JP2009033604A - Video signal coding apparatus and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To code a scene that a user regards important, easily with high image quality when performing compression coding on a video signal. <P>SOLUTION: When a user turns on a high image quality mode selection button (OD) 125, a command of a high image quality mode is outputted from a system control section 19 to a rate control section 28 of a compression coding section 20, and the rate control section 28 instructs a quantization section 24 and a de-quantization section 29 to change a quantization scale. Then, the quantization section 24 and de-quantization section 29 quantize a video signal so as to obtain an average coding rate of high image quality mode higher than an average coding rate of normal image quality mode. Thus, a scene important for the user can be easily coded with high image quality approximately without increasing costs. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a video signal encoding device and method for compressing and recording a video signal.

When a video signal is compressed and encoded and recorded, for example, a video signal encoding device that changes the encoding rate according to the input video signal in order to prioritize the recording image quality over the recording time efficiency with respect to the remaining capacity of the recording medium. is there. In this apparatus, when the input video is complicated, the encoding rate is set so as not to be lower than the average encoding rate, and the capacity of the remaining recording medium and the recordable time are displayed on the display panel (for example, (See Patent Document 1).
JP 2001-197437 A

  However, in the above-described conventional technology, it is assumed that the remaining capacity of the recording medium is relatively large, and the code amount, that is, the remaining recording amount is consumed even for a shooting period that is not particularly important by the user. There was a problem.

  In addition, there is a problem that an accurate recordable time cannot be displayed to the user by estimating the recordable time using the upper limit of the encoding rate or the encoding rate within a predetermined time after the start of recording.

  Therefore, an object of the present invention is to provide a video signal encoding apparatus and method that can easily encode a scene considered important by a user with high image quality when compressing and encoding a video signal.

  In order to achieve the above object, in the present invention, when a high-quality mode command is output when compressing and encoding a video signal, the average coding rate of the high-quality mode is higher than the average coding rate in the normal image quality mode. The video signal is compression-encoded based on the above. Here, the video signal is in the MPEG format, a high-quality mode command is output, and the video signal is compression-coded by changing to a target encoding rate of the high-quality mode higher than the target encoding rate in the normal image quality mode. In this case, the target encoding rate in the high image quality mode may be changed within the maximum encoding rate included in the sequence header of the video signal for compression encoding by the MPEG method. Also, when compressing and encoding video signals by intra-frame predictive encoding, when a high-quality mode command is output, the pixel block size for intra-frame predictive encoding is made smaller than in the normal image quality mode. Also good. Also, when compressing and encoding video signals by inter-frame predictive encoding, when a high-quality mode command is output, the target encoding rate of the high-quality mode is higher than the target encoding rate in the normal image quality mode. Thus, the vector search partial image size at the time of inter-frame predictive encoding may be made smaller than in the normal image quality mode so that the video signal is compressed and encoded.

  According to the present invention, when a high image quality mode command is output, the video signal is compressed and encoded at an average encoding rate in the high image quality mode higher than the average encoding rate in the normal image quality mode. It is possible to easily encode a scene important for the user with high image quality with almost no increase.

  Hereinafter, as an embodiment of a video signal encoding apparatus and method according to the present invention, a video camera using an optical disk, HDD, memory, tape, or the like as a recording medium will be described as an example. In such a video camera, since the video to be recorded, that is, the subject is valuable for the video camera user, or is used in an unusual event, the storability and the recording image quality are high. Often emphasized. In particular, MPEG2 and H.264 are used as encoding methods. When a high-efficiency encoding unit called H.264 is used, the optimum code for the input video changes greatly. Generally, the encoding rate is not fixed, but is made variable, thereby further improving the image quality and increasing the time. Often recorded. In this embodiment, a digital video camera will be described in detail.

Embodiment 1 FIG.

  FIG. 1 is a block diagram showing a configuration example of Embodiment 1 of a video signal encoding apparatus of the present invention.

