Method and apparatus for storing/reproducing transport stream, and digital receiver using the same

A method and apparatus for storing/reproducing a transport stream and a digital receiver using the same are disclosed. The method for storing the transport stream includes the steps of receiving a TS, selecting a storing stream type for the TS, and transcoding the TS into a PES or PS according to the selected stream type and storing the transcoded stream, or storing the TS as it is. Accordingly, the structure for storing the PS or TS overcomes incompatibility of the stored stream and difficulty in the rate control at the time of reproduction in the general PVR.

This application claims the benefit of the Korean Patent Application No. 10-2004-0001458, filed on Jan. 9, 2004, which is hereby incorporated by reference as if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a digital receiver, and more particularly, to a method and apparatus for efficiently storing/reproducing a transport stream, and a digital multimedia broadcast (DMB) receiver using the same.

2. Background of the Related Art

A broadcasting digitalization tendency has been accelerated through existing media such as ground wave, satellite and cable TV broadcasting, and progressively changed an environment of a broadcasting industry. Among the various media, a new medium representing harmony of broadcasting digitalization and communication is a DMB service.

If the DMB service is used in a full scale, it is expected that technologies applied to a general ground wave or satellite broadcasting receiver will be applied to a DMB receiver. It is also expected that new technologies suitable for mobility will be rapidly developed and used.

One of the technologies applied to the general ground wave or satellite broadcasting receiver and expected to be applied to the DMB receiver is a personal video recorder (PVR) function.

FIG. 1illustrates a structure of a general PVR embodied in a DMB receiver.

Referring toFIG. 1, the general PVR stores a packetized elementary stream (PES) obtained by demultiplexing an MPEG-2 transport stream (TS) in a hard disk drive (HDD)2that is a storing medium.

Here, necessary time synchronization information is stored with the stream in the form of additional information according to methods suitable for each local environment (for example, countries, companies, etc.)

When the stored stream is reproduced, the stream is read with the stored time information, or controlled to a storing rate at the time of transmission and displayed by using a request signal of an audio/video decoder1.

Therefore, in order to store the stream, the general PVR stores the additional time information for the rate control or requires the request signal.

However, the stream stored in the storing medium does not have compatibility with other PVR receivers, and the local time information must be individually stored.

Such disadvantages cause serious problems to the DMB receiver characterized by mobile reception.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a method and apparatus for storing/reproducing a transport stream, and a DMB receiver using the same that substantially obviate one or more problems due to limitations and disadvantages of the related art.

An object of the present invention is to provide a method for storing a PS that is improved from a general PVR method.

Another object of the present invention is to provide a variable structure which can select methods for storing a PES, a PS and a TS according to advantages in embodiment of a PVR system.

Yet another object of the present invention is to provide a structure for embodying a PVR in a DMB receiver.

To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, a method for storing a transport stream includes the steps of: receiving a TS; selecting a storing stream type for the TS; and transcoding the TS into a PES or PS according to the selected stream type and storing the transcoded stream, or storing the TS as it is.

The method for storing the PES transcodes the TS into the PES by demultiplexing, and stores the transcoded stream.

The method for storing the PS includes the steps of: transcoding the TS into a PES signal by demultiplexing; and transcoding the transcoded PES signal into a PS signal by multiplexing.

The PS transcoding step includes a step for generating an SCR value by using a local clock and a PCR value of the stream.

Preferably, when the TS is stored as the PES or PS, PSI information is also stored.

In another aspect of the present invention, a method for reproducing a transport stream includes the steps of: reading a stream stored in a storing medium; deciding a type of the read stream; and transcoding the stream into a PES according to the decided stream type, and decoding the transcoded stream.

When the stored stream is a PS, the PS is transcoded into a PES by demultiplexing.

When the stored stream is a TS, the TS is transcoded into a PES by demultiplexing.

In yet another aspect of the present invention, an apparatus for storing a transport stream includes: a DEMUX for receiving a TS, demultiplexing the TS into a PES, and outputting the PES; a PS MUX for receiving the outputted PES, and transcoding the PES into a PS; and a storing medium for storing any one type of stream selected from the PES, PS and TS.

