JP2007166555A - Encoding device and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain the high quality of image by performing an encoding with referring to as many frames when interframe coding is performed by effectively using a memory in the case that an SD image is recorded in an encoding device which records an HD picture. <P>SOLUTION: This encoding device is provided with a reference frame buffer (102) which memorizes a reference frame image, and encoding means (104-113) which encodes an input frame image by using the the reference frame image in the reference frame buffer. In the reference frame buffer, according to resolution of the input frame image, the number of frames which can memorize the reference frame image is changed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an encoding apparatus and method.

  In recent years, with the progress of high-definition video in digital video cameras and digital televisions, the demand for high-definition encoding devices that record high-definition images (HD images) using a high-efficiency encoding method such as H264 is increasing. In addition, it is required as a specification that the high-definition encoding apparatus not only records HD images but also can record standard definition images (SD images).

  Patent Document 1 below describes a video camera capable of recording both SD images and HD images.

JP-A-11-196336

  However, since the encoding apparatus as described above has specifications capable of encoding HD images, when encoding HD images, use the memory etc. of the apparatus sufficiently. It will be. However, when encoding an SD image, the memory cannot be used sufficiently effectively by the same method as encoding an HD image.

  An object of the present invention is to record more frames when inter-frame coding is performed effectively using a memory when recording an SD image in an encoding device that records an HD image using a high-efficiency encoding method such as H264. It is to realize high image quality by encoding with reference.

The encoding apparatus of the present invention includes a reference frame buffer that stores a reference frame image, and an encoding unit that encodes an input frame image using the reference frame image in the reference frame buffer, and the reference frame buffer Is characterized in that the number of frames in which the reference frame image can be stored changes according to the resolution of the input frame image.
The encoding apparatus according to the present invention further includes encoding means for encoding the input image by changing the encoding order of the input frame image in accordance with the resolution of the input image.
In addition, the encoding apparatus of the present invention includes encoding means for encoding an input image by changing a picture type composition ratio according to the resolution of the input image.
The encoding method of the present invention includes a storing step of storing a reference frame image in a reference frame buffer, and an encoding step of encoding an input frame image using the reference frame image in the reference frame buffer. In the reference frame buffer, the number of frames in which the reference frame image can be stored is changed according to the resolution of the input frame image.
In addition, the encoding method of the present invention includes an encoding step of encoding the input image by changing the encoding order of the input frame image according to the resolution of the input image.
In addition, the encoding method of the present invention includes an encoding step of encoding the input image by changing the picture type composition ratio according to the resolution of the input image.

  The reference frame buffer can be used effectively, and high image quality can be realized.

(First embodiment)
An encoding apparatus according to the first embodiment of the present invention will be described with reference to FIGS. 1, 2, and 3. FIG. In the first embodiment, the management method of the reference frame buffer 102 is changed according to the resolution of the input signal. Although the picture arrangement order in the GOP (Group of Pictures) is the same for the HD resolution and the SD resolution, the management method of the reference picture used for encoding is changed according to the resolution.

  FIG. 1 is an overall system configuration diagram of an encoding apparatus according to the first embodiment, and FIG. 2 is a diagram illustrating a relationship between an input picture and an encoded picture when an HD image is encoded by the present encoding apparatus. FIG. 3 is a diagram illustrating a relationship between an input picture and a coded picture when an SD image is encoded by the present encoding device. Note that the encoding method of this apparatus is H.264 / AVC, and the operation of this apparatus when the resolution is HD and SD is shown.

  H. In the H.264 / AVC encoding method, a motion vector is detected for each macroblock with reference to a plurality of encoded frame image signals (reference frame image signals) that are temporally different from the frame image signal as a prediction mode. Accordingly, a plurality of “inter prediction modes” for performing motion compensation inter-frame prediction and a plurality of “intra (inter)” predictions using spatially encoded pixel values of neighboring macroblocks on the same space. INTRA) prediction mode "is prepared. In the “INTER prediction mode”, motion detection, motion prediction, and motion compensation processes (details) are performed for each block (target region) obtained by further dividing the macroblock into arbitrary regions (for example, 8 pixels × 16 lines). Will be described later). The moving picture coding apparatus is configured to perform efficient information compression by switching the prediction mode in units of macroblocks according to the local nature of the input video signal.

