KR100935493B1 - Apparatus and method for transcoding based on distributed digital signal processing - Google Patents

Abstract

Disclosed are a DSP-based distributed transcoding apparatus and method. Each of the plurality of converters converts and outputs a bitstream encoded by the first compression standard in the input GOP unit into a bitstream encoded by the second compression standard. The host unit extracts the bitstream encoded by the first compression standard of the GOP unit from the bitstream encoded by the first compression standard input from the outside, and provides the bitstream encoded by the first compression standard to the selected transformer from among the plurality of transformers. The bitstreams encoded by the second compression standard are output in alignment in a time sequence. According to the present invention, by dividing a bitstream encoded by any video compression standard into GOP units and transcoding using a plurality of converters, it is possible to shorten the time required for converting a video compression format to various devices and Real-time streaming of multimedia data is possible in the environment.

MPEG-2, H.264, Transcoding, Bitstream, Distributed Processing

Description

Apparatus and method for transcoding based on distributed digital signal processing

The present invention relates to a DSP-based distributed transcoding apparatus and method, and more particularly, to a DSP-based distributed transcoding apparatus and method for converting an image encoded in the MPEG-2 standard into an image encoded in the H.264 standard. will be.

Image compression standards include the MPEG-x and H.26x families, standardized by ITU-T and ISO / IEC. In the field of video compression, transcoding not only changes the spatial resolution, frame rate, bit rate, etc. from homogeneous format, but also the heterogeneous format of the image compressed in a certain format. This includes changes.

Currently provided streaming services can be reproduced with limited spatial resolution and frame rate through a mobile terminal in a wireless local area network (CDMA) or a code-division multiple access (CDMA) network having limited channel capacity. In order to provide such a streaming service, existing video compression formats such as MPEG-x (ie, MPEG-2 or MPEG-4) can be replaced with H.26x (ie, H.263 or H.264) having a high compression rate in the field of current video compression. Transcoding to the compressed format is required. However, since heterogeneous transcoding that decodes MPEG-2 compressed video and then re-encodes H.264, syntaxes, motion vectors, and mode information of MPEG-2 and H.264 are different, When re-encoding with H.264, it is difficult to use the decrypted MPEG-2 information as it is. Therefore, heterogeneous transcoding requires a large amount of computation, and a large amount of computation required for heterogeneous transcoding acts as a limiting factor of the real-time streaming service.

The present invention provides a DSP-based distributed transcoding apparatus and method for a video sequence that can easily provide a real-time streaming service by reducing the time required to convert an MPEG-2 encoded image to H.264. There is.

The technical problem to be achieved by the present invention is to reduce the time required to convert MPEG-2 encoded video to H.264 to execute a DSP-based distributed transcoding method of a video sequence that is easy to provide a real-time streaming service on a computer The present invention provides a computer-readable recording medium having recorded thereon a program.

A distributed transcoding apparatus according to the present invention for achieving the above technical problem, a plurality of transformations for converting and outputting a bitstream encoded in the first compression standard of the input GOP unit into a bitstream encoded in the second compression standard part; And dividing the bitstream encoded by the first compression standard input from the outside into a bitstream encoded by the first compression standard of the GOP unit, and providing the converted bitstream to a converter selected from the plurality of converters, and inputting from each converter. And a host unit for sorting and outputting the bitstreams encoded by the second compression standard according to a time sequence.

In accordance with another aspect of the present invention, there is provided a distributed transcoding method comprising: (a) extracting a bitstream encoded with a first compression standard in GOP units from a bitstream encoded with a first compression standard input from the outside; Making; (b) selecting a converter to convert, from a plurality of converters, the bitstream encoded with the first compression standard in the extracted GOP unit into the bitstream encoded with the second compression standard; (c) the selected converter converting the bitstream encoded with the first compression standard in the GOP unit into the bitstream encoded with the second compression standard; And (d) sorting and outputting the bitstream encoded by the second compression standard in a time sequence.

According to the DSP-based distributed transcoding apparatus and method according to the present invention, an MPEG-2 image compression standard is divided into MPEG-2 bitstreams by Group of Picture (GOP) to compare an MPEG-2 image compression standard to an MPEG-2 image compression standard. By assigning to a plurality of converters for converting to the H.264 video compression standard having a compression performance of 50% or more, and taking the configuration that each converter performs the conversion, it is possible to shorten the time required to convert the video compression format Real-time streaming of multimedia data is possible in various devices and environments.

Hereinafter, exemplary embodiments of a DSP-based distributed transcoding apparatus and method according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a diagram showing the configuration of a preferred embodiment for a DSP-based distributed transcoding device according to the present invention.

Referring to FIG. 1, the DSP-based distributed transcoding apparatus 100 according to the present invention includes a host unit 110 and a plurality of converters 150-1 to 150-n. The control signal and the bitstream are input and output between the host 110 and the plurality of converters 150-1 to 150-1 through a wired or wireless transmission path. Preferably, the PCI bus is connected to the host 110 and the plurality of converters. Is employed as a transmission path between the conversion units 150-1 to 150-1.

