Signaling valid entry points in a video stream
First Claim
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1. In a computing device that implements a video encoder, a method comprising:
- with the computing device that implements the video encoder, determining one or more entry points for a sequence comprising plural video frames based at least in part on an entry point policy; and
with the computing device that implements the video encoder, inserting in a bitstream an entry point indicator that indicates a first frame of the plural frames is one of the one or more entry points, wherein the first frame is a field interlaced P/I-frame comprising a P-field followed by an I-field, the P-field and the I-field being arranged in the bitstream for decoding as individual fields, wherein a second frame immediately follows the field interlaced P/I-frame in presentation time, wherein the second frame is a predicted frame, wherein according to the entry point policy the video encoder makes coding decisions for the second frame to remove any motion compensation dependencies prior to the I-field of the field interlaced P/I-frame, and wherein the entry point policy comprises conditions that include;
after the field interlaced P/I-frame, at least one field interlaced P/P-frame is present in the bitstream before a progressive P-frame or frame interlaced P-frame;
after the field interlaced P/I-frame, a next P-field in the bit stream references the I-field of the field interlaced P/I-frame but not the P-field of the field interlaced P/I-frame;
after the field interlaced P/I-frame, a progressive B-frame or frame interlaced B-frame in the bitstream that has a later presentation time than the field interlaced P/I-frame is not encoded depending on the field interlaced P/I-frame; and
after the field interlaced P/I-frame, a next B-field in the bitstream that has a later presentation time than the field interlaced P/I-frame is not encoded depending on the P-field of the field interlaced P/I-frame.
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Abstract
Techniques and tools for coding/decoding of digital video, and in particular, for determining, signaling and detecting entry points in video streams are described. Techniques and tools described herein are used to embed entry point indicator information in the bitstream that receivers, editing systems, insertion systems, and other systems can use to detect valid entry points in compressed video.
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Citations
38 Claims
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1. In a computing device that implements a video encoder, a method comprising:
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with the computing device that implements the video encoder, determining one or more entry points for a sequence comprising plural video frames based at least in part on an entry point policy; and with the computing device that implements the video encoder, inserting in a bitstream an entry point indicator that indicates a first frame of the plural frames is one of the one or more entry points, wherein the first frame is a field interlaced P/I-frame comprising a P-field followed by an I-field, the P-field and the I-field being arranged in the bitstream for decoding as individual fields, wherein a second frame immediately follows the field interlaced P/I-frame in presentation time, wherein the second frame is a predicted frame, wherein according to the entry point policy the video encoder makes coding decisions for the second frame to remove any motion compensation dependencies prior to the I-field of the field interlaced P/I-frame, and wherein the entry point policy comprises conditions that include; after the field interlaced P/I-frame, at least one field interlaced P/P-frame is present in the bitstream before a progressive P-frame or frame interlaced P-frame; after the field interlaced P/I-frame, a next P-field in the bit stream references the I-field of the field interlaced P/I-frame but not the P-field of the field interlaced P/I-frame; after the field interlaced P/I-frame, a progressive B-frame or frame interlaced B-frame in the bitstream that has a later presentation time than the field interlaced P/I-frame is not encoded depending on the field interlaced P/I-frame; and after the field interlaced P/I-frame, a next B-field in the bitstream that has a later presentation time than the field interlaced P/I-frame is not encoded depending on the P-field of the field interlaced P/I-frame. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. In a computing device that implements a video decoder, a method comprising:
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receiving, at the computing device that implements the video decoder, a bitstream for a sequence comprising plural video frames, each of the plural video frames having a frame coding type, wherein the frame coding type for each of the plural video frames is one of progressive, field interlaced, and frame interlaced; with the computing device that implements the video decoder, detecting an entry point indicator in the bitstream, wherein the entry point indicator marks a first frame of the plural frames as an entry point for decoding and is positioned in the bitstream according to an entry point policy; and with the computing device that implements the video decoder, decoding at least a portion of the bitstream based at least in part on the entry point indicator; wherein the entry point policy comprises one or more conditions for entry point indicator positioning, wherein the first frame is a field interlaced P/I-frame comprising a P-field followed by an I-field, the P-field and the I-field being arranged in the bitstream for decoding as individual fields, wherein a second frame immediately follows the field interlaced P/I-frame in presentation time, and wherein the frame coding type of the second frame depends in part on the field interlaced P/I frame being an entry point; and wherein the one or more conditions of the entry point policy comprise; after the field interlaced P/I-frame, at least one field interlaced P/P-frame is present in the bitstream before a progressive P-frame or frame interlaced P-frame; after the field interlaced P/I-frame, a next P-field in the bit stream references the I-field of the field interlaced P/I-frame but not the P-field of the field interlaced P/I-frame; after the field interlaced P/I-frame a progressive B-frame or, frame interlaced B-frame in the bitstream that has a later presentation time than the field interlaced P/I-frame is not encoded depending on the field interlaced P/I-frame; and after the field interlaced P/I-frame, a next B-field in the bitstream that has a later presentation time than the field interlaced P/I-frame is not encoded depending on the P-field of the field interlaced P/I-frame. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31)
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32. In a computing device that implements a video decoder, a method comprising:
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receiving, at the computing device that implements the video decoder, a bitstream for a sequence comprising plural video frames; with the computing device that implements the video decoder, detecting an entry point indicator in the bitstream, wherein a first frame immediately following the entry point indicator is decodable without reference to any frames preceding the entry point indicator in the bitstream, wherein the first frame is a field interlaced P/I-frame comprising a P-field followed by an I-field, the P-field and the I-field being arranged in the bitstream for decoding as individual fields; and with the computing device that implements the video decoder, decoding at least a portion of the bitstream based at least in part on the entry point indicator, wherein, due to designation of the field interlaced P/I-frame as an entry point, a field following the field interlaced P/I-frame that might otherwise use the P-field of the field interlaced P/I-frame as a reference field in motion compensation is constrained to not use the P-field of the field interlaced P/I-frame as a reference field in motion compensation, and wherein the bitstream complies with the following conditions; after the field interlaced P/I-frame. at least one field interlaced P/P-frame is present in the bitstream before a progressive P-frame or frame interlaced P-frame; after the field interlaced P/I-frame, a next P-field in the bit stream references the I-field of the field interlaced P/I-frame but not the P-field of the field interlaced P/I-frame; after the field interlaced P/I-frame, a progressive B-frame or frame interlaced B-frame in the bitstream that has a later presentation time than the field interlaced P/I-frame is not encoded depending on the field interlaced P/I-frame; and after the field interlaced P/I-frame, a next B-field in the bitstream that has a later presentation time than the field interlaced P/I-frame is not encoded depending on the P-field of the field interlaced P/I-frame. - View Dependent Claims (33, 34, 35)
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36. In a computing device that implements a video decoder, a method comprising:
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receiving, at the computing device that implements the video decoder, a bitstream for a sequence comprising plural video frames; and with the computing device that implements the video decoder, decoding starting from an entry point signaled by an entry point indicator in the bitstream, wherein the entry point is a field interlaced P/I-frame comprising a P-field followed by an I-field within the plural video frames, wherein after he entry point indicator the bitstream includes the following elements for the entry point;
frame header, first field header, first field data, second field header, and second field data, and wherein the first field header and the first field data are for the P-field and the second field header and the second field data are for the I-field, the frame header being organized according to a different bitstream syntax than the first and second field headers. - View Dependent Claims (37, 38)
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Specification