Ittiam Systems (P) Ltd.

Sarat Chandra Vadapalli

Sriram Sethuraman

Anil Kv Kumar

Preethi Konda

Vinod Prakash

Biswadeep Sengupta

A method and device for tracking error propagation and refreshing a video stream is provided. The proposed subject matter comprises of an error propagation tracking method that works in the sub-sampled domain to reduce computational cycles and memory bandwidth. Further, the tracking based update of the error propagation metric is done differently for static and non-static regions to avoid unnecessary refresh of static areas. Through suitable thresholding of the metric at a macroblock (MB) level, a set of refresh MBs are selected for each frame. These refresh MBs are coded either as an intra MB or as an inter MB that is predicted from one or more reliable reference frames (&#x2014;frames that are known to be available at the decoder with negligible errors&#x2014;). Such inter coding of refresh MBs improves the compression efficiency when compared to pure intra coding of refresh MBs. Further, variants to the threshold selection are presented that result in temporally uniform distribution of the number of refresh MBs and a strict refresh scheme wherein all MBs are guaranteed to be with negligible errors following a packet loss within a committed refresh period. In addition, to using the error propagation metric, spatial connectivity to already chosen refresh MBs is used in the selection of additional refresh MBs within a frame and across frames; this reduces the rate of error propagation due to part of a macroblock predicting from older, erroneous neighboring MBs and in turn requiring more refresh MBs on the average per frame.

Method and device for tracking error propagation and refreshing a video stream

A system and method for adaptive intra refresh rate setting for each video frame in a video encoder is disclosed. In one embodiment, a video encoding method includes computing channel induced distortion values at multiple intra refresh rates for a coded video frame as a function of channel loss and spatiotemporal content, computing source coding distortion values at the multiple intra refresh rates for the coded video frame as a function of the spatiotemporal content and an operating bit-rate, selecting an intra refresh rate value for one or more video frames subsequent to the encoded video frame as a function of the sum of the corresponding computed channel induced distortion values and the source coding distortion values, and encoding the one or more video frames using the selected intra refresh rate value.

System and method for adaptive intra refresh rate setting in a video encoder

A technique to enhance audio quality of a quantized audio signal when a perceptual audio coder is operating at low bit rates. The perceptual audio coder uses a modified two-loop quantization technique that maintains audio quality at medium to high bit rates while eliminating artifacts at low bit rates. The perceptual audio coder saves vanishing bands by stealing bits from surviving bands to reduce artifacts at low bit rates.

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Bengaluru, India

Sarat Chandra Vadapalli