The host unit 110 divides the input MPEG-2 bitstream into GOP units and provides the transform units 150-1 to 150-n to each of the transform units 150-1 to 150-n. The input H.264 video stream is sorted in chronological order and output. The host unit 110 includes an input buffer 115, a GOP extractor 120, a demultiplexer 125, a multiplexer 130, an output buffer 135, and a controller 140.

The input buffer 115 stores a bitstream encoded by an MPEG-2 image compression standard input from the outside.

The GOP extractor 120 parses the header information of the MPEG-2 bitstream stored in the input buffer 115, sequentially extracts the bitstream in GOP units, and outputs the bitstream to the demultiplexer 125. An MPEG-2 video consists of a plurality of GOPs, and a GOP is a group of consecutive images in an image stream encoded by an MPEG. Such a GOP is composed of an I-frame (Intra coded picture), a P-frame (Predictive coded picture), and a B-frame (Bidirectionally predictive coded picture). An I-frame is a reference image corresponding to a fixed image, which is independent of other types of frames, and each GOP starts with an I-frame. A P-frame is a frame containing difference information obtained from a previous I-frame or a P-frame in time, and a B-frame is a frame containing difference information obtained from an I-frame or a P-frame before or after time. to be. Accordingly, the GOP extractor 120 detects I-frames included in the bitstream and outputs the frames constituting each GOP to the demultiplexer 125. The demultiplexer 125 provides each GOP input from the GOP extractor 120 to a converter selected by the controller 140 among the plurality of converters 150-1 to 150-n.

The multiplexer 130 receives an H.264 bitstream from each of the converters 150-1 to 150-n and outputs the H.264 bitstream to the output buffer 135 in a time sequence under the control of the controller 140. The output buffer 135 stores the H.264 bitstreams arranged in chronological order in a storage device (not shown) or transmits them through a wired or wireless communication network.

The controller 140 controls an operation of providing the MPEG-2 bitstream in units of GOPs to the converters 150-1 to 150-n by the demultiplexer 125. To this end, the control unit 140 manages the conversion operation performance status of each of the conversion units 150-1 to 150-n, and is extracted by the GOP extraction unit 120 and input to the demultiplexer 125. It manages the identification information of the bitstream of the conversion unit 150-1 to 150-n provided with the bitstream of the corresponding GOP unit. In addition, the control unit 140 is a multiplexing unit based on the identification information of the GOP corresponding to the H.264 bitstream input to the conversion unit and the multiplexer 130, the H.264 bitstream input to the multiplexer 130 The control unit 130 outputs the H.264 bitstreams provided from the plurality of conversion units 150-1 to 150-n to the output buffer 135 in time order. By the control operation of the controller 140, the converters 150-1 to 150-n for converting the MPEG-2 bitstream of the GOP unit into the H.264 bitstream can be utilized as efficiently as possible. This can be sorted by time order.

The converters 150-1 to 150-n convert the MPEG-2 bitstream in a GOP unit into an H.264 bitstream. Each of the conversion units 150-1 to 150-n has the same configuration and is composed of a decoding buffer 155, an MPEG-2 decoder 160, an H.264 encoder 165, and a stream buffer 170. . The converters 150-1 to 150-n may be manufactured as separate chips, or may be manufactured by software ported to a DSP (Digital Signal Processing) chip provided in a terminal device such as a general purpose computer, a mobile communication terminal device, a PDA, or the like. Can be.

The decoding buffer 155 stores the MPEG-2 bitstream input in the GOP unit from the host unit 110. The MPEG-2 decoder 160 reconstructs the original image by decoding the MPEG-2 bitstream in a GOP unit. The H.264 encoder 165 encodes the original image reconstructed by the MPEG-2 decoder 160 into H.264. The stream buffer 170 provides the H.264 encoded bitstream to the host unit 110. Among the components of the converting units 150-1 to 150-n, detailed configurations and functions of the MPEG-2 decoder 160 and the H.264 encoder 165 may be obtained by those skilled in the art. If you are familiar with the ramen, detailed descriptions are omitted.

2 is a flowchart illustrating a process of performing a preferred embodiment of the DSP-based distributed transcoding method according to the present invention.

Referring to FIG. 2, the GOP extractor 120 parses header information of an MPEG-2 bitstream stored in the input buffer 115 and sequentially extracts the bitstream in GOP units to the demultiplexer 125. Output (S200). The demultiplexer 125 converts each GOP inputted from the GOP extractor 120 by a control signal of the controller 140 among the plurality of converters 150-1 to 150-n through the PCI bus. Provided to the completed conversion unit (S210). The MPEG-2 decoder 160 decodes the MPEG-2 bitstream stored in the decoding buffer 155 to restore the original image (S220). The H.264 encoder 165 encodes the original image reconstructed by the MPEG-2 decoder 160 to H.264 (S230). The stream buffer 170 provides the multiplexer 130 with the H.264 encoded bitstream through the PCI bus (S240). The multiplexer 130 outputs the H.264 bitstream provided from each of the converters 150-1 to 150-n to the output buffer 135 in time order under the control of the controller 140 (S250). . The output buffer 135 stores the H.264 bitstreams arranged in chronological order in a storage device (not shown) or transmits them through a wired or wireless communication network (S260).

