A codec is a device or computer program for encoding or decoding a digital data stream or signal. Codec is a portmanteau of coder-decoder. According to different technical principles of audio compression, audio compre...A codec is a device or computer program for encoding or decoding a digital data stream or signal. Codec is a portmanteau of coder-decoder. According to different technical principles of audio compression, audio compression coding methods have their own characteristics. This paper considers that the coding quality is high and the digital rate is also high. In addition, according to the compressed data whether exists information loss, data compression coding can also be divided into two forms, which is lossless compression and lossy compression. Lossy compression method also called compression method for the amount of information. Lossy compression is always larger, widely used in audio compression. It is also familiar to us. However, for the more critical to the quality of people, especially the music enthusiast, lossy compression of audio files often cannot meet their quality on the requirements, and it is very necessary and lossless compression. Firstly, this paper has designed and executed tests to compare the performance ofcodecs by using my methodology. Then, it has analysed the results. Finally, there are conclusions on the relative merits of the codecs selected and some recommendations.展开更多
The demand for the telecommunication services,such as IP telephony,has increased dramatically during the COVID-19 pandemic lockdown.IP tele-phony should be enhanced to provide the expected quality.One of the issues th...The demand for the telecommunication services,such as IP telephony,has increased dramatically during the COVID-19 pandemic lockdown.IP tele-phony should be enhanced to provide the expected quality.One of the issues that should be investigated in IP telephony is bandwidth utilization.IP telephony pro-duces very small speech samples attached to a large packet header.The header of the IP telephony consumes a considerable share of the bandwidth allotted to the IP telephony.This wastes the network's bandwidth and influences the IP telephony quality.This paper proposes a mechanism(called Smallerize)that reduces the bandwidth consumed by both the speech sample and the header.This is achieved by assembling numerous IP telephony packets in one header and use the header'sfields to carry the speech sample.Several metrics have been used to measure the achievement Smallerize mechanism.The number of calls has been increased by 245.1%compared to the typical mechanism.The bandwidth saving has also reached 68%with the G.28 codec.Therefore,Smallerize is a possible mechanism to enhance bandwidth utilization of the IP telephony.展开更多
In the study and implementation of a programmable RS codec module in satellite communication modem, FPGA is used as the kernel in the implementation, while some ASICs are used as necessary assistant measures. The modu...In the study and implementation of a programmable RS codec module in satellite communication modem, FPGA is used as the kernel in the implementation, while some ASICs are used as necessary assistant measures. The module includes the RS codec unit, the interleaver and deinterleaver unit, the scrambler and descrambler unit and the frame synchronization unit. The module is realized successfully and it can be programmed on-line to meet the requirements of IESS 308/309/310 including many specifications about different service types and data rates. With the implementation combining FPGA with ASICs, size of the circuit is much reduced, its flexibility dramatically increased, and its stability further strengthened. Furthermore, the module is based on the software radio concept and can be easily integrated into the whole satellite communication modem.展开更多
以飞思卡尔公司的ARM11处理器IMX35为基础开发了一种车载信息娱乐系统,该系统包含蓝牙、USB、GPS、CODEC等信息娱乐部分,并通过MOST(Media Oriented System Transport)标准总线与车内的其他模块(如车内功率放大器、具有显示控制功能的DV...以飞思卡尔公司的ARM11处理器IMX35为基础开发了一种车载信息娱乐系统,该系统包含蓝牙、USB、GPS、CODEC等信息娱乐部分,并通过MOST(Media Oriented System Transport)标准总线与车内的其他模块(如车内功率放大器、具有显示控制功能的DVD机等)通信。展开更多
文摘A codec is a device or computer program for encoding or decoding a digital data stream or signal. Codec is a portmanteau of coder-decoder. According to different technical principles of audio compression, audio compression coding methods have their own characteristics. This paper considers that the coding quality is high and the digital rate is also high. In addition, according to the compressed data whether exists information loss, data compression coding can also be divided into two forms, which is lossless compression and lossy compression. Lossy compression method also called compression method for the amount of information. Lossy compression is always larger, widely used in audio compression. It is also familiar to us. However, for the more critical to the quality of people, especially the music enthusiast, lossy compression of audio files often cannot meet their quality on the requirements, and it is very necessary and lossless compression. Firstly, this paper has designed and executed tests to compare the performance ofcodecs by using my methodology. Then, it has analysed the results. Finally, there are conclusions on the relative merits of the codecs selected and some recommendations.
文摘The demand for the telecommunication services,such as IP telephony,has increased dramatically during the COVID-19 pandemic lockdown.IP tele-phony should be enhanced to provide the expected quality.One of the issues that should be investigated in IP telephony is bandwidth utilization.IP telephony pro-duces very small speech samples attached to a large packet header.The header of the IP telephony consumes a considerable share of the bandwidth allotted to the IP telephony.This wastes the network's bandwidth and influences the IP telephony quality.This paper proposes a mechanism(called Smallerize)that reduces the bandwidth consumed by both the speech sample and the header.This is achieved by assembling numerous IP telephony packets in one header and use the header'sfields to carry the speech sample.Several metrics have been used to measure the achievement Smallerize mechanism.The number of calls has been increased by 245.1%compared to the typical mechanism.The bandwidth saving has also reached 68%with the G.28 codec.Therefore,Smallerize is a possible mechanism to enhance bandwidth utilization of the IP telephony.
文摘In the study and implementation of a programmable RS codec module in satellite communication modem, FPGA is used as the kernel in the implementation, while some ASICs are used as necessary assistant measures. The module includes the RS codec unit, the interleaver and deinterleaver unit, the scrambler and descrambler unit and the frame synchronization unit. The module is realized successfully and it can be programmed on-line to meet the requirements of IESS 308/309/310 including many specifications about different service types and data rates. With the implementation combining FPGA with ASICs, size of the circuit is much reduced, its flexibility dramatically increased, and its stability further strengthened. Furthermore, the module is based on the software radio concept and can be easily integrated into the whole satellite communication modem.
