KR100672378B1 - Personal Video Recorder - Google Patents

Abstract

The present invention relates to a personal video recorder (PVR). The present invention provides a personal video recorder capable of storing stream data, comprising: a memory device for temporarily storing stream data input to the personal video recorder; A hard disk storing stream data to be output from the personal video recorder; A cache memory for temporarily storing the stream data before inputting the stream data temporarily stored in the memory device to the hard disk or before outputting the stream data stored in the hard disk to the memory device; And a cache memory controller configured to manage an operation of the cache memory in response to an input / output request of the stream data to the cache memory. According to the present invention, when a personal video recorder stores or plays back a huge stream in real time, the stream may be processed without degrading PVR performance.

Cache memory, PVR

Description

Personal Video Recorder {Personal Video Recorder}

1 is a view showing an example of a process in which data is stored on the hard disk and output in a conventional PVR system

2 is a diagram illustrating an example of uploading / downloading a file stored in a memory device to a hard disk in a conventional PVR system.

3 is a view showing an example of a process in which data is stored and output on a hard disk in an embodiment of a PVR system having a storage device according to the present invention;

4 is a diagram illustrating an example of uploading / downloading a file stored in a cache memory to a hard disk in an embodiment of a PVR system having a storage device according to the present invention.

5A illustrates an example of an access time required when a file is downloaded to a hard disk in a conventional PVR system.

5B illustrates an example of an access time required when downloading a file to a hard disk in an embodiment of a PVR system having a storage device according to the present invention.

5c illustrates another example of an access time required when downloading a file to a hard disk in an embodiment of a PVR system having a storage device according to the present invention.

6 is a structural diagram showing an example of a cache memory configuration of a PVR system according to the present invention;

<Description of Symbols for Main Parts of Drawing>

10: encoder 20: memory device

25: DMA controller

30: multiplexer 40: download controller

50: IDE controller 55: Buffer

60: hard disk 70: upload controller

80: demultiplexer 90: decoder

100: cache controller 200: cache memory

The present invention relates to a personal video recorder (PVR) system equipped with a hard disk, and more particularly, to a PVR system including a cache having a fast access speed as a memory device.

A PVR is a device capable of storing analog or digital broadcasts on a hard disk (hereinafter, used in the same sense), as well as a recording function as well as time shift, instant replay and other live broadcasts. It offers much improved functions than the existing video cassette recorder (VCR) such as trick play. In addition, the PVR is equipped with a function to store and view HD-quality high-definition digital broadcasting at any time on the hard disk, and provides a variety of additional services.

With the rapid development of storage technology, the capacity of the hard disk mounted on the PVR has greatly increased, and the amount of programs that can be recorded on the PVR device has also increased greatly. As a result, the technology for improving access to the vast amount of digital stream data stored in the hard disk has become the core technology of the PVR in the future. In particular, when the access efficiency to the hard disk is increased, the user can easily record a program or easily play back the recorded program.

However, in a conventional PVR system, data stored in a double data rate-synchronous dynamic random access memory (DDR-SDRAM) is reloaded through a direct memory access (DMA) controller when a hard disk is accessed. There is a problem in that it takes a long time to access the desired data because the data stored or stored in the hard disk is loaded into the DDR-SDRAM and reproduced. In addition, in the case of a PVR system using a high performance hard disk, the above problem is a cause of making the most of the performance of the hard disk.

Referring to FIG. 1, an example of a process in which a stream is stored on a hard disk and a stored stream is reproduced in the conventional PVR system is as follows. When each packetized elementary stream (PES) is generated by the video or audio encoder 10, the PES is stored in the DDR-SDRAM 20. The multiplexer 30 converts the stream stored in the DDR-SDRAM 20 into a downloadable transport stream (hereinafter referred to as a download TS) to be stored in the storage device and stores the stream in the DDR-SDRAM 20 again.

A download controller 40 converts the stored downloadable transport stream into a time-stamped transport stream (TST) and stores it in the DDR-SDRAM 20. An integrated drive electronics contrlloer (IDE) controller 50 downloads and stores the time-stamped transport stream (TTS) to the hard disk 60.

