Apparatus and method for managing a frame buffer for MPEG video decoding in a PC environment

• US 5,909,224 A
• Filed: 10/18/1996
• Issued: 06/01/1999
• Est. Priority Date: 10/18/1996
• Status: Expired due to Term

• Current Assignee: Samsung Semiconductor Incorporated (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Fung, Hei Tao
• Primary Examiner(s): Tung, Kee M.
• Application Number:
  US08/733,436
• Time in Patent Office: 956 Days
• Field of Search: 345/508, 345/509, 345/202, 345/501, 345/520, 345/521, 345/502, 348/411-416, 348/409, 348/423, 348/714-718
• US Class Current: 345/531
• CPC Class Codes: H04N 19/423 characterised by memory arrangements H04N19/433 takes precedence
• CPC Class Codes: H04N 19/44 Decoders specially adapted therefor, e.g. video decoders which are asymmetric with respect to the encoder
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 21/23406 involving management of server-side video buffer
• CPC Class Codes: H04N 21/4143 embedded in a Personal Computer [PC]
• CPC Class Codes: H04N 21/44004 involving video buffer management, e.g. video decoder buffer or video display buffer

Abstract

A four-buffer MPEG decoder is provided for decoding MPEG video frames. A four-buffer frame controller and control method manage the four frame buffers including decoding, displaying and discarding of I-frames, P-frames and B-frames so that video data decoding is accelerated. The four-buffer frame controller and control method frees one frame buffer when the frame buffer contains obsolete data, defined as data which is no longer useful for decoding additional frames and for which storage is not necessary for displaying pictures in a correct temporal order. One example of an obsolete frame is a B-frame that is displayed. Another example is a P-frame for I-frame which is no longer used for motion compensation and has been displayed.

Claims

1. An apparatus for preparing video signals for display in a computer system comprising:

a frame buffer memory including a plurality of frame buffers;

a video frame decoder coupled to the frame buffer memory, the video frame decoder decoding a frame data asynchronously with respect to a time frame; and

a frame buffer controller that controls storage of frame data in the plurality of frame buffers, the frame buffer controller storing a first reference frame and a second reference frame in two of the plurality of frame buffers and storing, when available, a first nonreference frame and a second nonreference frame in a further two of the plurality of frame buffers, the frame buffer controller generating data for display from a frame buffer selected from among the two frame buffers storing the reference frames and the two frame buffers storing the nonreference frames on the basis of the frame that is due to be displayed, the frame buffer controller determining when a frame data is obsolete and discarding a frame data when the frame data is obsolete.

2. An apparatus according to claim 1 wherein:

the video frame decoder is an MPEG video decoder that decodes reference frame data including I-frame data and P-frame data, and decodes nonreference data including B-frame data, the video frame decoder performing motion compensation.

3. An apparatus according to claim 2 wherein:

the frame buffer controller determines that a nonreference frame data is obsolete at the time the nonreference frame data is displayed and determines that a reference frame data is obsolete at the time the reference frame data is displayed and no longer used for motion compensation.

4. An apparatus according to claim 1 wherein:

the frame buffer memory is accessed by a plurality of applications in a multitasking environment.

5. An apparatus according to claim 1 further comprising:

a graphics processor coupled to the frame buffer memory for post-processing the video data.

6. An apparatus according to claim 1 wherein:

the frame buffer controller is a program code routine for executing on a processor in a multiprocessor multimedia system.

7. An apparatus according to claim 1 further comprising:

an audio signal processor;

an audio signal path coupled to the audio signal processor;

a video signal path including the a frame buffer memory, the video frame decoder, and the video display monitor;

an audio/video synchrony controller coupled to the audio signal path and the video signal path.

8. A method of displaying video signals in a computer system comprising:

decoding a video frame data asynchronously with respect to a time frame;

controlling storage of video frame data in a plurality of frame buffers including;

storing a first reference frame and a second reference frame in two of the plurality of frame buffers and storing, when available, a first nonreference frame and a second nonreference frame in a further two of the plurality of frame buffers,

generating data for display from a frame buffer selected from among the two frame buffers storing the reference frames and the two frame buffers storing the nonreference frames on the basis of which frame is due to be displayed;

determining when a video frame data is obsolete; and

discarding a video frame data when the frame data is obsolete.

9. A method according to claim 8 wherein:

decoding the video frame data is an MPEG video decoding operation for decoding reference frame data including I-frame data and P-frame data, and for decoding nonreference frame data including B-frame data.

