Scalable video coding method and apparatus using pre-decoder

• US 20050047503A1
• Filed: 08/25/2004
• Published: 03/03/2005
• Est. Priority Date: 08/26/2003
• Status: Abandoned Application

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Ha, Ho-jin, Han, Woo-jin, Lee, Bae-keun, Yim, Chang-hoon
• Application Number:
  US10/925,030
• Publication Number:
  US 20050047503A1
• Time in Patent Office: Days
• US Class Current: 375/240.10
• CPC Class Codes: H04N 19/10 using adaptive coding
• CPC Class Codes: H04N 19/115 Selection of the code volume for a coding unit prior to coding
• CPC Class Codes: H04N 19/132 Sampling, masking or truncation of coding units, e.g. adaptive resampling, frame skipping, frame interpolation or high-frequency transform coefficient masking
• CPC Class Codes: H04N 19/14 Coding unit complexity, e.g. amount of activity or edge presence estimation H04N19/146 takes precedence
• CPC Class Codes: H04N 19/147 according to rate distortion criteria rate-distortion as a criterion for motion estimation H04N19/567
• CPC Class Codes: H04N 19/15 by monitoring actual compressed data size at the memory before deciding storage at the transmission buffer
• CPC Class Codes: H04N 19/152 by measuring the fullness of the transmission buffer
• CPC Class Codes: H04N 19/177 the unit being a group of pictures [GOP]
• CPC Class Codes: H04N 19/19 using optimisation based on Lagrange multipliers
• CPC Class Codes: H04N 19/44 Decoders specially adapted therefor, e.g. video decoders which are asymmetric with respect to the encoder
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 19/619 the transform being operated outside the prediction loop
• CPC Class Codes: H04N 19/63 using sub-band based transform, e.g. wavelets
• CPC Class Codes: H04N 19/86 involving reduction of coding artifacts, e.g. of blockiness

Abstract

A method and an apparatus for controlling bitrates in an optimal manner by use of information available for use by the pre-decoder, in wavelet-based scalable video coding art using the pre-decoder. A method for controlling bitrates includes the steps of determining the amount of bits for each coding unit relative to a bitstream generated by encoding an original image so as to minimize distortion of the final image from the original image, and extracting a bitstream having the target amount of bits by truncating a part of the generated bitstream based on the determined amount of bits.

Claims

1. A method for controlling bitrates, comprising the steps of:

determining an amount of bits for each coding unit relative to a bitstream generated by encoding an original image so as to minimize distortion of a final image from the original image; and

extracting a bitstream having a target amount of bits by truncating a part of the generated bitstream based on the determined amount of bits.

2. The method as claimed in claim 1, wherein, to obtain the bit amount for the coding unit defined by use of a scene complexity function and the distortion of the final frame from the original frame, the determining step comprises the steps of:

determining the scene complexity function by use of bit distribution according to a number of bit planes per coding unit; and

determining the amount of the bits per coding unit using a method to minimize the distortion of the final frame from the original frame.

3. The method as claimed in claim 2, wherein the bit amount R(i) relative to the coding unit is defined as

15. A storage medium storing thereon a method according to claim 1, which is readable by a computer.

4. A method for scalable video coding, comprising the steps of:

generating a bitstream by encoding an original moving picture;

determining a scene complexity function by using bit distribution according to a number of bit planes of the generated bitstream, the determination being made by representing the generated bitstream by encoding the original moving picture as the scene complexity function relative to the bit amount per coding unit so that the distortion of the final frame from the original moving picture is minimized; and

extracting the bitstream having a target amount of bits by truncating a part of the generated bitstream based on the determined bit amount.

5. The method as claimed in claim 4, further comprising the step of recovering and decompressing image sequences of the original moving picture from the extracted bitstream.

6. The method as claimed in claim 4, wherein the bit amount R(i) relative to the coding unit is defined as

7. The method as claimed in claim 6, wherein the expression R(i) having the minimum value of D(i)² is obtained by use of Lagrangian method.

8. An apparatus for controlling bitrates, comprising:

an encoder for determining an amount of bits per coding unit by encoding an original image so that a distortion of a final frame from the original image is minimum; and

an extractor for extracting a bitstream having a target amount of bits by truncating a part of a generated bitstream based on the determined bit amount.

9. The apparatus as claimed in claim 8, wherein, to obtain the bit amount for the coding unit defined by use of a scene complexity function and the distortion of the final frame from the original frame, the encoder comprises:

a scene complexity determiner for determining the scene complexity function by use of bit distribution according to a number of bit planes per coding unit; and

a coding unit determiner for determining the amount of the bits per coding unit with the use of a method to minimize the distortion of the final frame from the original frame.

10. The apparatus as claimed in claim 9, wherein the bit amount R(i) relative to the coding unit is defined as

11. An apparatus for scalable video coding, comprising:

an encoder generating a bitstream by encoding an original moving picture;

a rate control module determining a scene complexity function by using bit distribution according to a number of bit planes of the generated bitstream, the determination being made by representing the generated bitstream by encoding the original moving picture as the scene complexity function relative to the bit amount per coding unit so that a distortion of a final frame from the original moving picture is minimized; and

a pre-decoder extracting the bitstream having the target amount of bits by truncating a part of the generated bitstream based on the determined bit amount.

12. The apparatus as claimed in claim 11, further comprising a decoder recovering and decompressing image sequences of the original moving picture from the extracted bitstream.

13. The apparatus as claimed in claim 11, wherein the bit amount R(i) relative to the coding unit is defined as

14. The apparatus as claimed in claim 13, wherein the expression R(i) of having the minimum value of D(i)² is obtained by use of Lagrangian method.