Transcoding of video data streams
First Claim
1. A method for minimising loss in picture quality when transcoding a video bitstream, the method comprising the steps of:
- (a) receiving a first bitstream present in a first format which comprises a sequence of encoded pictures;
(b) transcoding said first bitstream to create a second bitstream;
(c) inserting additional information derived from said first bitstream into said second bitstream;
(d) transmitting said second bitstream together with said additional information in a second format;
(e) receiving the second bitstream; and
(f) transcoding the second bitstream into a third bitstream in a third format, using said additional information to define picture structure for said second bitstream.
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Accused Products
Abstract
MPEG video bitstreams comprising a mixture of I-, P- and B-pictures are transcoded for transfer between apparatuses (110 and 112), using an intermediate bitstream format which comprise essentially I-pictures. Additional information (122) is inserted into the intermediate bitstream in user data fields, to identify which pictures were I-pictures in the original bitstream, and which were not. When transcoding again to IPB format (126), loss of picture quality can be minimised using this knowledge of the original video bitstream structure, in particular by encoding as I-pictures those pictures which were encoded as I-pictures in the original bitstream.
40 Citations
36 Claims
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1. A method for minimising loss in picture quality when transcoding a video bitstream, the method comprising the steps of:
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(a) receiving a first bitstream present in a first format which comprises a sequence of encoded pictures;
(b) transcoding said first bitstream to create a second bitstream;
(c) inserting additional information derived from said first bitstream into said second bitstream;
(d) transmitting said second bitstream together with said additional information in a second format;
(e) receiving the second bitstream; and
(f) transcoding the second bitstream into a third bitstream in a third format, using said additional information to define picture structure for said second bitstream. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 17, 20, 30, 31, 32, 33, 36)
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- 11. A method of transcoding a first bitstream in a first format to a second bitstream in a second format for transmission over a digital interface, the transcoding method including the step of embedding in said second bitstream additional information regarding the structure of said first bitstream in said first format.
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14. A method of transcoding a second bitstream in a second format to a third bitstream in a third format wherein said second bitstream in a second format is received over a digital interface and transcoded into said third bitstream in said third format using information embedded in said second bitstream, said information defining the structure of a first bitstream in a first format from which the second bitstream was previously derived.
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18. An electronic signal representing a video stream encoded in an intermediate format as a series of intra-coded pictures, the signal further comprising encoded additional historical functional information indicating the picture type and picture sequence from which said intra-coded pictures were derived.
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21. An apparatus for minimising loss in picture quality when transcoding a video bitstream, the apparatus comprising:
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(a) means for receiving a first bitstream present in a first format which comprises a sequence of encoded pictures;
(b) means for first transcoding said first bitstream to create a second bitstream;
(c) means for inserting additional information derived from said first bitstream into said second bitstream;
(d) means for transmitting said second bitstream together with said additional information in a second format;
(e) means for receiving the second bitstream; and
(f) means for transcoding the second bitstream into a third bitstream in a third format, using said additional information to define picture structure for said second bitstream. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 34)
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35. An apparatus for generating an electronic signal representing a video stream encoded in an intermediate format as a series of intra-coded pictures, the signal further comprising encoded additional historical functional information indicating the picture type and picture sequence from which said intra-coded pictures were derived.
Specification