
| 0x2b | 1 | a null byte (binary value 0) |
FAQ
Q1: Why can’t I play a CDA file after copying it to my computer?
A: Because you only copied the shortcut, not the audio data. The CDA file requires the original CD to be in the drive to function.
Q2: How do I convert a CDA file to MP3?
A: You don’t convert the CDA file itself. Instead, you use “rip” or “extract” function in a media player (like iTunes or Windows Media Player) to convert the audio tracks on the CD into MP3 files.
Q3: Are CDA files high quality?
A: CDA files have no quality themselves. The quality comes from the CD’s Red Book Audio standard, which is uncompressed and high fidelity (44.1 kHz, 16-bit). The quality of a ripped file depends on the format you choose (e.g., WAV for lossless, MP3 for lossy).
Q4: Can I create a CDA file?
A: You can only generate CDA files by burning an “Audio CD” using CD-burning software. Data CDs containing MP3s will not create CDA files when inserted into a player.
Q5: : Is the CDA format obsolete?
A: While physical CDs are less common, the format is not obsolete. Anyone using audio CDs with a Windows PC will encounter CDA files, so understanding their purpose remains relevant.