Pulse or digital communications – Bandwidth reduction or expansion – Television or motion video signal
Reexamination Certificate
1998-02-26
2002-04-09
Kelley, Chris (Department: 2613)
Pulse or digital communications
Bandwidth reduction or expansion
Television or motion video signal
Reexamination Certificate
active
06370193
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to MPEG multimedia data, and more preferably to compression and decompression of MPEG data.
BACKGROUND OF THE INVENTION
Multimedia data including audio, still video and motion video data is being widely used in video games, internet-related applications and other data processing related applications. As is well known to those having skill in the art, multimedia applications often require large quantities of video and audio data. In order to store and process large quantities of data, international standards for coding audio and video data have been prepared by the Moving Picture Expert Group (MPEG). Examples of MPEG standards are MPEG-1 and MPEG-2 standards. MPEG standards are widely used with multimedia data and need not be described further herein.
MPEG-1 or MPEG-2 standard data that has been compressed may be restored or decompressed using an MPEG-1 or MPEG-2 decoder. More specifically, MPEG data may include intra picture data, predictive picture data and bidirectionally predictive picture data. Moreover, each picture generally includes a luminance signal and a chrominance signal. Accordingly, notwithstanding the existence of MPEG compression and decompression, large size memories may still be needed to store multimedia data.
In one specific example, if the number of horizontal pixels are 720 and 480 respectively, the numerical value for discrimination between black/white and color signal is 2, and the number of bits per pixel is 8, in order to store all of the intra picture, predictive picture and bidirectionally predictive picture data, the total amount of data to be stored may become 720×480×3×8×2 or 15.2 Mbits. Accordingly, 15.2 Mbits of data may need to be stored in a memory to process the three pictures.
FIG. 1
is a block diagram of a conventional MPEG system decoder. Referring to
FIG. 1
, a conventional MPEG system decoder includes an MPEG bitstream decoder
10
, a memory management processor
12
, a memory
14
, an MPEG video restorer
16
(decompressor), and a video output processor
18
. The video output processor
18
provides video data to a display, such as a TV. It will be understood that the block diagram of
FIG. 1
illustrates only blocks for processing video data.
The MPEG bitstream decoder
10
receives an MPEG bitstream and separates the bitstream into video data, audio data, and system data. The memory
14
stores therein compressed video and audio data, and restored video and audio data. The MPEG video restorer
16
restores the compressed video data output from the memory
14
and provides the restored video data to the memory
14
. The memory management processor
12
controls the generation of addresses for storing or reading data in/out of the memory
14
. The video output processor
18
outputs the restored video data from the memory
14
to a video display.
A data processing method performed by a conventional MPEG system decoder of
FIG. 1
will now be described. Specifically, the memory management processor
12
stores the MPEG-compressed video data separated by and output from the MPEG bitstream decoder
10
in a compressed video data storage region of the memory
14
. The memory management processor
12
then outputs the MPEG-compressed video data stored in the memory
14
to the MPEG video restorer
16
. The MPEG video restorer
16
restores the MPEG-compressed video data. The memory management processor
12
stores the video data restored by the MPEG video restorer
16
in a restored video data storage region of the memory
14
. The memory management processor
12
outputs the restored data stored in the memory
14
to the video output processor
18
.
As described above, according to a conventional data processing method performed by a conventional MPEG system decoder, the video data restored by the MPEG video restorer
16
is stored in the memory
14
as is. Unfortunately, the storing of video data in the memory
14
may require an excessive amount of storage capacity. The large storage capacity may increase the cost and/or decrease the performance of the system that processes MPEG data.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide improved storage of MPEG data.
It is another object of the invention to provide compression of MPEG data to allow reduction in the storage space that need be used by the data.
These and other objects are provided, according to the present invention, by methods, systems or apparatus and computer program products that compress MPEG data by obtaining difference values between succeeding adjacent data values of MPEG video data and store the difference value if the difference value is less than a predetermined range. By storing the difference values rather than the data values if the difference value is less than a predetermined range, compression may be provided for MPEG data.
More specifically, according to the present invention, a series of data values of MPEG video data is separated from an MPEG bitstream. Difference values are obtained between succeeding adjacent data values of the MPEG video data. For each data value, the data value is stored if the difference exceeds a predetermined range, and the difference value is stored if the difference value is less than the predetermined range. A conversion flag is also stored for each data value, to indicate whether the data value or the difference value is stored. As an example, the predetermined range may be between −9 and 8.
According to another aspect of the present invention, after the data value or difference value is stored for each data value, a determination is made if the data values and difference values that were stored exceed a predetermined size. Each data value is divided by 2, and the divided data values are stored if the data values and difference values that were stored exceed the predetermined size. On the other hand, if the data values and difference values that were stored are less than the predetermined size, dummy bits may be added to the data, so that the data that was stored equals the predetermined size. A mode flag may be used to indicate whether difference values or divided values are stored.
Accordingly, MPEG data may be compressed by separating a series of n data values of m bits each of MPEG video data from an MPEG bitstream to obtain m×n bits of MPEG video data. The m×n bits of MPEG video data are compressed into (m×n)−n bits using adjacent value differencing and data value dividing. The (m×n)−n bits of compressed MPEG video data is stored.
Preferably, the (m×n)−n bits of compressed MPEG video data include n 1-bit conversion flags to indicate whether the data value or the difference value is stored for each of the n data values. A plurality of dummy bits are also preferably included, if needed, to increase the size of the compressed video data to (m×n)−n bits. Finally, the (m×n)−n bits of compressed MPEG video data also preferably include a 1-bit mode flag, to indicate whether difference values or divided values are stored.
The compressed MPEG data may be decompressed or restored by adding a compressed data value to an immediately preceding decompressed data value to obtain an associated decompressed data value if the conversion flag that is associated with the data value indicates that the difference is stored. Adjacent data value adding is preferably performed only if the mode flag has a first value to indicate that differencing was used in compression. If the mode flag has a second value, indicating that dividing was used to compress, then each compressed data value is multiplied by 2 to decompress the data.
Accordingly, (m×n)−n bits of compressed MPEG video data are decompressed into a series of n data values of m bits each of decompressed MPEG video data using adjacent data value adding and data value multiplying. The (m×n)−n bits of compressed MPEG video data include n 1-bit conversion flags to indicate whether the data
Kelley Chris
Myers Bigel & Sibley & Sajovec
Vo Tung
LandOfFree
MPEG data compression and decompression using adjacent data... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with MPEG data compression and decompression using adjacent data..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and MPEG data compression and decompression using adjacent data... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2876082