JP2011188377A - Encoding device, and encoding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an encoding device for improving the output quality by appropriate evaluation of encoding quality, and to provide an encoding method. <P>SOLUTION: In the encoding device, a plurality of encoder units 25-1 to 25-n operating with encoding algorithms different from one another for encoding an input video signal are arranged in parallel to one another. An image quality comparing unit 32 compares encoding outputs from the respective encoder units 25-1 to 25-n with the input video signal. An output selecting section 34 selects the encoding output having the best quality, based on the comparison result by the image quality comparison section 32. A mode-control section 31 sets a comparison unit, when the image quality comparison section 32 compares the encoding outputs with the input video signal. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an encoding apparatus and an encoding method.

  For example, in a video encoding apparatus having a single encoder, it is conceivable to perform multi-cycle encoding processing in order to improve output quality. In the multi-cycle encoding process, a loop process of encoding by the encoder and checking the image quality is performed until a desired quality (image quality) is obtained.

  The effectiveness of the encoding algorithm varies depending on the characteristics of the input video signal. A single encoder also uses a single encoding algorithm. For this reason, the output of the encoding device changes according to the characteristics of the input video signal. Therefore, depending on the encoding algorithm, the output image quality may deteriorate, for example, block noise may occur in the video output. In addition, since the multi-cycle encoding process is repeated until a desired image quality is obtained, there may be a delay in output. For example, when video output such as video conferencing or live broadcasting is used in real time, the occurrence of delay is not desirable. Further, when the encoding by the encoder is stopped due to problems such as hardware failure or algorithm weakness, the operation of the encoding device itself is stopped.

  As described above, in an encoding apparatus using a single encoder, output deterioration and delay, or a problem of stability of the encoding operation is likely to occur. Therefore, an encoding apparatus that performs encoding in parallel with a plurality of encoders is provided. It is considered. For example, in the encoding device described in Patent Document 1, encoding processing by a plurality of encoders is executed in parallel on the extracted block.

JP 2006-217425 A (paragraph 0062, FIG. 4)

  In the encoding device of Patent Literature 1, a block having a predetermined number of pixels is extracted from one image, and encoding processing is performed on each block by a plurality of encoders. Accordingly, it is necessary to perform encoding processing for a single image by a plurality of encoders many times, and the processing amount increases. Further, the content of the encoding process may be different for each block in one image.

  Although there is a method of encoding a moving image in units of GOP (group of pictures) composed of a plurality of frames, when encoding is performed in units of GOP, it is desirable to evaluate the image quality for each GOP. As described above, it is desirable that the moving picture encoding apparatus evaluates the encoding quality according to the encoding unit and selects an appropriate encoding method.

  The present invention has been made in view of the above problems, and an object thereof is to provide an encoding device and an encoding method that improve output quality by appropriate evaluation of encoding quality.

  An encoding device according to an embodiment of the present invention operates in parallel with different encoding algorithms, encodes an input video signal, and outputs encoded from each of the plurality of encoders as the input Comparing means for comparing with the video signal, output selecting means for selecting the best quality encoded output based on the comparison result by the comparing means, and the comparing means for comparing the encoded output with the input video signal Setting means for setting the comparison unit.

  An encoding method according to an embodiment of the present invention includes: receiving a plurality of encoded outputs generated by encoding input video signals by a plurality of encoders operating in parallel with different encoding algorithms; Comparing each of the encoded outputs with the input video signal, selecting the highest quality encoded output based on the comparison result, and comparing the encoded output with the input video signal. A step of setting a comparison unit for the determination.

  ADVANTAGE OF THE INVENTION According to this invention, the encoding apparatus and encoding method which improve output quality by appropriate evaluation of encoding quality can be provided.

The block diagram which shows the structure of the encoding apparatus which concerns on one Embodiment of this invention. The flowchart which shows operation | movement of the output control part shown by FIG. The table which defined the detail of the setting of the comparison mode in an output control part.

  Embodiments of an encoding apparatus according to the present invention will be described below with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration of an encoding apparatus according to an embodiment of the present invention.

  The encoding device includes a video input unit 10, an encoding unit 20, an output control unit 30, and a video output unit 40.

  The video input unit 10 receives a digital video input signal composed of a moving image signal and an audio signal. This video input signal is sent from the video input unit 10 to the encoding unit 20.

