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Journal of Electronic Imaging

Efficient bit allocation using new intra and inter-frame modeling for H.264/AVC
Author(s): Miryem Hrarti; Abdelhakim Saadane; Mohamed-Chaker Larabi; Driss Aboutajdine; Ahmed Tamtaoui
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Paper Abstract

Rate control is a critical issue in H.264/AVC video coding standard because it suffers from some shortcomings that make the bit allocation process not optimal. This leads to a video quality that may vary significantly from frame to frame. Our aim is to enhance the rate control efficiency in H.264/AVC baseline profile by handling two of its defects: the initial quantization parameter (QP) estimation for Intra-Frames (I-Frames) and the target number of bits determination for Inter-Frames (P-Frames) encoding. First, we propose a Rate-Quantization (R-Q) model for the I-Frame constructed empirically after extensive experiments. The optimal initial QP calculation is based on both target bit-rate and I-Frame complexity. The I-Frame target bit-rate is derived from the global target bit-rate by using a new non-linear model. Secondly, we propose an enhancement of the bit allocation process by exploiting frame complexity measures. The target number of bits determination for P-Frames is adjusted by combining two temporal measures: the first is a motion ratio based on actual bits used to encode previous frames; the second measure exploits the difference between two consecutive frames and the histogram of this difference. The simulation results, carried out using the JM15.0 reference software and the JVT-O016 rate control algorithm, show that the right choice of initial QP for I-Frame and first P-Frame allows improvement of both the bit-rate and peak signal-to-noise ratio (PSNR). Finally, the Inter-Frame bit allocation process further improves the bit-rates while keeping the same PSNR improvement (up to +1.33  dB/+2  dB for QCIF/CIF resolutions). Moreover, this process reduces the buffer level variation leading to a more consistent quality of reconstructed videos.

Paper Details

Date Published: 22 March 2012
PDF: 18 pages
J. Electron. Imaging. 21(1) 013013 doi: 10.1117/1.JEI.21.1.013013
Published in: Journal of Electronic Imaging Volume 21, Issue 1
Show Author Affiliations
Miryem Hrarti, XLIM-SIC (France)
Abdelhakim Saadane, XLIM-SIC (France)
Mohamed-Chaker Larabi, XLIM-SIC (France)
Driss Aboutajdine
Ahmed Tamtaoui, Institut National des Postes et Telecommunications (Morocco)

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