  As shown in FIG. 1, the encoding apparatus includes an input unit, a frame buffer 101, a reference frame buffer 102, a motion prediction unit 104, a motion compensation unit 105, and an intra prediction unit 106 as functional components. . Furthermore, the encoding apparatus includes an orthogonal transform unit 107, a quantization unit 108, an entropy encoding unit 109, an inverse quantization unit 110, an inverse orthogonal transform unit 111, and a switch 113. Hereinafter, each component will be described.

  The input unit is a part that rearranges moving image signals input from the outside for encoding, and the frame data after the rearrangement is stored in the frame buffer 101.

  The motion prediction unit 104 is a part that selects a prediction mode and detects a motion vector. When the “INTER prediction mode” is selected, the motion prediction unit 104 detects a motion vector using a reference frame signal. More specifically, the motion prediction unit 104 uses a reference frame signal, and within a predetermined search range from a plurality of encoded frame images stored in the reference frame buffer 102 in advance, An image signal pattern similar to the image signal pattern is searched for. Then, a motion vector that is a spatial displacement amount between both image signal patterns is detected. The motion prediction unit 104 sends a signal including the motion vector difference value, the reference frame number, and the selected prediction mode to the entropy encoding unit 109. The motion vector difference value is difference information between the detected motion vector and the optimal prediction motion vector (motion vector prediction value) calculated from the motion vector of the encoded adjacent block. The reference frame number indicates a reference frame image signal used for motion vector detection. At the same time, the motion prediction unit 104 sends a signal including the selected prediction mode, motion vector, and reference frame number to the motion compensation unit 105.

  In addition, the motion compensation unit 105 refers to the encoded image signal (reference frame image signal) of the frame indicated by the reference frame number in the reference frame buffer 102 using the motion vector transmitted from the motion prediction unit 104. . Then, the motion compensation unit 105 generates a predicted image signal of each block, sends it to the switch 113, takes the difference from the encoding target image, and sends it to the subsequent orthogonal transform unit 107.

  On the other hand, when the motion prediction unit 104 selects the “INTRA prediction mode”, the intra prediction unit 106 sends a prediction signal using pixel values of neighboring blocks that have been encoded in the same space to the switch 113. The subtracter takes the difference between the prediction signal and the encoding target image and sends the difference to the subsequent orthogonal transform unit 107.

  The orthogonal transform unit 107 generates an orthogonal transform coefficient by performing orthogonal transform on the prediction residual signal, and sends the orthogonal transform coefficient to the quantization unit 108.

  On the other hand, the quantization unit 108 quantizes the orthogonal transform coefficient transmitted from the orthogonal transform unit 107 to generate a quantized orthogonal transform coefficient, which is sent to the entropy encoding unit 109 and the inverse quantization unit 110. send.

  Next, the entropy encoding unit 109 is based on the quantized orthogonal transform coefficient transmitted from the quantization unit 108, the prediction mode transmitted from the motion prediction unit 104, the motion vector difference value, and the reference frame number. Entropy encoding is performed and multiplexed into a compressed stream. Then, the entropy encoding unit 109 transmits it to the outside.

  In addition, the inverse quantization unit 110 generates an orthogonal transform coefficient by performing inverse quantization on the quantized orthogonal transform coefficient transmitted from the quantization unit 108, and sends the orthogonal transform coefficient to the inverse orthogonal transform unit 111.

  Then, the inverse orthogonal transform unit 111 generates a prediction residual signal by performing inverse orthogonal transform on the orthogonal transform coefficient transmitted from the inverse quantization unit 110, and sends the prediction residual signal to the adder.

  The adder adds the prediction residual signal transmitted from the inverse orthogonal transform unit 111 and the prediction image signal transmitted from the switch 113 to generate a frame image signal, which is filtered by a loop filter (not shown), and then referred to Send to frame buffer 102. This frame image signal is stored in the reference frame buffer 102 and used as a reference frame image signal in the subsequent encoding process. In addition, information on motion vectors and reference frame numbers is also included in the reference frame image signal and stored simultaneously.

  An encoding method of the apparatus when the resolution of the image signal input to the apparatus is HD resolution will be described.

  In FIG. 2, F0 to F14 indicate input signals in units of frames, I0, B1, B2,... Are encoded pictures, and the target picture is encoded below each encoded picture. The reference frame buffer 102 used at this time is shown. The reference frame buffer 102 is also called a decoded picture buffer (DPB) in H.264, and the size of the reference frame buffer 102 is defined in accordance with the level resolution. For this reason, when the input image is an HD image, the level is 4 (assuming that there are no decimal places), and a memory area that can store four HD resolution images is required. This memory amount is defined on the decoding side, and encoding may be performed with a memory amount smaller than this. In the following description, it is assumed that there is a memory amount that can store four images.

