Multiplexer, multimedia communication apparatus and time stamp generation method

• US 6,987,767 B2
• Filed: 06/28/2001
• Issued: 01/17/2006
• Est. Priority Date: 06/30/2000
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Saito, Tatsunori
• Primary Examiner(s): MERED, HABTE
• Application Number:
  US09/892,502
• Publication Number:
  US 20020001309A1
• Time in Patent Office: 1,664 Days
• Field of Search: 370532-544, 370/252, 370/509, 370/265, 370/267, 370/477, 370/468, 370/508, 370/394, 370/395.4, 370/395.62, 370/521, 370/537, 348/14.13, 348/425.3, 348/426.1, 348/423, 348/512, 348/515
• US Class Current: 370/394
• CPC Class Codes: H04N 21/235 Processing of additional data, e.g. scrambling of additional data or processing content descriptors
• CPC Class Codes: H04N 21/23608 Remultiplexing multiplex streams, e.g. involving modifying time stamps or remapping the packet identifiers
• CPC Class Codes: H04N 21/43072 of multiple content streams on the same device
• 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 21/4345 Extraction or processing of SI, e.g. extracting service information from an MPEG stream
• CPC Class Codes: H04N 21/435 Processing of additional data, e.g. decrypting of additional data, reconstructing software from modules extracted from the transport stream
• CPC Class Codes: H04N 21/8547 involving timestamps for synchronizing content

Abstract

In order to allow the generation of a time stamp in consideration of a frame skip even in the case where the frame skip is generated, a PES generation section of a multiplexer detects the number of skipped frames by analyzing elementary video streams output from a video encoder to determine a PTS on the basis of the time difference between frames calculated on the basis of the number of skipped frames. Then, a frame to which a PTS is to be placed with the above stream analysis is cut out to insert the PTS into a PES header of this frame to be transmitted to the transmission channel.

Claims

1. A multiplexer for packetizing a plurality of encoded data streams, the multiplexer comprising:

means for inserting a time stamp to be used for reproduction of the encoded data streams into a first packet;

means for multiplexing a second packet packetized from the first packet;

means for detecting the number of skipped frames from the encoded data stream; and

means for generating a time stamp to be inserted into the first packet on the basis of the detected number of skipped frames,

wherein the number of skipped frame is detected on the basis of the time difference between a current frame of the encoded data stream and a past frames prior to the current frame.

2. The multiplexer according to claim 1, wherein said means for detecting detects a first local time stamp added to the current frame of the encoded data stream and a second local time stamp added to the past frame prior to the current frame.

3. A multimedia communication apparatus comprising:

means for individually encoding a plurality of media streams having time correlation to output encoded media streams respectively;

means for packetizing respectively said encoded media streams to create a first packet;

means for detecting the number of skipped frames from the encoded media streams;

means for generating a time stamp on the basis of the number of detected skipped frames;

means for inserting the time stamp into the first packet;

means for multiplexing a second packet packetized from the first packet to output transmission streams; and

means for transmitting the transmission streams to a transmission channel,

wherein said means for detecting detects the number of skipped frame on the basis of the time difference between a current frame of the coded media streams and the past frames prior to the current frame.

4. The multimedia communication apparatus according to claim 3, wherein said means for detecting detects the time difference on the basis of a first local time stamp added to the current frame of the encoded media streams and a second local time stamp added to the past frame prior to the current frame.

5. A method of generating a time stamp which is applied to a multiplexer, the method comprising the steps of:

packetizing a plurality of encoded data streams,

inserting a time stamp to be used for reproduction of the encoded data streams into a first packet;

multiplexing a second packet packetized from the first packet;

detecting the number of skipped frames from the encoded data streams; and

providing a time stamp to be inserted into the first packet on the basis of the number of skipped frames which have been detected,

wherein the step of detecting the number of skipped frame includes the steps of;

determining a time difference between a current frame of the encoded information data streams and past frame prior to the current frame; and

detecting the number of skipped frames on the basis of the determined time difference.

6. The method for generating a time stamp according to claim 5, wherein the step of determining time difference in the step of detecting the number of skipped frame determines the time difference on the basis of a first local time stamp added to the current frame of the encoded data streams, and a second local time stamp added to the past frame prior to the current frame.

7. A multimedia data encoding apparatus, comprising:

means for encoding multimedia data to generate encoded multimedia data;

first packetizing means for packetizing the encoded multimedia data into a first packet;

means for inserting a first time stamp to be used for reproduction of the multimedia data into the first packet;

means for detecting the number of skipped frames from the encoded multimedia data;

means for generating a second time stamp to be inserted into the first packet instead of the first time stamp on the basis of the detected number of skipped frames; and

second packetizing means for packetizing the first packet into a second packet,

wherein;

the encoded multimedia data includes a plurality of frames each having a local time stamp; and

the detecting means detects the number of skipped frames on the basis of a local time stamp of the current frame and a local time stamp of the past frame prior to the current frame.

8. A multimedia data encoding apparatus, comprising:

means for encoding multimedia data to generate encoded multimedia data;

first packetizing means for packetizing the encoded multimedia data into a packetized elementary stream (PES) packet;

means for inserting a first time stamp to be used for reproduction of the multimedia data into the PES packet;

means for detecting the number of skipped frames from the encoded multimedia data;

means for generating a second time stamp to be inserted into the PES packet instead of the first time stamp on the basis of the detected number of skipped frames; and

second packetizing means for packetizing the PES packet into a transport stream (TS) packet,

wherein;

the encoded multimedia data includes a plurality of frames each having a local time stamp; and

the detecting means detects the number of skipped frames on the basis of a local time stamp of the current frame and a local time stamp of the past frame prior to the current frame.