CN1274176C - Method for processing wavetable in mobile phone and chip - Google Patents

Abstract

The present invention discloses a method for processing wavetable in a chord chip of a mobile telephone, which belongs to the field of wavetable processing. The present invention is method for processing wavetable in a chord chip of a mobile telephone without increasing unnecessary consumption of a chip. The method uses an ADPCM decompression algorithm to decompress a sound sample of a corresponding musical instrument, and when a cycle start sampling point in wavetable synthesis is m, a group of coefficients Idx(m-1) and preVal (m-1) obtained by subtracting 1 from the decompression sampling point m, namely necessary coefficients for the decompression sampling point m, are stored into a register of a chip; by using the method of the present invention, the corresponding sound sample is playing back after decompression, synthesis and processing.

Description

The method that wave table on the mobile phone chord chip is handled

Affiliated field

The present invention relates to the wave table process field, relate in particular to the method that the wave table on the mobile phone chord chip is handled.

Background technology

The wave table synthetic technology is the tone color sampling of real instrument to be recorded to synthesize again handle, so the big more tone color sampling of wave table is just true more, effect is just good more.With regard to the sound card of PC, the minimum wave table that all will in the ROM of sound card, load 1M.But for the chord chip on the mobile phone, consider area of chip and cost, big like this wave table is unacceptable, thus must delete wave table, but what bring thus is exactly the loss of tone color.Such as the wave table of having deleted guitar, the guitar sound in so just can't synthesizing MIDI.So also brought the decline of chip performance.Therefore novel wave table compress technique is more and more expected by people.

In addition, the ADPCM compression algorithm is a kind of compression algorithm of called optical imaging, if in the chip is the wave table of taking the ADPCM compression algorithm to cross but be cured to, in the process of synthesizing MIDI, must at first carry out ADPCM to the wave table of the synthetic musical instrument of needs so and decompress, just can carry out further synthetic the processing then.Referring to Fig. 1, the transverse axis among Fig. 1 is represented sampled point, and the longitudinal axis is represented the numerical value of this sampled point.Because the decision of ADPCM algorithm, each ADPCM coding all is relevant with his coding in the past, and when decompressing each sampled point, the one group of coefficient that all needs a sampled point to produce when decompressing is represented with Idx and preVal here.Such as, the initial value of Idx and preVal all is 0, in decompressed sample point 0, has produced one group of coefficient Idx 0 and preVal 0, these two coefficients be decompressed sample put 1 o'clock necessary.The rest may be inferred, in decompress(ion) sampled point 2, just need Idx 1 and preVal 1, but drawing Idx 1 and preVal 1 necessary known Idx 0 and preVal0, thus in the ADPCM decoding, will carry out in proper order, and can not skip any one sampled point.Can bring a problem like this, because if the initial sampled point of circulation when wave table is synthetic is m, the loop termination sampled point is z, behind the sampled point z that uses, next needed sampled point be not 0 but m. but want decompress(ion) sampled point m just must all will decompress from these sampled points of 0 to m, can bring the unnecessary consumption of chip like this.Therefore how to use the ADPCM compression algorithm to compress wave table and do not increase chip unnecessary consumption becomes problem demanding prompt solution.

Summary of the invention

In order to solve above-mentioned the problems of the prior art, the method that the object of the present invention is to provide a kind of wave table that does not increase the unnecessary consumption of chip to handle on the mobile phone chord chip.

In order to realize the foregoing invention purpose, technical scheme of the present invention realizes as follows:

Method to the wave table on the mobile phone chord chip is handled the steps include: 1) paired pulses coded modulation wavetable base uses the ADPCM compression algorithm to compress; 2) wave table after will compressing is solidificated in the chip; 3) wave table of musical composition information after compression according to the record of MIDI file sends instruction, finds out corresponding sample sound from the wave table after the compression one by one; 4) use the ADPCM decompression algorithm that the sample sound of corresponding musical instrument is decompressed, and the initial sampled point of circulation when wave table is synthetic is m, then decompressed sample point m-1 resulting that group coefficient Idx (m-1) and preVal (m-1), just the necessary coefficient of decompressed sample point m is saved in the register of chip; 6) sample sound of the correspondence after will decompressing comes out through synthetic, processing back playback.