  The input signals F0, F1, and F2 are temporarily stored in the frame buffer 101 and the frames are rearranged. Thereafter, F2 is encoded as an I picture to generate I0. At this time, since the I0 picture is used as a reference picture for the next frame and thereafter, it is locally decoded inside the apparatus and stored in the reference frame buffer 102. The mechanism for performing local decoding is as described above. Next, F0 generates a B1 picture using the locally decoded I0 picture as a reference picture, and F1 also generates a B2 picture by referring to the locally decoded I0 picture. F5 generates a P3 picture with reference to the locally decoded I0 picture. Since it is used as a reference picture for subsequent encoding, F5 is locally decoded and stored in the reference frame buffer 102. Thereafter, the same operation is repeated to form an encoded signal while storing the local decode in the reference frame buffer 102.

  Here, a management method of the reference frame buffer 102 when encoding the F13 and F14 frames will be described. Since F14 is encoded as a forward prediction image (hereinafter referred to as a P picture), the preceding encoded picture is used as a reference picture, and at this time, the encoded frame I0, P3 is stored in the reference frame buffer 102. , P6 and P9 are stored as four images. F14 encodes P12 using these pictures, but F14 is a P picture and is used as a reference picture for the next frame and thereafter, and is locally decoded and stored in the reference frame buffer 102. Since P12 is used as a future reference frame at this time, the I0 picture stored in the reference frame buffer 102 is discarded and P12 is stored in the reference frame buffer 102.

  Since F13 is encoded as a B picture, the front and rear encoded pictures are used as reference pictures. At this time, the reference frame buffer 102 has already decoded P3, P6, P9, and P12 as local decodes. The four images are stored. F13 encodes B14 using these pictures.

  If the reference frame buffer 102 is managed as described above, the front four images are always used as reference pictures when the P picture is encoded, the B picture always uses the front three images, and the rear one image as the reference pictures. Can be used as

  Next, the encoding method of this apparatus when the resolution of the image signal input to this apparatus is SD resolution will be described.

  3, F0 to F14 indicate input signals in units of frames, I0, B1, B2,... Are encoded pictures, and the target picture is encoded under each encoded picture. The reference frame buffer 102 used at this time is shown. Note that when the input image is an SD image, the reference frame buffer 102 has a level of 3 (there are no decimal places) and requires a memory area capable of storing seven SD resolution images. However, as described above, it is not necessary to have seven memory areas on the encoding side, and encoding may be performed with a memory amount of six or less. However, since this apparatus already has a memory area for four HD resolutions as a memory area for encoding an HD resolution image, there is sufficient memory area for six SD resolutions. Therefore, when the resolution of the input signal is SD resolution, encoding is performed by effectively using the reference frame buffer 102, which is an area where HD resolution can be encoded.

  The input signals F0, F1, and F2 are temporarily stored in the frame buffer 101 and the frames are rearranged. Thereafter, F2 is encoded as an I picture to generate I0. At this time, since the I0 picture is used as a reference picture for the next frame and thereafter, it is locally decoded inside the apparatus and stored in the reference frame buffer 102. The mechanism for performing local decoding is as described above. Next, F0 generates a B1 picture using the locally decoded I0 picture as a reference picture, and F1 also generates a B2 picture by referring to the locally decoded I0 picture. F5 generates a P3 picture with reference to the locally decoded I0 picture. Since it is used as a reference picture for subsequent encoding, F5 is locally decoded and stored in the reference frame buffer 102. Thereafter, the same operation is repeated to form an encoded signal while storing the local decode in the reference frame buffer 102.

  Here, a management method of the reference frame buffer 102 when encoding the F13 and F14 frames will be described. Since F14 is encoded as a P picture, the front encoded picture is used as a reference picture. At this time, the reference frame buffer 102 has four encoded I0, P3, P6, and P9 locally decoded. Images are saved. F14 encodes P12 using these pictures, but F14 is a P picture and is used as a reference picture for the next frame and thereafter, and is locally decoded and stored in the reference frame buffer 102.

