Multi-mode audio codec and CELP coding adapted therefore
First Claim
1. A multi-mode audio decoder for providing a decoded representation of audio content on the basis of an encoded bitstream, a multi-mode audio decoder comprising a memory;
- and a processor configured todecode a global gain value per frame of the encoded bitstream, wherein a first subset of the frames being coded in a first coding mode and a second subset of the frames being coded in a second coding mode, with each frame of the second subset being composed of more than one sub-frames,decode, per sub-frame of at least a subset of the sub-frames of the second subset of frames, a corresponding bitstream element differentially to the global gain value of the respective frame, andcomplete decoding the bitstream using the global gain value and the corresponding bitstream element in decoding the sub-frames of the at least subset of the sub-frames of the second subset of frames and the global gain value in decoding the first subset of frames,wherein the multi-mode audio decoder is configured such that a change of the global gain value of the frames within the encoded bitstream results in an adjustment of an output level of the decoded representation of the audio content.
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Abstract
In an embodiment, bitstream elements of sub-frames are encoded differentially to a global gain value so that a change of the global gain value results in an adjustment of an output level of the decoded representation of the audio content. Concurrently, the differential coding saves bits. Even further, the differential coding enables the lowering of the burden of globally adjusting the gain of an encoded bitstream. In another embodiment, a global gain control across CELP coded frames and transform coded frames is achieved by co-controlling the gain of the codebook excitation of the CELP codec, along with a level of the transform or inverse transform of the transform coded frames. In another embodiment, the gain value determination in CELP coding is performed in the weighted domain of the excitation signal.
30 Citations
16 Claims
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1. A multi-mode audio decoder for providing a decoded representation of audio content on the basis of an encoded bitstream, a multi-mode audio decoder comprising a memory;
- and a processor configured to
decode a global gain value per frame of the encoded bitstream, wherein a first subset of the frames being coded in a first coding mode and a second subset of the frames being coded in a second coding mode, with each frame of the second subset being composed of more than one sub-frames, decode, per sub-frame of at least a subset of the sub-frames of the second subset of frames, a corresponding bitstream element differentially to the global gain value of the respective frame, and complete decoding the bitstream using the global gain value and the corresponding bitstream element in decoding the sub-frames of the at least subset of the sub-frames of the second subset of frames and the global gain value in decoding the first subset of frames, wherein the multi-mode audio decoder is configured such that a change of the global gain value of the frames within the encoded bitstream results in an adjustment of an output level of the decoded representation of the audio content. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 13)
- and a processor configured to
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9. A multi-mode audio encoder comprising a memory;
- and a processor configured to encode an audio content into an encoded bitstream with encoding a first subset of frames in a first coding mode and a second subset of frames in a second coding mode, wherein the second subset of frames is respectively composed of one or more sub-frames, wherein the multi-mode audio encoder is configured to determine and encode a global gain value per frame, and determine and encode, per sub-frames of at least a subset of the sub-frames of the second subset, a corresponding bitstream element differentially to the global gain value of the respective frame, wherein the multi-mode audio encoder is configured such that a change of the global gain value of the frames within the encoded bitstream results in an adjustment of an output level of a decoded representation of the audio content at the decoding side.
- View Dependent Claims (15)
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10. A multi-mode audio decoding method for providing a decoded representation of audio content on the basis of an encoded bitstream, the method comprising
decoding a global gain value per frame of the encoded bitstream, wherein a first subset of the frames being coded in a first coding mode and a second subset of the frames being coded in a second coding mode, with each frame of the second subset being composed of more than one sub-frames, decoding, per sub-frame of at least a subset of the sub-frames of the second subset of frames, a corresponding bitstream element differentially to the global gain value of the respective frame, and completing decoding the bitstream using the global gain value and the corresponding bitstream element in decoding the sub-frames of the at least subset of the sub-frames of the second subset of frames and the global gain value in decoding the first subset of frames, wherein the multi-mode audio decoding method is performed such that a change of the global gain value of the frames within the encoded bitstream results in an adjustment of an output level of the decoded representation of the audio content.
- 11. A multi-mode audio encoding method comprising encoding an audio content into an encoded bitstream with encoding a first subset of frames in a first coding mode and a second subset of frames in a second coding mode, wherein the second subset of frames is respectively composed of one or more sub-frames, wherein the multi-mode audio encoding method further comprises determining and encoding a global gain value per frame, and determine and encode, per sub-frames of at least a subset of the subframes of the second subset, a corresponding bitstream element differentially to the global gain value of the respective frame, wherein the multi-mode audio encoding method is performed such that a change of the global gain value of the frames within the encoded bitstream results in an adjustment of an output level of a decoded representation of the audio content at the decoding side.
Specification