Method and device for selecting a transcoding method among a set of transcoding methods

A method for selecting a method from a set of methods of transcoding digital multimedia data, the data being transferrable between at least two communication apparatuses via a communication network, said selection method comprising the following steps:

• for each transcoding method, obtaining a distortion value from a mathematical model for establishing the distortion taking into account said transcoding method, the distortion model being applied to information representing the content of the signal represented by the digital data to be transcoded;
• selecting a transcoding method as a function of the different distortion values obtained for the set of transcoding methods;
• for each transcoding method, obtaining a rate value from a mathematical model for establishing the rate taking into account said transcoding method, the rate model being applied to information representing digital data;
• and
• selecting a transcoding method according to (1) the different rate values, and (2) the different distortion values obtained for the set of transcoding methods,
• wherein the rate model establishes a relationship between the rate and the energy of the signal represented by the digital data, and
• wherein the rate model has the following form:
• O iƒS <1 R(S) ={αlog(S)+βS+γ otherwise,
• wherein R represents the rate, S is a measurement of the energy, and a, b, g, and l are parameters of the rate model which vary as a function of the transcoding method.

A device for selecting a method from a set of methods of transcoding digital multimedia data, the data being transferrable between at least two communication apparatuses via a communication network, the device comprising:

• for each transcoding method, means for obtaining a distortion value from a mathematical model for establishing the distortion taking into account said transcoding method, the distortion model being applied to information representing the content of the signal represented by the digital data to be transcoded;
• and
• means for selecting a transcoding method according to the different distortion values obtained for the set of transcoding methods,
• wherein the distortion model establishes a relationship between the distortion and the energy of the signal represented by the digital data, and
• wherein the distortion model has the following form:
• D
• ⁡
• (
• S
• )
• =
• {
• a
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• ⁢
• log
• n
• S
• ⁡
• (
• S
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• b
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• +
• cS
• +
• d
• ,
• if
• ⁢
• ⁢
• S
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• 1
• ⁢
• if
• ⁢
• ⁢
• 1
• ≤
• S
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• m
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• ⁢
• S
• ≥
• m
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• wherein D represents the distortion, S is a measurement of the energy, and a, b, c, d, l, m and n are parameters of the distortion model which vary as a function of the transcoding method.

A device for selecting a method from a set of methods of transcoding digital multimedia data, the data being transferrable between at least two communication apparatuses via a communication network, the device comprising:

• for each transcoding method, means for obtaining a distortion value from a mathematical model for establishing the distortion taking into account said transcoding method, the distortion model being applied to information representing the content of the signal represented by the digital data to be transcoded;
• means for selecting a transcoding method according to the different distortion values obtained for the set of transcoding methods;
• for each transcoding method, means for obtaining a rate value from a mathematical model for establishing the rate taking into account said transcoding method, the rate model being applied to information representing digital data;
• and
• means for selecting a transcoding method according to (1) the different rate values, and (2) the different distortion values obtained for the set of transcoding methods,
• wherein the rate model establishes a relationship between the rate and the energy of the signal represented by the digital data, and
• wherein the rate model has the following form:
• O iƒS <1 R(S) ={αlog(S) +βS+γ otherwise,
• wherein R represents the rate, S is a measurement of the energy, and a, b, g, and l are parameters of the rate model which vary as a function of the transcoding method.