GB2392359A - Allocating a bitrate for a data signal according to the complexity of an associated audio signal - Google Patents
Allocating a bitrate for a data signal according to the complexity of an associated audio signal Download PDFInfo
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- GB2392359A GB2392359A GB0219614A GB0219614A GB2392359A GB 2392359 A GB2392359 A GB 2392359A GB 0219614 A GB0219614 A GB 0219614A GB 0219614 A GB0219614 A GB 0219614A GB 2392359 A GB2392359 A GB 2392359A
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- 230000005236 sound signal Effects 0.000 title claims abstract description 74
- 238000000034 method Methods 0.000 claims description 41
- 230000001419 dependent effect Effects 0.000 claims description 7
- 238000012545 processing Methods 0.000 claims description 6
- 238000007906 compression Methods 0.000 claims description 4
- 230000006835 compression Effects 0.000 claims description 3
- 230000003247 decreasing effect Effects 0.000 abstract description 3
- 238000004891 communication Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000000873 masking effect Effects 0.000 description 2
- 238000012544 monitoring process Methods 0.000 description 2
- 238000013459 approach Methods 0.000 description 1
- 230000003139 buffering effect Effects 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 239000000284 extract Substances 0.000 description 1
- 230000002045 lasting effect Effects 0.000 description 1
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Classifications
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04H—BROADCAST COMMUNICATION
- H04H20/00—Arrangements for broadcast or for distribution combined with broadcast
- H04H20/28—Arrangements for simultaneous broadcast of plural pieces of information
- H04H20/30—Arrangements for simultaneous broadcast of plural pieces of information by a single channel
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- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10L—SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING
- G10L19/00—Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis
- G10L19/002—Dynamic bit allocation
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04H—BROADCAST COMMUNICATION
- H04H20/00—Arrangements for broadcast or for distribution combined with broadcast
- H04H20/42—Arrangements for resource management
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- Audiology, Speech & Language Pathology (AREA)
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- Acoustics & Sound (AREA)
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Abstract
A metric such as the sum of signal-to-mask ratios of the audio signal is used to determine the complexity 308 of the signal. During complex audio passage 312 the data bitrate 306 is decreased and vice versa for more simple audio passages 314. The invention is preferably used with frame based signals. The audio signal and data signal are combined into a variable or fixed rate signal having audio and data components and further including an indication of the data bitrate. The invention may be used to increase the amount of X-PAD data transmitted in a digital audio broadcast.
Description
Audio Processing This invention relates to the field of audio signals.
More specifically, this
invention relates to audio signals having associated data signals and, in a 5 preferred embodiment, to digital audio broadcasts (DAB).
In the field of audio communications some audio formats allow for a small
amount of data to be carried with an audio signal. It is however increasingly desirable to carry a higher data bitrate in parallel with an audio 10 signal than is provided for in existing formats.
Considering prior art DAB encoding for example, the total size of a DAB
audio frame is fixed by the chosen bitrate, and the audio coder has to reduce the audio to fit within this size. At 1 28kbiVs, each DAB frame 15 contains 384 bytes, of which just two bytes are reserved exclusively for data signals such as Dynamic Range Control (DRC) and Programme associated Data (PAD). This is insufficient to support even the most basic of PAD streams such as Dynamic Labels. To overcome this a DAB encoder can be configured to allocate some of the bytes normally used for 20 audio to the PAD stream. These extra bytes are known as X-PAD. Prior art
encoders can use anywhere between 4 and 192 bytes of X-PAD per frame, 8 bytes per frame (4% at 128kbiVs) being typical.
Allocating audio bytes to carry non audio data obviously reduces the 25 amount of audio data carried since the total length of the frame is fixed.
This requires the audio encoder to 'throw away' some of the audio to make space available for X-PAD. This can have a direct effect on the audio quality. 30 It is an object of the invention therefore, to provide an improved method for combining an audio signal and a data signal. It is a further object of the invention to provide an improved method of combining an audio signal and a data signal in a digital audio broadcast.
35 In a first aspect the invention provides a method for processing an audio signal and a data signal, the method comprising dynamically allocating a bitrate to said data signal which varies according to a metric representative of the complexity of said audio signal.