  Since F13 is encoded as a B picture, the front and rear encoded pictures are used as reference pictures. At this time, the encoded frame I0, P3, P6, P9, and P12 are locally stored in the reference frame buffer 102. Five decoded images are stored. F13 encodes B14 using these pictures.

  2 and 3 show only 1 GOP for the sake of simplicity. However, it is assumed that there are frames before and after the GOP, and the reference picture stored in the reference frame buffer 102 is an image obtained by locally decoding a P picture included in the GOP before the displayed GOP. Has been. In the case of an open GOP structure, it is possible to easily refer to GOPs. In the example shown here, the B picture is not used as a reference picture. However, in H.264 / AVC, the B picture can be used as a reference frame, so the B picture is locally decoded and the picture is referred to. It does not matter if such a form is used.

  When the reference frame buffer 102 is managed as described above, the front six images are always used as reference pictures when the P picture is encoded, and the front five images and the rear one are always used when the B picture is encoded. One image can be used as a reference picture. Therefore, in encoding of P picture and B picture that perform inter-frame prediction, it is possible to use a frame that is temporally distant from the encoding target frame as a reference picture, so that the prediction efficiency can be greatly improved. Become.

  In the present embodiment, the HD resolution and the SD resolution have been described as examples. However, the resolution is not limited to these two. In addition, the number of reference frames stored in HD resolution and SD resolution is opposite to that described above, and the number of reference frames when encoding an HD resolution signal is the number of reference frames when encoding an SD resolution signal. It is possible to have more.

  As described above, the present embodiment includes the reference frame buffer 102 that stores the reference frame image, and the encoding units 104 to 113 that encode the input frame image using the reference frame image in the reference frame buffer. . The reference frame buffer 102 changes the number of frames in which the reference frame image can be stored according to the resolution of the input frame image.

  The reference frame buffer 102 can store a reference frame image when the input image frame has a low resolution (SD resolution) and a reference frame image when the input image frame has a high resolution (HD resolution). More than the number of frames.

  Further, the reference frame buffer 102 has a smaller number of frames that can store a reference frame image when the input image frame has a low resolution than a number of frames that can store a reference frame image when the input image frame has a high resolution. May be.

(Second Embodiment)
An encoding apparatus according to the second embodiment of the present invention will be described with reference to FIGS. In the second embodiment, the encoding order is changed according to the resolution of the input signal.

  Since the overall system configuration diagram is the same as that of the first embodiment, it is not different from FIG. Therefore, the description of FIG. 1 is omitted since it has been described in the first embodiment. In the case of HD resolution, encoding is performed by the method shown in FIG. 2 and the first embodiment. FIG. 4 is a diagram illustrating a relationship between an input picture and a coded picture when an SD image is encoded by the present encoding device. Note that the encoding method of this apparatus is H.264 / AVC, and the operation of this apparatus when the resolution is HD and SD is shown.

  An encoding method of the apparatus when the resolution of the image signal input to the apparatus is the SD resolution will be described.

  4, F0 to F14 indicate input signals in units of frames, I0, P1, P2,... Are encoded pictures, and the target picture is encoded under each encoded picture. The reference frame buffer 102 used at this time is shown. Note that when the input image is an SD image, the reference frame buffer 102 has a level of 3 (there are no decimal places) and requires a memory area capable of storing six SD resolution images. However, as described above, it is not necessary to have six memory areas on the encoding side, and encoding may be performed with a memory amount of six or less. However, since this apparatus already has a memory area for four HD resolutions as a memory area for encoding an HD resolution image, there is sufficient memory area for six SD resolutions. Therefore, when the resolution of the input signal is SD resolution, encoding is performed by effectively using the reference frame buffer 102, which is an area where HD resolution HD resolution can be encoded.

  The input signals F0, F1, and F2 are temporarily stored in the frame buffer 101 and the frames are rearranged. Thereafter, F2 is encoded as an I picture to generate I0. At this time, since the I0 picture is used as a reference picture for the next frame and thereafter, it is locally decoded inside the apparatus and stored in the reference frame buffer 102. Note that the mechanism for performing local decoding is as described in the first embodiment. Next, the input signals F3, F4, and F5 are temporarily stored in the frame buffer 101, the frames are rearranged, and F5 is encoded using I0 as a reference picture to generate P1. This P1 is also used as a reference picture for a subsequent frame, and is locally decoded and stored in the reference frame buffer 102. Similarly, P2 is generated from F8 and the local decoded image is stored in the reference frame buffer 102.

