1. Field of the Invention
The present invention relates to an apparatus and method for processing data of an optical disk. More particularly, the present invention relates to an apparatus and method for processing data of an optical disk which can reduce the memory size needed for a high density optical disk.
2. Description of the Related Art
Recently, new high density optical disks capable of storing high quality video and audio data, e.g., Blu-ray discs (BD), have been widely developed. As the density of the optical disk increases, memory size needed to decode data and to perform data processing, e.g., error correction, also increases. The increased memory size leads to an increase in manufacturing costs.
FIG. 1 illustrates a block diagram of a typical data encoding of a Blu-ray disc. Referring to FIG. 1, in user data recorded in the Blu-ray disc, 64 KB data may form a single ECC (error correction code) cluster. The user data may include 32 frames, each having 2048 bytes. The user data may be encoded through a multilevel signal processing operation, which may include a data frame, a scrambled data frame, a data block, a long distance code (LDC) block, and a LDC cluster. In the LDC block, data may be interleaved twice while passing to the LDC cluster. Meanwhile, user control data, i.e., relevant information corresponding to the user data, may be encoded through another multilevel signal processing operation, which may include an access block, a burst indicator subcode (BIS) block, and BIS cluster.
The BIS cluster, encoded by multilevel signal processing the user control data, may form an ECC cluster by interfering with some data of the LDC cluster, encoded by multilevel signal processing the user data. As shown in FIG. 1, the interference may result in dividing the LDC cluster into four blocks, and the ECC cluster may include 155-byte columns and 496-byte rows.
The ECC cluster may be modularized into physical clusters for disk recording. In the physical cluster, for example, 20-bit frame sync, 25-bit data, and 1-bit dc control may be arranged at a leading portion, and 45-bit data and 1-bit dc control may be alternately arranged.
FIG. 2 illustrates a data structure of the LDC cluster of FIG. 1. As shown in FIG. 1, the data of the LDC cluster may include 152 bytes×496 rows. The LDC data may be arranged in 432 of the 496 rows, while parity may be arranged in the other 64 rows. When interleave is performed twice, data of two adjacent LDC blocks may be alternately arranged in a single column of the LDC cluster. Also, the data and parity may be shifted by three columns to the left for each of two rows.
In the processing of the above encoded data, as the amount of the data stored in the high density optical disk such increases, the capacity of a memory needed to process the data increases accordingly. Also, in storing the data in the memory, the required memory size needs to be reduced through efficient memory management.
However, in the conventional technology, it is a problem that the capacity of a memory needed for data processing, for example, reading out data from a disk, performing error correction, descrambling, and EDC (error detection code) processing, increases. For example, the data read out from the disk may all be stored in an inner memory formed of a static random access memory (SRAM) and error correction may be performed with respect to the stored data. The final data decoded according to the above process may be stored in a synchronous dynamic random access memory (SDRAM). Accordingly, the capacity of a memory needed by a high capacity optical disk reproducing apparatus increases. In particular, since the SRAM is expensive compared to the SDRAM, the increase in the capacity of the SRAM keeps the price of the optical disk reproducing apparatus high.