Title of Invention	"METHOD FOR PROCESSING TWO OR MORE AUDIO SIGNALS"
Abstract	Method for processing two or more audio signals, which have been initially decoded by corresponding decoders (21, 22, 23), said two or more initially decoded audio signals being received or replayed from a bitstream and having a different number of channels and/or different channel configurations, and which two or more initially decoded audio signals are combined by a mixer or mixing stage (27) and/or a mixing or switcher stage (28) before being presented (20) in a final channel configuration, wherein to each one of said initially decoded audio signals a corresponding specific channel configuration information item (ChannelConfig) is attached and the channel configuration information items for said two or more initially decoded audio signals demand channel configurations conflicting with each other, characterized by: controlling said mixer or mixing stage (27) and/or said mixing or switcher stage (28) by a control unit or stage (278) that receives related mixing and/or switching information provided from a content provider or broadcaster and that is embedded in said bitstream, such that in case of non-matching number of channels and/or non-matching types of channel configurations the number of the channels to be output and/or the configuration type of the channels to be output following said mixing and/or said switching is determined by said specific mixing and/or switching information attaching in a channel configuration node (30) to the combined data stream to be presented a correspondingly updated channel configuration information item.

Title of Invention

"METHOD FOR PROCESSING TWO OR MORE AUDIO SIGNALS"

Abstract

Method for processing two or more audio signals, which have been initially decoded by corresponding decoders (21, 22, 23), said two or more initially decoded audio signals being received or replayed from a bitstream and having a different number of channels and/or different channel configurations, and which two or more initially decoded audio signals are combined by a mixer or mixing stage (27) and/or a mixing or switcher stage (28) before being presented (20) in a final channel configuration, wherein to each one of said initially decoded audio signals a corresponding specific channel configuration information item (ChannelConfig) is attached and the channel configuration information items for said two or more initially decoded audio signals demand channel configurations conflicting with each other, characterized by: controlling said mixer or mixing stage (27) and/or said mixing or switcher stage (28) by a control unit or stage (278) that receives related mixing and/or switching information provided from a content provider or broadcaster and that is embedded in said bitstream, such that in case of non-matching number of channels and/or non-matching types of channel configurations the number of the channels to be output and/or the configuration type of the channels to be output following said mixing and/or said switching is determined by said specific mixing and/or switching information attaching in a channel configuration node (30) to the combined data stream to be presented a correspondingly updated channel configuration information item.

