Coded data generation or conversion – Digital code to digital code converters – Adaptive coding
Reexamination Certificate
2003-12-03
2004-11-09
Jeanglaude, Jean Bruner (Department: 2819)
Coded data generation or conversion
Digital code to digital code converters
Adaptive coding
C341S050000
Reexamination Certificate
active
06816093
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to digital media storage. Specifically, the invention relates to apparatus, methods, and systems for increasing recording throughput on digital media recording systems.
DESCRIPTION OF THE RELATED ART
Magnetic recording has played an important role in the electronic age for permanently storing and retrieving data. Magnetic recording media such as magnetic tape cartridges provide compact, reliable storage at a relatively low cost. In addition to storing data processing files, magnetic media have also been widely used to store data related to digital convergence such as digital music, video, photos, and personal data. Consumers and businesses have clearly benefited from the versatility of this constantly improving, media.
Despite the ubiquitous usage of magnetic storage, other types of storage such as flash memories have increased in popularity relative to magnetic storage. Part of the appeal of non-magnetic storage relates to the increased storage bandwidth or throughput available with such technologies albeit at a significantly higher cost per Megabyte of storage. What is needed are means and methods to improve the storage bandwidth of magnetic media systems.
One bottleneck on magnetic recording systems involves data compression—particularly context-based data compression of text and binary data files.
FIG. 1
illustrates a block diagram of a typical prior art storage unit
100
. The storage unit
100
includes a host interface
110
, a compression module
120
, a media interface
130
, a recording medium
140
, and a controller
150
. The storage unit
100
illustrates some of the challenges related to increasing data compression bandwidth within digital media recording systems in general and of magnetic recording systems in particular.
The host interface
110
receives data
102
and commands
104
from a host or other computer-based system. Typically, the host interface directs the commands
104
to a control bus
106
, and the data
102
to high-speed data bus
108
, or the like. The controller
150
may receive the commands on the control bus
106
and direct operations related to recording data to or retrieving data from the recording medium
140
.
The recording medium
140
is typically limited to a certain recording and retrieval rate for each track recorded on the recording medium
140
. However, data throughput may be increased by recording and retrieving multiple tracks concurrently. As a result, many recording systems have increased the number of concurrently written tracks, the bandwidth of the media interface
130
, and the aggregate data transfer rates associated therewith.
The compression module
120
compresses data and thereby potentially increases the effective throughput seen by the host to, and the capacity of, the storage unit
100
in that more information may be stored with less data written to media. However, the data transfer rates of the compression module
120
may be limited by semiconductor clock rates in that many compression algorithms, particularly context-based compression algorithms such as SLDC, compress on a byte boundary and thus are not readily extensible to compress more than one byte at a time. This is particularly problematic for data processing systems that rely heavily on context-based compression to compress text files, binary data files, and the like.
The limits of context-based compression algorithms place system designers in a quandary. On one hand, compression potentially increases the throughput and storage capacity of digital recording media such as magnetic media. On the other hand, compression places an upper bound on data transfer rates achievable with context-based compression.
What is needed are apparatus, means, and methods to increase the throughput achievable with digital recording media. In particular, what is needed are apparatus, methods, and systems to overcome the bottleneck currently associated with context-based compression within digital media recording systems.
BRIEF SUMMARY OF THE INVENTION
The present invention has been developed in response to the present state of the art, and in particular, in response to the problems and needs in the art that have not yet been fully solved by currently available digital recording means and methods. Accordingly, the present invention has been developed to provide an apparatus, method, and system to overcome many or all of the above-discussed shortcomings in the art.
In one aspect of the invention, an apparatus for increased recording throughput of digital media recorders includes a control module that distributes a source data stream to multiple compression paths that compress and buffer digital data to provide compressed data streams, and one or more media encoders that concurrently encode the compressed data streams to corresponding media tracks. In one embodiment, the control module monitors available buffer space within each compression path and distributes data to a selected compression path based on available buffer space. Each compression path may include a compression module that provides compressed data and a data buffer that buffers the compressed data.
In addition to distributing data to a selected compression path, the control module may initiate insertion of metadata within the compressed data streams that facilitate reconstruction of the source data stream from the corresponding set of compressed data streams. In certain embodiments, the metadata includes a swap command indicating selection of a particular compression path. The control unit may also adjust distribution of the source data stream based on feedback from a media encoder, such as skip events due to media defects on particular tracks, which slow or pause the throughput of one of the compression paths to media. The source data stream may be distributed in units large enough to maintain context and compressibility of the data.
In one embodiment, the media encoder encodes an active path identifier at each access point within the media tracks and each access point corresponds to a point in the compressed data stream that is context-free. The active path identifier identifies the active or ‘hot’ path from which the compressed data is preferably directed from for decompression. Placing an active path identifier at each access point facilitates decompressing data and reconstructing the original source data stream beginning at any access point.
In another aspect of the invention, an apparatus for increased retrieval throughput of digital media recorders includes one or more media decoders that concurrently decode multiple media tracks to provide a set of compressed data streams to a corresponding set of decompression paths that concurrently decompress and buffer the compressed data streams to provide a corresponding set of decompressed data streams, and a control module that merges the decompressed data streams into a merged data stream as directed by metadata contained within the compressed data streams. Each decompression path may include a decompression module that provides decompressed data and a data buffer that buffers the decompressed data.
In certain embodiments, the metadata comprises a swap command indicating selection of a particular decompression path. In one embodiment, the media decoder decodes an active or ‘hot’ path identifier at each access point within the media tracks in order to commence decompression beginning at any access point. In certain embodiments, the described functional units of the data recording and data retrieval units are merged into a single unit that streams data to and from a digital medium on parallel tracks in an efficient concurrent manner.
In one aspect of the invention, a method for increased recording throughput on digital media recorders includes distributing a source data stream to multiple compression paths to concurrently provide a corresponding set of compressed data streams, inserting metadata within the compressed data streams, and concurrently encoding the compressed data str
Jeanglaude Jean Bruner
Kunzler & Associates
LandOfFree
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