US 6,147,627 A · Coder for segmented coding of an input signal using controllable quantization based on quantization step size and buffer fullness

Abstract

A coder for segmented coding of an input signal (b) by using of a controllable quantizer (1C) and a buffer memory (6) is described. Data of the input signing (b), which are quantized and VLC-coded in operation, are buffered in the buffered memory (6). To avoid the conventional control, beset with drawbacks, of the quantizer (1C) by using of the filling state of the buffer memory (6), a controller (3, 4, 7, S1, S2, S3) provided with which a single adjustment of the quantizer (1C) for a signal segment to be coded is determined in that the signal segment is trial-coded at different adjustments of the quantizer (1C), the bit volume (the number of bits) is determined at each trial run, resulting in a VLC coding of the signal segment at the actually selected adjustment of the quantizer (1C), and that adjustment of the quantizer (1C) is used for the final coding and transmission of the signal segment which, during the trial runs, has yielded a bit volume which substantially corresponds to a nominal bit volume.

Claims22

Dependent claims

A coder for performing segmented coding on an input signal, comprising:

a controllable quantizer for quantizing the input signal;
a buffer for buffering the quantized input signal the buffer having at least a nominal bit volume;
a controller for controlling the quantizer and for providing a first quantization step size to the quantizer for use in quantizing a segment of the input signal;
and
a bit volume measurer for measuring a bit volume of the segment after the segment has been quantized at the first quantization step size;
wherein the controller compares the bit volume of the quantized segment at the first quantization step size to the nominal bit volume and, if the bit volume is less than or equal to the nominal bit volume, causes the quantized segment to pass to the buffer, otherwise the controller provides one or more subsequent quantization step sizes to the quantizer until a bit volume of a resulting quantized segment is less than or equal to the nominal bit volume, whereafter the controller causes the resulting quantized segment to pass to the buffer.

3 more elements

A method of coding an input video signal in accordance with a predetermined bit volume, where the predetermined bit volume corresponds to an output buffer threshold, the method comprising the steps of:

coding the input video signal at a first quantization step size to produce a first bitstream having a first bit volume and, if the first bit volume is less than the predetermined bit volume, outputting the first bitstream to the output buffer;
if the first bit volume is greater than the predetermined bit volume, coding the input video signal at a second quantization step size to produce a second bitstream having a second bit volume and, if the second bit volume is greater than the predetermined bit volume, outputting the second bitstream to the output buffer;
and
if the predetermined bit volume falls between the first bit volume and the second bit volume, determining a third quantization step size which is between the first and second quantization step sizes, coding the input video signal at the third quantization step size to produce a third bitstream, and outputting the third bitstream to the output buffer.

1 more element

An apparatus for coding an input video signal in accordance with a predetermined bit volume, where the predetermined bit volume corresponds to an output buffer threshold, the apparatus comprising:

a coder that is able to code the input video signal using at least first, second and third quantization step sizes so as to produce, respectively, first, second and third bitstreams having first, second and third bit volumes;
and
a controller which controls both the quantization step size of the coder and output of the bitstreams from the coder to the output buffer;
wherein the controller:
(i) determines if the first bit volume is less than the predetermined bit volume and, in that case, causes the coder to code the input video signal at the first quantization step size and to output the first bitstream to the output buffer;
(ii) determines if the second bit volume is greater than the predetermined bit volume and, in that case, causes the coder to code the input video signal at the second quantization step size and to output the second bitstream to the output buffer;
and
(iii) determines if the predetermined bit volume falls between the first bit volume and the second bit volume and, in that case, determines a third quantization step size which is between the first and second quantization step sizes, and causes the coder to code the input video signal at the third quantization step size to produce a third bitstream and to output the third bitstream to the output buffer.

5 more elements

Dependencies are inferred from the claim text.

Coder for segmented coding of an input signal using controllable quantization based on quantization step size and buffer fullness

Life of this patent

Coder for segmented coding of an input signal using controllable quantization based on quantization step size and buffer fullness

Life of this patent

Abstract

Claims22