  In FIG. 1, this video signal encoding apparatus is assumed to be a video camera that uses the MPEG2 system as an encoding apparatus and digitally converts and records an input video, and includes an HDD 10 as a recording medium, a CCD sensor 11, Camera signal processing DSP unit 12, character generation unit 13, LCD control unit 14, LCD display panel 15, operation button 16 as an operation unit, camera control unit 17, buffer RAM 18, and system as a control unit A control unit 19, a system internal bus 19a, and a compression encoding unit 20 are provided. In FIG. 1, the configuration of the decoding / reproducing portion for decoding and reproducing the encoded data recorded in the HDD 10 is omitted. Of course, the configuration of the decoding / reproducing portion may be used.

  The operation unit 16 is a button or the like for a user to execute a recording or reproduction command. When the touch panel type LCD display panel 15 is used, the LCD display panel 15 also serves as the operation unit 16.

  FIG. 2 is a diagram illustrating an appearance of a video camera to which the video signal encoding apparatus according to the first embodiment is applied and an example of operation button arrangement.

  2A shows the rear surface of the video camera with the LCD display panel 15 opened, and FIG. 2B shows the side surface of the video camera with the video camera body 100 closed.

  The video camera body 100 includes a shooting operation button (REC) 121, a zoom button (ZOOM) 122, a menu button (MENU) 123, a power source, and the like for starting and ending shooting and recording by turning on and off. In addition to the button (POWER) 124, an image quality mode selection button (OD) 125, which is a selection button for an image quality mode, which will be described later, is provided by turning it on and off.

  In addition, the display screen of the LCD display panel 15 indicates whether the encoding rate, which is a character generated by the character generation unit 13 via the camera control unit 17 by an instruction from the operation unit 16 or the like on the captured image, is in the normal image quality mode. Or, an image quality mode indicating whether the image quality mode is a feature of the present embodiment is displayed. When the user wants to record with a high image quality by looking at the subject, when the high image quality mode selection button (OD) 125 button is pressed, “high image quality mode (OD)” or the like is displayed on the display screen of the LCD display panel 15. Is displayed, a high-quality mode instruction is output to the system control unit 19, and the quantization unit 24 is controlled. As a result, the encoding rate is controlled as in the characteristics of FIG. 4, and recording can be performed with high image quality only while the high image quality mode selection button (OD) 125 button is on.

  Therefore, when the user of this video camera is recording a relatively general subject and suddenly encounters a precious subject, the user can immediately turn on the high image quality mode selection button (OD) 125 to turn on the high It can be switched to an image quality mode.

  In the present embodiment, under the control of the system control unit 19, display of the date and time of shooting on the LCD display panel 15, display of the remaining battery capacity, display of the remaining recordable time of the HDD 10 as a recording medium, The elapsed time from the start of recording is displayed. Here, the remaining time is displayed when the recording is performed in the standard image quality mode, that is, when the image quality mode is not turned on in the future.

  Therefore, the user of this video camera, for example, is recording in the high image quality mode with the high image quality mode selection button (OD) 125 turned on, and the remaining recordable time of the HDD 10 displayed on the LCD display panel 15 is reduced. If the user notices the above, by turning off the high image quality mode, the remaining recording time of the HDD 10 can be saved, and it is possible to avoid missing a valuable video. As a result, this display allows the user to monitor that the remaining amount of the recording medium has not run out at any time, so that the user can concentrate on shooting the subject.

  Further, when the high image quality mode is turned on, the remaining time when the image quality mode is turned on can be calculated. By displaying this, the user can know the recordable time in the strictest case. That is, it is possible to know the recordable time of both while switching the display even when the high image quality mode is OFF. As described above, only the remaining recording time calculated with either the maximum value or the minimum value may be displayed. However, for example, the display may be displayed as a plurality of lines and displayed simultaneously.

  When displaying the remaining recordable time of the HDD 10 as a recording medium, the maximum and minimum values of the encoding rate may not match the practical usage of shooting. In this case, the total time when the high image quality mode is turned on since the start of shooting and the total time when it is turned off are counted. Based on this value, the generated code amount used during shooting is calculated according to the following equation (1). Can be calculated.

