KR100268517B1 - Process for simultaneously transmitting sognals from n-signal dources - Google Patents

Abstract

A process is disclosed for simultaneously transmitting signals from N-signal sources over a corresponding number of transmission channels. The individual signals are subdivided into blocks and the blocks are converted into spectral coefficients by transformation or filtering, and the latter are then subjected to a data reduction process. The invention is characterized in that the blocks belonging to the individual signals are subdivided into section. The momentary sections of all signals are processed together, the admissible disturbance is determined for each section by using a perception-specific model and the momentarily required total transmission capacity is calculated. The allocation of the maximum available transmission capacity for each individual signal is calculated from the total available transmission capacity and the total momentarily required transmission capacity. Each individual signal is coded and transmitted with the thus determined capacity.

Description

How to send signals from N signal sources simultaneously

The present invention relates to a method for simultaneously transmitting signals from N signal sources via a corresponding number of transmission channels.

It is well known that individual (time) signals are divided into blocks and the blocks are transformed into spectral coefficients by transforming or filtering, the coefficients undergoing data reduction for some and encoded according to each data reduction. In this regard, reference is made by way of example to the article "Perceptual Audio coding" by Jorg Houpert in Studio-Technik or the article "Daten-Diat, Datenreduktion bei digitalisierten Audio-Signalen" by Stefanie Renner in Elrad, 1991. PCTA-document WO 88/01811, as well as the schematic paper, are hereby expressly referred to for the description of certain terms and procedures which are not made more explicit here.

In many cases, it is necessary to simultaneously transmit signals from several signal sources via a corresponding number of transmission channels. The transmission of stereo signals over two transmission channels is mentioned here as the simplest example. Transmission over a corresponding number of transport channels of signals from N signal sources has the problem of sizing the transport channel; If each individual transport channel is sized in this manner to transmit a "maximum projection bit flow" (German: Bit-Strom), a relatively large transmission capacity remains unused "on average."

When signals from many signal sources are transmitted through a corresponding number of transport channels, the transport channels are designed for only "average-demand" and short-term increased demand for each individual channel by allocation from other channels is achieved. Matching is known from digital telephone technology. Allocation is secured exclusively through signal statistics.

In the prior art, the following work "Ein digitales Sprachinterpolationsver fahren mit pradiktionsgesteuerter Wortaufteilung" by Dr. H. Gerhauser (1980), "Ein digitales Sprachinterpolationsverfahren mit monentaner Prioritatszuteilung", by R. Woitowitc (1977) and "Ein digitales Sprachinterpolationsverfahren mit blockweiser Prioritatszuteilung" by G. G. Klahnen bucher (1978).

An element of the present invention is a conventional method in digital telephony technology for adapting to changing demands when transmitting a large number of signals via a corresponding number of transport channels. If you go through, you do not get good results.

It is an object of the present invention to provide a method for simultaneously transmitting signals from N signal sources via a corresponding number of transmission channels, together with a "data-reduced signal" in which there is no significant, in other words, signal capacity. By way of example audible, transmission may be via a sized transport channel only for "average demand" without loss.

A solution of this object according to the invention is described in claim 1. Further refinements of the invention are the subject matter of the dependent claims.

In the present invention, rather than assigning individual signals according to statistical considerations when meeting the changing demands while simultaneously transmitting signals from N signal sources through the corresponding number of transmission channels, rather than reducing the signal data It is based on the basic concept of satisfying changing demands by appropriate means in the processing steps to be coded.

The basic concepts of the invention are described below using preferred embodiments with reference to the accompanying drawings.

1 is a block diagram for explaining the method of the present invention.

2a and 2b is a signal configuration of the present invention.

In the method of the invention, the individual signals are divided into blocks and the blocks are transformed into spectral coefficients by transforming or filtering. To meet changing demands, blocks belonging to individual signals are divided into sections and each current section of all signals is processed simultaneously. This is illustrated in FIG. 1 by the corresponding "function block".

By way of example, when a speech signal employs a recognition-designation model, which may be a pseudo-acoustic model in transmission, an acceptable interference is determined for each section and from which the overall transmission capacity currently required is calculated. The calculation of the overall transmission capacity, ie the number of bits required, takes place simultaneously in all blocks. The allocation of maximum processing capacity in processing from all processing transmission requirements and the overall transmission capacity currently required is calculated for each individual signal. With each "number of bits" assigned to each signal, the coding of the individual signals takes place and thus the transmission of the individual signals. In the simplest case, balance or equality only occurs at each required transmission capacity between channels.

In the further development described in claim 2, there is a storage capacity storage, a so-called bit storage, where the allocation of capacity occurs when the total transmission required from it exceeds the average capacity in processing.

