Video-on-demand system capable of performing a high-speed playback at a correct speed
First Claim
1. A video server apparatus for a video-on-demand system, for providing one of bit streams stored therein in response to a request from a terminal apparatus, the video server apparatus comprising:
- stream storage means for storing bit streams;
keyframe read/transmission bit rate calculating means for calculating a keyframe read bit rate and a keyframe transmission bit rate that are to be used in reading out only keyframes from one of the bit streams and a data length of the keyframes;
stream control means for determining, when only the keyframes are read out from the bit stream in accordance with a playback speed designated by the terminal apparatus, a minimum keyframe playback interval that allows complete transmission of the keyframes based on the keyframe read bit rate or the keyframe transmission bit rate, and the keyframe data length, and for determining a keyframe readout interval and a keyframe playback interval that satisfy the designated playback speed based on the minimum keyframe playback interval, a keyframe interval of the bit stream, and the designated playback speed;
stream reading means for reading out only the keyframes from the bit stream stored in the stream storage means in accordance with the keyframe readout interval, and for inserting or burying, as additional data, the keyframe playback interval into a stream including the read-out keyframes; and
stream transmitting means for transmitting the stream that is output from the stream reading means to the terminal apparatus.
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Accused Products
Abstract
A video server apparatus is provided with a stream control section which determines a keyframe readout interval and a keyframe playback interval that satisfy a playback speed designated by a terminal apparatus. The video server apparatus transmits data of the thus-determined keyframe playback interval to the terminal apparatus. The video server apparatus reads out keyframes of a stored bit stream from at the thus-determined keyframe readout interval, and transmits a stream including the read-out keyframes to the terminal apparatus. The terminal apparatus decodes and displays the transmitted stream at the received keyframe playback interval. This system can correctly perform a playback at an arbitrary speed that is designated by the terminal apparatus.
29 Citations
4 Claims
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1. A video server apparatus for a video-on-demand system, for providing one of bit streams stored therein in response to a request from a terminal apparatus, the video server apparatus comprising:
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stream storage means for storing bit streams;
keyframe read/transmission bit rate calculating means for calculating a keyframe read bit rate and a keyframe transmission bit rate that are to be used in reading out only keyframes from one of the bit streams and a data length of the keyframes;
stream control means for determining, when only the keyframes are read out from the bit stream in accordance with a playback speed designated by the terminal apparatus, a minimum keyframe playback interval that allows complete transmission of the keyframes based on the keyframe read bit rate or the keyframe transmission bit rate, and the keyframe data length, and for determining a keyframe readout interval and a keyframe playback interval that satisfy the designated playback speed based on the minimum keyframe playback interval, a keyframe interval of the bit stream, and the designated playback speed;
stream reading means for reading out only the keyframes from the bit stream stored in the stream storage means in accordance with the keyframe readout interval, and for inserting or burying, as additional data, the keyframe playback interval into a stream including the read-out keyframes; and
stream transmitting means for transmitting the stream that is output from the stream reading means to the terminal apparatus.
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2. A terminal apparatus for a video-on-demand system, for requesting a video server apparatus to provide one of bit streams stored therein, the terminal apparatus comprising:
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input control means for converting input instructions including a program instruction, a playback start position, and a playback speed instruction to corresponding commands;
command transmitting means for transmitting the commands to the video server apparatus;
stream receiving means for receiving a stream that is transmitted from the video server apparatus;
decoding means for decoding the received stream; and
decoding control means for extracting data of a keyframe playback interval that is inserted or buried in the received stream when the playback speed means a high-speed playback, and for controlling the decoding means based on the extracted keyframe playback interval.
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3. A video server apparatus for a video-on-demand system, for providing one of bit streams stored therein in response to a request from a terminal apparatus, the video server apparatus comprising:
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stream storage means for storing bit streams;
stream reading means for reading out only keyframes from one of the bit streams stored in the stream storage means in accordance with a keyframe readout interval and a keyframe read bit rate that are transmitted from the terminal apparatus when only the keyframes are read out from the bit stream in accordance with a playback speed designated by the terminal apparatus; and
stream transmitting means for transmitting a stream including the read-out keyframes to the terminal apparatus in accordance with a keyframe transmission bit rate that is transmitted from the terminal apparatus.
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4. A terminal apparatus for a video-on-demand system, for requesting a video server apparatus to provide one of bit streams stored therein, the terminal apparatus comprising:
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input control means for converting input instructions including a program instruction, a playback start position, and a playback speed instruction to corresponding commands;
stream receiving means for receiving a stream that is transmitted from the video server apparatus;
decoding means for decoding the received stream; and
decoding control means for controlling the decoding means based on the keyframe playback interval when the playback speed means a high-speed playback;
access table managing means for reading out keyframe information from an access table of the bit stream which access table is stored in the video server apparatus;
keyframe read/transmission bit rate on calculating means for calculating a keyframe read bit rate and a keyframe transmission bit rate that are to be used in reading out only keyframes from the bit stream and a data length of the keyframes;
stream control means for determining, when only the keyframes are read out in the video server apparatus from the bit stream in accordance with a playback speed designated by the terminal apparatus, a minimum keyframe playback interval that allows complete transmission of the keyframes based on the keyframe read bit rate or the keyframe transmission bit rate, and the keyframe data length, and for determining a keyframe readout interval and a keyframe playback interval that satisfy the designated playback speed based on the minimum keyframe playback interval, a keyframe interval of the bit stream, and the designated playback speed; and
control information transmitting means for transmitting data of the keyframe readout interval to the video server apparatus.
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Specification