In this novel method, by monitoring the audio signal and obtaining a measure of the complexity or redundancy of the audio signal, 'simple' audio passages can be identified. It has been found that during such passages, an increased amount of data can be communicated alongside 5 the audio signals in a given channel capacity, without any degradation in perceived quality. This may enable a data signal and an audio signal of a given quality to be communicated at a lower overall information rate than could otherwise have been achieved. Conversely, for a fixed channel capacity, a higher overall bitrate for a data signal can be achieved, again to without loss of perceived overall audio quality. By continually monitoring the audio signal the information rate of the data may be varied dynamically.
It is important to note that the bitrate assigned to the data is not dependent on the complexity of the data, but rather the complexity of another signal.
15 The data itself may be compressed.
Preferably, the metric used is dependent on the signal-to-mask ratios (SMR) of the audio signal. These values can be derived from masker sound levels and masking thresholds for the audio signal, which in turn 20 may be derived using a Fast Fourier Transform (FFT) of the audio signal.
More preferably the metric is dependent on the arithmetic sum of the signal-to-mask ratios (SSMR). It has been found that this value is very high for 'simple' audio such as a sine wave, but is much lower for complex audio such as white noise. Furthermore real broadcast audio typically has 25 SSMR values which vary quite significantly: musical pieces show a very rhythmic SSMR, while speech has much higher SSMR values during natural pauses, such as at the end of a sentence.
SSMR values can therefore be used for determining the bitrate to be 30 allocated to data signals being combined with an audio signal. When the SSMR value of the audio signal is high, the signal may contain a large amount of redundancy, and consequently the data bitrate may be increased, and any corresponding decrease in audio bitrate will have less perceived effect. In a similar fashion, when the SSMR value is low the 35 audio signal may contain relatively little redundancy, and so the data bitrate should preferably be reduced, to minimise reduction in audio quality.
It should be appreciated that other measures of audio complexity could be derived and used for determining data bitrate allocation. A very basic
embodiment for example might simply detect pauses between music and/or speech. Alternative measures for determining audio complexity are known in the field of audio coding and include, for example,the noise-to-
mask ratio (NMR). The metric may be derived from a measure of 5 complexity or quality used in a compression process, or may be an independent measure.
Preferably, the signal is divided into discrete time periods, and a measure of complexity is derived for each period. Audio and data bit rates may be 10 allocated accordingly for each period. Preferably the data signals are frame based, and more preferably, the bitrate of the data signals is determined on a frame-by-frame basis. In such a frame based system, the number of bytes assigned to data signals may vary from frame to frame.
15 In one embodiment, the dynamically varying bitrate allocated to the data stream may be represented in an output signal and passed to a separate encoder, for example a DAB encoder adapted to receive such a signal. In an alternative embodiment, the information representing the data stream bitrate may be combined with the data stream itself. In certain situations it 20 may be advantageous to operate a number of discrete data bitrates, and then it might be possible to set aside a small number of bits within each data segment to indicate the data rate for that particular segment. A variation on this approach would be to assign a data bit rate for each segment which varies incrementally, and to include an 'up or down' flag or 2s incremental adjustment in the data stream which might only comprise a single bit per segment. Indicating the data rate as a portion of the data signal might be of benefit where, for example, it is desired to further encode or multiplex the data signal. The signal will intrinsically carry with it information about the data bitrate, and it will consequently be easier to 30 decode.
The dynamic bitrate derived according to the invention can be used to encode or multiplex the data signal. Preferably the audio signal and data signal are combined to form an output signal.
This invention can be used advantageously when the bitrate of the combined signal is constrained as is often the case in communications applications, for example in a protocol with a limited channel capacity.
In a preferred application where the audio and data are carried in a fixed total channel capacity, the present invention may vary the bitrate of the audio signal conversely with the bitrate of the data signal. In this embodiment the bitrate of the combined signal is maintained constant, but 5 the bitrate allocated to the component signals is varied according to the derived value representative of the complexity of the audio signal.
Decreasing the bitrate of data during complex audio passages allows the audio signal to be represented at a greater bitrate to ensure high quality reproduction, while maintaining the total bitrate constant. In a similar 10 fashion, during 'simple' audio passages containing redundancy the data bitrate can be increased, with the audio signal able to be represented at a lower bitrate without loss of perceived quality.