  Next, F0 generates a B1 picture using the locally decoded I0, P1, and P2 as reference pictures, and F1 also generates a B2 picture by referring to the locally decoded I0, P1, and P2. Thereafter, the same operation is repeated to form an encoded signal while storing the local decoded image in the reference frame buffer 102.

  Here, the encoding sequence when encoding the F10 and F14 frames will be described. Since F14 is encoded as a P picture, the front encoded picture is used as a reference picture. At this time, four frames in which the encoded I0, P1, P2, and P7 are locally decoded are used in the reference frame buffer 102. Images are saved. F14 encodes P8 using these pictures, but F14 is a P picture and is used as a reference picture for the next frame and thereafter, and is locally decoded and stored in the reference frame buffer 102.

  Since F10 is encoded as a B picture, the front and rear encoded pictures are used as reference pictures. At this time, the reference frame buffer 102 stores encoded I0, P1, P2, P7, and P8. Five locally decoded images are stored. F10 encodes B12 using these pictures.

  FIG. 4 shows only one GOP for the sake of simplification, but it is assumed that there are frames before and after the GOP as in the first embodiment. In the reference picture stored in the reference frame buffer 102, an image obtained by locally decoding a P picture or the like included in a GOP before the displayed GOP is stored. In the case of an open GOP structure, it is possible to refer to the GOP across GOPs. Suppose it is possible easily. In the example shown here, the B picture is not used as a reference picture. However, in H.264 / AVC, the B picture can be used as a reference frame, so the B picture is locally decoded and the picture is referred to. It does not matter if such a form is used.

  As described above, if only the P picture is encoded first and then the encoding is performed in such an encoding order that the B picture is encoded, the six pictures in front always are encoded. Use the image as a reference picture. When a B picture is encoded, two or more backward pictures can be used as reference frames. Therefore, in encoding of P picture and B picture that perform inter-frame prediction, it is possible to use a frame that is temporally distant from the encoding target frame as a reference picture, so that the prediction efficiency can be greatly improved. Become.

  In the present embodiment, the HD resolution and the SD resolution have been described as examples. However, the resolution is not limited to these two. Also, the encoding order of the HD resolution and the SD resolution may be reverse to that described above. That is, the encoding order when encoding the HD resolution signal is the encoding order when encoding the SD resolution signal described above, and the encoding order when encoding the SD resolution signal is described above. It is also possible to use the encoding order when encoding the HD resolution signal.

  As described above, this embodiment includes an encoding unit that encodes an input image by changing the encoding order of the input frame image in accordance with the resolution of the input image. The encoding means performs encoding in units of a plurality of pictures, and encodes an intra-frame encoded image (I picture) when encoding a low resolution (SD resolution) input image. Thereafter, all of the forward prediction images (P pictures) included in the plurality of pictures are encoded, and then the bidirectional prediction image (B picture) is encoded.

  The encoding unit performs encoding in units of a plurality of pictures, encodes an intra-frame encoded image when encoding a high-resolution input image, and then performs forward prediction included in the plurality of pictures. It is also possible to perform all of the image coding and then perform the bi-directional prediction image coding.

(Third embodiment)
An encoding apparatus according to the third embodiment of the present invention will be described with reference to FIGS. In the third embodiment, the ratio of P pictures forming a GOP (Group of Pictures) is changed according to the resolution of the input signal.

  Since the overall system configuration diagram is the same as that of the first embodiment, it is not different from FIG. Therefore, the description of FIG. 1 is omitted since it has been described in the first embodiment. In the case of HD resolution, encoding is performed by the method shown in FIG. 2 and the first embodiment. FIG. 5 is a diagram illustrating a relationship between an input picture and a coded picture when an SD image is encoded by the present encoding device. Note that the encoding method of this apparatus is H.264 / AVC, and the operation of this apparatus when the resolution is HD and SD is shown.

  An encoding method of the apparatus when the resolution of the image signal input to the apparatus is the SD resolution will be described.

  In FIG. 5, F0 to F8 indicate input signals in units of frames, I0, P1, P2,... Are encoded pictures, and the target picture is encoded below each encoded picture. The reference frame buffer 102 used at this time is shown. When the input image is an SD image, the reference frame buffer 102 has a level of 3 (there is no decimal point) and requires a memory area that can store six SD resolution images. For the same reason as the second embodiment, there is sufficient memory area for six SD resolutions. Therefore, when the resolution of the input signal is SD resolution, encoding is performed by effectively using the reference frame buffer 102, which is an area where HD resolution HD resolution can be encoded.