Generated code amount = [HMr [Mbps] × HMt [s] / (HMt [s] + SMt [s])]
+ {SMr [Mbps] × SMt [s] / (HMt [s] + SMt [s])} (Formula 1)

  Here, HMr [Mbps] is the average coding rate in the standard image quality mode, and HMt [s] is the total shooting time in the standard image quality mode. SMr [Mbps] is the average coding rate in the high image quality mode, and SMt [s] is the total shooting time in the high image quality mode.

  The system control unit 19 calculates the remaining recording time of the HDD 10 from the generated code amount thus obtained and displays it on the LCD display panel 15 or the like as a finder. Thereby, the display suitable for a user's actual condition can be taken out easily. In the above formula 1, it is of course possible to use the data obtained by storing the data of the past shooting as the ratio of the shooting time in both modes.

  Next, the operation of this apparatus will be described.

  First, the CCD sensor 11 photoelectrically converts a subject image obtained via an optical lens (not shown) and outputs the subject image to the camera signal processing DSP unit 12. At that time, the CCD sensor 11 sets a change in the signal level in the optical system to a predetermined signal level by an AGC circuit or the like, and then performs A / D conversion to convert the analog signal into a digital signal and to the camera signal processing DSP unit 12. Output.

  In the camera signal processing DSP unit 12, the digital signal input from the CCD sensor 11 is converted into general Y, U, V, for example, 16-bit parallel data and output to the compression encoding unit 20. Further, the camera signal processing DSP unit 12 generates drive pulses necessary for the CCD sensor 11 and synchronization signals necessary for video output, and supplies them to each unit. At this time, the camera control unit 17 optimally controls the camera signal processing DSP unit 12 based on the state of the optical system, the video information obtained from the CCD sensor 11, and the information obtained from the operation of the entire camera. At the same time, an analog output such as an angular velocity sensor using a gyro or the like is AD converted and then taken into the camera control unit 17 to control the drive pulse of the CCD sensor 11. Thus, even when the user shakes his / her hand holding the camera, the camera signal processing DSP unit 12 is controlled so as to obtain a relatively stable image.

  The compression encoding unit 20 compresses and encodes the video data from the camera signal processing DSP unit 12 to about 1/60 in the MPEG2 encoding format, and outputs the compressed data to the system internal bus 19a in accordance with a command from the system control unit 19. Although the audio signal is not shown, the signal obtained from the microphone built in the camera is A / D converted and compressed as software processing in the system control unit 19, for example. Of course, a compression encoding unit for audio compression encoding may be provided. The audio compression encoded data and the video compression encoded data output from the compression encoding unit 20 are multiplexed to generate an MPEG data stream.

  Then, the system control unit 19 records the MPEG data stream on the HDD 10 via the buffer RAM 18 in order to avoid a write error due to vibration or shock received by the HDD 10.

  Next, a case where video data is reproduced from the HDD 10 will be described.

  Basically, a signal flows in the opposite direction to the above recording. First, recorded data is read from the HDD 10. Then, it is output to the system internal bus 19a as an MPEG2 video stream. At this time, even if a data reading error occurs during reading due to the impact received by the HDD 10 as in the case of recording, the buffer RAM 18 accumulates data for about several seconds, so that video can be continuously reproduced without practical problems. Transfer of video and audio data on the system internal bus 19a is controlled by a command from the system control unit 19.

  Then, under the control of the system control unit 19, the original video data is restored by the decompression operation of the compression encoding unit 20, and is converted into an NTSC signal by the camera signal processing DSP unit 12 as a 16-bit parallel signal in the same manner as recording. The image is displayed as a reproduced image on the LCD display panel 15 through the LCD control unit 14. Similarly, since the NTSC video signal is output from the camera signal processing DSP unit 12, it can be displayed on an external TV from a video output terminal (not shown) provided in the camera.

  Next, processing for controlling the encoding rate of video data by the compression encoding unit 20 and the system control unit 19 will be described in detail.

  FIG. 3 is a block diagram illustrating a configuration example of the compression encoding unit 20 illustrated in FIG. 1.