The invention is not, however, limited to fixed bitrate signals, and the 15 measure of complexity can be used to vary the data rate so that, over a period of time, a target bitrate is approximated. In an application where it is desired to transmit audio and associated data via a packet based medium, for example the intemet, the signal could be coded in order to achieve an overall data rate based on a measure of average bandwidth, for example 20 based on a user's connection speed, for example 64 kbiVs. The bitrate of the audio may be controlled directly, based on the bitrate allocated to the data and/or the measure of complexity. The audio might equally be compression encoded in such a way that less complex passages are automatically compressed into a lower bitrate, without direct control of the 25 overall audio bitrate.
Typically, the combined signal will have default, maximum and minimum data bitrate thresholds. Similarly, the audio signal will typically have maximum and minimum audio bitrate thresholds, and therefore the range 30 of audio bitrate to data bit rate ratios is likely to be limited in many applications. In one embodiment the audio signal may have a default bitrate which is allocated to the audio stream during audio passages exceeding a threshold 35 complexity. During this time a minimum data rate may also be maintained.
When the audio complexity falls below the threshold value, the audio bitrate may be decreased, and the data rate may be increased by a corresponding amount, keeping the total bitrate of the combined signal substantially or exactly constant. During audio passages with a large
amount of redundancy the audio bitrate may be reduced to a predetermined minimum value, and the data rate may increase to its maximum value correspondingly. Discrete values of audio and data bitrate may be assigned, and a coder might typically switch between these values S at predetermined audio complexity levels.
Although the bitrates of the component streams may vary dynamically, the encoding and decoding of the signal can be performed so as to provide an average' data rate over a continuous period. This can be achieved for 10 example using buffering.
It should be appreciated that the data signal may comprise a combination of individual data streams. The data may itself be compressed either by lossless or 'lossy' compression. Likewise it should be understood that the 15 data signal may comprise another audio stream. More than one audio channel may be carried (eg. stereo or multi channel) and the complexity of individual channels or an aggregate complexity may be determined.
In one embodiment, the audio signal and data signal comprise a digital 20 audio broadcast, and the data signal comprises programme associated data (PAD) In one embodiment, the invention is used to vary the amount of XPAD in a DAB signal according to a metric representative of the complexity of the 25 audio signal associated with said broadcast. In such an embodiment, dynamically varying the amount of X-PAD in the signal can be done in a way which is completely compatible with the existing DAB specification,
and will thus be backwards compatible with older receivers.
30 Typically the DAB signal will be frame based, and at a given bitrate, each DAB frame is constrained to a certain size. At 128 KbiVs each DAB frame contains 384 bytes.
In a second aspect the invention provides a method for allocating a bitrate 35 for a data signal associated with an audio signal, the method comprising analysing the audio signal to determine a metric representative of the complexity of said audio signal and dynamically allocating a bitrate for said data signal according to said metric.
In a third aspect the invention provides a method for combining an audio signal and a data signal to provide a frame based signal, the method comprising analysing the audio signal to determine a measure of audio complexity, comparing the measure of audio complexity with at least one 5 threshold value, and allocating a number of bytes to said data signal for each frame according to the results of the comparison.
In a fourth aspect the invention provides an apparatus for processing an audio signal and a data signal, comprising means for determining a metric 10 representative of the complexity of said audio signal, and means for dynamically allocating a bitrate for said data according to said metric.
Preferably the metric is dependent on the signal-to-mask ratios of the audio signal.
Preferably the bitrate of the data signals will be varied on a period-by period basis. More preferably the data signal will be frame based, and the data bitrate will be varied on a frame-to-frame basis.
20 The apparatus will desirably further comprise means for outputting the data signal at the allocated data rate, and still more desirably will combine the audio signal and the data signal to produce an output signal. The audio bitrate may be varied conversely with the data bitrate.
2s In a fifth aspect the invention provides a coder for combining an audio signal and a data signal comprising means for periodically varying the bitrate of said data signal according to the complexity of the audio signal.
In a sixth aspect the invention provides a signal representing an audio 30 stream and a data stream, said data stream having a dynamically varying bitrate, and said signal containing an indication of the bitrate of said data stream. Preferably the indication of the bitrate of said data stream is included in said data stream.
