JP2009089151A - Moving image recorder and its method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a moving image recorder of simple constitution, which encodes moving image data and detects the operating condition of recording through a recording means upon recording the encoded data on a recording medium to estimate a recording medium transfer rate based on the condition and control an encoding rate. <P>SOLUTION: When the moving image data is encoded and the encoded data is recorded on an HDD 116, the recording condition of the HDD 116 is detected to estimate HDD transfer rate based on the recording condition and adjust the HDD transfer rate so that the encoding rate becomes lower than the HDD transfer rate. According to this operation, the actual recording operation condition can be fed back into the HDD at encoding, thus the encoding can be performed at the encoding rate suitable to the actual condition of recording operation. Accordingly, the elimination of data by the overflow of a buffer 106 can be avoided. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a moving image recording apparatus and method for encoding moving image data and recording the encoded data on a recording medium such as a hard disk.

In recent years, recording media such as hard disks have rapidly increased in speed and capacity, and expectations for media for recording moving image data have increased. Moving image data captured by a movie camera or the like is stored in the recording medium in real time. Technology to do so is widespread.
In conventional moving image recording devices, in order to record high-quality data in real time, moving image data that requires real-time properties in consideration of seek time and rotation waiting time for moving the magnetic head onto the target track Is recorded in a zone on the outer peripheral side of the disc, and a still image or the like that does not require real-time performance is recorded in a zone on the inner peripheral side of the disc.
There is also a technique in which two encoders are provided, the encoding parameters are fed back from the first-stage encoding information, and the data amount is adjusted by the subsequent-stage encoder.

JP-A-9-186963 JP-A-7-177464

  However, in the above-described prior art, real-time writing processing to a recording medium to a hard disk or the like is realized by using the advantage of writing speed on the outer periphery of the disk, but it is variable for each picture as in the MPEG standard or the like. When a long code amount is generated, moving image data with an increased code amount may not be recorded even at the outer periphery of the disc.

Further, in the hard disk, there are cases where the transfer rate to the recording medium is reduced due to external factors such as fragmentation, and recording cannot be performed, or recording on the recording medium cannot be performed temporarily due to dropping or the like.
That is, the conventional technique has a problem that the actual recording operation state on the recording medium is not fed back to the encoding, and the encoding may be performed at an encoding rate that is incompatible with the actual recording operation state.
Moreover, when providing a some encoder, there exists a problem that a structure becomes complicated.

  The present invention has been made in view of the above-described problems of the prior art, and when encoding moving image data and recording the encoded data on a recording medium, encoding suitable for the actual recording state of the recording medium can be performed. An object of the present invention is to provide a moving image recording apparatus and a method thereof.

  In order to solve the above-described problems of the prior art and achieve the above-described object, a moving image recording apparatus of the present invention is a moving image recording apparatus that records encoded data on a recording medium, and the input moving image Encoding means for encoding data at a predetermined encoding rate, a memory for storing encoded data encoded by the encoding means, and reading the encoded data from the memory and recording it on the recording medium A recording operation state detecting unit for detecting a recording operation state by the recording unit; and the recording unit transmits the code to the recording medium based on the recording operation state detected by the recording operation state detection unit. Recording medium transfer rate prediction means for predicting the data transfer rate for recording the digitized data, and based on the data transfer rate predicted by the recording medium transfer rate prediction means And a coding rate control means for controlling the coding rate Te. Preferably, the recording operation state detection unit detects a recording stop state due to a fall of the apparatus as the recording operation state by the recording unit.

  The moving image recording method of the present invention is a moving image recording method for recording encoded data on a recording medium, encoding the input moving image data at a predetermined encoding rate to generate encoded data, An encoding process for writing the encoded data into the memory, a recording process for reading the encoded data written in the encoding process from the memory and recording it on the recording medium, and detecting a recording operation state by the recording means Based on the recording operation state detected in the recording operation state detection step and the recording operation state detection step to predict the data transfer rate for recording the encoded data on the recording medium in the recording step. A recording medium transfer rate prediction step to be performed; and the encoding rate is controlled based on the data transfer rate predicted in the recording medium transfer rate prediction step And a that coding rate controlling step.

  ADVANTAGE OF THE INVENTION According to this invention, when moving image data is encoded and it records encoded data on a recording medium, the moving image recording apparatus which can encode by the encoding rate suitable for the actual recording state of the recording medium And a method thereof.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a functional block diagram of an embodiment of the present invention.

