Video/audio transmission systsem and method

• US 5,045,940 A
• Filed: 12/22/1989
• Issued: 09/03/1991
• Est. Priority Date: 12/22/1989
• Status: Expired

• Current Assignee: Avid Technology Incorporated
• Original Assignee: Avid Technology Incorporated
• Inventors: Peters, Eric C., Rabinowitz, Stanley
• Primary Examiner(s): RICHARDSON, ROBERT
• Application Number:
  US07/455,567
• Time in Patent Office: 620 Days
• Field of Search: 358/185, 358/86, 358/335, 358/903, 358/143, 358/85, 360/8, 360/14.1, 379/53, 364/514, 364/521
• US Class Current: 348/472
• CPC Class Codes: G11B 27/005 Reproducing at a different information rate from the information rate of recording for television signals H04N5/783
• CPC Class Codes: G11B 27/034 on discs G11B27/036, G11B27/038 take precedence
• CPC Class Codes: G11B 27/10 Indexing; Addressing; Timing or synchronising; Measuring tape travel
• CPC Class Codes: H04N 21/23406 involving management of server-side video buffer
• CPC Class Codes: H04N 21/2368 Multiplexing of audio and video streams
• CPC Class Codes: H04N 21/43072 of multiple content streams on the same device
• CPC Class Codes: H04N 21/4325 by playing back content from the storage medium reproduction of recorded television signals H04N5/76; reproduction of recorded television signals H04N9/79
• CPC Class Codes: H04N 21/4341 Demultiplexing of audio and video streams
• CPC Class Codes: H04N 21/4398 involving reformatting operations of audio signals details of audio signal transcoding G10L19/173
• CPC Class Codes: H04N 21/44004 involving video buffer management, e.g. video decoder buffer or video display buffer
• CPC Class Codes: H04N 21/6332 directed to client
• CPC Class Codes: H04N 21/654 Transmission by server directed to the client
• CPC Class Codes: H04N 5/93 Regeneration of the television signal or of selected parts thereof
• CPC Class Codes: H04N 5/937 by assembling picture element blocks in an intermediate store
• CPC Class Codes: H04N 9/802 involving processing of the sound signal H04N9/806, H04N9/835 take precedence

Abstract

The invention is a data pipeline system which synchronizes the display of digitzed audio and video data regardless of the speed at which the data was recorded on its linear medium. To do this, the video data is played at a constant speed, synchronized by the audio speed. Further, the invention uses a method of "staging" data in storage buffers, i.e., ring buffers, which encourages efficient use of the viewer module resources by not permitting the viewer to read excessive amounts of data at any one time, i.e., to read only enough data into any one ring buffer so that the amount of data in the ring buffer is roughly equivalent to the amount of data in the other ring buffers and yet permitting the viewer to read large enough chunks of data to promote efficient use of the fill system.

Claims

1. A media pipeline system for displaying digitized audio and video, comprising:

a media file database for accepting and making available a plurality of media files, at least one of said media files having digitized audio media data and at least another one of said media files having video media data, each of said media files being divided into a plurality of frames;

a plurality of ring buffers;

a viewer module comprising procedures to synchronize the transfer of media data from the media files into said plurality of ring buffers, said ring buffers storing the media data before it is displayed;

a video accelerator connected to receive an output of at least one of said ring buffers for generating a video display output; and

a sound accelerator connected to receive an output of at least one of said ring buffers for generating an audio output.

2. The system of claim 1 wherein one of said ring buffers receives and stores only audio media and another of said ring buffers receives and stores only video media.

3. The system of claim 2, wherein two of said ring buffers receive and store only audio data.

4. The system of claim 2, further comprising a controller for signalling said sound accelerator to start playing a part of the media data found on a ring buffer containing audio data, said sound accelerator producing an output signal after playing said part, said controller being responsive to said sound accelerator output signal for signalling said video accelerator to start displaying part of the media data stored in a ring buffer containing video data.

5. The system of claim 1, wherein at least one of said audio media files contains audio data for a first audio channel and at least another of said audio media files contains audio data for a second audio channel.

6. The system of claim 5, wherein one of said ring buffers receives and stores only video media data, another one of said ring buffers receives and stores only audio media data for said first channel and another one of said ring buffers receives and stores only audio media data for said second channel.

7. The system of claim 1, wherein said viewer module procedures to synchronize media data transfer include a data transfer coordinator to stage the transfer of data to said plurality of ring buffers so that at any one time the amount of data in one ring buffer is approximately equivalent to the amount of data in at least one other ring buffer.

8. The system of claim 7, wherein said transfer coordinator acts so that at any one time the amount of data in one ring buffer is approximately equivalent to the amount of data in all other ring buffers.

9. The system of claim 1, wherein said viewer module further comprises procedures for determining which of said ring buffers contains the least media data and transferring media data to the ring buffer having the least media data.

10. The system of claim 9, wherein said viewer module procedures include a transfer coordinator for transferring data to a ring buffer in disregard of other conditions when said ring buffer contents are below a predetermined minimum.

14. The system of claim 1, wherein the ring buffers are preloaded with data (before playing begins) to increase efficiency.

16. The system of claim 1, further enhanced by a set of capture masks used to efficiently play back material that was captured at fewer than 30 frames per second.

11. A method of displaying digitized media data on a monitor, comprising the steps of:

storing the media data in a plurality of media files and a plurality of ring buffers, at least one of which contains video media data and at least one of which contains audio media data;

determining which of the ring buffers contains the least media data;

reading media data from one of the media files into the ring buffer having the least media data;

signaling a sound accelerator card which plays a part of the media data found one of the audio ring buffers;

waiting for an interrupt from the sound accelerator card;

signaling a video accelerator card which plays the a part of the media data found in one of the video ring buffers.

12. The method of claim 11, further comprising the step of executing a critical read operation when the number of bytes contained in a ring buffer is less than a predefined minimum.

13. The method of claim 12, further comprising the step of executing an efficient read operation when the number of bytes contained in a ring buffer is greater than a predefined number.

15. The method of claim 11, further comprising the step of determining the number of bytes of audio needed to properly synchronize with a given amount of video by using a proportion with the amount of video that was associated with this audio when it was digitized.