Cisco Technology, Inc.

Broadcom Corporation

Avago Technologies General IP (singapore) Pte. Ltd.

Microsoft Technology Licensing, LLC

Georgia Tech Research Corporation

Junlin Li

Wen-hsiung Chen

Dihong Tian

Alexander Garland MacInnis

Pi Sheng Chang

Ghassan AlRegib

Brian Francis Schoner

Jason William Herrick

Hongtao Zhu

Jim Chen Chou

Dinei A Florencio

Li-wei He

Brad Albert Delanghe

Lei Zhang

Yian Xu

Various methods and systems are provided for reduction of I-pulsing artifacts. In one example, a portion of a picture is modified to be encoded as an I picture based in part upon a picture that precedes the picture. The modification can reduce an I-pulsing artifact associated with the I picture. The modified picture is intra-coded for inclusion in a series of encoded pictures, which may then be transmitted. In another example, an encoder includes adaptive pre-processing circuitry and intra-encoding processing circuitry. The pre-processing circuitry modifies a portion of a first picture based in part upon a second picture that precedes the first picture in a series of video pictures. For example, the modification may be based upon coding noise associated with the preceding picture. The intra-encoding processing circuitry encodes the modified picture as an I picture.

Reduction of I-pulsing artifacts

Disclosed are various embodiments directed to transcoding a bit stream comprising audio and video frames that contains discontinuities. The video and/or audio portion of the bit stream may be divided into segments, where some of the segments are transcoded in parallel using a plurality of transcoder devices. In some embodiments, a discontinuity is detected in the bit stream before encoding, where the discontinuity is associated with a shift in a set of time stamps associated with the bit stream. A magnitude of the discontinuity is determined. The transcoding system aligns at least a portion of the audio frames to the series of video frames according to at least the discontinuity and the magnitude of the discontinuity. In other embodiments, the discontinuity is detected after encoding by analyzing time stamps that have been established during the transcoding process.

Audio and video management for parallel transcoding

Disclosed are various embodiments directed to transcoding a media file in parallel. A media file may be accessed, the media file comprising a bit stream expressing a series of pictures. A first random access point in the bit stream and a second random access point in the bit stream are identified. An input segment of the bit stream is generated, the input segment comprising a starting point, the starting point being the first random access point. One of a plurality of transcoders is selected to transcode the input segment for generating a corresponding output segment, each transcoder being configured to operate concurrently in parallel. The output segment is stored in a memory.

Parallel transcoding

Disclosed are various embodiments directed to transcoding a bit stream in parallel. A bit stream may be divided into a plurality of segments, where a plurality of transcoders encode at least a portion of the segments in parallel. If encoding is performed using variable bit rate (BR) encoding, each encoder may encode a segment and vary a BR for the segment. A measured average BR is compared with a target average BR to determine whether to adjust a video quality level (VQL) or any other encoder parameter. A relatively constant subjective quality may be maintained using variable BR encoding while achieving a target average BR. When using constant BR encoding, a VQL or other encoder parameter is used by encoders to achieve relatively constant subjective quality. For example, a relatively continuous quantization parameter between adjacent encoded segments may be achieved.

Managing encoder parameters for parallel transcoding

Techniques are provided herein to shift at an encoding device a portion of a video sequence by a first predetermined number of pixels horizontally and by a first predetermined number of pixels vertically to produce a shifted first portion of the video sequence. The shifted first portion of the video sequence is encoded to produce a first video description. The portion of the video sequence is shifted by a second predetermined number of pixels horizontally and by a second predetermined number of pixels vertically to produce a shifted second portion of the video sequence. The shifted second portion of the video sequence is encoded to produce a second video description, and the first video description and the second video description are transmitted. The techniques are scalable to shift and encode the portion of the video sequence a plurality of times to produce any number of video descriptions. Similarly, techniques are provided herein to perform such functions in reverse at a decoder.

