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US 2026/0212875 A1Published application
Methods and apparatus for unified speech and audio decoding improvements
AssigneeDolby International AB
InventorsMichael Franz BEER, Eytan RUBIN, Daniel FISCHER, Christof FERSCH, Markus WERNER
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Abstract
Described herein are methods, apparatus and computer products for decoding an encoded MPEG-D USAC bitstream. Described herein are such methods, apparatus and computer products that reduce a computational complexity.
Claims5
A decoder for decoding an encoded MPEG-D USAC bitstream, the decoder comprising:
- a receiver, implemented by a processor, to receive the encoded bitstream, wherein the bitstream represents a sequence of audio sample values and comprises a plurality of frames, wherein each frame comprises associated encoded audio sample values, wherein the bitstream comprises a pre-roll element including one or more pre-roll frames needed by the decoder to build up a full signal so as to be in a position to output valid audio sample values associated with a current frame, and wherein the bitstream further comprises a USAC configuration element comprising a current USAC configuration as payload and a current bitstream identification;
- a determiner, implemented by a processor, to determine whether the current USAC configuration differs from a previous USAC configuration by checking a length of the current USAC configuration config_length in_bits against the length of the previous USAC configuration, and, if the current USAC configuration differs from the previous USAC configuration, store the current USAC configuration, wherein the determiner is configured to jump back to a start position of the USAC configuration element in the bitstream and to bulk read and store an unparsed USAC configuration payload;
- and
- an initializer, implemented by a processor, to initialize the decoder if the determiner determines that the current USAC configuration differs from the previous USAC configuration, wherein initializing the decoder comprises:
- decoding the one or more pre-roll frames included in the pre-roll element,
- switching the decoder from the previous USAC configuration to the current USAC configuration, thereby configuring the decoder to use the current USAC configuration if the determiner determines that the current USAC configuration differs from the previous USAC configuration, and
- wherein the decoder discards and does not decode the pre-roll element if the determiner determines that the current USAC configuration is identical with the previous USAC configuration.
4 more elements
A method of decoding, by a decoder, an encoded MPEG-D USAC bitstream,
- the method comprising:
- receiving the encoded bitstream, wherein the bitstream represents a sequence of audio sample values and comprises a plurality of frames, wherein each frame comprises associated encoded audio sample values, wherein the bitstream comprises a pre-roll element including one or more pre-roll frames needed by the decoder to build up a full signal so as to be in a position to output valid audio sample values associated with a current frame, and wherein the bitstream further comprises a USAC configuration element comprising a current USAC configuration as payload and a current bitstream identification;
- determining whether the current USAC configuration differs from a previous USAC configuration by checking a length of the current USAC configuration config_length in_bits against the length of the previous USAC configuration, and, if the current USAC configuration differs from the previous USAC configuration, storing the current USAC configuration, wherein the determining includes jumping back to a start position of the USAC configuration element in the bitstream and bulk reading and storing an unparsed USAC configuration payload;
- and
- initializing the decoder if it is determined that the current USAC configuration differs from the previous USAC configuration,
- wherein initializing the decoder comprises:
- decoding the one or more pre-roll frames included in the pre-roll element, and switching the decoder from the previous USAC configuration to the current USAC configuration thereby configuring the decoder to use the current USAC configuration if it is determined that the current USAC configuration differs from the previous USAC configuration,
- wherein the method further comprises:
- discarding and not decoding, by the decoder, the pre-roll element if it is determined that the current USAC configuration is identical with the previous USAC configuration.
6 more elements
A method of decoding an encoded MPEG-D USAC bitstream by a decoder implementing a forward-aliasing cancellation, FAC, tool, for canceling time-domain aliasing and/or windowing when transitioning between Algebraic Code Excited Linear Prediction, ACELP, coded frames and transform coded, TC, frames within a linear prediction domain, LPD, codec, the method including:
- performing a transition from frequency domain, FD to the LPD, and applying the FAC tool if a first
- decoded window was coded with ACELP, wherein the same FAC tool is used in both transitions from the LPD to the FD, and from the FD to the LPD, wherein using the same F AC tool corresponds to calling the same function in the code of a decoding application regardless of current coding domain being LPD or FD, and wherein said function receives information relating to one or more of:
- filter coefficients, zero input response, subframe length, FAC length, and/or FAC signals as an input.
Dependencies are inferred from the claim text.