Method for coding and decoding impulse responses of audio signals
The transmission and use of real, i. e. of measured, room impulse responses for the reproduction of sound signals with this room characteristic compatible to the MPEG-4 standard is made possible by inserting impulse responses in multiple successive control parameter fields, especially the params[128] array. A first control parameter field contains information about the number and content of the following fields. For presentation of the sound signals the content of the successive control parameter fields is separated, stored in an additional memory of a node and used during the calculation of the room characteristic.
1. Method for coding impulse responses of audio signals, wherein said impulse responses allow reproduction of sound signals corresponding to a certain room characteristic, comprising:
using an MPEG-4 encoder to encode multiple successive MPEG-4 PROTO params fields of an MPEG-4 BIFS stream for transmission of one or more impulse responses associated with a coded audio signal as defined in the following steps:
inserting into a first of said multiple successive MPEG-4 PROTO params fields information about the following MPEG-4 PROTO params fields by said MPEG-4 encoder, wherein said information comprises a number of the following MPEG-4 PROTO params fields to be used and a number of impulse responses to be transmitted; and
inserting into said following MPEG-4 PROTO params fields for each of said impulse responses a length information of the impulse response and samples representing the impulse response.
2. Method according to claim 1 , wherein a scalable transmission of the room impulse responses is enabled.
3. Method according to claim 2 , wherein in a broadcast mode short versions of room impulse responses are frequently transmitted and a long sequence is less frequently transmitted.
4. Method according to claim 2 , wherein in an interleaved mode a first part of the room impulse responses is frequently transmitted and the later part of the room impulse responses is less frequently transmitted.
5. Method for decoding impulse responses of audio signals by an MPEG-4 decoder, wherein said impulse responses allow reproduction of sound signals corresponding to a certain room characteristic, comprising:
receiving, at an MPEG-4 decoder, one or more impulse responses in multiple successive MPEG-4 PROTO params fields of an MPEG-4 BIFS stream, wherein a first of said multiple successive MPEG-4 PROTO params fields includes information about the following MPEG-4 PROTO params fields, said information comprising a number of the following MPEG-4 PROTO params fields used and a number of impulse responses transmitted, and wherein said following MPEG-4 PROTO params fields include for each of said impulse responses a length information of the impulse response and samples representing the impulse response;
separating said samples representing said one or more impulse responses based on said information in said first MPEG-4 PROTO params field and said length information in said following MPEG-4 PROTO params fields by said MPEG-4 decoder;
and
using said one or more impulse responses represented by said separated samples for calculation by said MPEG-4 decoder of a reverberation effect corresponding to said room characteristic.
6. Method according to claim 5 , wherein the room impulse responses are received following a scalable transmission of said room impulse responses.
7. Method according to claim 6 , wherein in a broadcast mode short versions of room impulse responses are frequently received and a long sequence is less frequently received.
8. Method according to claim 6 , wherein in an interleaved mode a first part of the room impulse responses is frequently received and the later part of the room impulse responses is less frequently received.
9. Apparatus for coding impulse responses of audio signals, wherein the impulse responses allow reproduction of sound signals corresponding to a certain room characteristic, comprising;
an MPEG-4 encoder that encodes multiple successive MPEG-4 PROTO params fields of an MPEG-4 BIFS stream for transmission of one or more impulse responses associated with a coded audio signal, said MPEG-4 encoder
inserts into a first of said multiple successive MPEG-4 PROTO params fields information about the following MPEG-4 PROTO params fields by said MPEG-4 encoder, wherein said information comprises a number of the following MPEG-4 PROTO params fields to be used and a number of impulse responses to be transmitted; and
inserts into said following MPEG-4 PROTO params fields for each of said impulse responses a length information of the impulse response and samples representing the impulse response.