  In FIG. 3, the compression encoding unit 20 includes an image translating unit 21, a subtractor 22, a DCT unit 23, a quantization unit 24, a VLC unit 25, a buffer memory unit 26, a system control unit 19, and the like. The rate control unit 28, the inverse quantization unit 29, the inverse DCT unit 30, the adder 31, the first frame memory 32, the motion compensation unit 33, the motion detection unit 34, and the second frame memory 35. The system control unit 19 is the same as the system control unit 19 shown in FIG.

  Next, the operation of the compression encoding unit 20 shown in FIG. 3 will be described.

  First, when the video signal digitized by the camera signal processing DSP unit 12 is input to the compression encoding unit 20, in the compression encoding unit 20, first, the image rearrangement unit 21 inputs the video signal, and MPEG2 For example, the main profile (Main Profile at Main Level) is rearranged so that it can be easily coded. If the inter-frame mode, the subtracter 22 and the motion detector 34 are arranged. If the intra-frame mode, the DCT unit 23 is arranged. Output.

  The motion detection unit 34 receives the video data output from the image rearrangement unit 21, detects a motion vector, and outputs it to the motion compensation unit 33. In the motion compensation unit 33, the difference between the reference image obtained by shifting the temporally moving image by the amount of motion of the video by the motion vector obtained from the motion detection unit 34 and the reference image extracted from the video data called a template. Data is generated and output to the DCT unit 23.

  The DCT unit 23 can decompose the frequency components of the video signal. When a screen with a large flat area is input to the input video, the DCT unit 23 outputs code data concentrated on the low frequency components. On the other hand, when a screen with many fine parts is input to the input video, code data in which a lot of high frequency components are generated is output.

  The quantization unit 24 digitally thins out the code decomposed into the frequency components output from the DCT unit 23, particularly in the high frequency portion, and performs quantization. If the amount to be thinned out is reduced and quantized to a code close to the video data output by the DCT unit 23, a high-definition video faithful to the input video can be obtained. On the contrary, if the thinning interval is widened, the generated code amount is reduced, and the compression rate of the entire compression encoding unit 20 is improved, but the image quality is impaired.

  The VLC unit 25 compresses the quantized code according to a law called variable length coding, and outputs the compressed code to the buffer memory unit 26 as encoded data. This encoded data is finally recorded data that is recorded on a recording medium such as the HDD 10.

  At this time, the system control unit 19 needs to control the code amount of data per unit time generated in the entire compression encoding unit 20. Therefore, the system control unit 19 sends an instruction to the rate control unit 28 according to an encoding rate appropriate for the image quality of the video camera, and controls the data thinning amount of the quantization unit 24.

  In a video camera using the MPEG2 system, in the case of a so-called complex video, for example, a video in which the motion component of the input video is large and the TV signal has many high-frequency components in the horizontal and vertical directions, the image quality of the recorded video is improved. For this reason, it is generally known that recording is performed while the rate control is operated in accordance with the input video and the encoding rate is successively varied. At this time, it is necessary to perform recording at an encoding rate that is equal to or higher than the encoding rate appropriate for the video camera image quality.

  Next, code amount rate control in the present embodiment will be described.

  In this embodiment, a dedicated mode of the high image quality mode is provided in the recording mode selection of the video camera.

  FIG. 4 is a flowchart showing operations in the standard image quality mode and the high image quality mode in the first embodiment.

  First, in this embodiment, for example, an average of 3 [Mbps] is set as the average encoding rate target value in the normal standard image quality mode, for example, according to the motion and complexity of the recorded video (step S410). An average of 6 [Mbps] is set as the average encoding rate target value in the high image quality mode (step S420). Here, in either mode, the system controller 19 controls the buffer memory unit 26 as a VBV buffer (Video Buffering Verifier) so that neither overflow nor underflow occurs.

  Then, when shooting is started, recording is performed in the standard image quality mode under the control of the system control unit 19 (step S430).

  At this time, if the high image quality mode button is not pressed by the user of the video camera (step S440 “NO”), the process returns to step S430 until data recording is completed (step S470 “YES”), and data recording is performed in the standard image quality mode. to continue.

  On the other hand, when the high image quality mode button is turned on by the user of the video camera (step S440 “YES”), the system control unit until the high image quality mode button is turned off by the user (step S440 “NO”). 19 temporarily changes from the normal image quality mode at the normal encoding rate to the high image quality mode (step S450). When the high image quality mode button is turned off by the user (step S460 “YES”), data recording is continued in the standard image quality mode in step S430.