Now, a process for uploading and decoding a transport stream stored in the hard disk 60 will be described. When the stream is reproduced, the timestamp transport stream stored in the hard disk 60 is converted into an upload transport stream (upload TS) by the upload controller 70 and stored in the DDR-SDRAM 20. And, the demultiplexer 80 The stored upload TS is divided into audio and video PES and output to the video or audio decoder 90, and the decoder 90 decodes and outputs the stream.

Referring to FIG. 2, in an example of a conventional PVR system, a time-stamp transport stream stored in a DDR-SDRAM is downloaded to a hard disk, or a time-stamp transport stream stored in a hard disk is uploaded to a DDR-SDRAM. The process is described in detail as follows.

The DMA controller 25 outputs the time-stamped transport stream stored in the DDR-SDRAM 20 through a memory bus and buffers the buffer 55 in a predetermined size. The IDE controller 50 outputs the buffered stream and stores the buffered stream in the hard disk 60 through the IDE bus. The upload process is the reverse of the above process. When the IDE controller 50 receives the stream stored in the hard disk 60 through the IDE bus and outputs it to the buffer 55, the DMA controller 25 stores the stream again in the DDR-SDRAM 20 through the memory bus. .

As described above, the above-described process is performed through access of DDR-SDRAM, which can be a memory device of the PVR system. Therefore, the bandwidth and access to the PVR system bus are handled when processing a large amount of data such as an HD stream. There is a problem that the number of times increases. And when the PVR system processes the HD stream in real time, there is a problem that the performance of the PVR system is degraded.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a personal video recorder capable of processing the stream without degrading the PVR performance when the PVR system stores or plays back a huge stream in real time.

Another object of the present invention is to provide a personal video recorder which has high input / output throughput when accessing a hard disk and can reduce the number of times of use of the system's memory bus.

In order to achieve the above object, the present invention provides a personal video recorder capable of storing stream data, comprising: a memory device for temporarily storing stream data input to the personal video recorder; A hard disk storing stream data to be output from the personal video recorder; A cache memory for temporarily storing the stream data before inputting the stream data temporarily stored in the memory device to the hard disk or before outputting the stream data stored in the hard disk to the memory device; And a cache memory controller configured to manage an operation of the cache memory in response to an input / output request of the stream data to the cache memory.

Preferably, the cache memory stores the temporarily stored transport stream by using the time stamp information of the temporarily stored transport stream. Timestamp information can be used to upload or download transport streams on a granular basis without the need to implement algorithms for complex cache coherency or cache replacement policies.

The cache memory may preferably include any one of upload status information and download status information for the transport stream when temporarily storing the transport stream. In the case of including the up / download status information, the cache memory may include action performance information indicating whether a transport stream has completed an upload status or a download status.

In addition, the cache memory preferably includes history information on the number of input / output times of the temporarily stored transport stream.

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention that can specifically realize the above object will be described.

An example of a process of storing and outputting stream data in a hard disk in an embodiment of a PVR system according to the present invention will be described with reference to FIG. 3 as follows. First, the process of downloading digital signals will be described. The encoder 10 outputs the PES and stores the PES in the DDR-SDRAM 20. The multiplexer 30 converts the stream stored in the DDR-SDRAM 20 into a download TS and stores the stream in the DDR-SDRAM 20 again.

A download controller 40 converts the stored download TS into a time-stamped transport stream (TSS) and stores it in the cache memory 200. An integrated drive electronics contrlloer (IDE) controller 50 downloads and stores the time-stamp transport stream to the hard disk 60.

The time-stamp transport stream stored in the hard disk is uploaded as follows. The IDE controller 50 outputs the time-stamp transport stream (TTS) stored in the hard disk 60 to the cache memory 200. The upload controller 70 converts the stream stored in the cache memory 200 into an upload TS and stores the stream in the DDR-SDRAM 20. Demultiplexer 80 The upload TS is separated into PES and output to the video or audio decoder 90, respectively, and the decoder 90 decodes and outputs the stream.

