CN1595393A

CN1595393A - Real-time pre-processing software-hardware system for audio encoder interface and method and uses

Info

Publication number: CN1595393A
Application number: CNA2003101226420A
Authority: CN
Inventors: 丁晟昊
Original assignee: SVA INFORMATION INDUSTRY Co Ltd
Current assignee: SVA INFORMATION INDUSTRY Co Ltd
Priority date: 2003-12-22
Filing date: 2003-12-22
Publication date: 2005-03-16

Abstract

The invention relates to a real time interface pre-processing software and hardware system of the audio encoder, which belongs to the computer image processing technique field, Its hardware is composed of the keyboard, the audio A/D converter used to digitalize the analog audio signal and such signal devices. The system may execute the following activities. Analyze the command input by the keyboard. Initialize and turn off the audio A/D chip and the DMA mechanism. Allocate and release the buffer area. Setup and dissolve the buffer queue. Digitalize the current frame analog TV signal with the PCM signal imported to the pre-processing algorithm to be transformed to the needed format audio signal. The resulted signal is saved to the documents or transferred to the following module. The invention can be applied to audio encoder, broadcasting and such pre-processing technique field.

Description

Real-time audio encoder interfaces pre-service software and hardware system and method and purposes

(technical field)

The invention relates to computer digit signal processing technology field, specifically embedded pc system is under the processing of the control of drive controlling program and certain tool audio frequency Preprocessing Algorithm, a kind of device and method that the simulated audio signal after the sampling is carried out down-sampled rate and precision is handled.

(technical background)

Because the audio sample chip that our company selects for use is only supported 18, but the PCM signal of present international audio coder input sample is 16; By this chip sample frequency is two-channel 32kHz, 44.1kHz and 48kHz, but, company handles the resource that takies resource system that the data of these sample frequency can be undue because considering audio coder, as memory source, cpu resource or the like, so the sample frequency of two-channel 22.05kHz is adopted in decision.

(summary of the invention)

The purpose of the invention is that digital audio technology and computer digit signal processing technology are combined, connect audio A/D conversion chip by digital audio source, audio A/D conversion chip connected storage, storer connects central processing unit (CPU) CPU, realize audio A/D conversion chip and storer control by CPU element, use the C language algorithm of standard that the PCM signal after sampling further is converted to the needed form of follow-up module simultaneously.

For realizing above-mentioned purpose, designed the pretreated software and hardware system of a cover real-time audio encoder interfaces.Its hardware unit comprises: as the keyboard of instruction input, be used for simulated audio signal is carried out digitizing ground audio frequency A/D conversion chip, is used to the DSP that stores the storage device of PCM signal, drive controlling program and Preprocessing Algorithm and be used for working procedure.Its software section comprises: for the analysis program of keyboard instruction, cache management program, audio A/D parallel operation is driven and the program of control and two-channel 18-bit, 44.1kHz audio frequency PCM conversion of signals after the sampling become two-channel 16-bit, 22.05kHz audio frequency PCM signal.

The method of real-time audio encoder interfaces pre-service software and hardware system has adopted the following step:

(1) pending pretreated control program of real-time audio encoder interfaces and related algorithm are written in the memory of this embedded system;

(2) resolve the keyboard input instruction, as require the voice data of how many frames of pre-service;

(3) initialization audio A/D chip, as sample frequency, channel number or the like are set;

(4) allocation buffer and set up buffer queue is for DMA and Preprocessing Algorithm provide necessary buffer zone;

(5) initialization DMA mechanism is as data volume and the various parameter that transmits by DMA at every turn;

(6) simulated audio signal of digitizing present frame obtains the PCM signal, this step preface and each later step genus concurrency relation;

(7) by the DMA transfer mechanism, this PCM signal is sent into appointed buffer;

(8) this PCM signal is imported Preprocessing Algorithm and handle, be translated into desired PCM signal;

(9) signal after will transforming deposits file in, after adding header information, forms the wav file; Perhaps send into follow-up module, as send into the audio coder module;

(10) judge whether to satisfy the instruction that is obtained in step preface (2), as the pretreated frame number that meets the demands: be, then quit a program, close audio A/D converter and DMA mechanism, dismiss buffer queue, discharge employed buffer zone; Not, then change step preface (8) over to, enter the next frame pre-service;

The invention is compared with prior art, provides a cover the complete pretreated algorithm of audio frequency.Its distinctive feature is, has introduced the two divided-frequency technology in down-sampled rate.

The technical characterstic of the invention maximum has been abandoned dependence special audio process chip exactly, and directly adopts the method for software processes to solve these problems: a, has dirigibility.Concerning the user, the audio frequency preprocessing function of the inside of IC solidifies, and some technical parameter that provides can't satisfy user's demand, and some function is unnecessary, can not arbitrarily customize according to user's demand, and this is the most fatal weakness of IC; Just can avoid this point with the algorithm that software is realized; B, has upgradability.Very flexible has just caused its upgradability not strong, concerning the user, if wish to obtain more fully audio frequency preprocessing function, that just has to replace original IC chip with better IC chip, to do pcb board again and write a cover driver again toward contact, product just is difficult in a short time and dominates the market like this, and its vitality is had a greatly reduced quality; If realize with software, do pcb board at least again and can exempt from writing again once this two step of cover driver, the user only needs can embed new software algorithm under original hardware environment.