10. A method according to claim 8 further comprising:

performing motion compensation.

11. A method according to claim 10 wherein:

determining when a video frame data is obsolete includes asserting that a nonreference frame data is obsolete at the time the nonreference frame data is displayed and asserting that a reference frame data is obsolete at the time the reference frame data is displayed and no longer used for motion compensation.

12. A method according to claim 8 further comprising:

accessing the frame buffer memory by a plurality of applications in a multitasking environment.

13. A method according to claim 8 further comprising:

post-processing the video data.

14. A method according to claim 8 wherein:

controlling storage of video frame data is executed as a program code routine for executing on a processor in a multiprocessor multimedia system.

15. A multimedia system comprising:

a processor;

a frame buffer memory including a plurality of frame buffers;

a video frame decoder coupled to the frame buffer memory, the video frame decoder decoding a frame data asynchronously with respect to a time frame; and

a frame buffer controller that controls storage of frame data in the plurality of frame buffers, the frame buffer controller storing a first reference frame and a second reference frame in two of the plurality of frame buffers and storing, when available, a first nonreference frame and a second nonreference frame in a further two of the plurality of frame buffers, the frame buffer controller generating data for display from a frame buffer selected from among the two frame buffers storing the reference frames and the two frame buffers storing the nonreference frames on the basis of which frame is due to be displayed, the frame buffer controller determining when a frame data is obsolete and discarding a frame data when the frame data is obsolete.

16. A multimedia system according to claim 15 wherein:

the video frame decoder is an MPEG video decoder that decodes reference frame data including I-frame data and P-frame data, and decodes nonreference data including B-frame data, the video frame decoder that performs motion compensation.

17. A multimedia system according to claim 15 wherein:

the frame buffer controller determines that a nonreference frame data is obsolete at the time the nonreference frame data is displayed and determines that a reference frame data is obsolete at the time the reference frame data is displayed and no longer used for motion compensation.

18. A multimedia system according to claim 15 wherein:

the frame buffer memory is accessed by a plurality of applications in a multitasking environment.

19. A multimedia system according to claim 15 wherein:

a graphics processor coupled to the frame buffer memory for post-processing the video data.

20. A multimedia system according to claim 15 wherein:

the frame buffer controller is a program code routine for executing on a processor in a multiprocessor multimedia system.

21. A multimedia system according to claim 15 further comprising:

an audio signal processor;

an audio signal path coupled to the audio signal processor;

a video signal path including the a frame buffer memory, the video frame decoder, and the video display monitor;

an audio/video synchrony controller coupled to the audio signal path and the video signal path.

22. A method of providing multimedia system comprising:

providing a processor;

providing a frame buffer memory including a plurality of frame buffers;

a video frame decoder coupled to the frame buffer memory, the video frame decoder that decodes a frame data asynchronously with respect to a time frame; and

providing a frame buffer controller that controls storage of frame data in the plurality of frame buffers, the frame buffer controller storing a first reference frame and a second reference frame in two of the plurality of frame buffers and storing, when available, a first nonreference frame and a second nonreference frame in a further two of the plurality of frame buffers, the frame buffer controller that generates data for display from a frame buffer selected from among the two frame buffers storing the reference frames and the two frame buffers storing the nonreference frames on the basis of which frame is due to be displayed, the frame buffer controller that determines when a frame data is obsolete and discards a frame data when the frame data is obsolete.

23. An apparatus for preparing video signals for display in a computer system comprising:

a frame buffer memory including a plurality of frame buffers;

a video frame decoder coupled to the frame buffer memory, the video frame decoder that decodes a frame data asynchronously with respect to a time frame; and

a frame buffer controller that controls storage of frame data in the plurality of frame buffers, the frame buffer controller storing up to four frames of frame data in the plurality of frame buffers, a decoded data frame being stored in a vacant frame buffer that has previously discarded frame data, the frame buffer controller generating data for display from a frame buffer holding frame data that is due to be displayed, the frame buffer controller determining when a frame data is obsolete and discarding a frame data when the frame data is obsolete.

24. An apparatus according to claim 23 wherein:

the frame buffer controller determines that a nonreference frame data is obsolete at the time the nonreference frame data is displayed and determines that a reference frame data is obsolete at the time the reference frame data is displayed and no longer used for motion compensation.