  FIG. 5 is a diagram showing a change in the coding rate when the high image quality mode in the invention is turned on / off during normal mode recording.

  In both modes, there is a change in the encoding rate when recording is performed by operating the rate control according to the complexity of the input video. For example, when the high image quality mode is off, rate control is performed such that the target encoding rate is 3 [Mbps], as in the standard image quality mode shown in FIG. That is, when the input image is complex and dynamic based on the target encoding rate of 3 [Mbps], the rate control unit 28 increases the code amount accordingly according to an instruction from the system control unit 19. On the other hand, for a relatively simple image, encoding is performed such that the code amount is suppressed and the average code amount is 3 [Mbps].

  On the other hand, in the high image quality mode, the system control unit 19 performs rate control so that the target coding rate is 6 [Mbps] as in the high image quality mode shown in FIG. That is, when the input image is complex and dynamic based on an encoding rate of 6 [Mbps], the rate control unit 28 increases the code amount accordingly according to an instruction from the system control unit 19. For simple images, the code amount is reduced.

  For this reason, there is an improvement in image quality in scenes that are important for the user from the start of shooting to the end of shooting, compared with the case of recording only in the high quality mode, compared to the case of recording only in the standard image quality mode. There is an advantage that it can be suppressed.

  In addition, even when compared with a constant image quality type VBR in which only the maximum encoding rate and the minimum encoding rate are set and the encoding rate increases or decreases in proportion to the video content, the accuracy of the remaining recording time determination is improved, Ensuring image quality and code efficiency in important scenes can be expected.

  In the present embodiment, VBR (Variable Bit Rate) having two different average encoding rate target values is described as an example, but one or both modes are set to CBR (Constant Bit Rate). ). For example, the standard image quality mode can be an average 3 Mbps VBR, the high image quality mode can be 6 Mbps CBR, the standard image quality mode can be an average 3 Mbps CBR, and the image quality mode can be 6 Mbps CBR.

  However, in this embodiment, there is no distinction in the sequence header of MPEG2 encoded data regardless of whether the setting is CBR or VBR. Even when the CBR is set, it is assumed that the rate control fluctuation in the VBR is reduced in the same image quality mode.

  In general, in MPEG2, in order to control the amount of generated code so that the decoder-side virtual buffer (Video Buffering Verifier) does not overflow, a maximum encoding rate called a bit rate value included in the sequence header of MPEG encoded data is set. ing. Therefore, in order to seamlessly switch between the standard image quality mode and the high image quality mode without interrupting shooting, in this embodiment, the standard image quality mode and the high image quality mode share the maximum coding rate called this bit rate value. Then, the target average encoding rate of the standard image quality mode and the high image quality mode is changed within the common maximum encoding rate. This is because the limit parameter, which is the maximum encoding rate called the bit rate value included in the sequence header of MPEG encoded data, can be set only once per sequence. When the rate is changed to be larger than the maximum encoding rate included in the sequence header of the MPEG2 encoded data in the standard image quality mode, it is necessary to reset the maximum encoding rate and it is divided as another sequence. This is because a 0.5 second blank is generated.

  Therefore, in this embodiment, the maximum encoding rate common to the standard image quality mode and the high image quality mode is, for example, 6 Mbps or higher, which is higher than the target average encoding rate of both the 3 Mbps standard image quality mode and the 6 Mbps image quality mode in FIG. For example, 9 Mbps is set in the sequence header.

  Then, the system control unit 19 controls the average coding rate within the maximum coding rate set in the sequence header even if the rate is controlled at the target average coding rate in each of the standard image quality mode and the high image quality mode. Therefore, encoding capable of seamless reproduction can be performed without switching the sequence.

