System and method for automatic identification of speech coding scheme
First Claim
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1. A method for speech decoding, comprising:
- accepting communication packets that carry encoded speech, which was encoded in accordance with a speech coding scheme whose identity is not accessibly identified in the communication packets, wherein accepting the communication packets comprises accepting with each packet a respective time stamp indicating a reception time of the packet;
using a processor, processing the encoded speech so as to automatically identify the speech coding scheme that was used to encode the speech;
decoding the encoded speech using the identified speech coding scheme, wherein processing the encoded speech comprises decoding the encoded speech in accordance with the two or more possible speech coding schemes, so as to produce two or more respective output streams; and
deducing the identity of the speech coding scheme responsively to the output streams, wherein deducing the identity of the speech coding scheme comprises reconstructing occurrence times of speech activity in the output streams and matching the reconstructed occurrence times with the respective time stamps.
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Abstract
Methods and systems for extracting speech from such packet streams. The methods and systems analyze the encoded speech in a given packet stream, and automatically identify the actual speech coding scheme that was used to produce it. These techniques may be used, for example, in interception systems where the identity of the actual speech coding scheme is sometimes unavailable or inaccessible. For instance, the identity of the actual speech coding scheme may be sent in a separate signaling stream that is not intercepted. As another example, the identity of the actual speech coding scheme may be sent in the same packet stream as the encoded speech, but in encrypted form.
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Citations
20 Claims
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1. A method for speech decoding, comprising:
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accepting communication packets that carry encoded speech, which was encoded in accordance with a speech coding scheme whose identity is not accessibly identified in the communication packets, wherein accepting the communication packets comprises accepting with each packet a respective time stamp indicating a reception time of the packet; using a processor, processing the encoded speech so as to automatically identify the speech coding scheme that was used to encode the speech; decoding the encoded speech using the identified speech coding scheme, wherein processing the encoded speech comprises decoding the encoded speech in accordance with the two or more possible speech coding schemes, so as to produce two or more respective output streams; and deducing the identity of the speech coding scheme responsively to the output streams, wherein deducing the identity of the speech coding scheme comprises reconstructing occurrence times of speech activity in the output streams and matching the reconstructed occurrence times with the respective time stamps. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. Apparatus for speech decoding, comprising:
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an interface, which is configured to accept communication packets that carry encoded speech, which was encoded in accordance with a speech coding scheme whose identity is not accessibly identified in the communication packets, wherein accepting the communication packets comprises accepting with each packet a respective time stamp indicating a reception time of the packet; and a processor, which is configured to process the encoded speech so as to automatically identify the speech coding scheme that was used to encode the speech, and to decode the encoded speech using the identified speech coding scheme, wherein processing the encoded speech comprises decoding the encoded speech in accordance with the two or more possible speech coding schemes, so as to produce two or more respective output streams, and deducing the identity of the speech coding scheme responsively to the output streams, wherein deducing the identity of the speech coding scheme comprises reconstructing occurrence times of speech activity in the output streams and matching the reconstructed occurrence times with the respective time stamps. - View Dependent Claims (15, 16, 17, 18)
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19. A method for speech decoding, comprising:
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accepting communication packets that carry encoded speech, which was encoded in accordance with a speech coding scheme whose identity is not accessibly identified in the communication packets; using a processor, processing the encoded speech so as to automatically identify the speech coding scheme that was used to encode the speech, wherein processing the encoded speech further comprises identifying two or more candidate speech coding schemes that are suspected of being used to encode the speech, wherein identifying the candidate speech coding schemes comprises assigning the candidate speech coding schemes respective likelihoods of being used to encode the speech; decoding the encoded speech using the identified candidate speech coding scheme; and reporting the candidate speech coding schemes to an operator, wherein reporting the candidate speech coding schemes comprises presenting the likelihoods to the operator. - View Dependent Claims (20)
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Specification