Method and apparatus for preventing overflow and underflow of an encoder buffer in a video compression system
First Claim
1. A method for preventing overflow and underflow of an encoder buffer in a video compression system, the method comprising the steps of:
- a) using a virtual buffer, in a rate controller, to model a decoder buffer fullness;
b) generating a sequence of bits by an encoder, wherein the encoder is controlled by the rate controller to prevent a decoder buffer underflow and overflow;
c) receiving the sequence of bits by the encoder buffer to produce a bitstream;
d) transmitting the bitstream from the encoder buffer to a decoder buffer following a delay to produce a delayed bitstream, wherein the delayed bitstream corresponds to an instantaneous channel bitrate; and
e) controlling the delay by the rate controller to synchronize an encoder buffer fullness with a virtual buffer fullness, wherein the synchronization prevents overflow and underflow of the encoder buffer,wherein a predetermined encoder buffer size is larger than a predetermined decoder buffer size,wherein the delay is based on the predetermined decoder buffer size, an initial decoder buffer fullness, a predetermined average channel bitrate, and a predetermined frame rate.
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Abstract
The present invention is method and apparatus for preventing overflow and underflow of an encoder buffer in a video compression system. A virtual buffer is created in a rate controller to model the decoder buffer fullness (102). A sequence of bits is generated by an encoder (104). The encoder is controlled by the rate controller to prevent a decoder buffer underflow and overflow. Then, the sequence of bits is received by the encoder buffer to produce a bitstream (106). The bitstream corresponds to an instantaneous channel bitrate. The bitstream is transmitted from the encoder buffer to a decoder buffer following a delay (108). The delay is controlled by a rate controller to synchronize an encoder buffer fullness with a virtual buffer fullness (110). The synchronization prevents overflow and underflow of the encoder buffer.
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Citations
7 Claims
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1. A method for preventing overflow and underflow of an encoder buffer in a video compression system, the method comprising the steps of:
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a) using a virtual buffer, in a rate controller, to model a decoder buffer fullness; b) generating a sequence of bits by an encoder, wherein the encoder is controlled by the rate controller to prevent a decoder buffer underflow and overflow; c) receiving the sequence of bits by the encoder buffer to produce a bitstream; d) transmitting the bitstream from the encoder buffer to a decoder buffer following a delay to produce a delayed bitstream, wherein the delayed bitstream corresponds to an instantaneous channel bitrate; and e) controlling the delay by the rate controller to synchronize an encoder buffer fullness with a virtual buffer fullness, wherein the synchronization prevents overflow and underflow of the encoder buffer, wherein a predetermined encoder buffer size is larger than a predetermined decoder buffer size, wherein the delay is based on the predetermined decoder buffer size, an initial decoder buffer fullness, a predetermined average channel bitrate, and a predetermined frame rate. - View Dependent Claims (2, 3)
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4. A apparatus for preventing overflow and underflow of an encoder buffer in a video compression system, the apparatus comprising:
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an encoder, operably coupled to a rate controller, for generating a sequence of bits based on an input video frame; the encoder buffer, operably coupled to the encoder, for receiving the sequence of bits to produce a bitstream; a switch, operably coupled to the encoder buffer and to the rate controller, for providing a delay and preventing the transmission of the bitstream from the encoder buffer to a decoder buffer to produce a delayed bitstream, wherein the delayed bitstream corresponds to an instantaneous channel bitrate; the decoder buffer, operably coupled to the switch, for receiving the bitstream; and the rate controller, operably coupled to the switch, for controlling the encoder to prevent a decoder buffer underflow and overflow and for controlling the delay of the switch to prevent overflow and underflow of the encoder buffer, wherein a predetermined encoder buffer size is larger than a predetermined decoder buffer size, wherein the delay is based on the predetermined decoder buffer size, an initial decoder buffer fullness, a predetermined average channel bitrate, and a predetermined frame rate. - View Dependent Claims (5, 6, 7)
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Specification