Full Text	The present invention relates to a method for processing two or more audio signals. The invention relates to a method and to an apparatus for processing two or more initially decoded audio signals re¬ceived or replayed from a bitstream, that each have a dif¬ferent number of channels and/or different channel configu¬rations, and that are combined before being presented in a final channel configuration. Background In the MPEG-4 standard ISO/IEC 14496:2001, in particular in part 3 Audio and in part 1 Systems, several audio objects that can be coded with different MPEG-4 format coding types can together form a composed audio system representing a single soundtrack from the several audio substreams. User interaction, terminal capability, and speaker configuration may be used when determining how to produce a single sound¬track from the component objects. Audio composition means mixing multiple individual audio objects to create a single soundtrack, e.g. a single channel or a single stereo pair. A set of instructions for mixdown is transmitted or trans¬ferred in the bitstream. In a receiver the multiple audio objects are decoded separately, but not directly played back to a listener. Instead, the transmitted instructions for mixdown are used to prepare a single soundtrack from the de¬coded audio objects. This final soundtrack is then played for the listener. ISO/IEC 14496:2001 is the second version of the MPEG-4 Audio standard, whereas ISO/IEC 14496 is the first version. In the above MPEG-4 Audio standard nodes for presenting au¬dio are described. Header streams that contain configuration information, which is necessary for decoding the audio sub-streams are transported via MPEG-4 Systems. In a simple au- dio scene the channel configuration of the audio decoder- for example 5.1 multichannel-can be fed inside the Com- positor from one node to the following node so that the channel configuration information can reach the presenter, which is responsible for the correct loudspeaker mapping. The presenter represents that final part of the audio chain which is no more under the control of the broadcaster or content provider, e. g. an audio amplifier having volume con- trol and the attached loudspeakers. Node'means a processing step or unit used in the above MPEG-4 standard, e. g. an interface carrying out time syn- chronisation between a decoder and subsequent processing units, or a corresponding interface between the presenter and an upstream processing unit. In general, in ISO/IEC 14496-1: 2001 the scene description is represented using a parametric approach. The description consists of an encoded hierarchy or tree of nodes with attributes and other infor- mation including event sources and targets. Leaf nodes in this tree correspond to elementary audio-visual data, whereas intermediate nodes group this material to form au- dio-visual objects, and perform e. g. grouping and transfor- mation on such audio-visual objects (scene description nodes). Audio decoders either have a predetermined channel configu- ration by definition, or receive e. g. some configuration in- formation items for setting their channel configuration. Invention Normally, in an audio processing tree the channel configura- tion of the audio decoders can be used for the loudspeaker mapping occurring after passing the sound node, see ISO/IEC 14496-3: 2001, chapter 1.6. 3.4 Channel Configuration. There- fore, as shown in Fig. 1, an MPEG-4 player implementation passes these information items, that are transmitted within a received MPEG-4 bitstream, together with the decoder out- put or outputs through the audio nodes AudioSource and Sound2D to the presenter. The channel configuration data ChannelConfig is to be used by the presenter to make the correct loudspeaker association, especially in case of multi-channel audio (numChan > 1) where the phaseGroup flags in the audio nodes are to be set. However, when combining or composing audio substreams having different channel assignments, e. g. 5.1 multichannel sur- round sound and 2.0 stereo, some of the audio nodes (AudioMix, AudioSwitch and AudioFX) defined in the current MPEG-4 standard mentioned above can change the fixed channel assignment that is required for the correct channel repre- sentation, i. e. such audio nodes have a channel-variant be- haviour leading to conflicts in the channel configuration transmission. A problem to be solved by the invention is to deal properly with such channel configuration conflicts such that the pre- senter can replay sound with the correct or the desired channel assignments. This problem is solved by the method disclosed in claim 1. An apparatus that utilises this method is disclosed in claim 3. The invention discloses different but related ways of solv- ing such channel configuration confusion by using channel- variant audio nodes. An additional audio channel configura- tion node is