Topic
Adaptive Multi-Rate audio codec
About: Adaptive Multi-Rate audio codec is a research topic. Over the lifetime, 1467 publications have been published within this topic receiving 19736 citations. The topic is also known as: AMR & Adaptive Multi-Rate.
Papers published on a yearly basis
Papers
More filters
18 Nov 2011
TL;DR: This work considers audio coding with a pre- and post-filtered predictive structure that was recently proven to be asymptotically optimal in the rate-distortion sense, and shows that this audio coding is efficient in achieving the state-of-the-art performance.
Abstract: A natural approach to audio coding 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 predictive coding, we consider audio coding 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 audio coding 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.
6 citations
01 Jan 2015
TL;DR: The audio quality assessed by the objective and subjective manners shows that the proposed design outperforms the well-known commercial codec.
Abstract: Wireless audio service attracts increasing attention both in mobile and in home audio market. For high quality audio service especially on wireless network, the audio codec with low latency is indispensible since the latency prevents a user from being immersed in the service. This paper presents a low latency audio coder design with a short length window. Side effects due to the short length window are mitigated by the proposed coding tools such as pitch coding and low frequency masking threshold control. The audio quality assessed by the objective and subjective manners shows that the proposed design outperforms the well-known commercial codec.
6 citations
20 Sep 1995
6 citations
TL;DR: A hybrid digital audio codec based on deltamodulation has been developed as an alternative to PCM and offers high quality audio performance at overall bit rates of 250-350 kb/s/channel.
Abstract: A hybrid digital audio codec based on deltamodulation has been developed as an alternative to PCM. System gain and emphasis are dynamically variable under control of a sophisticated companding algorithm; separate control bit-streams are generated for subsequent transmission to the decoder. The system offers high quality audio performance at overall bit rates of 250-350 kb/s/channel.
6 citations
18 Sep 2003
TL;DR: The fast codebook search method is proposed that is simply modified version of the depth first tree search method used in algebraic code book search in the AMR codec by using the fast search method and exploiting the DSP architecture and managing the memory structure efficiently.
Abstract: The adaptive multi-rate speech codec consists of eight source codecs with bit rates from 4.75 to 12.2 kbit/s. This paper presents an AMR implementation especially focused on reducing the computational complexity. In order to reduce the computational load, we propose the fast codebook search method that is simply modified version of the depth first tree search method used in algebraic codebook search in the AMR codec. For the AMR implementation we designed the 16 bit fixed-point DSP based on the TeakLite DSP core, which was tailored for the AMR implementation. The implemented AMR codec requires only 19.6 MIPS of computation for the highest complexity mode of the AMR by using the fast search method and exploiting the DSP architecture and managing the memory structure efficiently. It is verified with all the test vectors provided by 3GPP, and stable operation on the real-time testing board was also confirmed.
6 citations