Method and apparatus for frame accurate access of digital audio-visual information
DCFirst Claim
1. A method for playing at a second presentation rate an audio-visual work that has been digitally encoded in a digital data stream for playback at a first presentation rate, wherein said digital data stream includes a sequence of video frame data, each video frame data in said sequence of video frame data corresponding to a video frame in said audio-visual work, the method comprising the computer-implemented steps of:
- selecting a selected set of video frames from said audio-visual work based on said second presentation rate and sizes of video frame data that correspond to said video frames;
constructing a second digital data stream that includes the video frame data that corresponds to each video frame of said selected set of video frames; and
transmitting said second digital data stream to a decoder.
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Accused Products
Abstract
A method and apparatus for use in a digital video delivery system is provided. A digital representation of an audio-visual work, such as an MPEG file, is parsed to produce a tag file. The tag file includes information about each of the frames in the audio-visual work. During the performance of the audio-visual work, data from the digital representation is sent from a video pump to a decoder. Seek operations are performed by causing the video pump to stop transmitting data from the current position in the digital representation, and to start transmitting data from a new position in the digital representation. The information in the tag file is inspected to determine the new position from which to start transmitting data. To ensure that the data stream transmitted by the video pump maintains compliance with the applicable video format, prefix data that includes appropriate header information is transmitted by said video pump prior to transmitting data from the new position. Fast and slow forward and rewind operations are performed by selecting video frames based on the information contained in the tag file and the desired presentation rate, and generating a data stream containing data that represents the selected video frames. A video editor is provided for generating a new video file from pre-existing video files. The video editor selects frames from the pre-existing video files based on editing commands and the information contained in the tag files of the pre-existing video files. A presentation rate, start position, end position, and source file may be separately specified for each sequence to be created by the video editor.
382 Citations
25 Claims
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1. A method for playing at a second presentation rate an audio-visual work that has been digitally encoded in a digital data stream for playback at a first presentation rate, wherein said digital data stream includes a sequence of video frame data, each video frame data in said sequence of video frame data corresponding to a video frame in said audio-visual work, the method comprising the computer-implemented steps of:
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selecting a selected set of video frames from said audio-visual work based on said second presentation rate and sizes of video frame data that correspond to said video frames; constructing a second digital data stream that includes the video frame data that corresponds to each video frame of said selected set of video frames; and transmitting said second digital data stream to a decoder. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method for playing at a slower presentation rate an audio-visual work that has been digitally encoded in a digital data stream for playback at a first presentation rate, wherein said digital data stream includes a sequence of video frame data, each video frame data in said sequence of video frame data corresponding to a video frame in said audio-visual work, the method comprising the computer-implemented steps of:
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constructing from video frame data retrieved from said digital data stream a second digital data stream which is digitally encoded for playing said audio-visual work at said slower presentation rate; and transmitting said second digital data stream to a decoder; wherein said steps of constructing and transmitting are performed in parallel. - View Dependent Claims (15, 16, 17)
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18. A method of preprocessing an original digital data stream that represents an audio-visual work to create tag information, the audio-visual work including a sequence of frames, the original digital data stream including a sequence of frame data, each frame data corresponding to a frame in said sequence of frames, the method comprising the steps of:
for each frame in said sequence of frames, performing the steps of determining boundaries within said original digital data stream for the frame data corresponding to said frame; generating tag data that includes boundary data that indicates said boundaries of said frame data; and storing said tag data separate from said original digital data stream. - View Dependent Claims (19, 20, 21)
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22. A method for selecting frames for display during a performance at a specified presentation rate of a work represented in a digital video file, wherein the performance is produced by decoding a data stream generated from the digital video file over a channel having a predetermined data transfer rate, the method comprising:
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selecting for display a first frame represented by frame data in said digital video file, said first frame being associated with a first time; inspecting a second frame that is represented by frame data in said digital video file, said second frame being associated with a second time; determining a bit budget based on said presentation rate, a time difference between said first time and said second time and said predetermined data transfer rate; comparing the bit budget to the size of the frame data that represents said second frame; if the size of the frame data exceeds the bit budget, then skipping the second frame; and if the size of the frame data is less than the bit budget, then selecting the second frame for display. - View Dependent Claims (23, 24)
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25. A method for creating a second digital video stream from one or more other digital video streams, the method comprising the computer-implemented steps of:
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receiving a series of editing commands, each editing command in said series of editing commands specifying a start position, an end position, and a presentation rate; for each editing command in said series of editing commands, performing the steps of selecting a selected set of video frames between said start position and said end position in said one or more other digital video streams based on said presentation rate; and storing frame data corresponding to said selected set of video frames in said second digital video stream.
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Specification