Marten van Dijk
Consultant, Inventor, Researcher, Applied Mathematician, & Computer Scientist
Blu-ray Disc:
Optical and magnetic storage applications use cooperating codes for error correction (classical examples
are the CIRC code in CD and the interleaved product code in D-VSH). Also in DVD (digital versatile disc)
and Blu-ray disc (digital video recording) the error correcting code is a cooperating code. They are
designed such that most occurring combinations of random byte errors and bursts of errors can be corrected.
Random byte errors are mostly due to jitter causing the demodulator (which is the decoder corresponding to
the run length limited code, also called the channel code) to output erroneous bytes. Bursts of errors can
be caused by dust, fingerprints, scratches, etc. In practice, burst errors turn out to limit the actual
performance of an error correcting code system in optical recording.
A Blu-ray disc is read out by using blue laser light; compared to DVD, this higher frequency laser light
allows bits to be stored in smaller pit-land structures, thereby increasing the density of information on
disc. For Blu-ray disc (see http://www.blu-raydisc.com/ and http://www.blu-ray.com/) we designed
a new cooperating code called the picket code [1,2,3,4]. All the redundancy in a picket code is put in
vertically oriented Reed-Solomon (RS) codes. In the picket code we recognize picket columns and normal
columns. The picket columns are special in the sense that compared to the normal columns they contain more
redundancy leading to a stronger error correcting capability. The picket columns are designed such that with
extremely high probability their RS codes can be properly decoded, i.e., all their errors can be corrected.
The location of the corrected bytes serve as pickets indicating the likely position of burst errors
affecting the bytes between these pickets in the normal columns. When subsequent pickets have fallen, it is
likely that all bytes located physically in between these pickets were corrupted by a burst of errors. We
erase such bytes. An erasure and error decoding algorithm of RS code words in the normal columns makes use
of this erasure information to correct these bursts together with random errors.
During a standardization meeting and a visit to Sony in 2001, we introduced the possibility of a compatible
extra layer of error correction which leads to extra error correcting capabilities if no bursts are present,
making Blu-ray disc superior to DVD in all regions of interests [5,6].
An interesting topic of research in optical storage is to improve the density of information. In optical
storage a stream of binary bits (satisfying a certain run length limited constraint) is stored in a pit-land
structure. On top of this main channel it is possible to add a secondary channel, e.g. a so-called
"peanut"-structure can be made or the depth and/or width of the pits can be varied. We showed that the
merging bits of a RLL code can also be used to establish a secondary channel [7,8,9]. In general, the
secondary channel is embedded in the main channel via multi-level coding. The errors in the stream of bits
stored in the secondary channel can be corrected by using the corrected stream of bits stored in the main
channel [10,11].
Other issues in optical storage are synchronisation [12] and addressing [13,14]. In particular, our technique
of coding with side information is used for fast address retrieval in Blu-ray disc; often the most significant
bytes of an address are known, this information can be used to improve the error correcting capabilities if
the code is constructed by using our technique.
I am the lead inventor of the error correcting codes accepted in the digital video recording standard for
Blu-ray disc (the picket code [3] and the coding technique used for fast address retrieval [14]).
I co-authored the paper "Optical Disc System for Digital Video Recording'' on Philips' contributions to
Blu-ray disc technology [2], which got reprinted in the book "Origins and Successors of the Compact Disc
Contributions of Philips to Optical Storage", http://www.ieee.be/milestone.html, published as a result
of the IEEE Milestone in Electrical Engineering and Computing dedicated to Philips for the development of
the compact disc audio player.
[1] T. Narahara, S. Kobayashi, M. Hattori, Y. Shimpuku, G.J. van den Enden, J.A.H.M. Kahlman,
M. van Dijk, and R. van Woudenberg, Optical Disc System for Digital Video Recording,
Jpn. J. Appl. Phys. Vol.39 (2000), Part 1, No. 2B, 912-919, February 2000. An abstract has been published
in the Proc. of ODS/ISOM, Hawaii, July, 1999.
[2] W. Coene, H. Pozidis, M. van Dijk, J. Kahlman, R. van Woudenberg, and B. Stek, Channel coding and
signal processing for optical recording systems beyond DVD,
IEEE Trans. on Magn., Vol.37 (2001), Issue 2, Part 1, 682-688, March 2001.
[3] M.E. van Dijk, L.M.G.M. Tolhuizen, J.A.H.M. Kahlman, C.P.M.J. Baggen, M. Hattori, K. Yamamoto,
T. Narahara, and S. Senshu, Encoding multiword information by wordwise interleaving, US 6367049, 2002.
[4] M.E. van Dijk, L.M.G.M. Tolhuizen, and C.P.M.J. Baggen, Method and apparatus for encoding multiword
information with error locative clues directed to low protectivity words, US 6378100, 2002.
[5] M.E. van Dijk and K. Yamamoto, Method and apparatus for embedding an additional layer of error
correction into an error correcting code, US 7188295, 2007.
[6] M.E. van Dijk, , K. Yamamoto, and M. Hattori, Method and apparatus for embedding an additional layer
of error correction into an error correcting code, US 7340663, 2008.
[7] M.E. van Dijk, W.M.J.M. Coene, and C.P.M.J. Baggen, Method of decoding a stream of channel bits of a
signal relating to a binary channel signal into a stream of source bits of a signal relating to a binary
source signal, US 6362754, 2002.
[8] C.P.M.J. Baggen, M.E. van Dijk, and W.M.J.M Coene, Method of storing or decoding a stream of bits,
US 7174497, 2007.
[9] W.M.J.M Coene, M.E. van Dijk, and C.P.M.J. Baggen, Method and device for encoding information words,
method and device for decoding information words, storage medium and signal, US 2002/0157055, 2002.
[10] M.E. van Dijk, W.M.J.M. Coene, and C.P.M.J. Baggen, Information carrier, device for encoding, method
for encoding, device for decoding and method for decoding, US 6529147, 2003.
[11] M.E. van Dijk, W.M.J.M. Coene, and C.P.M.J. Baggen, Information carrier, device for encoding, method
for encoding, device for decoding and method for decoding, US 6650257, 2003.
[12] S. Egner, C.P.M.J. Baggen, and M.E. van Dijk, Method for generating a serial bitstream comprising
information for synchronization, US 2002/0106044, 2002.
[13] M. van Dijk, S. Baggen, and L. Tolhuizen, Coding for Informed Decoders,
Proc. of ISIT 2001, p. 202, 2001.
[14] M.E. van Dijk, C.P.M.J. Baggen, and L.M.G.M. Tolhuizen, Coding for informed decoders,
US 7103829, 2006.
© 2009 Marten van Dijk .
All rights reserved.