Method and apparatus for changing the output delay of audio or video data encoding

• US 20010026327A1
• Filed: 03/27/2001
• Published: 10/04/2001
• Est. Priority Date: 03/29/2000
• Status: Active Grant

• Current Assignee: Thomson Broadband Systems, Deutsche Thomson-Brandt Gmbh (Vantiva SA)
• Original Assignee: Thomson Broadband Systems, Deutsche Thomson-Brandt Gmbh (Vantiva SA)
• Inventors: Schreiber, Ulrich, Chouquet, Stephane
• Granted Patent: US 6,891,573 B2
• Time in Patent Office: Days
• US Class Current: 348/518
• CPC Class Codes: H04N 21/23608 Remultiplexing multiplex streams, e.g. involving modifying time stamps or remapping the packet identifiers
• CPC Class Codes: H04N 21/2365 Multiplexing of several video streams
• CPC Class Codes: H04N 21/2368 Multiplexing of audio and video streams
• CPC Class Codes: H04N 21/4341 Demultiplexing of audio and video streams
• CPC Class Codes: H04N 21/4344 Remultiplexing of multiplex streams, e.g. by modifying time stamps or remapping the packet identifiers
• CPC Class Codes: H04N 21/4347 Demultiplexing of several video streams
• CPC Class Codes: H04N 21/8106 involving special audio data, e.g. different tracks for different languages
• CPC Class Codes: H04N 21/8547 involving timestamps for synchronizing content

Abstract

For TV broadcasting purposes encoding systems with related video encoders and audio encoders are used. The audio and video delay are aligned before multiplexing and transmitting the audio and video streams. According to a time stamping mechanism input time stamps are generated which become linked with data to be encoded, and are replaced before output by output time stamps, which are derived from the input time stamps by using a data delay constant. The input time stamps are used to control the delay of the encoding process and the output time stamps are indicating the output time. In order to allow a switchable output delay the data delay constant can be changed. Already assigned output time stamps remained unchanged. For data for which output time stamps are not already assigned, the output time stamps are calculated using the new delay constant.

Claims

1. Method for changing the output delay of audio or video data encoding, wherein input time stamps are generated which become linked with audio or video data to be encoded and are used to control the delay of the encoding process, wherein output time stamps are derived from the input time stamps by using a data delay constant and are assigned to the encoded data for indicating the output time, and wherein the encoded data with assigned output time stamps are buffered before output, characterised in that for a change of the output delay said data delay constant is changed, that already assigned output time stamps remain unchanged and that for data for which output time stamps are not already assigned, the output time stamps are calculated using the new data delay constant.

2. Method according to

claim 1

, wherein during a gap in the sequence of output time stamps appearing at delay increase, stuffing data or zero data or even no data are sent.

3. Method according to

claim 1

, wherein for data with same or overlapping output time stamps appearing at delay reduction, the later data indicating output time stamps that are already passed are discarded.

4. Method according to any of claims 1, wherein for delay reduction no further data are written into the output delay buffer beginning with the delay change request for a time duration corresponding to the difference between the old data delay constant and the new data delay constant, and wherein the new data delay constant is used for the calculation of the output time stamps for all following data.

5. Method according to

claim 1

, wherein discontinuities of the audio or video data are softened by the encoder.

6. Method according to

claim 1

, wherein the discontinuities are softened by fading in before the gap or skipped part and fading out after the gap or skipped part.

7. Apparatus for performing a method according to

claim 1

.