Method and device for producing a scalable data stream, and method and device for decoding a scalable data stream while taking a bit bank function into account

• US 20040107289A1
• Filed: 12/19/2003
• Published: 06/03/2004
• Est. Priority Date: 01/18/2001
• 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: Grill, Bernhard, Sperschneider, Ralph, Lutzky, Manfred, Teichmann, Bodo
• Granted Patent: US 7,496,517 B2
• Time in Patent Office: Days
• US Class Current: 709/231
• CPC Class Codes: G10L 19/24 Variable rate codecs, e.g. for generating different qualities using a scalable representation such as hierarchical encoding or layered encoding

Abstract

In a method for generating a scalable data stream from one or several blocks of output data of a first encoder and from one or several blocks of output data of a second encoder a determining data block for a current section of an input signal is written. In addition, output data of the second encoder representing a preceding section of the input signal are written in transmission direction from an encoder to a decoder after the determining data block. When the output data of the second encoder are written for a preceding section of the input signal, the output data of the second encoder are written representing the current section of the input signal. In order to signalize where the output data of the second encoder for the preceding section end and where the output data of the second encoder for the current section begin, buffer information is written into the scalable data stream. By the fact that output data of a preceding section follow a determining data block for the current section, a bit savings bank function may be implemented in the scalable encoder and simply be signalized in the bit stream.

Claims

1. Method for generating a scalable data stream from one or several blocks of output data of a first encoder and from one or several blocks of output data of a second encoder, wherein the one or the several blocks of output data of the first encoder together represent a number of samples of the input signal for the first encoder forming the current section of the input signal for the first encoder, and wherein the one block or the several blocks of output data of the second encoder together represent a number of samples of the input signal for the second encoder, wherein the number of samples for the second encoder represent a current section of the input signal for the second encoder, wherein the number of samples for the first encoder and the number of samples for the second encoder are equal and wherein the current sections for the first and the second encoders are identical or shifted to each other by a period of time, comprising:

writing a determining data block for the current section of the input signal for the first or the second encoder;

writing output data of the second encoder representing a preceding section of the input signal for the second encoder, in transmission direction from an encoder to a decoder after the determining data block;

writing output data of the second encoder representing the current section of the input signal for the second encoder, when the output data of the second encoder for the preceding section of the input signal are written;

writing buffer information into the scalable data stream, wherein the buffer information indicates how far the output data of the second encoder for the preceding section extend beyond the determining data block for the second encoder; and

writing the one or the several blocks of output data of the first encoder into the scalable data stream.

2. Method according to claim 1,

wherein the lengths of the blocks of output data of the second encoder are different for sections of the input signal of the same length, wherein the lengths of the blocks of output data depend on signal characteristics of the input signal;

wherein the one or the several blocks of output data of the first encoder are of equal length for sections of the input signal of equal length; and

wherein the transmission rate of the bit stream is constant.

3. Method according to claim 1,

wherein the second encoder comprises a bit savings bank function, wherein the maximum size of the bit savings bank is given by maximum buffer size information, and wherein the current level of the bit savings bank is given by current buffer information,

wherein the buffer information is current buffer information, and

wherein the size, how far the output data of the second encoder for the preceding time section extends beyond the determining data block, may be derived from the difference between the maximum buffer size information and the current buffer information.

4. Method according to claim 1,

wherein the writing of output data of the first encoder is performed so that a block of output data of the first encoder is arranged directly after a determining data block, and

wherein the length of this determining data block and the length of the present output data blocks of the first encoder and possibly present data of further scaling layers are ignored when determining the amount how far the output data of the second encoder extend beyond the determining data block, using the current buffer information and the maximum buffer size information.

5. Method according to claim 1,

wherein means for writing the one or the several blocks of output data of the first encoder is implemented to write the blocks of output data of the first encoder equidistantly into the scalable data stream.

6. Method according to claim 1,

wherein the first encoder is a celp encoder,

wherein the second encoder is an AAC encoder, and

wherein the determining data block is an LATM header according to MPEG 4.