  In the encoding unit 20, a plurality of encoder units 25-1 to 25-n are arranged in parallel. Each of the plurality of encoder units 25-1 to 25-n operates according to different encoding algorithms. For example, when the encoding apparatus according to the present embodiment is compatible with the MPEG-2 system, the encoding algorithms of the plurality of encoder units 25-1 to 25-n conform to the MPEG-2 system, but use different encoding parameters. . Similarly, for example, the encoding apparatus according to this embodiment is H.264. In the case of supporting the H.264 system, the encoding algorithms of the plurality of encoder units 25-1 to 25-n are each H.264. H.264 is used, but different encoding parameters are used. Examples of the encoding parameter include a bit rate, selection of a DCT coefficient, a quantization level, and the like. A plurality of encoded output signals from the plurality of encoder units 25-1 to 25-n are sent to the output control unit 30.

  The output control unit 30 includes a processor, a program memory, and a work memory (not shown). A predetermined program stored in the program memory is executed by the processor, whereby the operation of the output control unit 30 is performed.

  The output control unit 30 includes a mode control unit 31, an image quality comparison unit 32, an output selection unit 33, and a user interface (I / F) 34. The user interface 34 is connected to an input device such as a mouse or a keyboard (not shown), and receives user instructions.

  The mode control unit 31 sets the comparison mode in the output control unit 30. The image quality comparison unit 32 compares the plurality of encoded output signals with the input video signal according to the set comparison mode. The image comparison unit 32 uses, for example, the signal-to-noise ratio (SNR) or standard deviation of each signal as a comparison parameter.

  FIG. 3 shows a table defining details of setting of the comparison mode in the output control unit. As shown by the table 35 in FIG. 3, when the encoding is performed only in the I frame (encoding mode without using inter-frame prediction), the comparison mode is set to “frame mode”. In the frame mode, the image quality comparison unit 32 compares the plurality of encoded output signals of the encoding unit 20 with the input video signal for each frame.

  On the other hand, when encoding with LONG GOP (encoding mode using inter-frame prediction) is performed over a plurality of frames, the comparison mode is set to “group mode”. In the group mode, the image quality comparison unit 32 compares the plurality of encoded outputs of the encoding unit 20 with the input video signal in units of GOP (group of pictures).

  Other mode setting information may also be set in the table 35 in advance. The comparison mode setting information represents the relationship between the encoding unit and the comparison unit. The table 35 can be set in advance so that the image quality comparison unit 32 performs comparison according to the encoding unit. Note that this table 35 is stored in advance in the program memory of the output control unit 30.

  Further, the comparison mode may be set according to the type of the input video signal. For example, information specifying the comparison mode may be added to the header of the input video signal. Alternatively, the comparison mode may be set based on a user instruction via the user interface 34. Further, the comparison mode may be set according to control information provided from the encoding unit 20 to the output control unit 30.

  The output selection unit 33 selects the encoded output signal with the highest quality based on the comparison result by the image quality comparison unit 32. The selected encoded output signal is sent to the video output unit 40.

  The video output unit 40 includes a storage unit that stores the selected encoded output signal. The encoded output signal stored in the storage unit is output to the outside as necessary. For example, the encoded output signal may be transferred to a portable storage medium such as an optical disk or flash memory connected to the video output unit 40. Alternatively, the encoded output signal may be sent to a transmission device connected to the video output unit 40 and output from the transmission device as a broadcast wave. The encoded output signal may be output to the outside via a wired or wireless network (for example, a wireless LAN).

  Next, the operation of the encoding apparatus configured as described above will be described.

  FIG. 2 is a flowchart showing the operation of the output control unit 30 shown in FIG.

  The output control unit 30 first receives a plurality of encoded output signals from the plurality of encoder units 25-1 to 25-n of the encoding unit 20 (step S201).

  The mode control unit 31 sets the comparison mode of the output control unit 30 (step S202). For example, as shown in FIG. 3, the mode control unit 31 sets a frame mode in the case of encoding with only an I frame, and sets a group mode in the case of encoding with a LONG GOP.

  The image quality comparison unit 32 compares the plurality of encoded output signals with the input video signal according to the set comparison mode (step S203). For example, if the frame mode is set, the image quality comparison unit 32 compares the plurality of encoded output signals with the input video signal for each frame. When the group mode is set, the image quality comparison unit 32 compares each of the plurality of encoded outputs with the input video signal in GOP units.

