A natural approach to audiocoding is to use a rate-distortion optimal design combined with a perceptual model. While this approach is common in transform coding, existing predictive-coding based audio coders are gene...
详细信息
ISBN:
(纸本)9781457706936
A natural approach to audiocoding is to use a rate-distortion optimal design combined with a perceptual model. While this approach is common in transform coding, existing predictive-coding based audio coders are generally not optimal and they benefit from heuristically motivated post-filtering. As delay requirements often force the use of predictivecoding, we consider audiocoding with a pre- and post-filtered predictive structure that was recently proven to be asymptotically optimal in the rate-distortion sense [1]. We show that this audiocoding is efficient in achieving the state-of-the-art performance. We also show that the pre- filter plays a relatively minor role. This leads to an analytic approach for optimizing the post-filter and the predictor at each rate, eliminating the need for manual re-tuning whenever a different rate is called for. In a subjective test, the theoretically optimized post-filter provided a better performance than a conventional post-filter.
In this paper we present and evaluate Several concealment strategies for packet losses in the context of it low delay predictiveaudio coder. Our goal is to minimize the audible impact of a packet loss. The problem is...
详细信息
ISBN:
(纸本)0780391543
In this paper we present and evaluate Several concealment strategies for packet losses in the context of it low delay predictiveaudio coder. Our goal is to minimize the audible impact of a packet loss. The problem is that the predictive coder is backward adaptive, hence depending on past values. There is a predictor reset, but to increase coding efficiency. the distance between two resets is several hundred packets. Hence, not only the lost packet itself cannot be reconstructed, but the transmitted data LIP to the next reset does not result in an exact reconstruction of the audio signal. Our approach is to try to use its much information as possible from the still available data until the next reset. and to reconstruct an audio signal such that distortions are least objectionable. To compare different approaches, we conducted it listening test. The result is that an adaptive reconstruction filter works best in this context.
暂无评论