The economic benefit of the invention is low cost, and the audio sample chip price that contains preprocessing function is generally at tens U.S. dollars or tens U.S. dollars, and this certainly will increase the price of every product; If realize this function with software, the user only needs the R﹠D costs in early stage, and as transplanting, modification and upgrading etc. to this algorithm, the production cost in later stage just can save, and can economize appreciable cost obviously.

The invention can be applicable to preconditioning technique fields such as audio coder, broadcasting, long-distance education, audio workstation, digital recording technology, disc.

(description of drawings)

Fig. 1 is the hardware block diagram of the invention.

Fig. 2 is the invention standard C written program process flow diagram.

Fig. 3 is the two divided-frequency technology realization figure of the invention.

Fig. 4 is 16-bit, 18-bit and the ordered state of original audio sample in internal memory.

Appointment Fig. 1 is a Figure of abstract.

(embodiment)

Be described in further detail below in conjunction with accompanying drawing.

Referring to Fig. 1, among the figure → the expression control line, Expression data flow line (unidirectional),

Expression data flow line (two-way).Square frame one, the simulated audio signal source, audio frequency output, FM or the AM of the sound accompaniment in the TV, VCD or DVD and acoustic pickup obtain the number voice signal.Providing simulating signal, this signal to audio A/D device conversion is continuous analog signal.Square frame two, audio A/D conversion chip.Simulated audio signal is carried out digitizing, for follow-up pre-service provides needed PCM signal.Square frame three, storer is deposited PCM signal place, and provides needed storage space for audio frequency preprocessor and follow-up audio coding algorithm routine.Square frame four, CPU, i.e. central processing unit.Be used to move the drive controlling program to realize control to square frame two (audio A/D conversion chip) and square frame three (storer), be used to move Preprocessing Algorithm simultaneously, the PCM signal after the sampling further is converted to the needed form of follow-up module (just being meant audio coder here).This module is the core of all hardware and software.The composition of this product and method of attachment are clearly to this professional people.

Referring to Fig. 2, Fig. 2 has provided the C programmer process flow diagram of the invention.

Referring to Fig. 3 is exactly by the two divided-frequency technology to the sample of two-channel, 44.1kHz, extract the needed two-channel of audio coder, 22.05kHz sample equably, because increasing of sampling interval is twice, so the number of samples of the audio frequency of this moment is than lacking half without pretreated.

Referring to Fig. 4, wherein The expression invalid bit.

The singularity of algorithm

1, on method,, obtains needed audio samples by the two divided-frequency technology;

2, on the mode that realizes from algorithm, this algorithm is to apply mechanically the algorithm that standard C language is write, and itself and hardware, processor instruction set and operating system independent are so versatility is very strong.Portable is gone in the module of any audio A/D, just is directly embedded in the audio sample device driver.

3, on practicality, alternative some audio A/D preprocessed chip in the market is to save research and development and production cost.

Claims

1, a kind of real-time audio encoder interfaces pre-service software and hardware system comprises:

(1) keyboard of importing as instruction;

(2) be used for simulated audio signal is carried out digitized audio A/D conversion chip

(3) be used to store the storage device of PCM signal, drive controlling program and Preprocessing Algorithm;

(4) DSP of execution driving and control program and transfer algorithm; It is characterized in that this software and hardware system can carry out following action:

A, parsing keyboard input instruction;

B, initialization and close audio A/D chip and DMA mechanism;

C, distribution and buffer release district;

D, foundation and dismission buffer queue;

The anolog TV signals of e, digitizing present frame;

F, this PCM signal is imported Preprocessing Algorithm handle, be translated into the sound signal of required specification;

G, the signal after will transforming deposit file in or send into follow-up module;

2, the method for a kind of real-time audio encoder interfaces pre-service software and hardware system as claimed in claim 1 is characterized in that having adopted the following step:

(1) simulated audio signal that desire is carried out is converted in the control program of required specification sound signal and the memory that related algorithm is written into this embedded system;

(2) resolve the keyboard input instruction, as require several frames of pre-service;

(3) initialization audio A/D chip and DMA mechanism;

(4) allocation buffer and set up buffer queue;

(5) simulated audio signal of digitizing present frame obtains the PCM signal;

(6) by the DMA transfer mechanism, this PCM signal is sent into the internal memory assigned address;

(7) this PCM signal is imported Preprocessing Algorithm and handle, be translated into the frame signal of required specification;

(8) signal after will transforming deposits file in or sends into follow-up module;

(9) judge whether to satisfy the instruction that is obtained in step preface (2): be, then quit a program, close audio A/D converter and DMA mechanism, dismiss buffer queue, discharge employed buffer zone; Not, then change step preface (6) over to, enter the next frame pre-service;

3, a kind of real-time audio encoder interfaces pre-service software and hardware system as claimed in claim 1 is characterized in that can be used for preconditioning technique fields such as audio coder, broadcasting, long-distance education, audio workstation, digital recording technology, disc.