used, or its functionality is added to the ex- isting audio mixing and/or switching nodes. This additional audio channel configuration node tags the correct channel configuration information items to the decoded audio data streams that pass through the Sound2D node to the presenter. Advantageously, the invention enables the content provider or broadcaster to set the channel configuration in such a way that the presenter at receiver side can produce a cor- rect channel presentation under all circumstances. An escape code value in the channel configuration data fa- cilitates correct handling of not yet defined channel combi- nations even in case signals having different channel con- figurations are mixed and/or switched together. The invention can also be used in any other multi-channel application wherein the received channel data are passed through a post processing unit having the inherent ability to interchange the received channels at reproduction. In principle, the inventive method is suited for processing two or more initially decoded audio signals received or re- played from a bitstream, that each have a different number of channels and/or different channel configurations, and that are combined by mixing and/or switching before being presented in a final channel configuration, wherein to each one of said initially decoded audio signals a corresponding specific channel configuration information is attached, and wherein said mixing and/or switching is controlled such that in case of non-matching number of channels and/or types of channel configurations the number and/or configuration of the channels to be output following said mixing and/or fol- lowing said switching is determined by related specific mix- ing and/or switching information provided from a content provider or broadcaster, and wherein to the combined data stream to be presented a correspondingly updated channel configuration information is attached. In principle the inventive apparatus includes: - at least two audio data decoders that decode audio data received or replayed from a bitstream; - means for processing the audio signals initially decoded by said audio data decoders, wherein at least two of said decoded audio signals each have a different number of chan- nels and/or a different channel configuration, and wherein said processing includes combination by mixing and/or switching; - means for presenting the combined audio signals in a final channel configuration, wherein to each one of said initially decoded audio signals a corresponding specific channel con- figuration information is attached, - wherein in said processing means said mixing and/or switching is controlled such that in case of non-matching number of channels and/or types of channel configurations the number and/or configuration of the channels to be output following said mixing and/or following said switching is de- termined by related specific mixing and/or switching infor- mation provided from a content provider or broadcaster, and wherein to the combined data stream fed to said presenting means a correspondingly updated channel configuration infor- mation is attached. Advantageous additional embodiments of the invention are disclosed in the respective dependent claims. We claim: 1. Method for processing two or more audio signals, which have been initially decoded by corresponding decoders (21, 22, 23), said two or more initially decoded audio signals being received or replayed from a bitstream and having a different number of channels and/or different channel configurations, and which two or more initially decoded audio signals are combined by a mixer or mixing stage (27) and/or a mixing or switcher stage (28) before being presented (20) in a final channel configuration, wherein to each one of said initially decoded audio signals a corresponding specific channel configuration information item (ChannelConfig) is attached and the channel configuration information items for said two or more initially decoded audio signals demand channel configurations conflicting with each other, characterized by: controlling said mixer or mixing stage (27) and/or said mixing or switcher stage (28) by a control unit or stage (278) that receives related mixing and/or switching information provided from a content provider or broadcaster and that is embedded in said bitstream, such that in case of non-matching number of channels and/or non-matching types of channel configurations the number of the channels to be output and/or the configuration type of the channels to be output following said mixing and/or said switching is determined by said specific mixing and/or switching information; attaching in a channel configuration node (30) to the combined data stream to be presented a correspondingly updated channel configuration information item. 2. Method as claimed in claim 1, wherein said bitstream has MPEG-4 format.

