Video coding with trade-off between frame rate and chroma fidelity

• US 10,547,860 B2
• Filed: 08/22/2016
• Issued: 01/28/2020
• Est. Priority Date: 09/09/2015
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Inventors: Zhou, Minhua
• Primary Examiner(s): Vazquez Colon, Maria E
• Application Number:
  US15/242,742
• Publication Number:
  US 20170070743A1
• Time in Patent Office: 1,254 Days
• CPC Class Codes: H04N 19/152 by measuring the fullness of the transmission buffer
• CPC Class Codes: H04N 19/154 Measured or subjectively estimated visual quality after decoding, e.g. measurement of distortion use of rate-distortion criteria H04N19/147
• CPC Class Codes: H04N 19/172 the region being a picture, frame or field
• CPC Class Codes: H04N 19/186 the unit being a colour or a chrominance component
• 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 19/55 Motion estimation with spatial constraints, e.g. at image or region borders
• CPC Class Codes: H04N 19/587 involving temporal sub-sampling or interpolation, e.g. decimation or subsequent interpolation of pictures in a video sequence

Abstract

A video decoder or encoder can be used to convert and process different video streams having different combinations of frame rate and Chroma fidelity. Rather than setting the maximum sample rate of the encoder based on a Luma sample rate, the encoder'"'"'s throughput is set based on a maximum color sample rate. Additionally, the picture buffer size can be set based on a maximum number of color pictures. An input of the video decoder receives an input video stream having a given display resolution and encoded in a first format employing a first combination of frame rate and Chroma fidelity. Processing circuitry in the decoder converts the input video stream from the first format to an output video stream having a second format, the second format having the given display resolution and employing a second combination of frame rate and Chroma fidelity different from the first combination.

Claims

1. A video decoder comprising:

an input configured to receive an input video stream encoded in any of a plurality of different formats, wherein the plurality of different formats includes;

a first format having a first combination of frame rate and Chroma fidelity;

a second format having a second combination of frame rate and Chroma fidelity;

a picture buffer configured to buffer reference pictures and currently reconstructed pictures during video decoding, wherein the picture buffer has a size selected to accommodate a maximum number of color pictures; and

a processor and associated memory configured to decode both a first input video stream encoded in the first format and a second input video stream encoded in the second format using the same picture buffer, a same amount of memory bandwidth, and a same pixel processing speed by exercising a trade-off between Chroma fidelity and frame rate.

2. The video decoder of claim 1, wherein:

the first format is encoded using a 4;

2;

0 Chroma fidelity;

the second format is encoded using 4;

4;

4 Chroma fidelity; and

the first format has a frame rate double the frame rate of the second format.

3. The video decoder of claim 1, wherein the size of the picture buffer is selected to account for differences in video-bit depth.

4. The video decoder of claim 1, wherein the processor and associated memory are further configured to:

decode a mixed input video stream having a first portion encoded using the first format and a second portion encoded using the second format.

5. The video decoder of claim 4, wherein the processor and associated memory are further configured to:

perform inter-prediction processing on the mixed input video stream, where the inter-prediction processing crosses a transition boundary between the first portion encoded using the first format, and the second portion encoded using the second format.

6. The video decoder of claim 4, wherein the processor and associated memory are further configured to:

perform inter-prediction processing on the mixed input video stream, where the inter-prediction processing is restricted from crossing a transition boundary between the first portion encoded using first format, and the second portion encoded using the second format.

7. A video decoder comprising:

an input configured to receive input video bitstreams encoded in a plurality of different formats, the plurality of different formats including a first and second format, the first format having a decreased Chroma fidelity, a doubled maximum frame-rate and requiring a greater number of reference pictures relative to the second format;

processing circuitry configured to decode a particular input video bitstream, regardless of whether the particular input video bitstream is encoded the first format or the second format, wherein decoding is performed using a constant amount of memory bandwidth and pixel processing speed for both the first and second formats by exercising a trade-off between Chroma fidelity and frame rate, the processing circuitry including;

an entropy decoder coupled to the input and configured to generate quantized transform coefficients, intra prediction modes, motion data, and filter parameters;

an inverse quantization module coupled to the entropy decoder and configured to generate residual blocks based on the quantized transform coefficients;

a prediction feedback loop coupled to the entropy decoder and configured to generate residuals based, at least in part, on the intra prediction modes and the motion data; and

a picture buffer configured to store reference pictures and currently reconstructed pictures during video decoding, and having a maximum capacity determined by a maximum number of color pictures, wherein the same picture buffer is used to decode input video bitstreams encoded in the plurality of different formats.

8. The video decoder of claim 7, wherein:

the first format has an increased frame rate and a decreased Chroma fidelity compared to the second format.

9. The video decoder of claim 7, wherein:

the maximum capacity of the picture buffer takes into account differences in video-bit depth between the first format and the second format.

10. The video decoder of claim 7, wherein the processing circuitry is further configured to:

decode a mixed input video stream having a first portion encoded using the first format and a second portion encoded using the second format.

11. The video decoder of claim 10, wherein the processing circuitry is further configured to:

perform inter-prediction processing on the mixed input video stream, where the inter-prediction processing is restricted from crossing a transition boundary between the first portion encoded using first format, and the second portion encoded using the second format.

12. The video decoder of claim 10, wherein the processing circuitry is further configured to:

perform inter-prediction processing on the mixed input video stream, where the inter-prediction processing crosses a transition boundary between the first portion encoded using the first format, and the second portion encoded using the second format.