FIG. 1 shows a basic configuration of a moving image recording apparatus that compresses and encodes image data, among MPEG encoding apparatuses that compress and encode image data (moving image data) and audio data by the MPEG method.
As illustrated in FIG. 1, the moving image recording apparatus 10 includes an input terminal 101, an operation unit 102, a DCT unit 103, a quantization unit 104, a VLC unit 105, a buffer 106, an inverse quantization unit 107, an inverse DCT unit 108, an operation. Unit 109, image memory 110, motion compensation prediction unit 111, coding rate control unit 112, HDD state detection unit 114, HDD access control unit 115, HDD transfer rate prediction unit 117, and writes image data to HDD 116 It is configured as follows. The HDD 116 may be another recording medium such as a flash memory, a DVD, or a BD.

  Here, the HDD 116 corresponds to the recording medium of the present invention, the buffer 106 is the memory of the present invention, the HDD access control unit 115 is the recording unit of the present invention, the HDD state detection unit 114 is the recording operation state detection unit of the present invention, and the HDD. The transfer rate prediction unit 117 corresponds to the recording medium transfer rate prediction unit, the encoding rate control unit 112 corresponds to the encoding rate control unit of the present invention, and the DCT unit 103, the quantization unit 104, the VLC unit 105, etc. This corresponds to the encoding means. Further, the HDD transfer rate in this embodiment corresponds to the recording medium transfer rate of the present invention.

  Next, the operation of this embodiment will be described.

  When image data is input to the moving image recording apparatus 10, the input terminal 101 outputs the input image data to the calculation unit 102 and the motion compensation prediction unit 111.

  The calculation unit 102 obtains a difference between the image data decoded by the motion compensation predictor 111 and the image data input from the input terminal 101, and outputs the difference image data to the DCT unit 103.

  The DCT unit 103 orthogonally transforms the difference image data input from the arithmetic unit 102 and outputs the orthogonally transformed DCT coefficients to the quantization unit 104.

  The quantization unit 104 quantizes the DCT coefficient input from the DCT unit 103 and outputs the quantized data to the VLC unit 105 and the inverse quantization unit 107.

  At this time, the quantization unit 104 controls the generated code amount by controlling the quantization scale largely based on the code amount control signal from the coding rate control unit 112, or controls the quantization scale small. Change the amount of generated code. The generation of the code amount control signal in the coding rate control unit 112 will be described later.

  The inverse quantization unit 107 inversely quantizes the quantized data from the quantization unit 104 and outputs the inversely quantized DCT coefficient to the inverse DCT unit 108. The inverse DCT unit 108 receives the DCT from the inverse quantizer 107. The coefficient data is subjected to inverse DCT and then output to the calculation unit 109.

  In the intra mode, the calculation unit 109 adds the difference image input from the motion compensation prediction unit 111 to the data input from the inverse DCT unit 108, outputs the difference image to the image memory 110, and stores it as a reference image. Thereby, the image data is restored. In the inter mode, no addition is performed.

  When an input image is input from the input terminal 101, the motion compensation prediction unit 111 performs motion compensation prediction with reference to the reference image stored in the image memory 110, and calculates the difference image obtained by the prediction by the calculation unit 102 and the calculation. While outputting to the unit 109, the detected motion vector and the prediction mode are output to the VLC unit 105.

  The VLC unit 105 performs variable length coding on the quantized data from the quantizing unit 104, the motion vector, the coding parameter of the prediction mode, and the like from the motion compensated prediction unit 111, and outputs them to the buffer 106.

  The buffer 106 temporarily stores the variable length encoded data from the VLC unit 105, and the HDD access control unit 115 reads the encoded data stored in the buffer 106 and stores the encoded data in the HDD 116 at a predetermined transfer rate. Transfer and record the encoded data.

  Then, although details will be described later, the HDD status detection unit 114 detects the recording status of the HDD 116, the HDD transfer rate prediction unit 117 predicts the transfer rate to the HDD 116 from the recording status, and the encoding rate control unit 112 detects the HDD 116. The coding rate is determined based on the transfer rate to the image, and the quantization unit 104 controls the quantization.

FIG. 2 shows temporal changes in the HDD transfer rate and the encoding rate when image data is recorded on the HDD 116. The horizontal axis represents the elapsed time (seconds) from the start of recording, and the vertical axis represents the bit rate.
As shown in FIG. 2, when image data is encoded by the MPEG method, the encoding rate varies because each picture has a variable amount of code.