  As described above, according to the first embodiment, the high image quality mode selection button (OD) 125 is provided, and when the user turns on the high image quality mode selection button (OD) 125, the system control unit 19 performs compression encoding. The high-quality mode command is output to the rate control unit 28 of the unit 20, and the rate control unit 28 instructs the quantization unit 24 and the inverse quantization unit 29 to change the quantization scale (quantization step). The quantization unit 24 and the inverse quantization unit 29 change the quantization scale to quantize the video signal so that the average encoding rate in the high image quality mode is higher than the average encoding rate in the normal image quality mode. Therefore, it is possible to easily encode a scene important for the user with high image quality with almost no increase in cost.

  In the first embodiment, the maximum encoding rate common to the standard image quality mode and the high image quality mode is higher than the average encoding rate of both the standard image quality mode and the high image quality mode as shown in FIG. Since 9 Mbps is set as the bit rate value included in the MPEG sequence header, it is not necessary to change the bit rate value even if the average encoding rate is increased in the high image quality mode than in the standard image quality mode. It is possible to perform encoding capable of seamless reproduction without switching between.

  As a result, for example, it is effective when it is desired to record before and after an important scene at the time of video camera shooting, and when it is desired to save the code amount as much as possible except for the important scene. In addition, when an unimportant scene such as a surveillance camera has a very long time or becomes an important scene instantaneously, the high image quality mode selection button (OD) 125 is turned on, or the high image quality mode selection button (OD) ) When an abnormality is detected by detecting abnormal sound or analyzing an image instead of turning on 125, it is possible to seamlessly shift to the high image quality mode.

  In the first embodiment, it has been described that the two image quality modes, the standard image quality mode and the high image quality mode, are switched by turning on / off the high image quality mode selection button (OD) 125. Not limited to this, three or more image quality modes may be selected. For example, if the high image quality mode selection button 21 is pressed once, the standard image quality mode 3 Mbps is changed to 6 Mbps in the high image quality mode 1, and if pressed again, the high image quality mode 2 is 9 Mbps.

  In the first embodiment, the video signal is compressed and recorded / recorded / reproduced according to the MPEG2 format. However, the present invention is similarly applied to the compression / recording / recording / reproduction of a still image signal according to the JPEG format. This is because the JPEG encoding operation is almost the same as the MPEG I picture encoding operation, and the compression encoding unit 20 can also perform the JPEG encoding operation by switching only part of the operation of the circuit. The still image output from the compression encoding unit 20 is recorded in the HDD 10 as one file, for example. Also, it is possible to record only audio data, and audio can be recorded effectively with a very small amount of data.

Embodiment 2. FIG.
In the first embodiment, the video signal compression coding apparatus and method adopting the MPEG2 coding method have been described as an example. A video signal compression coding apparatus and method employing the H.264 / AVC (Advanced Video Coding) method will be described as an example.

  FIG. 2 is a block diagram illustrating a configuration example of a video signal compression coding apparatus according to a second embodiment adopting an H.264 / AVC coding system.

  In FIG. 6, the compression encoding unit 20 of the second embodiment is the H.264 standard. Since the H.264 / AVC encoding method is used, the in-loop filter 61, the intra-frame prediction unit 62, the inter-frame prediction unit 63, and the rate control unit are different from the compression encoding unit 20 of the first embodiment shown in FIG. 64 and the changeover switch 65, and the other components are the same as the configuration of the compression encoding unit 20 of the first embodiment shown in FIG. 2 and the configuration shown in FIG.

  Next, a specific operation of the second embodiment will be described.

  In the second embodiment, the changeover switch 65 switches between the intra-frame prediction (intra prediction) unit 62 and the inter-frame prediction (motion compensation prediction) unit 63 according to a command from the rate control unit 64.

  First, a case will be described where intra-frame prediction (intra prediction) unit 62 of compression encoding unit 20 of the second embodiment performs intra-frame prediction by prediction at a pixel level from an adjacent block.