7. Method according to claim 1, wherein the at least one block of output data of the second encoder and the at least one block of output data of the first encoder is payload data in a superframe which comprises exactly one determining data block apart from the payload data.

8. Method according to claim 1,

wherein in the step of writing the blocks of output data of the first encoder at least one block of output data of the first encoder for the current section of the input signal is written for the first encoder in transmission direction before the determining data block for the current time section.

9. Device for generating a scalable data stream from one or several blocks of output data of a first encoder and from one or several blocks of output data of a second encoder, wherein the one or the several blocks of output data of the first encoder together represent a number of samples of the input signal for the first encoder, forming a current section of the input signal for the first encoder, and wherein the one block or the several blocks of output data of the second encoder together represent a number of samples of the input signal for the second encoder, wherein the number of samples for the second encoder form a current section of the input signal for the second encoder, wherein the number of samples for the first encoder and the number of samples for the second encoder are equal and wherein the current sections for the first and the second encoders are identical or shifted from each other by a period of time, comprising:

means for writing a determining data block for the current section of the input signal for the first or the second encoder;

means for writing output data of the second encoder representing a preceding section of the input signal for the second encoder, in transmission direction from an encoder to an decoder after the determining data block;

means for writing output data of the second encoder representing the current section of the input signal for the second encoder when the output data of the second encoder for the preceding section of the input signal are written;

means for writing buffer information into the scalable data stream, wherein the buffer information indicates how far the output data of the second encoder for the preceding section extend beyond the determining data block for the second encoder; and

means for writing the one or the several blocks of output data of the first encoder into the scalable data stream.

10. Method for decoding a scalable data stream from one or several blocks of output data of a first encoder and from or several blocks of output data of a second encoder, wherein the one or the several blocks o-f output data of the first encoder together represent a number of samples of the input signal for the first encoder, forming a current section of the input signal for the first encoder, and wherein the one block or the several blocks of output data of the second encoder together represent a number of samples of the input signal for the second encoder, wherein the number of samples for the second encoder form a current section of the input signal for the second encoder, wherein the number of samples for the first encoder and the number of samples for the second encoder are equal, and wherein the current sections for the first and the second encoder are identical or shifted to each other by a period of time, wherein the scalable data stream comprises a determining data block for the current section for the first or the second encoder, output data of the second encoder for a preceding section of the input signal in transmission direction after the determining data block, and buffer information, indicating how far the output data of the second encoder for the preceding section extend beyond the determining data block, comprising the following steps:

reading the determining data block for the current section of the input signal for the first or the second encoder;

reading the output data of the first encoder for the current section of the first encoder;

reading the buffer information;

reading the output data of the second encoder for the current section starting from a position in the scalable data stream indicated by the buffer information; and

decoding the output data of the second encoder and the output data of the first encoder to obtain a decoded signal.

11. Device for decoding a scalable data stream from one or several blocks of output data of a first encoder and from or several blocks of output data of a second encoder, wherein the one or the several blocks of output data of the first encoder together represent a number of samples of the input signal for the first encoder, forming a current section of the input signal for the first encoder, and wherein the one block or the several blocks of output data of the second encoder together represent a number of samples of the input signal for the second encoder, wherein the number of samples for the second encoder form a current section of the input signal for the second encoder, wherein the number of samples for the first encoder and the number of samples for the second encoder are equal, and

wherein the current sections for the first and the second encoder are identical or shifted to each other by a period of time, wherein the scalable data stream comprises a determining data block for the current section for the first or the second encoder, output data of the second encoder for a preceding section of the input signal in transmission direction after the determining data block, and buffer information, indicating how far the output data of the second encoder for the preceding section extend beyond the determining data block, comprising:

a bit stream demultiplexer, adapted to be able to perform the following steps;

reading the determining data block for the current section of the input signal for the first or the second encoder;

reading the output data of the first encoder for the current section of the first encoder;

reading the buffer information;

reading the output data of the second encoder for the current section starting from a position in the scalable data stream indicated by the buffer information; and

means for decoding the output data of the second encoder and the output data of the first encoder to obtain a decoded signal.