The bit storage is filled whenever the required transfer capacity is less than the transfer capacity being processed (claim 3).

In some cases, in order to prevent the increase in the bit store, it is necessary to allocate the forced bits to individual channels if the capacity is much less than the capacity being processed. The force allocation preferably takes place only for the channel, each signal source, which reported a need greater than average demand. In fact, a demand greater than average demand means that the signal is actually more difficult to code than a communication signal.

In some cases it is desirable to comply with claim 9 if the entire block is formed from all separately coded signals from the signal source. The overall block consists of a fixed area containing information from which signal separation can be determined and several areas of more flexible length for receiving code signals. This is shown in Figure 2a.

Subsequent savings in transmission capacity are achieved by the same input signal being recognized and transmitted only once by a suitable transmission format (claim 6). This is shown in Figure 2b.

In some cases, the currently required transmission capacity can be determined or only evaluated accurately (claims 7 and 8).

Furthermore, the process of the invention can be conducted in parallel to a considerable extent. For this purpose, it is preferable if the coding of the individual signals has already taken place during the calculation of the allocation of transmission capacity for each signal according to claim 10.

Another preferred implementation of the basic concept of the invention is set forth in claim 11:

If no allocation can be made from the bit store because the required capacity exceeds the processing capacity being processed, the value of the allowable interference for all signals will be raised in such a way that the total required transmission capacity does not exceed the processing capacity. (Claim 15).

In the following, a numerical example of the processing method for an audio signal is given. It is clearly pointed out that the basic concept of the present invention is not limited to the audio signal but also to the video signal or other signals under recognition-specified evaluation can be similarly handled.

Examples of possible processing methods for the audio signal: Assume that y (t) is a sample value of the audio signal.

1) The audio signal y is decomposed or separated in a known manner to become a sampling value y (t), and the value is digitized. The digitized sample values are broken or decomposed into blocks of length 2n, which in the selected embodiment are intersecting blocks with n intersections:

X (k, b) = y (b ^* n + k) for k = 0 ... 2n (b is the number of blocks).

2) The length n of each block is converted into spectral coefficients by Fast Fourier Transformatim or Cosinus transformation, for example.

x (j, b) = SUM (1 = 0 ... 2n; x (1, b) ^* f (1) ^* cos (pi * (21 + 1 + n) (2j + 1) / (4n)) for j = o ... n with f (1) = sqrt (2) ^* sin (pi ^* (1 + 0.5) / (2n))

3) Each block is divided into sections and energy density is calculated for each section:

E (l, b) = (SUM (k = (a (i) +1 ... a (i + 1); X (k, n) 2)) / (a (i + 1) -a (i )) for i = 1 ... C,

The coefficient a (i) is obtained from Table 1 below.

4) Allowable interference is calculated for each section with a suitable quasi-acoustic model, see above. Band-to-band masking is produced from allowed interference.

T (i, b) = MAX (k = 1 ... i-1; E (k, b) ^* z (ik))

Masking in band;

s (i, b) = max (E (i, b) ^* e (i), T (i, b))

And masking between blocks:

ss (i, b) = max (s (i, b-1) / 16, s (i, b))

Follow the calculation of the number of bits required for each block.

5) Calculation of the number of bits required for the block.

a) Coding as in the case of OCF (Huffman Coating)

p = pO + SUM (i = 1 ... c; (a (i + 1) -a (i) ^* (s (i, b) / ss (i, b)))

b) for PCM coating (SNR = 6dB / bit):

As additional information, the size element and the number of bits per sampling value are transmitted for each section.

p = pO + SUM (i = 1 ... c; (a (i + 1)) * 10/6 * log (E (i, b) / ss (i, b)))

The individual values, the fitted values for each individual constant, are given in the table below.

n = 512

c = 23

pO = 1200 for OCF (average number of bits per block)

pO = 345 for PCM (size factor: 10 bit / section, coding of quantization step number: 5 bit / section)

This is accompanied by the allocation of the number of bits for the individual signals. For this it is assumed that k (k) -bits are required to code the k input signal while the psoll number of bits is being processed.

psum = Sum ((p) k))

Derivation required at this stage;

1) If psum = psoll, each signal receives the required number of bits.

z (k) = p (k)

2) If psum <psoll, each signal receives more than the required number of bits:

z (k) = (psoll / psum) * p (k)

e.g., k = 2, psoll = 1600, p (1) = 540, p (2) = 660

psum = 1200

z (1) = 1600/1200 * 540 = 720 (more than 180 bits)

z (2) = 1600/1200 * 660 = 880 (more than 200 bits)

