Method and system for transcoding video data

• US 7,606,305 B1
• Filed: 02/24/2003
• Issued: 10/20/2009
• Est. Priority Date: 02/24/2003
• Status: Active Grant

• Current Assignee: VIXS Systems Incorporated (Pixelworks Incorporated)
• Original Assignee: VIXS Systems Incorporated (Pixelworks Incorporated)
• Inventors: Rault, Patrick
• Primary Examiner(s): WONG, ALLEN C
• Application Number:
  US10/375,166
• Time in Patent Office: 2,430 Days
• Field of Search: 375/240.2, 375/240, 375/240.01, 375/240.03, 375/240.13, 375/240.23, 375/240.12
• US Class Current: 375/240.12
• CPC Class Codes: H04N 19/103 Selection of coding mode or of prediction mode
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/40 using video transcoding, i.e. partial or full decoding of a coded input stream followed by re-encoding of the decoded output stream
• CPC Class Codes: H04N 19/577 Motion compensation with bidirectional frame interpolation, i.e. using B-pictures
• CPC Class Codes: H04N 19/61 in combination with predictive coding

Abstract

A first method of transcoding video data is disclosed that generates a motion vector for a macroblock encoded as a dual prime macro block that has a direct motion vector, and differential motion vector for its two fields respectively. Another method of transcoding includes replacing a skipped P-macroblock that has been used to backward predict a B-Frame with a P-macroblock having a motion vector of zero. Another method of transcoding includes replacing a skipped B-Macroblock with a macroblock having a motion vector from a macroblock of the same frame of the skipped B-Macroblock that is not co-located.

Claims

1. A video processing device comprising:

an open loop transcoder having an input to receive an input video data and an output to provide a first transcoded representation of the input video data;

a closed loop transcoder having an input coupled to the input of the open loop transcoder, and an output coupled to the output of the open loop transcoder to provide a second transcoded representation of the input video data; and

a select module to select the first transcoded representation for output as an output video data in response to determining the input video data is lossless encoded.

2. The video processing device of claim 1, wherein the closed loop transcoder further comprises:

a first decoder portion having an input to receive the input video data, and an output; and

an encoder portion having an input coupled to the output of the decoder portion output, and an output to provide the second transcoded representation.

3. The video processing device of claim 2, wherein the input of the encoder portion is coupled to the output of the first decoder portion through a frame buffer.

4. The video processing device of claim 2, wherein the closed loop transcoder further comprises:

a second decoder portion having an input coupled to the output of the encoder portion, and an output coupled to the input of the encoder portion.

5. The video processing device of claim 4, wherein the input of the encoder portion is coupled to the output of the second decoder portion through a frame buffer.

6. The video processing device of claim 4, wherein the input of the encoder portion is coupled to the output of the first decoder portion through a first frame buffer.

7. The video processing device of claim 6, wherein the input of the encoder portion is coupled to the output of the second decoder portion through a second frame buffer.

8. The video processing device of claim 7, wherein the first and second frame buffers are a common frame buffer.

9. The video processing device of claim 2 further comprising an control module coupled to the first encoder to enable the first decoder in response to video data of a first type being received at the input of the first decoder and to disable the first decoder in response to video data of a second type being received at the input of the first decoder.

10. The video processing device of claim 9, wherein the video data of the first type is frame data of a B-type.

11. The video processing device of claim 10, wherein the video data of the second type is frame data of a P-type.

12. The video processing device of claim 10, wherein the video data of the second type is frame data of an I-type.

13. The video processing device of claim 1, wherein the open loop transcoder is a lossless transcoder.

14. The video processing device of claim 1, wherein the closed loop transcoder is a lossy transcoder.

15. The video processing device of claim 1, wherein the open loop transcoder includes a scalar.

16. The video processing device of claim 1 wherein the select module further is to select the second transcoded representation for output as the output video data in response to determining the input video data is lossy encoded.

17. A method comprising:

determining, at a video processing device, whether a video input data is to be scaled with respect to a data rate of the video input data; and

transcoding the video input data using an open loop transcoder of the video processing device to generate a first decoded video data to generate a first decoded video data in response to determining the video input data is not to be scaled; and

transcoding the video input data using a closed loop transcoder of the video processing device in response to determining the video input data is to be scaled, wherein transcoding the video input data using the closed loop transcoder comprises;

using the first decoded video data and a second decoded video data to encode a first output video data; and

using the first output video data and a third decoded video data to encode a second output video data.

18. A method comprising:

receiving a first frame of video at an open loop transcoder of a video processing device;

decoding, at the video processing device, the first frame of video to generate a first decoded video data;

receiving a second frame of video at a closed loop transcoder of the video processing device;

using the first decoded video data at the video processing device to determine a second decoded video data in response to determining the second frame is lossless transcoded; and

disregarding the first decoded video data for use in determining the second decoded video data at the video processing device in response to determining the second frame of video is lossy transcoded.