35 In a seventh aspect the invention provides a method of demultiplexing a signal representing an audio stream and a data stream, said data stream having a dynamically varying bitrate, the method comprising analysing the signal to detect an indication of the bitrate of said data stream, and demultipiexing the signal accordingly.
In an eighth aspect the invention provides an apparatus for demuitiplexing a signal representing an audio stream and a data stream, said data stream having a dynamically varying bitrate, comprising means for analysing said s signal and detecting an indication of the bitrate of said data stream, and means for demultiplexing the signal accordingly.
The invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a schematic diagram of a basic DAB audio encoder Figure 2 illustrates the structure of a DAB frame Figure 3 illustrates variable bitrate allocation in a communications channel according to an embodiment of the invention.
15 Figure 4 is a schematic diagram of a demultiplexer according to a further embodiment of the invention Figure 1 shows the basic structure of a prior art DAB encoder which uses a
slightly modified version of MPEG-1 Layer-ll (MP2) audio encoding. The 20 encoder receives a PCM audio input 102 and a programme associated data (PAD) input 104. The PCM audio is fed into an audio encoder 106, with one feed to an analysis filterbank 108 and another feed to a Fast Fourier Transform (FFT) stage 109. From the FFT of the signal, masking thresholds are calculated, and from these, signal-to-mask ratios 110 are 25 calculated. The signal-to-mask ratios are fed into an audio bit and scalefactor allocation stage 111, along with scalefactors derived from the audio signal after it has passed through the analysis filterbank. The audio signal then undergoes scaling and quantising based on the bit and scalefactor allocation. The final stage 112 of the encoder is to combine the 30 encoded audio, along with audio coding information, with the PAD from input 104 and optionally with data from a dynamic range control (DRC) generator 1 14.
Figure 2 illustrates the different components in a DAB frame. As described 35 in the introduction, a small number of bytes per frame (typically 2) are
allocated exclusively for DRC and PAD, with the rest being used for audio (Figure 2a). In prior art encoders a number of X-PAD bytes might be used
in place of some audio bytes to increase the data rate, but at the expense of available space to transmit audio (Figure 2b).
Figure 3 illustrates an embodiment of the present invention wherein variation of the bitrate of a data signal in a given period can be achieved dynamically. An audio signal and an associated data signal are multiplexed 5 into a channel of fixed capacity 300. The signal is frame based, and each frame comprises an audio portion 302, a default data portion 304 and a variable data portion 306. A measure of the complexity 308 of the audio signal is determined, and for each frame (lasting one frame period shown as 310) a complexity level can be ascertained. The number of bytes 10 comprising the variable data potion in each frame is determined according to the complexity level for that frame. A period of complex audio 312 results in a lower data rate, and vice versa for a period of low complexity audio 314.
15 Referring to Figure 4, a demultiplexer according to a further embodiment of the invention will be described. An input signal is fed into an analysis stage 402 which extracts an indication of the bitrate which is contained within the input signal. The bitrate indication and the input signal are then fed to a demultiplexer 404, which separates the combined signal into audio and 20 data signals, according to the data bitrate. The audio and data signals may then be passed to decoding stages (not shown) which may be largely conventional. It should be appreciated that embodiments described above are given 2s merely for example and in no way limit the scope of the invention. Whilst a measure of complexity has been shown as a continuous variable, it might equally be derived as a discrete variable. Although DAB has been illustrated as an example, the invention will find application in a wide range of communication applications. Each feature described herein may be 30 provided independently unless otherwise stated.
Claims (42)
1. A method for processing an audio signal and a data signal, the method comprising dynamically allocating a bitrate for said data signal which varies according to a metric representative of the complexity of said audio signal.
2. A method according to Claim 1, wherein the bitrate for said data
signal is increased during periods of low complexity audio.
3. A method according to any preceding claim, wherein the metric is dependent upon the signal-to-mask ratios of the audio signal.
4. A method according to any preceding claim, wherein the metric is dependent upon the arithmetic sum of the signal-to-mask ratios of the audio signal.
5. A method according to any preceding claim, wherein the metric is derived from a metric determined during compression encoding of the audio signal.
