Motion video signal processing for recording or reproducing – Local trick play processing – With randomly accessible medium
Reexamination Certificate
1998-03-10
2001-08-07
Chevalier, Robert (Department: 2615)
Motion video signal processing for recording or reproducing
Local trick play processing
With randomly accessible medium
C386S349000
Reexamination Certificate
active
06272284
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image/audio reproducing apparatus for decoding/reproducing digitally compressed/coded image and audio data.
2. Description of the Prior Art
An image/audio reproducing apparatus for decoding/reproducing digitally compressed/coded image and audio data includes a system decoder for demultiplexing the multiplexed compressed/coded data into image data and audio data, a video decoder for decoding/reproducing the image data, and an audio decoder for decoding/reproducing the audio data.
FIG. 1
is a block diagram showing the arrangement of a conventional image/audio reproducing apparatus.
In the conventional image/audio reproducing apparatus, each of a system decoder
22
, a video decoder
23
, and an audio decoder
24
has an independent data memory. First, multiplexed compressed/coded data is loaded from a data storage unit
21
into a data memory (SBS memory)
25
of the system decoder
22
. The system decoder
22
demultiplexes the data, and the demultiplexed image and audio data themselves are copied to the data memories (a VBS memory
26
and an ABS memory
27
) of the video decoder
23
and audio decoder
24
, respectively, so the data are transferred between the decoders. The video decoder
23
and audio decoder
24
sequentially load the data from the data memories
26
and
27
, respectively, and decode the data.
Such a conventional image/audio reproducing apparatus is disclosed in Japanese Unexamined Patent Publication No.
7-153192.
In the above-described conventional apparatus, particularly, as the bit rate (the number of bits to be processed per second) of coded data rises, the load necessary for memory copy of data between the decoders increases to degrade the decoding performance of the reproducing apparatus.
Especially, when decoding is executed on the basis of software, the data processing capability become low, so real-time reproduction may be disabled. The data are not reproduced in real time (the original image/audio reproduction rate).
If real-time reproduction is disabled, decoding of appropriate frames must be omitted (time-lapse reproduction) in the image reproducing apparatus to synchronize the image and audio data. However, this generates a sense of incompatibility in viewing the image.
SUMMARY OF THE INVENTION
The present invention has been made in consideration of the above situation of the prior art and has as its object to provide an image/audio reproducing apparatus capable of solving the problem of degradation of performance of the reproducing apparatus in data transfer between decoders.
According to the first aspect of the present invention, there is provided an image/audio reproducing apparatus comprising:
a data storage unit for storing coded data;
a BS memory for temporarily storing the coded data read out from the data storage unit;
an image data area lookup table for storing address information of a data string having continuous image data in the BS memory;
an audio data area lookup table for storing address information of a data string having continuous audio data in the BS memory;
a system decoder for loading the coded data from the data storage unit to the BS memory, analyzing a header of the coded data to detect an image data string and an audio data string, and upon detecting the image data string, storing address information of the image data string in the image data area lookup table, and upon detecting the audio data string, storing address information of the audio data string in the audio data area lookup table;
a video decoder for accessing the BS memory in accordance with the address information in the image data area lookup table to read out the image data stored in the BS memory and decoding the image data; and
an audio decoder for accessing the BS memory in accordance with the address information in the audio data area lookup table to read out the audio data stored in the BS memory and decoding the audio data.
According to the second aspect of the present invention, each of the image data area lookup table and the audio data area lookup table in the first aspect is a set of table entries in which a set of start address information and length information of the data string having continuous image or audio data in the BS memory is stored.
According to the third aspect of the present invention, the BS memory in the first aspect comprises a ring buffer having a predetermined size.
According to the fourth aspect of the present invention, the image/audio reproducing apparatus further comprises a whole control section for designating an amount of the coded data to be demultiplexed into the image data and the audio data to the system decoder and designating the number of frames to be decoded to the video decoder and the audio decoder.
The apparatus of the present invention shares the data memory (BS memory) for temporarily storing coded data among the system decoder, the video decoder, and the audio decoder, and has the image data area lookup table for storing the address information of the data string having continuous image data in the BS memory and the audio data area lookup table for storing address information of the data string having continuous audio data. Data transfer between decoders is indirectly performed with reference to the data area lookup tables storing the address information in the BS memory.
Therefore, the conventional problem, i.e., degradation in data processing capability of the reproducing apparatus due to the load in data transfer processing between decoders, which disables real-time reproduction, can be almost solved.
As described above, according to the present invention, degradation in data processing capability of the reproducing apparatus due to the load in data transfer processing between decoders, which disables real-time reproduction, can be almost solved. Even when the data processing capability of the reproducing apparatus is absolutely low, the number of frames to be time-lapsed to synchronize the image and audio data decreases, so the sense of incompatibility in the image can be minimized.
The above and many other advantages, features and additional objects of the present invention will become manifest to those versed in the art upon making reference to the following detailed description and accompanying drawings in which preferred embodiments incorporating the principles of the present invention are shown by way of illustrative examples.
REFERENCES:
patent: 4777537 (1988-10-01), Ueno et al.
patent: 5512106 (1996-04-01), Tamai et al.
patent: 6-295894 (1994-10-01), None
Chevalier Robert
Foley & Lardner
NEC Corporation
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