Method to the wave table on the mobile phone chord chip is handled the steps include: 1) paired pulses coded modulation wavetable base uses the ADPCM compression algorithm to compress; 2) wave table itself is carried out preliminary treatment, the wave table that compressed is carried out the decompression of analog chip processing procedure with software, if the initial sampled point of circulation of sample sound was m when wave table was synthetic, then decompressed sample point m-1 resulting that group coefficient Idx (m-1) and preVal (m-1), the necessary coefficient of decompressed sample point m just is saved in the back of this sample sound; 3) wave table after will compressing is solidificated in the chip; 4) wave table of musical composition information after compression according to the record of MIDI file sends instruction, finds out corresponding sample sound from the wave table after the compression one by one; 5) use the ADPCM decompression algorithm that the sample sound of corresponding musical instrument is decompressed; 6) corresponding sample sound comes out through synthetic, processing back playback.

Above-mentioned steps 2) necessary that group coefficient Idx (m-1) of decompressed sample point m and preVal (m-1) also can be saved to the last of whole compression wave table in, and the method for standby retrieval extracts when needs.

Above-mentioned steps 1) the ADPCM compression algorithm in is the IMA-ADPCM compression algorithm.

Paired pulses coded modulation wavetable base of the present invention uses the ADPCM compression algorithm to compress.ADPCM is a kind of lossy compression method, and it has lost partial information.Because people's ear is to the insensitivity of sound, suitable lossy compression method is little to the influence of audiovisual result of broadcast.The quantized value of ADPCM record is not the amplitude of each sampled point, but this amplitude and previous sampled point amplitude is poor.PCM to 16bitd compresses like this, and the quantization of each sampled point does not just need 16bit, can reduce the capacity of signal thus.If the initial sampled point of circulation when wave table is synthetic is m, the present invention puts m-1 resulting that group coefficient Idx (m-1) and preVal (m-1) with decompressed sample, the necessary coefficient of decompressed sample point m just is saved in the last of the register of chip or whole wave table.Like this, next time again decompress(ion) sampled point m the time, just directly coefficient of utilization Idx (m-1) and preVal (m-1) need not decompress 0 again to all sampled points of m, need not increase the unnecessary consumption of chip.

Description of drawings

Fig. 1 is the ADPCM wave table figure of certain musical instrument;

Fig. 2 is the workflow diagram of the embodiment of the invention 1;

Fig. 3 is the workflow diagram of the embodiment of the invention 2;

Fig. 4 is the pretreated schematic diagrames of the embodiment of the invention 2 wave tables;

Fig. 5 carries out the schematic diagram of pulse code modulation for the present invention.

Embodiment

Specify embodiments of the present invention below in conjunction with accompanying drawing.

Referring to Fig. 1 and Fig. 2, the method to the wave table on the mobile phone chord chip is handled the steps include: 1) paired pulses coded modulation wavetable base uses the ADPCM compression algorithm to compress.2) wave table after will compressing is solidificated in the chip.3) wave table of musical composition information after compression according to the MIDI file logging sends instruction, finds out corresponding sample sound from the wave table after the compression one by one.4) use the ADPCM decompression algorithm that the sample sound of corresponding musical instrument is decompressed, and the initial sampled point of circulation when wave table is synthetic is 10, ending sampled point is 24, then decompressed sample is put 9 resulting those group coefficient Idx9 and preVal9, just decompressed sample is put 10 necessary coefficients, is saved in the register of chip.Like this, behind the sampled point 24 that decompressed, next time again decompress(ion) sampled point 10 time, just can directly use coefficient Idx9 in the register and preVal9, need not decompress 0 to 10 all sampled point again.6) sample sound of the correspondence after will decompressing comes out through synthetic, processing back playback.

Referring to Fig. 3 and Fig. 4, the method to the wave table on the mobile phone chord chip is handled the steps include: 1) paired pulses coded modulation wavetable base uses the ADPCM compression algorithm to compress.2) wave table itself is carried out preliminary treatment, the wave table that compressed is carried out the decompression of analog chip processing procedure with software, if the initial sampled point of circulation when wave table is synthetic is 10, ending sampled point is 24, then decompressed sample is put 9 resulting those group coefficient Idx9 and preVal9, just decompressed sample is put 10 necessary coefficients, is saved in the back of this sample sound.Like this, behind the sampled point 24 that decompressed, again decompress(ion) sampled point 10 time, just can directly just can directly read the 25th, 26 points next time, know coefficient Idx9 and preVal9, need not decompress 0 to 10 all sampled point again.3) wave table after will compressing is solidificated in the chip.4) wave table of musical composition information after compression according to the record of MIDI file sends instruction, finds out corresponding sample sound from the wave table after the compression one by one.5) use the ADPCM decompression algorithm that the sample sound of corresponding musical instrument is decompressed.6) corresponding sample sound comes out through synthetic, processing back playback.