6. A method according to any preceding claim, wherein the bitrate for said data signal is allocated on a period-by-period basis.
7. A method according to any preceding claim, wherein said data signal is frame based and wherein the bitrate for said data signal is allocated on a frame-by-frame basis.
8. A method according to any preceding claim, wherein the bitrate for said data signal has a minimum threshold.
9. A method according to any preceding claim, wherein the bitrate for said data signal has a maximum threshold.
10.A method according to any preceding claim, wherein said data signal comprises more than one individual data stream.
11.A method according to any preceding claim, wherein said data signal comprises an audio stream.
12.A method according to any preceding claim, further comprising outputting said data signal at said allocated bitrate.
13.A method according to Claim 12, further comprising varying the bitrate of said audio signal conversely with the bitrate of said data signal.
14. A method according to Claim 13, wherein the bitrate of said audio signal has a minimum threshold value.
15.A method according to Claim 13, wherein the bitrate of said audio signal has a maximum threshold value.
16.A method according to any preceding claim, further comprising combining said audio and said data signal to produce an output signal.
17. A method according to Claim 16, wherein the bitrate of the combined signal is constrained.
18.A method according to any preceding claim, wherein said audio signal and said data signal comprise a digital audio broadcast (DAB).
19.A method according to any preceding claim, wherein said data signal comprises programme associated data (PAD).
20.A method according to any preceding claim, further comprising producing an output indicating the bitrate allocated to said data signal.
21.A method according to Claim 20, wherein said output indicating the bitrate allocated to said data signal is combined with said data signal.
22.A method for allocating a bitrate for a data signal associated with an audio signal, the method comprising analysing the audio signal to determine a metric representative of the complexity of said audio
signal and dynamically allocating a bitrate for said data signal according to said metric.
23.A method for combining an audio signal and a data signal to provide a frame based signal, the method comprising analysing the audio signal to determine a measure of audio complexity, comparing the measure of audio complexity with at least one threshold value, and allocating a number of bytes to said data signal for each frame according to the results of the comparison.
24.Apparatus for processing an audio signal, comprising means for determining a metric representative of the complexity of said audio signal, and means for dynamically allocating a bitrate for an accompanying data signal according to said metric.
25. Apparatus for processing an audio signal and a data signal, comprising means for determining a metric representative of the complexity of said audio signal, and means for dynamically allocating a bitrate for said data signal according to said metric.
26.Apparatus according to Claim 24 or Claim 25, wherein the bitrate for said data signal is increased during periods of low complexity audio.
27.Apparatus according to any one of Claims 24 to 26, wherein the metric is dependent upon the signal-to-mask ratios of the audio signal.
28. Apparatus according to any one of Claims 24 to 27, wherein the bitrate for said data signal is varied on a period-by-period basis.
29.Apparatus according to any one of Claims 24 to 28, wherein said data signal is frame based, and wherein the bitrate for said data signal is varied on a frame-by-frame basis.
30.Apparatus according to any one of Claims 24 to 29, further comprising means for outputting said data signal at said allocated data rate.
31.Apparatus according to any one of Claims 24 to 30, further comprising means for varying the bitrate of said audio signal conversely with the bitrate of said data signal.
32.Apparatus according to any one of Claims 24 to 31, further comprising means for combining said audio signal and said data signal to produce an output signal.
33.Apparatus according to Claim 32, wherein the bitrate of the combined signal is constrained.
34.Apparatus according to any one of Claims 24 to 33, further comprising an output for indicating the bitrate allocated to said data signal.
35. Apparatus according to Claim 34, wherein said output indicating the bitrate allocated to said data signal is combined with said data signal.
36.A coder for combining an audio signal and a data signal comprising means for periodically varying the bitrate of said data signal according to the complexity of the audio signal.
37.A signal comprising an audio signal and a data signal, said data signal having a bitrate which varies dynamically according to the complexity of the audio signal, said signal further comprising an indication of the bitrate of said data signal.
38.A signal according to Claim 37, wherein the indication of the bitrate of said data stream is included in a portion of said data stream.