According to an embodiment of the present invention, unlike the conventional PVR system, the output of the download controller is stored in the cache memory 200 when the stream is downloaded. In addition, during uploading, the IDE controller outputs the stream stored in the hard disk 60 to the cache memory 200, and the upload controller 70 converts the stream stored in the cache memory 200 into the upload TS to DDR-SDRAM. Save to 20.

An example of uploading / downloading a file stored in a cache memory to a hard disk in an embodiment of a PVR system according to the present invention will be described with reference to FIG. 4. The PVR system according to the present invention can remove the buffer included in the conventional PVR system of FIG. Therefore, the cache controller 100 accesses the cache memory 200 to upload a temporarily stored stream or stores a download TS in the cache memory 200 without a buffering process. In addition, the IDE controller 50 may interface with the cache memory 200 so that the IDE controller 50 stores the stream stored in the cache memory 200 on the hard disk 60 or the hard disk 60. ) May be output to the cache memory 200. The cache controller 100 may manage the stream temporarily stored in the cache memory 200 using history information, upload, and download information about the memory stored in the cache memory 200. This will be described in the detailed description of FIG. 6.

An embodiment of the PVR system according to the present invention described with reference to FIG. 4 is compared with the conventional PVR system described with reference to FIG. 2 as follows. According to an embodiment of the present invention, when storing the time-stamp transport stream, the process of storing the stored stream in the DDR-SDRAM through the DMA controller and outputting the stored stream back to the IDE controller is omitted. Therefore, the memory device (DDR-SDRAM) that requires a long access time is not accessed. Instead, the timestamp transport stream is output directly to cache memory and stored, and then stored back on the hard disk. Since the speed of accessing the cache memory is faster than the speed of accessing the memory device (DDR-SDRAM), the time for storing the stream on the hard disk can be shortened. It can also lower the utilization of the system bus, which can be problematic when processing large amounts of data such as HD streams in real time.

Referring to FIG. 5, a theoretical memory access time of a conventional PVR system and an embodiment of the PVR system of the present invention are compared and described. For ease of explanation, it is assumed that the bandwidth of the memory bus is 16 bytes and the size of the stream to be transmitted is 192 bytes.

5A shows an access time required when downloading a stream to a hard disk in a conventional PVR system. In the conventional PVR system, the download controller 40 stores the stream in the memory device 20. The IDE controller 50 reads the stream and stores the stream in the buffer, and then stores the stream stored in the buffer in the hard disk 60 again. Therefore, the number of accesses to the memory device 20 is required twice, and the number of cycles required for each one access is 12 (192 bytes ÷ 16 bytes). In addition, while the IDE controller 50 and the download controller 40 access the memory device (DDR-SDRAM) 12 times (192 bytes ÷ 16 bytes) to store data on the hard disk, the required time caused by buffering is randomly determined. Can be displayed using numbers. alpha represents any number indicating additional cycles that result from accessing the memory device using the shared memory bus.

In addition, the conventional PVR system reduces the number of accesses to the system memory device in order to process a large amount of data in real time, and accesses by increasing the unit of data accessed at one time. To achieve this, the buffer size of the IDE controller can be used N times the transport stream. In such a case, the time required to load data into the memory device (DDR-SDRAM) 20 or to reload data from the memory device becomes (12 + alpha) * N * 1 unit cycles, respectively, To access the memory device twice in total, it takes about 2 * (12 + alpha) * N * 1 unit cycles of memory access time.

5B and 5C illustrate an example of access time required when downloading a stream to a hard disk in an embodiment of the PVR system according to the present invention. 5B and 5C show the same amount of data as in the example of FIG. 5A. In FIG. 5B, the output of the download controller 40 is directly stored in the cache memory 200, and the IDE controller may directly access the cache memory 200. In the following, additional cycles arising from accessing the cache memory using the shared memory bus are shown in beta. Therefore, when the download controller outputs data from the memory device 20 and stores the data in the hard disk 60 via the cache memory, (12 + beta) * N * 1 unit cycles are required.

delete

5C illustrates an example of an access time when the download controller stores data in a cache memory using a dedicated bus unlike FIG. 5B. Accordingly, in the case of FIG. 5C, an access time of 12 * N * 1 unit cycles is required.