Full Text

The present invention relates to a method for processing two or more audio signals.
The invention relates to a method and to an apparatus for processing two or more initially decoded audio signals re¬ceived or replayed from a bitstream, that each have a dif¬ferent number of channels and/or different channel configu¬rations, and that are combined before being presented in a final channel configuration.
Background
In the MPEG-4 standard ISO/IEC 14496:2001, in particular in part 3 Audio and in part 1 Systems, several audio objects that can be coded with different MPEG-4 format coding types can together form a composed audio system representing a single soundtrack from the several audio substreams. User interaction, terminal capability, and speaker configuration may be used when determining how to produce a single sound¬track from the component objects. Audio composition means mixing multiple individual audio objects to create a single soundtrack, e.g. a single channel or a single stereo pair. A set of instructions for mixdown is transmitted or trans¬ferred in the bitstream. In a receiver the multiple audio objects are decoded separately, but not directly played back to a listener. Instead, the transmitted instructions for mixdown are used to prepare a single soundtrack from the de¬coded audio objects. This final soundtrack is then played for the listener.
ISO/IEC 14496:2001 is the second version of the MPEG-4 Audio standard, whereas ISO/IEC 14496 is the first version. In the above MPEG-4 Audio standard nodes for presenting au¬dio are described. Header streams that contain configuration information, which is necessary for decoding the audio sub-streams are transported via MPEG-4 Systems. In a simple au-
dio scene the channel configuration of the audio decoder- for example 5.1 multichannel-can be fed inside the Com- positor from one node to the following node so that the channel configuration information can reach the presenter, which is responsible for the correct loudspeaker mapping.
The presenter represents that final part of the audio chain which is no more under the control of the broadcaster or content provider, e. g. an audio amplifier having volume con- trol and the attached loudspeakers.
Node'means a processing step or unit used in the above MPEG-4 standard, e. g. an interface carrying out time syn- chronisation between a decoder and subsequent processing units, or a corresponding interface between the presenter and an upstream processing unit. In general, in ISO/IEC 14496-1: 2001 the scene description is represented using a parametric approach. The description consists of an encoded hierarchy or tree of nodes with attributes and other infor- mation including event sources and targets. Leaf nodes in this tree correspond to elementary audio-visual data, whereas intermediate nodes group this material to form au- dio-visual objects, and perform e. g. grouping and transfor- mation on such audio-visual objects (scene description nodes).
Audio decoders either have a predetermined channel configu- ration by definition, or receive e. g. some configuration in- formation items for setting their channel configuration.
Invention Normally, in an audio processing tree the channel configura- tion of the audio decoders can be used for the loudspeaker mapping occurring after passing the sound node, see ISO/IEC 14496-3: 2001, chapter 1.6. 3.4 Channel Configuration. There- fore, as shown in Fig. 1, an MPEG-4 player implementation passes these information items, that are transmitted within a received MPEG-4 bitstream, together with the decoder out- put or outputs through the audio nodes AudioSource and Sound2D to the presenter. The channel configuration data ChannelConfig is to be used by the presenter to make the correct loudspeaker association, especially in case of multi-channel audio (numChan > 1) where the phaseGroup flags in the audio nodes are to be set.
However, when combining or composing audio substreams having different channel assignments, e. g. 5.1 multichannel sur- round sound and 2.0 stereo, some of the audio nodes (AudioMix, AudioSwitch and AudioFX) defined in the current MPEG-4 standard mentioned above can change the fixed channel assignment that is required for the correct channel repre- sentation, i. e. such audio nodes have a channel-variant be- haviour leading to conflicts in the channel configuration transmission.
A problem to be solved by the invention is to deal properly with such channel configuration conflicts such that the pre- senter can replay sound with the correct or the desired channel assignments. This problem is solved by the method disclosed in claim 1. An apparatus that utilises this method is disclosed in claim 3.
The invention discloses different but related ways of solv- ing such channel configuration confusion by using channel- variant audio nodes. An additional audio channel configura- tion node is used, or its functionality is added to the ex- isting audio mixing and/or switching nodes. This additional audio channel configuration node tags the correct channel configuration information items to the decoded audio data streams that pass through the Sound2D node to the presenter.
Advantageously, the invention enables the content provider or broadcaster to set the channel configuration in such a way that the presenter at receiver side can produce a cor- rect channel presentation under all circumstances.
An escape code value in the channel configuration data fa- cilitates correct handling of not yet defined channel combi- nations even in case signals having different channel con- figurations are mixed and/or switched together.
The invention can also be used in any other multi-channel application wherein the received channel data are passed through a post processing unit having the inherent ability to interchange the received channels at reproduction.
In principle, the inventive method is suited for processing two or more initially decoded audio signals received or re- played from a bitstream, that each have a different number of channels and/or different channel configurations, and that are combined by mixing and/or switching before being presented in a final channel configuration, wherein to each one of said initially decoded audio signals a corresponding specific channel configuration information is attached, and wherein said mixing and/or switching is controlled such that in case of non-matching number of channels and/or types of channel configurations the number and/or configuration of the channels to be output following said mixing and/or fol- lowing said switching is determined by related specific mix- ing and/or switching information provided from a content provider or broadcaster, and wherein to the combined data stream to be presented a correspondingly updated channel configuration information is attached.
In principle the inventive apparatus includes: - at least two audio data decoders that decode audio data received or replayed from a bitstream; - means for processing the audio signals initially decoded by said audio data decoders, wherein at least two of said decoded audio signals each have a different number of chan- nels and/or a different channel configuration, and wherein said processing includes combination by mixing and/or switching; - means for presenting the combined audio signals in a final channel configuration, wherein to each one of said initially decoded audio signals a corresponding specific channel con- figuration information is attached, - wherein in said processing means said mixing and/or switching is controlled such that in case of non-matching number of channels and/or types of channel configurations the number and/or configuration of the channels to be output following said mixing and/or following said switching is de- termined by related specific mixing and/or switching infor- mation provided from a content provider or broadcaster, and wherein to the combined data stream fed to said presenting means a correspondingly updated channel configuration infor- mation is attached.
Advantageous additional embodiments of the invention are disclosed in the respective dependent claims.