3) if psoll〉 psum

Each signal receives less than the required number of bits:

a) For OCF:

z (k) = (psoll / psum) * p (k)

b) About PCM:

The minimum number of bits for each signal shall not be undercut:

z (k) = pO + ((psoll-K ^* pO)) * (p (k) -po)

e.g., K = 2, psoll = 1600, pO = 500, p (1) = 600,

p (2) = 1200

then Psum = 1800

z (1) = 500 + (1600-2 * 500) / (1800-2 * 500) * (600-500) = 575

(25 bits less)

z (2) = 500 + (1600-2 * 500) / (1800-2 * 500) * (1200-500) -1025

(175 bits less)

To correct for acceptable interference, the following derivative is needed if p bits are required for each signal except that Z bits are allocated:

1) If the number of bits allocated is equal to the required number:

No correction is required.

2) If more bits than required are allocated:

About OCF:

No correction is required.

About PCM:

The number of bits being processed for quantization in each section is increased by (Z-P) / 512.

3) If the number of bits allocated is less than required:

About OCF:

ss (i, b) = s (i ^* b) + (z-po) / (p-oO ^* (ss (i, b) -s (i, b))

for p〉 po

ss (i, b) = s (i, b) for p <= po

About PCM:

The number of bits being processed for quantization in each section is increased by (z-p) / 512. In the case of PCM, rounding to an integer per ATW is required: for this purpose all bits / ATW are rounded up to the next lowest integer and the resulting bit sum is determined from it.

If there are still bits being processed, more than one bit / ATW will be placed in processing during the first evaluation run for each band starting with the lowest band until the number of bits being processed is different.

The present invention has been described above using the preferred embodiments. Of course, many other variations are possible within the scope of the invention as a whole:

The fixed overall block length can be employed with the replacement of a coder that fills the bit being used or is not yet finished. Later, flexible block lengths are adopted, and the maximum block lengths are determined and averaged at the next time.

Claims (11)

Individual signals are divided into blocks and the blocks are transformed into spectral coefficients by transforming or filtering, and the spectral coefficients are simultaneously transmitted via a corresponding number of transmission channels from N signal sources, which undergo data reduction. In the method, the blocks belonging to the individual signals are divided into sections, each current section of all signals are processed simultaneously, and the allowable interference for each section is determined using a recognition-designation model. The total transmission capacity currently required is calculated, and-the allocation of the maximum transmission capacity being processed for each individual signal is calculated from the total transmission capacity being processed and the capacity currently determined according to the total required transmission capacity and each of the individual signals being coded accordingly. The signal from the N signal sources, characterized in that transmitted to Simultaneously transmitting via a corresponding number of transmission channels. 2. A corresponding number of signals from N signal sources as claimed in claim 1, characterized in that there is a storage of the storage capacity (bit storage) where the allocation takes place if the total transmission capacity required exceeds the average transmission capacity in processing. Simultaneous transmission via a transmission channel. 3. The method of claim 2, wherein if the required transmission capacity is much smaller than the processing capacity being processed, then a forced allocation takes place to prevent the bit storage from growing too large. Simultaneously transmitting via a corresponding number of transmission channels. 4. Signals from N signal sources as claimed in claim 3, wherein if the required transmission capacity is much smaller than the processing capacity being processed, then forced allocation takes place to prevent the bit storage from increasing too large. Simultaneously transmitting via a corresponding number of transmission channels. 5. A method as claimed in claim 4, wherein if there is a demand that is larger than the average request, only the forced allocation takes place, simultaneously via the corresponding number of transmission channels. 6. A method according to any one of claims 1 to 5, characterized in that the acknowledgment input signal is recognized and transmitted only once in an appropriate transmission format via the corresponding number of transmission channels simultaneously. Way. 2. A method according to claim 1, wherein the determination of the currently required transmission capacity takes place accurately, via signals of N number of transmission channels. 2. A method according to claim 1, wherein the determination of the currently required transmission capacity is only evaluated, via the corresponding number of transmission channels. 2. The information of claim 1, wherein the entire block is formed from all of the separately coded signals from the signal source, and the entire block is information such that the separation of the individual signals can be determined so that it can consist of several regions of flexible length. And transmitting the signals from the N signal sources simultaneously through a corresponding number of transmission channels. 2. The method according to claim 1, wherein said coding of said individual signals occurs already during the calculation of the transmission capacity allocation for each signal simultaneously via the corresponding number of transmission channels. How to. 2. The method of claim 1, wherein if the required number of bits exceeds the total number of bits being processed, the allowable interference is increased for all signal sources, resulting in a reduced bit request. Simultaneously transmitting via a corresponding number of transmission channels.