Multiple description coding with spatial shifting

A coding method for an ordered series of quantized transform coefficients of a block of image data, including a context adaptive position coding process to encode the position of clusters of non-zero-valued coefficients, e.g., a multidimensional position coder that uses one of a plurality of code mappings selected according to at least one criterion including at least one context-based criterion, and an amplitude encoding process to encode any amplitudes remaining to be coded, the amplitude coding using one or a plurality of amplitude code mappings selected according to at least one criterion, including a context-based criterion. A context-based selection criterion means a criterion that during encoding is known or derivable from one or more previously encoded items of information. Also a coding apparatus, a decoding apparatus, a computer readable medium configured with instructions that when executed implement a coding method, and another medium for a decoding method.

Context adaptive hybrid variable length coding

A coding method, apparatus, and storage media with instructions to carry out a method. The method operates on an ordered series of transform coefficients of a block of image data, and for a fixed quantization method, and includes quantizing and encoding the ordered series to form a coded bitstream. The quantizing and encoding uses one or more variable length code (VLC) mappings. The quantizing includes quantizing to have amplitude-1 at least one coefficient that would be quantized by the fixed quantization method to have zero amplitude, quantizing to have zero amplitude at least one coefficient that would be quantized by the fixed quantization method to have amplitude-1, and using the fixed quantization method to quantize any coefficient that is quantized by the fixed quantization method not to have zero amplitude, amplitude-1, or amplitude-2.

Locally variable quantization and hybrid variable length coding for image and video compression

A coding method for an ordered series of quantized transform coefficients of a block of image data, including a context adaptive position coding process to encode the position of clusters of non-zero-valued coefficients, e.g., a multidimensional position coder that uses one of a plurality of code mappings selected according to at least one criterion including at least one context-based criterion, and an amplitude encoding process to encode any amplitudes remaining to be coded, the amplitude coding using one or a plurality of amplitude code mappings selected according to at least one criterion, including a context-based criterion. A context-based selection criterion is meant a criterion that during encoding is known or derivable from one or more previously encoded items of information. Also a coding apparatus, a decoding apparatus, a computer readable medium configured with instructions that when executed implement a coding method, and another medium for a decoding method.

A coding method, apparatus, and medium with software encoded thereon to implement a coding method. The coding method includes encoding cluster of consecutive non-zero-valued coefficients, the encoding of a cluster including jointly encoding joint events that each are defined by at least two parameters: the number of zero-valued coefficients preceding the cluster, and the number of non-zero-valued coefficients in the cluster. The encoding of the cluster also includes encoding a parameter indicative of the number of amplitude-1 trailing non-zero-valued coefficients in the cluster, in one version with the parameter indicative of the number of trailing amplitude-1 coefficients part of the joint events such that the coding is according to a 3-dimensional joint variable length coding table. The method further includes encoding the amplitudes of the non-zero-valued coefficients that are not encoded by the joint encoding, e.g., encoding the amplitudes of the other than the trailing amplitude-1 coefficients.

Variable length coding of coefficient clusters for image and video compression

A coding method, apparatus, and medium with software encoded thereon to implement a coding method. The coding method includes jointly encoding joint events that each are defined by a cluster of consecutive non-zero-valued coefficients, each joint event defined by three parameters: the number of zero-valued coefficients preceding the cluster, the number of non-zero-valued coefficients in the cluster, and an indication of which trailing coefficients up to a maximum number of M trailing coefficients have amplitude greater than 1, with the coding using a 3-dimensional joint VLC table. The method further includes encoding the amplitude of the non-zero-valued trailing coefficients that have amplitude greater than 1 encoding the amplitude of any remaining non-zero-valued coefficients in the clusters that have more than M non-zero-valued coefficients.

Joint amplitude and position coding of coefficients for video compression

A 'Client-Side Echo Canceller' provides a unique system and method for reducing Multipoint Control Unit (MCU) computational overhead in a multi-point audio conference. In general, the local audio input signal of each client is transmitted in real-time to the MCU. The MCU then combines the audio input signals of all clients to create a single composite signal that is transmitted back to all clients in real-time. Each client then locally processes the composite signal to remove each client's local contribution to the composite signal prior to local playback in order to eliminate a local echo of each client's local audio input. In various embodiments, local cancellation of the local audio input from the composite signal is performed on either a time domain or a transform domain representation of the composite signal. Further, since each client receives the same signal, MCU transmission bandwidth can be reduced via multicast transmissions.

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Junlin Li