  The input signals F0 to F8 are temporarily stored in the frame buffer 101 and the frames are rearranged. Thereafter, F2 is encoded as an I picture to generate I0. At this time, since the I0 picture is used as a reference picture for the next frame and thereafter, it is locally decoded inside the apparatus and stored in the reference frame buffer 102. Note that the mechanism for performing local decoding is as described in the first embodiment. Next, F4 generates P1 using the locally decoded I0 as a reference picture, F6 generates P2 using the locally decoded I0 and P1 as a reference picture, and F8 similarly generates P3. Thereafter, F0 generates B4 using I0, P1, P2, and P3 as reference pictures, and thereafter repeats the same operation to form an encoded signal while storing the local decoded image in the reference frame buffer 102.

  Here, the encoding order when encoding F5 will be described. Since F5 is encoded as a B picture, a front encoded picture and a rear encoded picture are used as reference pictures. However, at this time, the reference frame buffer 102 stores four images obtained by local decoding of the encoded I0, P1, P2, and P3. F5 uses these pictures to encode B7.

  FIG. 5 shows only one short GOP for the sake of simplicity, but it is assumed that there are frames before and after the GOP as in the first embodiment. In the reference picture stored in the reference frame buffer 102, an image obtained by locally decoding a P picture or the like included in a GOP before the displayed GOP is stored. In the case of an open GOP structure, it is possible to refer to the GOP across GOPs. Suppose it is possible easily. In the example shown here, the B picture is not used as a reference picture. However, in H.264 / AVC, the B picture can be used as a reference frame, so the B picture is locally decoded and the picture is referred to. It does not matter if such a form is used.

  As described above, when the ratio of the P pictures constituting the GOP is changed, the encoding is always performed with reference to up to six pictures at the front when the P picture is encoded. When encoding a B picture, it is possible to encode a frame from the beginning to the end of a frame forming a GOP as a reference picture. Therefore, in encoding of P picture and B picture that perform inter-frame prediction, it is possible to use a frame that is temporally distant from the encoding target frame as a reference picture, so that the prediction efficiency can be greatly improved. Become.

  In the present embodiment, the HD resolution and the SD resolution have been described as examples. However, the resolution is not limited to these two. Further, the ratio of the P picture of the HD resolution and the SD resolution is opposite to that described above, and the ratio of the P picture when the HD resolution signal is encoded is more than the ratio of the P picture when the SD resolution signal is encoded. Can also be increased.

  As described above, this embodiment includes an encoding unit that encodes an input image by changing the picture type configuration ratio according to the resolution of the input image. When the encoding means encodes a low-resolution input image in GOP units, the ratio of forward predicted images (P pictures) constituting the GOP is the GOP when encoding a high-resolution input image. Are encoded so as to be larger than the ratio of the forward-predicted images. The low resolution is, for example, the SD resolution.

  Further, the encoding means configures the GOP when encoding a high-resolution input image such that a ratio of forward prediction images configuring the GOP when encoding a low-resolution input image in GOP units. The encoding may be performed so as to be smaller than the ratio of the forward prediction images.

  As described above in detail, according to the first to third embodiments, in the present encoding apparatus capable of encoding various resolution signals, a reference picture management method when performing interframe encoding is described as an input image. Change according to the resolution. As a result, it is possible to generate a high-quality encoded signal by effectively using the memory and performing encoding while referring to many frames.

  Also, in this device, by changing the coding order when performing interframe coding according to the resolution of the input image, coding is performed while referring to many frames using the memory effectively, and high-quality coding is performed. Can be generated.

  In this device, by changing the ratio of P pictures that form a GOP according to the resolution of the input image, encoding is performed while referring to many frames using the memory effectively, and high-quality encoded signals are converted. Can be generated.

  The encoding means is H.264. It may be encoded by the H.264 encoding method or may be encoded by the MPEG encoding method. The encoding device of the above embodiment can be applied to an encoding device such as a digital video camera having an optical disk or a magnetic tape as a recording medium.

  The above-described embodiments are merely examples of implementation in carrying out the present invention, and the technical scope of the present invention should not be construed as being limited thereto. That is, the present invention can be implemented in various forms without departing from the technical idea or the main features thereof.