In yet another aspect of the present invention, an apparatus for reproducing a transport stream includes: a storing medium for storing a PES, PS or TS; a DEMUX for transcoding the PS and TS of the stored streams into the PES by demultiplexing; and a decoder for decoding and outputting the stored PES or the demultiplexed stream.

In yet another aspect of the present invention, a digital receiver includes: a PID filter for filtering and outputting a TS by programs; a TS DEMUX for demultiplexing the TS from the PID filter into a PES signal; a PS MUX for transcoding the PES into a PS; a download controller for receiving the TS, PES and PS from each block, and storing the received streams in a storing medium in any one of types; an upload controller for reading the stream stored as the TS, PES or PS; and a decoder for receiving the PES from the upload controller or the TS DEMUX, decoding the received stream, and outputting an audio/video signal.

The digital receiver further includes a PS DEMUX for transcoding the PS stored in the storing medium into the PES.

When the type of the stream stored in the storing medium is the TS, the TS is inputted to the PID filter through the upload controller.

In accordance with the present invention, the structure and method for storing the PS or TS are suggested to overcome incompatibility of the stored stream and difficulty in the rate control at the time of reproduction in the general PVR.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present inventors mostly select the publicly-known terms to describe the present invention, but also use the terms that the present inventors deem most appropriate to describe new technologies. The meanings of such terms are clearly explained in the corresponding parts. Therefore, it is recognized that the present invention must not be understood by the names of the terms but by the meanings of the terms.

FIG. 2illustrates a structure of a PVR for storing a PS in accordance with the present invention.

As illustrated inFIG. 2, a transport stream (TS) is transcoded into a packetized elementary stream (PES) by a TS DEMUX201, transcoded into a program stream (PS) by a PS MUX202, and stored in a storing medium203such as a hard disk drive (HDD).

When the PS stored in the storing medium203is reproduced, the PS is demultiplexed by a PS DEMUX204to be transcoded into the PES, and the PES is decoded by an audio/video decoder205, and displayed.

In order to solve the problems that occur when the PES is stored, the TS is transcoded into the PS and stored. Since the PS is a packet multiplexing standard for the storing medium, a rate and A/V synchronization can be controlled by using a system clock reference (SCR) value of the stream.

FIG. 3illustrates a header structure of the PS packet.

As shown inFIG. 3, the PS includes a few PES packets, and is formed in pack units. Each pack includes a pack header and a payload.

The PES packet has a variable length. Especially, there is no limit to divide the PES packets. Therefore, the pack comprised of the PES packets may not have a PES packet or may have a lot of PES packets. The pack header displays the SCR that is time information of the PS, thereby controlling the rate and A/V synchronization.

FIG. 4illustrates a header structure of the PES packet, andFIG. 5illustrates a header structure of the TS packet.

The present invention also suggests a method for storing a TS as it is. That is, the TS is stored in the memory as it is without demultiplexing.

Advantages and disadvantages of the methods for storing the PES, PS and TS will now be described.

Differently from the TS, when the PS and the PES are stored, a program specific information (PSI) packet must be individually stored or transmitted. Since the TS have the PSI packet, the PSI packet needs not to be individually stored or transmitted. For reference, the PSI packet is inserted into the payload part of the TS packet, and has information notifying which of the packets needs to be decoded by which of the programs.

When the PES is stored, the TS or PS DEMUX is not required to decode the stored stream. As compared with the TS or PS, the PES reduces data waste.

Because the methods for storing the TS, PES and PS have different advantages and disadvantages, the present invention adopts the PVR structure for selectively taking advantages of each structure as shown inFIG. 6.

FIG. 6illustrates the PVR for storing/reproducing the PES, PS or TS in accordance with the present invention.

As depicted inFIG. 6, the PVR receives a TS, and a TS DEMUX301decides to store the TS as a PS, PES or TS.

In order to store the PS, the TS DEMUX301parses the TS, and outputs the PES to a PS MUX302to be transcoded into the PS. The PS generated by the PS MUX302is stored in a storing medium303as it is. An HDD is used as the storing medium303.

When the stored PS is reproduced, the PS read from the storing medium303is transcoded into the PES by a PS DEMUX304, and the PES is decoded by an audio/video decoder301and displayed.