In general, the beta value of FIG. 5B is very small compared to alpha. 5A and 5B, when using a shared memory bus, ((alpha-beta) * N) * 1 unit cycle + (12 + alpha) * N * 1 unit cycle can reduce the memory access time. 5B and 5C, the memory access time can be further shortened when a dedicated bus is used. As can be seen by comparing FIG. 1 and FIG. 3, the memory access time can be significantly reduced compared to the related art, since the number of accesses of the memory device can be reduced. Therefore, the present invention can be very useful for processing HD stream having a large amount of data.

Referring to Figure 6 describes the structure of the cache memory of the PVR system according to an embodiment of the present invention. The cache memory of the PVR system according to an exemplary embodiment of the present invention stores a stream by using time stamp information. As described above, the cache memory of the PVR system according to the preferred embodiment of the present invention uses a time stamp of a predetermined unit by using time stamp information without implementing an algorithm for a cache coherency policy or a cache replacement policy used in a conventional cache memory implementation. You can upload or download the transport stream.

In general, a cache memory has a width and a depth of a line memory for caching. The size of a cache memory according to an embodiment of the present invention is history information and action performance information for each line memory. It is desirable to store the transport stream including the Done in Fig. 6, upload / download information, and time stamp information.

The history information indicates the number of times the transport stream has been input and output to the cache memory. The up / download information is information indicating whether the stream stored in the cache memory is in the upload process (indicated by u in FIG. 6) or in the download process (indicated by d in FIG. 6). Action performance information (Done in FIG. 6) indicates whether the upload or download of the transport stream stored in the same line memory is completed. The time stamp information is predetermined information including time information included in a header of a transport stream to distinguish the transport stream.

The PVR system according to the present invention can take full advantage of the cache memory because the memory access pattern of the data stored in the cache memory is very regular and continuous. In addition, since the above information is included in a time stamp serving as a header of the time stamp transport stream, it is not necessary to separately generate information necessary for cache memory management.

When uploading and downloading are simultaneously performed or time shifting is performed for the same stream, the conventional PVR system accesses the hard disk every time to store or read the stream. However, the present invention requires the request. Because of the high probability that a stream will remain in cache memory, the number of times the hard disk is accessed can be greatly reduced. Therefore, the time required for uploading or downloading the same amount of streams can be reduced more than the theoretical time described with reference to FIG. 5.

The effects of the personal video recorder according to the present invention described above are as follows.

First, according to the present invention, when the PVR system stores or reproduces a massive stream in real time, the stream may be processed without degrading PVR performance.

Second, according to the present invention, the input / output throughput is high when the hard disk is accessed, and the number of times of use of the memory bus of the system can be reduced.

Third, according to the present invention, the access speed to the hard disk can be improved, and the load on the system memory can be distributed.

Claims (5)

In a personal video recorder that can store stream data, A memory device for temporarily storing stream data input to the personal video recorder; A hard disk storing stream data to be output from the personal video recorder; A cache memory for temporarily storing the stream data before inputting the stream data temporarily stored in the memory device to the hard disk or before outputting the stream data stored in the hard disk to the memory device; And And a cache memory controller configured to manage an operation of the cache memory in response to an input / output request of the stream data to the cache memory. The method of claim 1, And the cache memory distinguishes and stores the temporarily stored transport stream based on time stamp information of the temporarily stored transport stream. The method of claim 1, And the cache memory includes any one of upload status information and download status information for the transport stream when temporarily storing the transport stream. The method of claim 3, And the cache memory includes action performance information indicating whether the transport stream has completed an upload state or a download state. The method of claim 1, And the cache memory includes history information on the number of input / output times of the temporarily stored transport stream.

Images