It is a block diagram which shows the structural example of the encoding apparatus by the 1st Embodiment of this invention. It is a figure which shows the relationship between the input frame at the time of encoding an HD resolution signal in an encoding apparatus, and an encoding frame. In the 1st Embodiment of this invention, it is a figure which shows the relationship between the input frame at the time of encoding an SD resolution image, and an encoding frame. In the 2nd Embodiment of this invention, it is a figure which shows the relationship between the input frame at the time of encoding an SD resolution image, and an encoding frame. In the 3rd Embodiment of this invention, it is a figure which shows the relationship between the input frame at the time of encoding an SD resolution image, and an encoding frame.

Explanation of symbols

101 Frame buffer 102 Reference frame buffer 104 Motion prediction unit 105 Motion compensation unit 106 Intra prediction unit 107 Orthogonal transformation unit 108 Quantization unit 109 Entropy coding unit 110 Inverse quantization unit 111 Inverse orthogonal transformation unit 113 Switch

Claims (18)

A reference frame buffer for storing a reference frame image;
Encoding means for encoding an input frame image using a reference frame image in the reference frame buffer;
The encoding apparatus according to claim 1, wherein the reference frame buffer changes the number of frames in which the reference frame image can be stored according to the resolution of the input frame image.   The reference frame buffer is characterized in that the number of frames that can store a reference frame image when the input image frame has a low resolution is larger than the number of frames that can store a reference frame image when the input image frame has a high resolution. The encoding apparatus according to claim 1.   The reference frame buffer is characterized in that the number of frames that can store a reference frame image when the input image frame has a low resolution is smaller than the number of frames that can store a reference frame image when the input image frame has a high resolution. The encoding apparatus according to claim 1.   The encoding means includes H.264. The encoding apparatus according to any one of claims 1 to 3, wherein encoding is performed using an H.264 encoding method.   The encoding apparatus according to any one of claims 1 to 3, wherein the encoding means performs encoding using an MPEG encoding method.   An encoding apparatus comprising encoding means for encoding an input image by changing an encoding order of the input frame image in accordance with the resolution of the input image.   The encoding means performs encoding in units of a plurality of pictures, encodes an intra-frame encoded image when encoding a low-resolution input image, and thereafter, in the order included in the plurality of pictures. The encoding apparatus according to claim 6, wherein encoding of the direction prediction image is performed, and thereafter, the bidirectional prediction image is encoded.   The encoding means performs encoding in units of a plurality of pictures, encodes an intra-frame encoded image when encoding a high-resolution input image, and thereafter, in the order included in the plurality of pictures. The encoding apparatus according to claim 6, wherein encoding of the direction prediction image is performed, and thereafter, the bidirectional prediction image is encoded.   The encoding means includes H.264. The encoding apparatus according to any one of claims 6 to 8, wherein encoding is performed using an H.264 encoding method.   The encoding apparatus according to any one of claims 6 to 8, wherein the encoding means performs encoding by an MPEG encoding method.   An encoding apparatus comprising encoding means for encoding an input image by changing a picture type composition ratio in accordance with the resolution of the input image.   The encoding means is configured such that when a low-resolution input image is encoded in GOP units, a ratio of forward-predicted images constituting the GOP is the order in which the GOP is formed when a high-resolution input image is encoded. 12. The encoding apparatus according to claim 11, wherein encoding is performed so as to be larger than a ratio of the direction prediction images.   The encoding means is configured such that when a low-resolution input image is encoded in GOP units, a ratio of forward-predicted images constituting the GOP is the order in which the GOP is formed when a high-resolution input image is encoded. 12. The encoding apparatus according to claim 11, wherein encoding is performed so as to be smaller than a ratio of the direction prediction image.   The encoding means includes H.264. The encoding apparatus according to any one of claims 11 to 13, wherein encoding is performed using an H.264 encoding scheme.   The encoding apparatus according to any one of claims 11 to 13, wherein the encoding means performs encoding using an MPEG encoding method. Storing a reference frame image in a reference frame buffer;
An encoding step of encoding an input frame image using a reference frame image in the reference frame buffer;
The encoding method according to claim 1, wherein the reference frame buffer changes the number of frames in which the reference frame image can be stored according to the resolution of the input frame image.   An encoding method comprising: an encoding step of encoding an input image by changing an encoding order of the input frame image in accordance with the resolution of the input image.   An encoding method comprising: an encoding step of encoding an input image by changing a picture type composition ratio according to a resolution of the input image.

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