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In this paper we present a rate control algorithm to control the encoded picture size in a video sequence within a specified maximum limit. The need to control the encoded picture size arises in several video applications; (i) video conferencing to ensure the glass to glass delay is within acceptable conversational delay, (ii) video encoders complying with H.241 MTU packetization constraints to ensure...
In this paper, we present a multipoint video conferencing system that adapts to heterogeneous members including mobiles. The system is built upon a low complexity scalable extension of our H.264 codec DAVC, and a congestion-aware dynamic adaptation layer. Our temporally scaled video codec DSVC has the same RD performance as the non-scaled version with comparable configuration. We achieve this by QP...
The use of Flexible Macroblock Ordering (FMO) in H.264/AVC as an error-resilient tool incurs extra overhead bits that reduces coding efficiency at low bit rate. To improve coding efficiency, we present an improved frame-layer H.264/AVC rate control that takes into consideration the effects of using FMO for video transmission. In this paper, we propose a new header bits model, an enhanced frame complexity...
In this paper, we propose a hardware implementation of H.264 intra frame encoder to achieve the real-time operation for video conference applications. The H.264 intra frame encoder is composed by intra 4×4 prediction, intra 16×16 prediction, integer transform, quantization (AC & DC), inverse integer transform, inverse quantization (AC &DC), hadamard, and inverse hadamard transform. This method...
Video transmission is affected by two types of distortions: source distortion, which is caused by the encoder parameters; and channel distortion for which the error prone characteristics of the wireless network is responsible. In this paper, we vary the quantization parameter (QP) to determine the effect of source distortion. In a capacity constrained network, changing QP has contradictory effects:...
ITU-R BT.1361 defined the range of input signal for gamma correction was [-0.25, 1.33]. This paper calculated the widest color gamut and the corresponding three primary colors under this range for video system based on trichromatic principle using colorbar signal widely used in TV system, developed a kind of nonlinear quantization method to convey this gamut compatibly in current conventional color...
We propose to use two parameters, the scene complexity (C) and the level of motion (M), to capture the video content characteristics that matter most to the quality of compressed videos transmitted over IP networks, either with or without packet losses. Two simple but robust formulas are designed to calculate these two parameters from the following variables: bits of coded intra (I-) frames (BitsI...
Rate control plays a crucial role for video communication applications. It ensures that the generated compressed bit streams satisfy bandwidth and buffer constraints. Rate control algorithms recommended by H.264/AVC adopt rate-distortion (R-D) models for inter-frames to determine quantization parameters (QPs) but not for intra-frames. Instead, they directly compute QPs without any considerations of...
This paper proposed a novel Region of Interest (ROI) based rate control algorithm for video communication systems, in which the subjective quality of ROI can be adjusted according to users' requirements. In the proposed scheme, in order to analyze the relationship between subjective quality and encoding parameters, a structural similarity index map - quantization parameter (SSIM-QP) model is established...
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