Encoder, decoder and methods for encoding and decoding data segments representing a time-domain data stream

• US 9,043,202 B2
• Filed: 04/10/2014
• Issued: 05/26/2015
• Est. Priority Date: 12/12/2006
• Status: Active Grant

• Current Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Original Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Inventors: Geiger, Ralf, Neuendorf, Max, Yokotani, Yoshikazu, Rettelbach, Nikolaus, Herre, Juergen, Geyersberger, Stefan
• Primary Examiner(s): YEN, ERIC L
• Application Number:
  US14/250,306
• Publication Number:
  US 20140222442A1
• Time in Patent Office: 411 Days
• Field of Search: 704/205, 704/211, 704/220, 704/225
• US Class Current: 704/205
• CPC Class Codes: G10L 19/00 Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis in musical instruments G10H
• CPC Class Codes: G10L 19/02 using spectral analysis, e.g. transform vocoders or subband vocoders
• CPC Class Codes: G10L 19/022 Blocking, i.e. grouping of samples in time; Choice of analysis windows; Overlap factoring
• CPC Class Codes: G10L 19/032 Quantisation or dequantisation of spectral components
• CPC Class Codes: G10L 19/18 Vocoders using multiple modes
• CPC Class Codes: G10L 19/265 Pre-filtering, e.g. high frequency emphasis prior to encoding
• CPC Class Codes: H04N 19/00 Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
• CPC Class Codes: H04N 21/2368 Multiplexing of audio and video streams
• CPC Class Codes: H04N 21/2383 Channel coding or modulation of digital bit-stream, e.g. QPSK modulation arrangements for detecting or preventing errors in the information received by adapting the channel coding H04L1/0009; analogue front ends or means for connecting modulators, demodulators or transceivers to a transmission line H04L27/0002
• CPC Class Codes: H04N 21/2662 Controlling the complexity of the video stream, e.g. by scaling the resolution or bitrate of the video stream based on the client capabilities
• CPC Class Codes: H04N 21/4341 Demultiplexing of audio and video streams
• CPC Class Codes: H04N 21/4382 Demodulation or channel decoding, e.g. QPSK demodulation analog front ends or means for connecting modulators, demodulators or transceivers to a transmission line H04L27/0002

Abstract

An apparatus for decoding data segments representing a time-domain data stream, a data segment being encoded in the time domain or in the frequency domain, a data segment being encoded in the frequency domain having successive blocks of data representing successive and overlapping blocks of time-domain data samples. The apparatus includes a time-domain decoder for decoding a data segment being encoded in the time domain and a processor for processing the data segment being encoded in the frequency domain and output data of the time-domain decoder to obtain overlapping time-domain data blocks. The apparatus further includes an overlap/add-combiner for combining the overlapping time-domain data blocks to obtain a decoded data segment of the time-domain data stream.

Claims

1. An apparatus adapted for generating an encoded data stream based on a time-domain data stream, the time-domain data stream comprising samples of a signal, the apparatus comprising

a segment processor adapted for providing data segments from the data stream, two consecutive data segments comprising a first or a second overlapping region, the second overlapping region being smaller than the first overlapping region;

a time-domain encoder adapted for encoding a windowed data segment in the time domain;

a frequency-domain encoder adapted for applying weights to samples of the time-domain data stream according to a first or second windowing function to acquire a windowed data segment, the first windowing function being adapted to the first overlapping region, the second windowing function being adapted to the second overlapping region, the frequency-domain encoder being adapted for encoding a windowed data segment in the frequency domain;

a time-domain data analyzer adapted for determining a transition indication associated with a data segment; and

a controller adapted for controlling the apparatus such that for data segments to which a first transition indication is associated, output data of the time-domain encoder is comprised by the encoded data stream and for data segments to which a second transition indication is associated, output data of the frequency-domain encoder is comprised by the encoded data stream.