  H. In the intra-frame prediction of H.264 / AVC, nine prediction modes are defined for a 4 × 4 pixel block in the case of a luminance signal. For example, the prediction image is generated by performing the prediction in the vertical direction using the decoded pixel data adjacent to the upper side of the prediction target 4 × 4 pixel block. This prediction mode is an effective prediction mode when there is a vertical edge in the image area to be predicted. Each of the other prediction modes is also a prediction mode effective for an edge in a specific direction, and a prediction image is generated based on the decoded pixels of the adjacent block. In the case of a luminance signal, four prediction modes are defined not only for a 4 × 4 pixel block but also for a 16 × 16 pixel block. There are a total of 13 prediction modes including the street prediction modes. Therefore, an optimal intra prediction mode is selected from these 13 intra prediction modes and used for intra prediction encoding. For the color difference signal, four prediction modes are defined for the 8 × 8 pixel block, and the prediction mode can be encoded independently of the luminance signal.

  In this way, H.C. The intra-frame prediction unit 62 adopting the H.264 / AVC encoding scheme has a high degree of freedom by providing various prediction modes, and an encoder is suitable for improving the encoding efficiency in inter-frame prediction. It is necessary to select a prediction mode.

  Therefore, in the video signal compression encoding apparatus according to the second embodiment, the intra-frame prediction pixel block in the intra-frame prediction unit 62 is changed based on an instruction from the rate control unit 64 in the high image quality mode. Instantly perform high-quality encoding.

  That is, for example, the pixel block size of intra-frame prediction in the standard image quality mode is performed only in 4 prediction modes of 16 × 16 pixel blocks, and in the high image quality mode, 9 prediction modes of 4 × 4 pixel block size are added to them. And intra-frame predictive coding is performed.

  Thus, according to the second embodiment, in the high image quality mode, intra-frame prediction is performed with a smaller pixel block size than in the standard image quality mode, the code amount in the standard image quality mode is reduced, and in the high image quality mode. Since code amount allocation increases, reproduction image quality can be improved by performing intra-frame predictive coding in the high-quality mode during a specific instantaneous time period.

  H. In H.264 / AVC, there are a total of seven types of macroblocks (16 × 16 pixels), 16 × 8 pixels, 8 × 16 pixels, 8 × 8 pixels, 8 × 4 pixels, 4 × 8 pixels, and 4 × 4 pixel units. Motion compensation can be performed with a block size. By performing motion compensation with a small block, the prediction error per unit area can be kept small. On the other hand, there is a possibility that the number of motion vectors to be encoded increases and the amount of codes increases.

  Therefore, the inter-frame prediction unit 63 of the image encoding unit 20 in the second embodiment changes the vector search partial image size for inter-frame prediction based on an instruction from the rate control unit 64 in the high image quality mode. .

  That is, for example, in the standard image quality mode, the vector search partial image size for inter-frame prediction is limited to 16 × 16 pixels, and in the high image quality mode, the optimal block size is selected from seven patterns of 16 × 16 to 8 × 8 pixel blocks. As described above, the vector search partial image size for inter-frame prediction in the standard image quality mode is increased, while the vector search partial image size for inter-frame prediction in the high image quality mode is decreased.

  Thus, according to the second embodiment, in the high image quality mode, the vector search partial image size is made smaller than that in the standard image quality mode to perform inter-frame prediction, the code amount in the standard image quality mode is reduced, and the high image quality mode. Therefore, the reproduction image quality can be improved by performing the inter-frame predictive coding in the high image quality mode in the instantaneous specific time zone.

  H. In H.264 / AVC, it is known that the amount of calculation varies greatly depending on the processing for improving the encoding efficiency. For example, when the number of selected patterns of pixel blocks in the above processing increases, the number of calculations increases by the number of patterns, so that power consumption also increases proportionally. Therefore, in general, there are many cases where processing for increasing coding efficiency is limited in consideration of power consumption. Therefore, by applying the high image quality mode of the second embodiment to encoding efficiency, not only the amount of code but also power consumption can be saved.

  Therefore, according to the second embodiment, the H.264 standard. When the H.264 / AVC encoding method is employed and the user turns on the high image quality mode selection button (OD) 125, a high image quality mode command is output, and the intra prediction or inter frame prediction unit 63 in the intraframe prediction unit 62 is output. In normal image quality mode, the pixel block size for intra-frame predictive coding and the vector search partial image size for inter-frame predictive coding are changed between normal image quality mode and high image quality mode. Since the video signal is compression-encoded at an average encoding rate in a high image quality mode higher than the average encoding rate of the image, as in the first embodiment, there is almost no increase in cost and the user is added to the sequence. It is possible to easily encode a scene important for the image with high image quality.