  The output selection unit 33 selects the encoded output signal with the best quality based on the comparison result (step S204).

  The selected encoded output signal is output to the video output unit 40 (step S205).

  The encoded output signal stored in the storage unit of the video output unit 40 can be externally output via a broadcast wave or a network depending on the application.

  As described above, according to the output control unit 30 of the encoding device according to the present embodiment, the input video signal and the encoded output signal are compared according to the encoding unit. For this reason, an encoding result can be appropriately evaluated according to an encoding unit.

  In the encoding apparatus according to the present embodiment, the encoder units 25-1 to 25-n of the encoding unit 20 operate with different encoding algorithms, and the respective encoded outputs are compared with the input video signal. The encoded output having the best quality is used as the output of the entire encoding apparatus. For this reason, the quality of the output signal can be improved.

  Also, since the encoder units 25-1 to 25-n operate in parallel, the problem of delay occurring in the output of the encoding device is reduced.

  By taking a redundant configuration including the encoder units 25-1 to 25-n in parallel, the encoder units 25-1 to 25-n serve as backups for each other. Even if a failure occurs in any of the encoder units, the operations of the other encoder units are possible, so that a more stable operation is guaranteed against the failure.

  The image quality comparison unit 32 compares the encoded output signal and the input video signal in units specified by the set comparison mode. For this reason, efficient comparison and quality evaluation according to the encoding unit can be performed.

  For example, when encoding is performed using only I frames, the comparison is performed for each frame. The best quality frame is then selected as the output of the entire encoding device. When encoding is performed using a LONG GOP, the comparison is performed for each GOP. Then, the GOP having the highest quality is selected as the output of the entire coding apparatus.

  As described above, the encoded output obtained as a result of stable and high-quality encoding without delay is output from the video output unit 40 and used for, for example, a video conference or live television broadcasting.

  The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention at the stage of implementation. Further, each of the embodiments includes inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some constituent elements are deleted from all the constituent elements shown in one embodiment or the constituent elements shown in some embodiments are combined, they are described in the column of the problem to be solved by the invention. In the case where the problems described above can be solved and the effects described in the “Effects of the Invention” can be obtained, a configuration in which these constituent requirements are deleted or combined can be extracted as an invention.

  DESCRIPTION OF SYMBOLS 10 ... Video input part, 20 ... Encoding part, 25-1-25-n ... Encoder part, 30 ... Output control part, 31 ... Mode control part, 32 ... Image quality comparison part, 33 ... Output selection part, 34 ... User Interface, 40... Video output unit.

Claims (8)

A plurality of encoders each operating in parallel with different encoding algorithms to encode the input video signal;
Comparison means for comparing the encoded output from each of the plurality of encoders with the input video signal;
Based on the comparison result by the comparison means, an output selection means for selecting the encoded output with the best quality;
Setting means for setting a comparison unit when the comparison means compares the encoded output with the input video signal;
An encoding device comprising:   The encoding apparatus according to claim 1, wherein the setting unit sets the comparison unit according to an encoding unit by the plurality of encoders.   2. The encoding according to claim 1, wherein, when encoding is performed only with an I frame, the setting unit sets the comparison unit so that the comparing unit compares the encoded output with the input video signal for each frame. apparatus.   The setting unit sets the comparison unit so that the comparison unit compares the encoded output and the input video signal for each GOP when encoding is performed by a LONG GOP (group of pictures). The encoding device described. Receiving a plurality of encoded outputs generated by encoding an input video signal by a plurality of encoders each operating in parallel with different encoding algorithms;
Comparing each of the plurality of encoded outputs with the input video signal;
Selecting the best quality encoded output based on the comparison result;
Setting a unit of comparison when the encoded output and the input video signal are compared;
An encoding method comprising:   6. The encoding method according to claim 5, wherein the comparison unit is set according to a unit of encoding by the plurality of encoders.   6. The encoding method according to claim 5, wherein when encoding is performed with only I frames, the comparison unit is set so that the encoded output and the input video signal are compared for each frame.   6. The encoding method according to claim 5, wherein, when encoding is performed by a LONG GOP (group of pictures), the comparison unit is set so that the encoded output and the input video signal are compared for each GOP.

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