In the above description, an example of converting a bitstream encoded by the MPEG-2 video compression standard into a bitstream of the H.264 video compression standard has been described. In addition to .264, it may be applied to converting into a bitstream of other video compression standards. In this case, the H.264 encoder of the converter is replaced by an encoder encoding with another video compression standard.

The invention can also be embodied as computer readable code on a computer readable recording medium. The computer-readable recording medium includes all kinds of recording devices in which data that can be read by a computer system is stored. Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage, and the like, and may also be implemented in the form of a carrier wave (for example, transmission over the Internet). Include. The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion.

Although the preferred embodiments of the present invention have been shown and described above, the present invention is not limited to the specific preferred embodiments described above, and the present invention belongs to the present invention without departing from the gist of the present invention as claimed in the claims. Various modifications can be made by those skilled in the art, and such changes are within the scope of the claims.

1 is a diagram showing the configuration of a preferred embodiment of a DSP-based distributed transcoding device according to the present invention, and

2 is a flowchart illustrating a process of performing a preferred embodiment of the DSP-based distributed transcoding method according to the present invention.

Claims (9)

A plurality of converters converting the bitstream encoded by the first compression standard in the input GOP unit into a bitstream encoded by the second compression standard; And A bitstream encoded by the first compression standard input from the outside is divided into a bitstream encoded by the first compression standard of the GOP unit, and provided to a transform unit selected from the plurality of transformers, and input from each transformer. And a host unit for sorting and outputting the bitstreams encoded by the second compression standard in a time sequence. Each of the plurality of converters transmits and receives a control signal and a bitstream through the host bus and the PCI bus. The method of claim 1, The host unit, An input buffer for storing a bitstream encoded with a first compression standard input from an external device; A GOP extraction unit for parsing header information of a bitstream encoded with a first compression standard stored in the input buffer and sequentially extracting and outputting a bitstream encoded with a first compression standard in a GOP unit; A demultiplexer for providing a bist stream encoded by a first compression standard of each GOP unit input from the GOP extractor to a transform unit selected from the plurality of transform units; A multiplexer for outputting the bitstream encoded by the second compression standard input from each of the converters in time order; An output buffer for storing bitstreams encoded in a second compression standard arranged in chronological order in a storage device or for transmitting over a wired or wireless communication network; And A second compression standard input to the multiplexing unit is managed by the conversion unit to manage the performance of each conversion operation, the identification information of the bit stream of the GOP unit extracted by the GOP extraction unit and the corresponding identification information of the conversion unit, The multiplexer encodes the second compression standard provided from the plurality of converters based on the identification information of the converter that provides the encoded bitstream and the identification information of the bitstream encoded by the first compression standard of the corresponding GOP unit. And a controller for controlling the outputted bitstreams to be output to the output buffer in a time sequence. The method according to claim 1 or 2, Each of the conversion unit, A decoding buffer for storing a bitstream encoded with a first compression standard in a GOP unit input from the host unit; A first compression standard decoder which reconstructs the original image by decoding a bitstream encoded by the first compression standard of the GOP unit; A second compression standard encoder for encoding the reconstructed original image into a second compression standard; And And a stream buffer for providing a bitstream encoded by the first compression standard to the host unit. delete (a) extracting the bitstream encoded with the first compression standard in GOP units from the bitstream encoded with the first compression standard input from the outside; (b) selecting a converter to convert, from a plurality of converters, the bitstream encoded with the first compression standard in the extracted GOP unit into the bitstream encoded with the second compression standard; (c) the selected converter converting the bitstream encoded with the first compression standard in the GOP unit into the bitstream encoded with the second compression standard; And (d) sorting and outputting the bitstream encoded by the second compression standard in a time sequence. In the step (a), distributed transcoding, wherein the header information of the bitstream encoded by the first compression standard input from the outside is parsed and extracted into a bitstream encoded by the first compression standard of the GOP unit. Way. delete The method of claim 5, In the step (b), the converter which has completed the conversion operation on the bitstream encoded by the first compression standard in the GOP unit, which has been extracted and provided among the plurality of converters, is used as the first compression standard in the extracted GOP unit. A distributed transcoding method comprising selecting an encoded bitstream as a converter to convert. The method of claim 5, In step (d), the bitstream encoded with the first compression standard in GOP units corresponding to the identification information of the converter providing the bitstream encoded with the second compression standard and the bitstream encoded with the second compression standard. And aligning the bitstreams encoded by the first compression standard provided by the plurality of converters in chronological order based on the identification information of the plurality of converters. A computer-readable recording medium having recorded thereon a program for executing the distributed transcoding method according to any one of claims 5, 7, or 8 on a computer.

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