Pulse or digital communications – Bandwidth reduction or expansion – Television or motion video signal
Reexamination Certificate
2000-12-18
2004-08-31
Philippe, Gims (Department: 2613)
Pulse or digital communications
Bandwidth reduction or expansion
Television or motion video signal
C370S232000, C348S423100
Reexamination Certificate
active
06785337
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an MPEG picture processing apparatus and a data transferring method using the apparatus in which a decoding operation based on MPEG (Moving Picture Experts Group) is performed and MPEG data is transferred.
2. Description of Related Art
In a picture and audio processing LSI such as an MPEG-
2
video and audio decoder, a frame memory, which is used to store a frame of picture data, or a system memory such as an SDRAM (static dynamic random access memory) having an area of an FIFO (first-in first-out) buffer used for an input bit stream is arranged in the inside or outside of the LSI. In this LSI, it is required to perform the transfer of a large quantity of data between a data processing unit and the system memory (or the frame memory). However, the integration in the system LSI has been advanced, the number of functions given to one chip has been increased, and the number of types of data has been increased. Therefore, because a quantity of data and the number of types of data have been increased, it is required to efficiently use a data transfer band. Also, because an inter-frame prediction coding is performed in the picture compression based on the MPEG, picture data used for the prediction is extracted from a frame of picture data, which is stored in a frame memory and precedes or succeeds time-wise to a current frame to be processed, and is used for the decoding operation performed in the video decoder, and decoded data of a reconstructed picture obtained in the video decoder is again written in the frame memory. Therefore, the decoding of picture data closely relates to the data transfer of the picture data from/to the frame memory. In this case, to efficiently operate the video decoder, it is required to transfer the picture data between the video decoder and the frame memory at an optimum timing of the picture data.
FIG. 8
is a block diagram showing the configuration of a conventional picture processing apparatus having a video decoder and a transfer request processing unit. In
FIG. 8
,
1
indicates a decoding processing unit for decoding picture data. In the decoding processing unit
1
,
2
indicates a video decoder, and
3
indicates a video decoding control unit for producing and outputting a plurality of transfer requests, which respectively indicate a request for the data transfer of a type of data, in a pre-set order.
4
indicates a request processing unit for receiving the transfer requests output from the video decoding control unit
3
one after another and outputting a transfer start instruction, which indicates an instruction for the starting of the data transfer of a particular type of data, in response to one transfer request corresponding to the particular type of data for each transfer request.
5
indicates a selector for receiving a plurality of possible data transfer quantities (respectively indicating a possible quantity of a type of data to be transferred), selecting one possible data transfer quantity of the particular type of data, which corresponds to the transfer start instruction, each time the transfer start instruction is output from the request processing unit
4
and outputting the selected possible data transfer quantity as a data transfer quantity (indicating a quantity of data to be transferred) of the particular type of data.
6
indicates a transfer ACK producing unit for producing an acknowledgment signal ACK, which indicates the acknowledgment of the data transfer of the particular type of data, according to the transfer start instruction output from the request processing unit
4
and outputting the acknowledgment signal ACK to the video decoding control unit
3
.
Next, an operation of the conventional picture processing apparatus is described.
In an example showing in
FIG. 8
, the transfer of five types of data dr, dw, a, b and c from the decoding processing unit
1
to an SDRAM (not shown) is performed. Here, the data dr and the data dw denote types of data for a reconstructed picture (called for-reconstructed-picture data), and the data a, the data b and the data c denote types of data other than the for-reconstructed-picture data.
In the video decoding control unit
3
, a plurality of transfer requests q-dr, q-dw, q-a, q-b and q-c corresponding to the types of data dr, dw, a, b and c are produced and output to the request processing unit
4
in a pre-set order. For example, the transfer requests q-dr, q-dw, q-a, q-b and q-c are output in that order. Also, a data transfer quantity of the data dr and a data transfer quantity of the data dw are respectively predetermined to a fixed value. In contrast, a possible data transfer quantity of each of the types of data a, b and c is changeable according to an empty capacity of a buffer, to which the corresponding type of data is transferred, and a data filled quantity of a buffer from which the corresponding type of data is transferred. The possible data transfer quantity of the type of data a is indicated by a sign wc-a, the possible data transfer quantity of the type of data b is indicated by a sign wc-b, and the possible data transfer quantity of the type of data c is indicated by a sign wc-c.
Initially, a transfer request q-dr of the data dr produced in the video decoding control unit
3
is output to the request processing unit
4
. In the request processing unit
4
, the transfer request q-dr is received, and a transfer start instruction of the data dr is actually output. Therefore, the data transfer of the data dr is started. Thereafter, in the transfer ACK producing unit
6
, an acknowledgment signal ACK-dr, which indicates the acknowledgment of the transfer of the data dr, is produced according to the transfer start instruction of the data dr and is output to the video decoding control unit
3
. In the video decoding control unit
3
, a transfer request q-dw of the data dw corresponding to a next data transfer is produced in response to the acknowledgment signal ACK-dr and is output to the request processing unit
4
. In the request processing unit
4
, when the transfer of the data dr currently performed is completed, a transfer start instruction of the data dw, for which the transfer request q-dw has been already received in the request processing unit
4
, is output. Therefore, the data transfer of the data dw is started. Thereafter, in the transfer ACK producing unit
6
, an acknowledgment signal ACK-dw is produced according to the transfer start instruction of the data dw and is output to the video decoding control unit
3
. In the video decoding control unit
3
, a transfer request q-a of the data a corresponding to a next data transfer is produced in response to the acknowledgment signal ACK-dw and is output to the request processing unit
4
. In the request processing unit
4
, when the transfer of the data dw currently performed is completed, a transfer start instruction of the data a, for which the transfer request q-a has been already received in the request processing unit
4
, is output. In this case, in the transfer of the data a, because a possible data transfer quantity of the data a is changeable in dependence on the output timing of the transfer start instruction of the data a, a possible data transfer quantity wc-a determined at the output timing of the transfer start instruction of the data a is selected in the selector
5
according to the transfer start instruction of the data a, and the possible data transfer quantity wc-a is output as a data transfer quantity of the data a. Therefore, the data transfer of the data a is started to transfer the data a of the data transfer quantity. In the same manner, the data transfer of the data b and the data transfer of the data c are started in that order to transfer the data b of a data transfer quantity and the data c of a data transfer quantity. Thereafter, in response to an acknowledgment signal ACK-c output from the transfer ACK producing unit
6
, the transfer request q-dr of the type of data dr is again produced in the vi
Okawahara Ryohei
Takabatake Akihiko
Burns Doane Swecker & Mathis L.L.P.
Philippe Gims
Renesas Technology Corp.
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