CD-R

CD-R (Compact Disc Recordable, 可记录光盘) is a write-once optical disc whose physical and recording specifications are defined by the Orange Book standard. Blank CD-Rs can be written to incrementally by a burner; once written, the content cannot be erased or overwritten. New tracks or sessions may still be appended to unused areas when conditions permit. It differs in recording layer structure from rewritable CD-RWs and factory-pressed read-only CDs.

Blank discs are pre-pressed with a spiral guide track for the burner to follow. The guide track has a slight wobble and contains control information, such as the absolute pre-recording time, enabling the device to determine position, speed, and the writable range. During burning, the focused laser causes irreversible optical changes in the organic dye recording layer, forming marks with different reflectivity; A reading device interprets these changes as signals corresponding to the pit sequence on the pressed disc. The term “recording” therefore does not refer to the mechanical engraving of visible grooves on the disc surface. A CD-R can be written as a CD-DA audio disc, a CD-ROM data disc, a Video CD, or other content that complies with the relevant logical specifications. The media type merely indicates that it can be recorded on once; it does not determine which application format is used. “Music CD-Rs,” designed specifically for home audio recorders, typically bear markings for recognition by consumer-grade recording equipment and may involve specific licensing mechanisms; however, their basic recording principle does not thereby constitute a different audio coding scheme.

Writing can be performed in a single pass covering the entire disc, in a single pass for a single track, or in batches. Multi-segment and multi-session formats allow content to be appended in stages, but early devices or players that only recognize the first session may not be able to access subsequent data. Ending a track, closing a session, or finalizing the disc writes the necessary directory and exit area; a finalized disc generally offers broad read compatibility but loses the ability to add further content. The term “disc completed” used by different software may refer to closing the current session or finalizing the entire disc; the meaning must be determined in conjunction with the writing method.

The dye material, reflective layer, writing speed, and burning power of a CD-R all collectively affect signal quality. Burners can select power strategies based on disc information, but so-called “high-speed” discs do not guarantee consistent read performance on all older devices. Because the reflective properties of CD-Rs differ from those of pressed CDs, some early players and optical drives are unable to focus or track the disc reliably. A successful write does not guarantee that the data will remain permanent; exposure to light, high temperatures, high humidity, material aging, and corrosion of the reflective layer can all reduce long-term readability.

Audio CD-Rs are still subject to the CD-DA specification of 44.1 kHz, 16-bit stereo PCM. When burning high-sampling-rate files to a standard audio CD, authoring software must first convert the sampling rate and bit depth; if you simply copy FLAC, MP3, or other files to a CD-R data disc, the result is a data CD, and whether it can be played depends on the device’s support for the file system and the corresponding encoding.