  In the second embodiment, as in the first embodiment, the system control unit 19 outputs a high-quality mode command to the rate control unit 64 of the compression encoding unit 20, and the rate control unit 64 The quantization unit 24 and the inverse quantization unit 29 are instructed to change the quantization scale, and the quantization unit 24 and the inverse quantization unit 29 average the high image quality mode higher than the average coding rate in the normal image quality mode. Quantize the video signal by changing the quantization scale so that the encoding rate is the same, and compress and encode the video signal at an average encoding rate in the high image quality mode higher than the average encoding rate in the normal image quality mode. Of course.

  In the description of the first and second embodiments, the HDD 10 has been described as an example of the recording medium. However, the present invention is not limited to this, and the present invention is not limited to this, and an optical disk such as a DVD-RAM, ± R, ± RW, BD, etc. May be a volatile semiconductor memory. In addition to the video camera that captures the subject obtained from the lens as described above, the image quality of important scenes can be secured by applying the first and second embodiments to a stationary video recorder having a video encoder. However, efficient recording becomes possible.

It is a block diagram which shows the structural example of Embodiment 1 of the video signal encoding apparatus of this invention. It is the figure which showed the example of arrangement | positioning of the external appearance of the video camera which applied the video signal encoding apparatus of Embodiment 1, and an operation button. It is a block diagram which shows the structural example of the compression encoding part 20 shown in FIG. 3 is a flowchart illustrating operations in a standard image quality mode and a high image quality mode in the first embodiment. It is the figure which showed the change of the encoding rate at the time of turning on and off the high quality mode in invention during normal mode recording. H. 2 is a block diagram illustrating a configuration example of a video signal compression coding apparatus according to a second embodiment adopting an H.264 / AVC coding system.

Explanation of symbols

16 Operation buttons (operation unit)
19 System control unit (control unit)
20 Compression encoder

Claims (5)

A compression encoding unit that compresses and encodes a video signal;
A recording unit for recording the video signal compressed and encoded by the compression encoding unit on a recording medium;
An operation unit that is operated by a user to output a high-quality mode command;
When the high-quality mode command is output from the operation unit, the compression encoding unit changes the target encoding rate of the high-quality mode higher than the target encoding rate in the normal image quality mode and compresses the video signal A control unit that controls to encode;
A video signal encoding device comprising: The video signal encoding device according to claim 1, wherein
The compression encoding unit compresses and encodes the video signal according to the MPEG method,
The controller is
The high-quality mode command is output from the operation unit, and the compression encoding unit changes the target encoding rate of the high-quality mode higher than the target encoding rate in the normal image quality mode, and compresses and encodes the video signal In this case, the target encoding rate of the high image quality mode is changed within the maximum encoding rate included in the sequence header of the compression encoded video signal by the MPEG method. The video signal encoding device according to claim 1 or 2,
The compression encoding unit compresses and encodes the video signal by intra-frame prediction encoding;
The controller is
When the high-quality mode command is output from the operation unit, the compression encoding unit changes the target encoding rate of the high-quality mode higher than the target encoding rate in the normal image quality mode and compresses the video signal A video signal encoding apparatus for reducing a pixel block size at the time of intra-frame predictive encoding as compared with the case of the normal image quality mode. The video signal encoding device according to claim 1 or 2, wherein
The compression encoding unit compresses and encodes the video signal by inter-frame predictive encoding,
The controller is
When the high-quality mode command is output from the operation unit, the compression encoding unit changes the target encoding rate of the high-quality mode higher than the target encoding rate in the normal image quality mode and compresses the video signal A video signal encoding apparatus for reducing a vector search partial image size in the inter-frame predictive encoding as compared with the case of the normal image quality mode. Compressing and encoding the video signal;
Outputting a high-quality mode command operated by a user;
A step of compressing and encoding the video signal based on an average encoding rate of the high image quality mode higher than an average encoding rate in the normal image quality mode when the high image quality mode command is output;
A video signal encoding method comprising:

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