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NEC to further develop noise suppression technology

Feb 16, 2011 at 18:33 GMT

NEC has announced its noise suppression technology has been integrated into the Casio Exilim EX-ZR10 digital compact camera. The technology, a development of the work first touted back in 2009, records the sounds of zoom and focus motors and subtracts them in real time, from any recorded audio. The technique starts with a reference set of lens and motor sounds and adapts to take into account the characteristics of the individual camera's motor sounds and microphone behavior. The system allows motors to be run at full speed, rather than having to be slowed in an attempt to reduce noise.

Press Release:

NEC Noise Suppression Technologies Adopted by Digital Cameras

Tokyo, February 16, 2011 - NEC Corporation (NEC; TSE: 6701) announced today the development of technologies for digital cameras in movie mode that suppress the noise produced by motors and other mechanisms used for optical zooming *1 and that these technologies are featured on system LSI *2 for the EXILIM EX-ZR10 digital camera by Casio Computer Co., Ltd.

Conventionally, the sound generated by lens drivers for digital cameras in movie mode is recorded as noise by microphones. These new technologies suppress noise through a method that records and saves the core characteristics of sounds created by a camera lens' driving mechanisms, then subtracts this information from signals that are recorded by microphones.

Furthermore, these technologies automatically adapt to lens and microphone characteristics among different products, which eliminates the need for customized product adjustment. Moreover, real-time processing is achieved while recording movies as a result of optimizing the number of calculations for noise suppression.

Use of these technologies also makes it possible to preserve ambient environmental sound, while only suppressing the noise generated by a camera's motor. Digital cameras equipped with these technologies can operate motors at a high speed, which achieves smoother zoom operation and creates a user friendly filming experience similar to the use of a dedicated video camera.

These newly developed technologies feature the following:

Effective zoom noise suppression without adjusting for individual microphone characteristics
In addition to existing technologies *3 that suppress noise from cameras and lenses, these new technologies use microphones to record and process a range of additional noises. Furthermore, automatic noise correction for individual cameras is enabled by comparing reference noise, which is based on statistical analysis of incoming signals, to the noise suppression information saved on a user's camera. As a result, no adjustments are needed for individual microphones during production and shipment, and the suppression of zoom noise is optimized

Real-time processing while shooting video and a reduced number of operations for noise suppression
As a result of reducing the number of operations to 80MIPS *4, *5, processors are required to perform fewer operations and noise suppression takes place in real-time while shooting video. This specialized software is adopted on system LSI.

In order for conventional digital cameras to minimize noise levels while shooting video, such measures as expensive low noise level motors, motors with limited speed and filters that prevent the passage of strong motor noise frequencies were adopted. This gave rise to a number of problems that include a camera's lack of ability to take fast moving sports footage, and sound distortion due to filters that suppress ambient sound.

NEC's new technologies resolve these problems and have already been adopted by a popular commercial product.

Looking forward, NEC will continue to develop noise suppression technologies and to deploy them throughout the digital camera and video camera markets.

*1 Optical zoom is a method for continuously changing a camera's focal distance, including wide angles and long distances, through lens movements that are similar to the use of a general film camera.
*2 System LSI An integrated circuit on a semiconductor chip that is required for many of the operations carried out by equipment and systems.
*3 NEC Press Release: November 18, 2009 "NEC Develops Noise Suppression Technologies for Digital Cameras" http://www.nec.co.jp/press/en/0911/1802.html
*4 Million Instructions per Second (MIPS)
*5
Operation number if equipped with a Digital Signal Processor (DSP) (44.1 kHz sampling, stereo input)