When the PS MUX302generates the PS, the PS MUX302generates the SCR value by using a local clock and a program clock reference (PCR) value. The generated SCR value is used to control the rate of the PS DEMUX304reading the stream, thereby controlling synchronization.

In addition, the TS DEMUX301can store the PES or TS without using the PS MUX302.

Since the PES or PS does not have program guide information, the PES must store the PSI information.

Conversely, since the TS has the PSI packet, such information needs not to be individually managed.

When the PES or TS is reproduced, a buffer state of the audio/video decoder301must be checked. Therefore, the reading rate of the stored stream from the storing medium can be controlled to prevent overflow of the buffer.

FIGS. 7 and 8illustrate sequential steps of the method for storing/reproducing the PES, PS or TS in the PVR in accordance with the present invention.

FIG. 7illustrates sequential steps of the method for storing the stream from the PVR as the PES, PS or TS. As shown inFIG. 7, when the TS is inputted (S10), the stream storing type is selected (S20).

When the selected type is the PES, the TS is transcoded into the PES by demultiplexing (S30). The transcoded PES is stored in the storing medium (S40).

On the other hand, when the selected type is the PS, the TS is transcoded into the PES by demultiplexing (S50). Thereafter, the transcoded PES stream is multiplexed into the PS (S60), and the PS is stored in the storing medium (S70).

When the selected type is the TS, the TS is stored in the storing medium as it is (S80).

FIG. 8illustrates sequential steps of the method for reproducing the PES, PS or TS stored in the PVR. As illustrated inFIG. 8, the stream stored in the storing medium is read (S10).

The type of the read stream is decided (S20). When the type of the stream is the PES, the PES is decoded and outputted (S30).

When the type of the read stream is the PS, the PS is transcoded into the PES by demultiplexing (S40), and the transcoded PES is decoded and outputted (S50).

When the type of the read stream is the TS, the TS is transcoded into the PES by demultiplexing (S60), and the transcoded PES is decoded and outputted (S70).

FIG. 9illustrates one example of applying the PVR structure to the DMB receiver in accordance with the present invention.

Referring toFIG. 9, a TS inputted to the DMB receiver is transmitted to a packet identifier (PID) filter402through a channel input (CIN) block401. The PID filter402filters the input packet to be decoded or stored by programs.

When the filtered TS is intended to be stored in a storing medium (not shown), the TS is transmitted to a download controller405, and stored in the storing medium through the download controller405.

When the filtered TS is decoded, the TS is transmitted to an MPEG-2 TS DEMUX403. The MPEG-2 TS DEMUX403transcodes the TS into a PES by demultiplexing.

The transcoded PES is transmitted to the download controller405to be stored, and to a PES DEMUX408to be decoded.

When the PES is stored, the PES is stored in the storing medium through the download controller405without passing through a PS MUX404. To store a PS, the transcoded PES is transmitted to the PS MUX404and transcoded into the PS. The transcoded PS is stored in the storing medium through the download controller405.

As described above, in order to reproduce the TS, PES and PS stored in the storing medium, the stored TS is transmitted to the PID filter402through an upload controller406, and transcoded into the PES by the MPEG-2 TS DEMUX403.

The stored PES is transmitted directly from the upload controller406to the PES DEMUX408, and the PS is demultiplexed by a PS DEMUX407to be transcoded into the PES, and inputted to the PES DEMUX408.

The PES DEMUX408receives the PES, and demultiplexes a sync layer (SL) under the MPEG-4 standard. An MPEG-4 SL DEMUX409receives the SL and outputs an access unit (AU).

An MPEG-4 AV decoder410decodes and outputs audio and video signals by the AU for display.

As discussed earlier, in accordance with the present invention, the method and apparatus for storing/reproducing the TS, and the digital receiver using the same have the following advantages.

First, the structure and method for storing the PS or TS are suggested to overcome incompatibility of the stored stream and difficulty in the rate control at the time of reproduction in the general PVR.

Second, the PVR structure applied to the DMB receiver for storing the PS, TS and PES is suggested to improve competitiveness of the DMB receiver and facilitate development of various application products.