摘要:
In one aspect, for a first interlaced video frame in a video sequence, a decoder decodes a bitplane signaled at frame layer for the first interlaced video frame. The bitplane represents field/frame transform types for plural macroblocks of the first interlaced video frame. For a second interlaced video frame in the video sequence, for each of at least one but not all of plural macroblocks of the second interlaced video frame, the decoder processes a per macroblock field/frame transform type bit signaled at macroblock layer. An encoder performs corresponding encoding.
摘要:
Techniques and tools for bitstream-controlled filtering are described. For example, a video encoder puts control information into a bitstream for encoded video. A video decoder decodes the encoded video and, according to the control information, performs post-processing filtering on the decoded video with a de-ringing and/or de-blocking filter. Typically, a content author specifies the control information to the encoder. The control information itself is post-processing filter levels, filter selections, and/or some other type of information. In the bitstream, the control information is specified for a sequence, scene, frame, region within a frame, or at some other syntax level.
摘要:
With adaptive multiple quantization, a video or other digital media codec can adaptively select among multiple quantizers to apply to transform coefficients based on content or bit rate constraints, so as to improve quality through rate-distortion optimization. The switch in quantizers can be signaled at the sequence level or frame level of the bitstream syntax, or can be implicitly specified in the syntax.
摘要:
A video encoder/decoder utilizes a bistream syntax that provides an independently decodable, partial picture unit, which may be in the form of a unit containing one or more contiguous rows of macroblocks (called a slice). This slice layer provides a flexible combination of error-resilience and compression efficiency. The slice layer encodes an efficient addressing mechanism (e.g., a syntax element specifying a beginning macroblock row of the slice layer), as well as an efficient mechanism to optionally retransmit picture header information. The slice layer provides decoding and reconstruction independence by disabling all forms of prediction, overlap and loop-filtering across slice-boundaries. This permits a slice coded in intra-mode to be reconstructed error-free, irrespective of errors in other regions of the picture.
摘要:
Techniques and tools for code table selection and joint coding/decoding of macroblock mode information for macroblocks of interlaced forward-predicted frames are described. For example, a video decoder decodes a variable length code that jointly signals macroblock mode information for a motion-compensated macroblock. The jointly signaled information includes a macroblock type, whether a coded block pattern is present or absent, and whether motion vector data is present or absent for the motion-compensated macroblock. A video encoder performs corresponding encoding.
摘要:
A video encoder/decoder utilizes a bistream syntax that provides an independently decodable, partial picture unit, which may be in the form of a unit containing one or more contiguous rows of macroblocks (called a slice). This slice layer provides a flexible combination of error-resilience and compression efficiency. The slice layer encodes an efficient addressing mechanism (e.g., a syntax element specifying a beginning macroblock row of the slice layer), as well as an efficient mechanism to optionally retransmit picture header information. The slice layer provides decoding and reconstruction independence by disabling all forms of prediction, overlap and loop-filtering across slice-boundaries. This permits a slice coded in intra-mode to be reconstructed error-free, irrespective of errors in other regions of the picture.
摘要:
A video codec provides efficient repeat padding of hybrid video sequences having arbitrary video resolution. The video codec repeat pads to expand the active content of pictures in the video sequence out to meet an adaptive vertical macroblock alignment restriction that varies by picture type. For progressive type pictures, the video codec repeats the last row or horizontal boundary edge of the active content. For interlaced type pictures, the video coded repeats the last two rows (last row of each interlaced field) of the active content. This repeat padding differing by picture type provides a better prediction (lower prediction error residual) for macroblocks in following predicted frames whose motion vector points into the padded region.
摘要:
A decoder decodes skipped macroblocks of an interlaced frame. Skipped macroblocks use exactly one motion vector and have no motion vector differential information, and lack residual information. The skipped macroblock signal indicates one-motion-vector coding. The skipped macroblock signal can be a compressed bitplane (in a selected bitplane coding mode) sent at frame layer in a bitstream, or an individual bit sent at macroblock layer. In another aspect, an encoder jointly encodes motion compensation type and field/frame coding type for a macroblock in an interlaced P-frame. The encoder also can jointly encode other information for the macroblock (e.g., the presence of a differential motion vector). A decoder decodes a joint code (e.g., a variable length code in a variable length code table) to obtain both motion compensation type and field/frame coding type (and potentially other information) for the macroblock.
摘要:
Techniques and tools for using motion vector block patterns in video encoding and decoding are described. In general, a motion vector block pattern signals the presence or absence of motion vector data for a macroblock with multiple motion vectors. For example, a video decoder decodes variable length codes that represent motion vector block patterns. Each motion vector block pattern has one bit per corresponding luminance motion vector of a macroblock with multiple luminance motion vectors, where the one bit indicates whether or not motion vector data for the corresponding luminance motion vector is signaled. A video encoder performs corresponding encoding.
摘要:
A video codec provides for encoding and decoding pictures of a video sequence at various coded resolutions, such that pictures can be encoded at lower coded resolutions based on bit rate or other constraints while maintaining a consistent display resolution. The video codec further provide for encoding and decoding pictures of the video sequence at ranges lower than that used for display, and then expanding the range after decoding for display. The video codec applies post-processing operations, such as de-blocking, de-ringing, and color conversion, at the native resolution and range of the decoded video, prior to range expansion and upsampling for display.