ADPCM (Adaptive Differential Pulse Code Modulation) is called adaptive difference pulse code.The quantized value of ADPCM record is not the amplitude of each sampled point, but this amplitude and previous sampled point amplitude is poor.Because the PCM that the musical instrument sound information of general wave table is all recorded with the precision of 44.1KHz, 16Bit is to reach the truest playback effect.PCM to 16bitd compresses like this, and the quantization of each sampled point does not just need 16bit, can reduce the capacity of signal thus.

Referring to Fig. 5, above-mentioned steps 1) the pulse code modulation PCM in may further comprise the steps: 1) simulated audio signal with set of pulses sampled clock signal and input multiplies each other, and multiplied result is the digitlization of input signal on time shaft; 2) the later signal amplitude of sampling is quantized, the simplest quantization method is balanced the quantification, and the process of this quantification is finished by quantizer; 3) signal after quantizer A/D conversion is encoded again, promptly the signal level that quantizes is converted to the binary system code character, the binary system dateout sequence x (n) that obtains dispersing, n represents that the time series that quantizes, the value of x (n) are exactly that amplitude after n quantizes is constantly represented and record with binary form.

Referring to Fig. 5, for same audio analog signals, use same sampling precision (being generally 16bit or 8bit) to sample, the binary file of the low more formation of sample frequency is just more little, and vice versa.Such as to one 500 milliseconds audio analog signals, sample with the sampling precision of 16bit, if sample frequency is 44.1k 44100 points of just sampling each second, the size of so formed binary file is:

44100×16bit×0.5s＝352800bit＝44100byte

If adopt the sample frequency of 22.05k to sample, the binary file of Xing Chenging is just little one times so.

22050×16bit×0.5s＝146700bit＝22050byte

But, meanwhile can lose some high fdrequency components in some analog signals, but in the sound system of mobile phone, these high fdrequency components of some musical instrument not very outstanding, be difficult for being distinguished by people's ear.So just can adopt the 22.05k sample rate to the wave table of these musical instruments, the 16bit sampling precision reaches the purpose of preliminary reduction wave table size.

The present invention equally also can be applied to the wavetable base on the chord chip of other communication terminal is compressed.Application the present invention compresses the wavetable base on other chord chips and all belongs to protection scope of the present invention.For those skilled in the art, can easily realize additional advantage and make amendment, therefore under the situation of the spirit and scope of the universal that does not deviate from claim and equivalency range and limited, the examples shown that the present invention is not limited to specific details, representational equipment and illustrates here and describe.

Claims (5)

1, the method that the wave table on the mobile phone chord chip is handled the steps include: 1) paired pulses coded modulation wavetable base uses the ADPCM compression algorithm to compress; 2) wave table after will compressing is solidificated in the chip; 3) wave table of musical composition information after compression according to the record of MIDI file sends instruction, finds out corresponding sample sound from the wave table after the compression one by one; 4) use the ADPCM decompression algorithm that the sample sound of corresponding musical instrument is decompressed, and the initial sampled point of circulation when wave table is synthetic is m, then decompressed sample point m-1 resulting that group coefficient Idx (m-1) and preVal (m-1), just the necessary coefficient of decompressed sample point m is saved in the register of chip; 5) sample sound of the correspondence after will decompressing comes out through synthetic, processing back playback.

2, the method that the wave table on the mobile phone chord chip is handled the steps include: 1) paired pulses coded modulation wavetable base uses the ADPCM compression algorithm to compress; 2) wave table itself is carried out preliminary treatment, the wave table that compressed is carried out the decompression of the processing procedure of analog chip with software, if the initial sampled point of circulation when wave table is synthetic is m, then decompressed sample point m-1 resulting that group coefficient Idx (m-1) and preVal (m-1), the necessary coefficient of decompressed sample point m just is saved in the back of sample sound; 3) wave table after will compressing is solidificated in the chip; 4) wave table of musical composition information after compression according to the record of MIDI file sends instruction, finds out corresponding sample sound from the wave table after the compression one by one; 5) use the ADPCM decompression algorithm that the sample sound of corresponding musical instrument is decompressed; 6) corresponding sample sound comes out through synthetic, processing back playback.

According to the described method that wave table on the mobile phone chord is handled of claim 1, it is characterized in that 3, the ADPCM compression algorithm in the described step 1) is the IMA-ADPCM compression algorithm.

According to the described method that wave table on the mobile phone chord is handled of claim 2, it is characterized in that 4, the ADPCM compression algorithm in the described step 1) is the IMA-ADPCM compression algorithm.

5, according to the described method that wave table on the mobile phone chord is handled of claim 2, it is characterized in that, step 2) necessary that group coefficient Idx (m-1) of decompressed sample point m and preVal (m-1) also can be saved to the last of whole compression wave table in, and the method for standby retrieval extracts when needs.

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