2. The apparatus of claim 1, wherein the time-domain data analyzer is adapted for determining the transition indication from the time-domain data stream, the data segments or from data directly provided by the segment processor.

3. The apparatus of claim 1, wherein the time-domain data analyzer is adapted for determining a transition measure, the transition measure being based on the level of transience in the time-domain data stream or the data segment and wherein the transition indicator indicates whether a level of transience exceeds a predetermined threshold.

4. The apparatus of claim 1, wherein the segment processor is adapted for providing data segments with the first and the second overlapping regions,

the time-domain encoder is adapted for encoding the data segments,

the frequency-domain encoder is adapted for encoding the windowed data segments, and

the controller is adapted for controlling the time-domain encoder and the frequency-domain encoder such that for data segments to which a first transition indication is associated, output data of the time-domain encoder is comprised by the encoded data stream and for windowed data segments to which a second transition indication is associated, output data of the frequency-domain encoder is comprised by the encoded data stream.

5. The apparatus of claim 1, wherein the controller is adapted for controlling the segment processor for providing the data segments either to the time-domain encoder or the frequency-domain encoder.

6. The apparatus of claim 1, wherein the frequency-domain encoder is adapted for applying weights of windowing functions according to the AAC-specifications.

7. The apparatus of claim 1, wherein the frequency-domain encoder is adapted for converting a windowed data segment to the frequency domain to acquire a frequency-domain data segment.

8. The apparatus of claim 7, wherein the frequency-domain encoder is adapted for quantizing the frequency-domain data segment.

9. The apparatus of claim 8, wherein the frequency-domain encoder is adapted for evaluating the frequency-domain data segment according to a perceptual model.

10. The apparatus of claim 9, wherein the frequency-domain encoder is adapted for utilizing a cosine-modulated filterbank, an extended lapped transform, a low-delay filterbank or a polyphase filterbank to acquire the frequency-domain data segments.

11. The apparatus of claim 7, wherein the frequency-domain encoder is adapted for utilizing a modified discrete cosine transform to acquire the frequency-domain data segments.

12. The apparatus of claim 1, wherein the time-domain encoder is adapted for using a prediction filter for encoding the data segments.

13. A method for generating an encoded data stream based on a time-domain data stream, the time-domain data stream comprising samples of a signal, comprising

providing data segments from the data stream, two consecutive data segments comprising a first or a second overlapping region, the second overlapping region being smaller than the first overlapping region;

determining a transition indication associated with the data segments;

encoding a data segment in the time domain, and/or applying weights to samples of the time-domain data stream according to a first or a second windowing function to acquire a windowed data segment, the first windowing function being adapted to the first overlapping region, the second windowing function being adapted to the second overlapping region, and encoding the windowed data segment in the frequency domain and;

controlling such that for data segments to which a first transition indication is associated, output data being encoded in the time-domain is comprised by the encoded data stream and for data segments to which a second transition indication is associated, output data being encoded in the frequency domain is comprised by the encoded data stream,

wherein the method is performed using a hardware apparatus, or using a computer, or using a combination of a hardware apparatus and a computer.

14. A non-transitory computer readable medium comprising a computer program comprising a program code for performing the method for generating an encoded data stream based on a time-domain data stream, the time-domain data stream comprising samples of a signal, the method comprising

providing data segments from the data stream, two consecutive data segments comprising a first or a second overlapping region, the second overlapping region being smaller than the first overlapping region;

determining a transition indication associated with the data segments;

encoding a data segment in the time domain, and/or applying weights to samples of the time-domain data stream according to a first or a second windowing function to acquire a windowed data segment, the first windowing function being adapted to the first overlapping region, the second windowing function being adapted to the second overlapping region, and encoding the windowed data segment in the frequency domain and;

controlling such that for data segments to which a first transition indication is associated, output data being encoded in the time-domain is comprised by the encoded data stream and for data segments to which a second transition indication is associated, output data being encoded in the frequency domain is comprised by the encoded data stream,

when the program code runs on a computer.