The HDD transfer rate lowering point shown in FIG. 2 is assumed that the HDD transfer rate decreases due to factors such as the fact that empty sectors in the HDD 116 exist discretely (occurrence of fragmentation) as the number of files increases. This is the point.
Up to the HDD transfer rate drop point, for example, the HDD transfer rate is normal because the seek time to the empty sector and the rotation waiting time are small and the HDD transfer rate is equal to the encoding rate, and the encoded data is lost. It is possible to record stably without doing.
However, after the HDD transfer rate lowering point, for example, the seek time and rotation waiting time until reaching the next empty sector increases, and the HDD transfer rate decreases, and as a result, HDD transfer rate <sign It becomes the conversion rate. In this case, the image data cannot be recorded in real time in a stable state. For example, the image data is lost in units of several frames (or several tens of frames), and when the image data recorded in the HDD 116 is reproduced, frames are dropped. It becomes an image. The same applies when a state in which data cannot be temporarily written to the HDD 116 due to a drop or the like occurs.

  Therefore, in the present embodiment, when fragmentation occurs or falls in the HDD 116 and the HDD transfer rate <the encoding rate, the encoding rate is dynamically changed according to the time change of the HDD transfer rate. Thus, the image data amount (code amount) is appropriately increased or decreased.

  Next, code amount control based on HDD status detection in this apparatus will be described.

  FIG. 3 is a flowchart showing an example of code amount control operation based on HDD status detection in this apparatus.

  When the HDD access control unit 115 starts recording on the HDD 116 (step ST01), the HDD state detection unit 114 detects the recording state of the HDD 116 from the HDD access control unit 115 constantly or periodically (step ST02). Here, the HDD state detection unit 114 detects time information such as a seek time, a rotation waiting time, and a recording time as the recording state of the HDD 116.

  Here, the seek time of the HDD 116 is the time until the magnetic head moves to the target track, and the rotation waiting time is the time from when the magnetic head moves to the target track until the magnetic head reaches just above the target sector. The time and recording time are times required to record image data in an empty sector. Since the total time is the time to complete data recording in the HDD 116, the HDD transfer rate can be predicted from these information.

  The HDD transfer rate prediction unit 117 predicts the HDD transfer rate based on information such as a seek time, a rotation waiting time, and a recording time based on the state of the HDD 116 detected by the HDD state detection unit 114, and an encoding rate control unit It outputs to 112 (step ST03).

  The encoding rate control unit 112 compares the HDD transfer rate from the HDD transfer rate prediction unit 117 with the current encoding rate controlling the quantization unit 10, and “HDD transfer rate ≧ encoding rate”. And the code amount in the quantization unit 104 is controlled so that the buffer 106 does not overflow (step ST04).

  That is, if “HDD transfer rate ≧ encoding rate”, which is a normal recording state of the HDD 116, the encoding rate control unit 112 maintains the encoding rate or the encoding rate is “HDD transfer rate ≧ The encoding rate is increased within a range that satisfies the relationship of “encoding rate” (step ST05). Specifically, when “HDD transfer rate ≧ encoding rate”, the encoding rate control unit 112 may maintain the encoding rate as an initial value, or “HDD transfer rate ≧ encoding rate”. Of course, the encoding rate may be raised from the initial value within a range that satisfies the above. In addition, when fragmentation or the like occurs in the HDD 116, the HDD transfer rate decreases, and the encoding rate is also lowered accordingly. Then, when the HDD transfer rate returns to the initial value or the like by releasing the fragmentation, the encoding rate is changed. It may be raised to the initial value or the like, or of course, the coding rate may be raised from the initial value in a range satisfying “HDD transfer rate ≧ coding rate”.

  On the other hand, if fragmentation or the like occurs in the HDD 116 and “HDD transfer rate <encoding rate”, the encoding rate control unit 112 determines that the encoding rate is such that “HDD transfer rate ≧ encoding rate”. And the code amount in the quantization unit 104 is controlled (step ST06). At this time, since the encoding rate control unit 112 always monitors the buffer 106 so as not to overflow, it is not necessary to immediately decrease the encoding rate even if the condition “HDD transfer rate <encoding rate” occurs. However, if it is determined that the condition of “HDD transfer rate <encoding rate” continues and the buffer 106 is likely to overflow, the encoding rate is lowered so as to satisfy the relationship of “HDD transfer rate ≧ encoding rate”. Of course.

  The coding rate control unit 112 determines whether or not the recording process is finished (step ST07), and if the recording process is finished, the operation is finished. If the recording process is not completed, the process returns to step ST02.

  In this manner, by repeatedly executing the increase / decrease of the encoding rate, that is, the code amount according to the recording state of the HDD 116 until the image recording process is completed, the image data is recorded on the HDD 116 while maintaining a constant image quality. Can do.

  As described above, in the moving image recording apparatus 10 of the present embodiment, when the image data is encoded and the encoded data is recorded on the HDD 116, the recording state of the HDD 116 is detected, and the HDD transfer rate is set based on the recording state. Predict and adjust the encoding rate to be lower than the HDD transfer rate. Thereby, the actual recording operation state to the HDD 116 can be fed back to the encoding, and encoding can be performed at an encoding rate suitable for the actual recording operation state. Therefore, it is possible to avoid the data loss due to the overflow of the buffer 106.