We claim:
1. Method for processing two or more audio signals, which have been initially decoded by corresponding decoders (21, 22, 23), said two or more initially decoded audio signals being received or replayed from a bitstream and having a different number of channels and/or different channel configurations, and which two or more initially decoded audio signals are combined by a mixer or mixing stage (27) and/or a mixing or switcher stage (28) before being presented (20) in a final channel configuration, wherein to each one of said initially decoded audio signals a corresponding specific channel configuration information item (ChannelConfig) is attached and the channel configuration information items for said two or more initially decoded audio signals demand channel configurations conflicting with each other, characterized by: controlling said mixer or mixing stage (27) and/or said mixing or switcher stage (28) by a control unit or stage (278) that receives related mixing and/or switching information provided from a content provider or broadcaster and that is embedded in said bitstream, such that in case of non-matching number of channels and/or non-matching types of channel configurations the number of the channels to be output and/or the configuration type of the channels to be output following said mixing and/or said switching is determined by said specific mixing and/or switching information;
attaching in a channel configuration node (30) to the combined data stream to be presented a correspondingly updated channel configuration information item.

2. Method as claimed in claim 1, wherein said bitstream has MPEG-4 format.

Documents:

1949-DELNP-2005-Abstract-(08-09-2008).pdf

1949-DELNP-2005-Abstract-(11-02-2008).pdf

1949-DELNP-2005-Abstract-(12-06-2008).pdf

1949-delnp-2005-abstract.tif

1949-DELNP-2005-Claims-(08-09-2008).pdf

1949-DELNP-2005-Claims-(11-02-2008).pdf

1949-DELNP-2005-Claims-(12-06-2008).pdf

1949-delnp-2005-claims.tif

1949-delnp-2005-correspondence-other.tif

1949-DELNP-2005-Correspondence-Others-(08-09-2008).pdf

1949-DELNP-2005-Correspondence-Others-(11-02-2008).pdf

1949-DELNP-2005-Correspondence-Others-(12-06-2008).pdf

1949-DELNP-2005-Description (Complete)-08-09-2008.pdf

1949-DELNP-2005-Description (Complete).pdf

1949-DELNP-2005-Drawings-(11-02-2008).pdf

1949-DELNP-2005-Drawings-(12-06-2008).pdf

1949-delnp-2005-drawings.tif

1949-DELNP-2005-Form-1-(08-09-2008).pdf

1949-DELNP-2005-Form-1-(11-02-2008).pdf

1949-DELNP-2005-Form-2-(08-09-2008).pdf

1949-DELNP-2005-Form-2-(11-02-2008).pdf

1949-DELNP-2005-Form-2-(12-06-2008).pdf

1949-DELNP-2005-Form-3-(11-02-2008).pdf

1949-delnp-2005-form1.tif

1949-delnp-2005-form13.tif

1949-delnp-2005-form18.tif

1949-delnp-2005-form2.tif

1949-delnp-2005-form3.tif

1949-delnp-2005-form5.tif

1949-DELNP-2005-GPA-(11-02-2008).pdf

1949-DELNP-2005-Petition-137-(11-02-2008).pdf

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Patent Number

223947

Indian Patent Application Number

1949/DELNP/2005

PG Journal Number

42/2008

Publication Date

17-Oct-2008

Grant Date

24-Sep-2008

Date of Filing

09-May-2005

Name of Patentee

THOMSON LICENSING S.A.

Applicant Address

46 QUAI ALPHONSE LE GALLO, F-92100 BOULOGNE-BILLANCOURT, FRANCE

Inventors:

#	Inventor's Name	Inventor's Address
1	JURGEN SCHMIDT	AKAZIENSTR. 5B, 31515 WUNSTORF, GERMANY
2	JENS SPILLE	KLEINES FELD 58, 30966 HEMMINGEN, GERMANY
3	ERNST F. SCHROE DER	PINKENBURGER STR. 25 D, 30655 HANNOVER, GERMANY
4	JOHANNES BOEHM	SIEBERWEG 35, 37081 GOETTINGEN, GERMANY

PCT International Classification Number

H04S1/00

PCT International Application Number

PCT/EP03/013172

PCT International Filing date

2003-11-24

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	02026779.5	2002-12-02	EUROPEAN UNION