Patent ID: 7505825

Claim:
A computer storage medium having stored thereon a data structure defining an aggregated data stream, said structure comprising: a first data field defining audio data having M channels to be specified in a first stream of the aggregated data stream; and a second data field specifying a header wherein the header includes metadata including a channel mask and specifying a continuously varying conversion function to be specified in a second stream of the aggregated data stream, said second stream being separate from the first stream, said conversion function being executed for converting the M channels of the audio data into N channels of data, wherein the N channels of data are dynamically determined upon the aggregated data stream being received at a destination device, wherein the conversion function is continuously adjustable depending on the destination device, wherein the conversion function includes a fold-down function specified by the metadata includes a plurality of coefficients which define a conversion of a Y audio data set having the M channels (Y 1 -Y M channels) to an X audio data set having the N channels (X 1 -X N channels), wherein the audio data comprises a 5.1 audio stream having six channels having left front, right front, center, low frequency, left surround and right surround channels such that M=6, wherein the destination device comprises a stereo destination device having left and right channels such that N=2, wherein the coefficients include B, SMIX, CMIX and LFEMIX and wherein the fold-down function comprises: L ( N )= B*[L ( M )+ S MIX* LS ( M )+ C MIX* C ( M )+ LFE MIX* LFE ( M )] and R ( N )= B*[R ( M )+ S MIX* RS ( M )+ C MIX* C ( M )+ LFE MIX* LFE ( M )] wherein: L(N) is the data for the left channel of the stereo destination device; L(M) is the left front channel data of the 5.1 audio stream; LS(M) is the left surround channel data of the 5.1 audio stream; C(M) is the center channel data of the 5.1 audio stream; LFE(M) is the low frequency channel data of the 5.1 audio stream; R(N) is the data for the right channel of the stereo destination device; R(M) is the right front channel data of the 5.1 audio stream; and RS(M) is the right surround channel data of the 5.1 audio stream, wherein B=1/(1+SMIX+CMIX+LFEMIX) and wherein fold-down function is based on the following mix table wherein: L(M) R(M) C(M) LFE(M) LS(M) RS(M) L(N) W −INFINITY Y Z X −INFINITY R(N) −INFINITY W Y Z −INFINITY X wherein: W=20*65536*log 10 (B) X=20*65536*log 10 (SMIX*B); Y=20*65536*log 10 (CMIX*B); Z=20*65536*log 10 (LFEMIX*B); and -INFINITY represents negative infinity, and wherein the metadata includes the following string format representation for the mix table: W,-INFINITE,-INFINTE,W,Y,Y,Z,Z,X,-INFINITE,-INFINITE,X.