Patent Application
20050278043
The present invention relates to a method and a device for solving the sound distortion problem of a sound playback and recording device and, more particularly, to a method making use of gamma tables to avoid the signal overdrive phenomenon during conversion between digital and analog formats, thereby solving the sound distortion problem generated when a sound playback and recording device plays an analog signal.
Sound processing can generally be divided into analog and digital methods. Along with progress of the information and computer technology, the combination of analog and digital methods has become inevitable in sound playback devices.
Integrating advantages of the analog and digital methods not only can provide situated sound feel, but also can facilitate self music editing for users. Conventional products have thus been gradually replaced with integrated sound playback devices of this kind.
During conversion between an analog signal and a digital signal, however, if the amount of input data is too large, the data overflow phenomenon may happen. For a sound playback device, if the input sound signal is stronger, the converted digital sound signal will have a large probability of signal overdrive.
Similarly, if the digital sound signal with overflow is to be converted into analog format for output, an analog sound signal with overflow will be generated, hence causing the sound distortion phenomenon. In other words, a front-stage distorted signal will naturally produce a back-stage distorted output signal.
In the prior art, there has been a method for solving the signal overdrive problem, wherein an auto-level control component is installed at the front stage of the sound playback device to avoid the signal overdrive phenomenon during conversion of a sound signal between analog and digital formats. However, an extra auto-level control component is required in this method, hence increasing the cost of the sound playback device.
Accordingly, the present invention aims to propose a method and a device for solving the sound distortion problem of a sound playback and recording device, which make use of at least a gamma table to adjust amplifications to solve the sound distortion problem due to data overflow.
An object of the present invention is to propose a method and a device for solving the sound distortion problem of a sound playback and recording device to overcome the data overflow problem during conversion between digital and analog formats of the sound playback and recording device. In this method, an analog sound signal is first input. Next, the analog sound signal is converted into a digital sound signal. At least a gamma table is then used to amplify smaller volumes with larger amplifications and amplify larger volumes with smaller amplifications. Subsequently, the digital sound signal amplified with the gamma table is stored. Similarly, a gamma table is also used for amplification for output to restore the digital sound signal to the analog sound signal without the signal overdrive phenomenon. The probability of sound distortion of the sound playback and recording device can thus be reduced.
The various objects and advantages of the present invention will be more readily understood from the following detailed description when read in conjunction with the appended drawings, in which:
The foregoing aspects and many of the attendant advantages of this invention will be more readily appreciated as the same becomes better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:
The present invention provides a method and a device for solving the sound distortion problem of a sound playback and recording device, which make use of at least a gamma table to solve the signal overdrive problem during conversion between digital and analog formats of a sound playback and recording device to avoid the sound distortion phenomenon generated when the sound playback and recording device plays an analog signal. As shown in
The processing unit 50 is used to perform various kinds of processing such as conversion, amplification and compression to the analog sound signal in turn. First, the analog sound signal is converted into a digital sound signal. Next, the digital sound signal is sent to a memory unit 30 for storage. When a user wants to play the sound signal, the processing unit 50 will fetch the digital sound signal from the memory unit 30 and perform inverse actions such as decompression, amplification, and conversion to restore the digital sound signal back to the analog sound signal. Finally, the analog sound signal is output to a sound playing unit 60 for playback of the analog sound signal.
In
As shown in
The gamma amplifier 25 adjusts the volumes of the digital sound signal according to specific amplifications. If the input volume is smaller, the amplification is increased. Contrarily, if the input volume is larger, the amplification is decreased. The sound distortion phenomenon due to data overflow can thus be avoided when the sound playing unit 60 plays sound.
The amplifications can be adjusted according to a gamma table. That is, after a designer builds a gamma table, it is immediately set in the gamma amplifier 25 so that the volumes of a subsequently input digital sound signal can be adjusted according to the gamma table to avoid signal overdrive after conversion between analog and sound formats.
After amplified by the gamma amplifier 25, the digital sound signal is output to a compression/decompression unit 40 for compressing the digital sound signal to increase the storage capacity of the memory unit 30. When the digital sound signal is output from the memory unit 30, the compression/decompression unit 40 is required for decompression to restore the digital sound signal.
Similarly, when a user wants to play a digital sound signal in the memory unit 30, the processing unit 50 first fetches the digital sound signal from the memory unit 30. The compression/decompression unit 40 then decompresses the digital sound signal. Next, a gamma amplifier 25 amplifies the digital sound signal according to specific amplifications. An analog/digital converter 20 then restores the digital sound signal into the analog sound signal. Finally, the analog sound signal is output to a sound playing unit 60 for playing sound.
Reference is made to
In this embodiment, it is not necessary to store the digital sound signal in a memory unit 30. The digital sound signal can be directly output. The digital sound signal is amplified with the gamma table again (S307) to avoid too small volumes of the output. Next, the digital sound signal is restored to an analog sound signal by an analog/digital converter 20 (S309). Finally, the analog sound signal is played by a sound playing unit 60 (S311). The data overflow phenomenon of the sound playback and recording device 100 during conversion between analog/digital formats can be avoided. Moreover, the sound distortion problem generated when the sound playback and recording device plays sound can be avoided.
As shown in
If the input volume exceeds a certain value, the output volume is kept at level 256 to avoid the sound distortion phenomenon when the sound playback and recording device 100 plays sound. In this embodiment, the gamma table is a nonlinear graph. In practical application, it can also be designed to be a linear transformation.
As shown in
As shown in
To sum up, the present invention provides a method and a device for solving the sound distortion problem of a sound playback and recording device to effectively solve the data overflow problem during conversion between digital and analog formats of the sound playback and recording device and also decrease the probability of sound distortion when the sound playback and recording device 100 plays sound.
Although the present invention has been described with reference to the preferred embodiments thereof, it will be understood that the invention is not limited to the details thereof. Various substitutions and modifications have been suggested in the foregoing description, and others will occur to those of ordinary skill in the art. Therefore, all such substitutions and modifications are intended to be embraced within the scope of the invention as defined in the appended claims.