39.A method of demultiplexing a signal comprising an audio signal and a data signal, said data signal having a bitrate which varies dynamically according to the complexity of the audio signal, the method comprising analysing the signal to detect an indication of the bitrate of said data signal, and demultiplexing the signal accordingly.
40.Apparatus for demultiplexing a signal comprising an audio signal and a data signal, said data signal having a bitrate which varies dynamically according to the complexity of the audio signal, the
method comprising analysing the signal to detect an indication of the bitrate of said data signal, and means for demultiplexin3 the signal accordingly.
41.A method substantially as herein described with reference to the accompanying drawings.
42.Apparatus substantially as herein described with reference to the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0219614A GB2392359B (en) | 2002-08-22 | 2002-08-22 | Audio processing |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0219614A GB2392359B (en) | 2002-08-22 | 2002-08-22 | Audio processing |
Publications (3)
| Publication Number | Publication Date |
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| GB0219614D0 GB0219614D0 (en) | 2002-10-02 |
| GB2392359A true GB2392359A (en) | 2004-02-25 |
| GB2392359B GB2392359B (en) | 2005-07-13 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB0219614A Expired - Fee Related GB2392359B (en) | 2002-08-22 | 2002-08-22 | Audio processing |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2248263A1 (en) * | 2008-01-31 | 2010-11-10 | Agency for Science, Technology And Research | Method and device of bitrate distribution/truncation for scalable audio coding |
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| JPH06334998A (en) * | 1993-05-25 | 1994-12-02 | Hitachi Ltd | Portable visual telephone |
| DE4430864A1 (en) * | 1994-08-31 | 1996-03-07 | Corporate Computer Systems Eur | Transmission and storage method for embedding additional information in data stream |
| WO1997028620A1 (en) * | 1996-01-30 | 1997-08-07 | Oy Nokia Ab | Coding of file segments on a digital radio channel |
| EP0843429A2 (en) * | 1996-11-18 | 1998-05-20 | Kabushiki Kaisha Kenwood | Broadcast receiver for receiving digital audio broadcast comprising supplementary data |
| WO1998042090A1 (en) * | 1997-03-14 | 1998-09-24 | Siemens Aktiengesellschaft | Method for transmitting information to a mobile receiver such as a pager, using radio transmitters |
| EP0899886A2 (en) * | 1997-08-26 | 1999-03-03 | Samsung Electronics Co., Ltd. | High quality audio encoding/decoding apparatus |
| WO2000007303A1 (en) * | 1998-07-29 | 2000-02-10 | British Broadcasting Corporation | Method for inserting auxiliary data in an audio data stream |
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2002
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH06334998A (en) * | 1993-05-25 | 1994-12-02 | Hitachi Ltd | Portable visual telephone |
| DE4430864A1 (en) * | 1994-08-31 | 1996-03-07 | Corporate Computer Systems Eur | Transmission and storage method for embedding additional information in data stream |
| WO1997028620A1 (en) * | 1996-01-30 | 1997-08-07 | Oy Nokia Ab | Coding of file segments on a digital radio channel |
| EP0843429A2 (en) * | 1996-11-18 | 1998-05-20 | Kabushiki Kaisha Kenwood | Broadcast receiver for receiving digital audio broadcast comprising supplementary data |
| WO1998042090A1 (en) * | 1997-03-14 | 1998-09-24 | Siemens Aktiengesellschaft | Method for transmitting information to a mobile receiver such as a pager, using radio transmitters |
| EP0899886A2 (en) * | 1997-08-26 | 1999-03-03 | Samsung Electronics Co., Ltd. | High quality audio encoding/decoding apparatus |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2248263A1 (en) * | 2008-01-31 | 2010-11-10 | Agency for Science, Technology And Research | Method and device of bitrate distribution/truncation for scalable audio coding |
| EP2248263A4 (en) * | 2008-01-31 | 2012-03-14 | Agency Science Tech & Res | Method and device of bitrate distribution/truncation for scalable audio coding |
| US8442836B2 (en) | 2008-01-31 | 2013-05-14 | Agency For Science, Technology And Research | Method and device of bitrate distribution/truncation for scalable audio coding |
Also Published As
| Publication number | Publication date |
|---|---|
| GB0219614D0 (en) | 2002-10-02 |
| GB2392359B (en) | 2005-07-13 |
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