  In the above embodiment, the HDD state detection unit 114 detects time information such as seek time, rotation waiting time, and recording time as the recording state of the HDD 116 from the HDD access control unit 115. Not limited to this, when a G sensor (not shown) for drop detection is provided in the apparatus, for example, in the HDD access control unit 115 or the HDD 116 or as the HDD state detection unit 114, Instead of the time information or together with the time information, the drop detection information from the G sensor and the recording stop state of the HDD 116 due to the drop may be detected as the recording state of the HDD 116. When the drop detection information from the G sensor or the recording stop state of the HDD 116 due to a drop is used as the recording state of the HDD 116, the HDD transfer rate prediction unit 117 predicts the transfer rate of the HDD 116 as zero. In this case, the process of ST06 in FIG. 3 is repeated many times, and the encoding rate is lowered step by step. In this case as well, overflow of the buffer 106 can be prevented.

The present invention is not limited to the embodiment described above.
That is, those skilled in the art may make various modifications, combinations, subcombinations, and alternatives regarding the components of the above-described embodiments within the technical scope of the present invention or an equivalent scope thereof.

  In the embodiment described above, a movie camera is cited as an example of a moving image recording apparatus, but there is no particular limitation as long as moving image data is encoded and recorded on a recording medium.

  As a data encoding standard, H.264 is used. The present invention can also be applied to H.264 / MPEG-4 AVC and later standards.

  Further, although fragmentation and dropping are cited as factors of the HDD transfer rate lowering point, any situation may be used as long as the data transfer rate to the recording medium is decreased.

  In addition, the encoding rate is adjusted so that the HDD transfer rate ≧ the encoding rate, but the condition is not limited as long as stable writing to the recording medium is realized.

  In addition, as long as stable writing to the recording medium is realized as a return condition for returning the HDD transfer rate and the encoding rate after changing the encoding rate, the present invention is not limited to this condition.

  Further, as a means for detecting the state of the recording medium, other functions or mechanisms may be provided.

  The present invention can be applied to an apparatus that encodes moving image data and records it on a recording medium such as a hard disk.

It is a functional block diagram shown in order to demonstrate the main functional blocks of the moving image recording device which concerns on embodiment of this invention. FIG. 2 is a diagram for explaining temporal changes in HDD transfer rate and encoding rate from the start of recording in the moving image recording apparatus shown in FIG. 1. 2 is a flowchart shown for explaining a flow of main functions in the moving image recording apparatus shown in FIG. 1.

Explanation of symbols

10: Moving image recording device,
101: Input terminal,
102: arithmetic unit,
103 ... DCT section,
104: Quantization unit,
105 ... VLC section,
106 ... buffer,
107: Inverse quantization unit,
108: Inverse DCT section,
109 ... arithmetic unit,
110: Image memory,
111 ... a motion compensation prediction unit,
112 ... Coding rate control unit,
114... HDD state detection unit,
115... HDD access control unit,
116: HDD,
117... HDD transfer rate prediction unit

Claims (3)

A moving image recording apparatus for recording encoded data on a recording medium,
Encoding means for encoding the input moving image data at a predetermined encoding rate;
A memory for storing the encoded data encoded by the encoding means;
Recording means for reading the encoded data from the memory and recording it on the recording medium;
A recording operation state detection unit for detecting a recording operation state by the recording unit;
A recording medium transfer rate prediction means for predicting a data transfer rate for the recording means to record the encoded data on the recording medium based on the recording operation state detected by the recording operation state detection means; ,
And a coding rate control unit for controlling the coding rate based on the data transfer rate predicted by the recording medium transfer rate prediction unit.   The moving image recording apparatus according to claim 1, wherein the recording operation state detection unit detects a recording stop state due to a fall of the apparatus as a recording operation state by the recording unit. A moving image recording method for recording encoded data on a recording medium,
An encoding process in which the input moving image data is encoded at a predetermined encoding rate to generate encoded data, and the encoded data is written in a memory;
A recording step of reading out the encoded data written in the encoding step from the memory and recording it on the recording medium;
A recording operation state detection step of detecting a recording operation state by the recording means;
A recording medium transfer rate prediction step for predicting a data transfer rate for recording the encoded data on the recording medium in the recording step based on the recording operation state detected in the recording operation state detection step; ,
And a coding rate control step of controlling the coding rate based on the data transfer rate predicted in the recording medium transfer rate prediction step.