TH83058B - Methods of video encoding and decoding. - Google Patents

Abstract

Revised 08/03/2021 The encoding control unit (110) and the format selection unit (109) were assembled. The encoding control unit (110) determines the encoding sequence for a large number of contiguous B images placed between Image I and Image P so that the B image whose temporal distance from the two preceding encoded images in the display sequence is encoded with importance to reorder B images in the encoding sequence. When the current image is encoded in direct mode, the format selection unit 109 divides the leading motion vector of the block which is included in the backward reference image of the current image and places it together with the current block if it is used for block encoding. ---------------------------------------------------------------------------------------------------- DC60 (23/05/2003) The encoding control unit (110) and the format selection unit (109) were assembled. The encoding control unit (110) determines the encoding sequence for a large number of contiguous B images placed between Image I and Image P so that the B image whose temporal distance from the two preceding encoded images The furthest image in the display sequence is encoded with importance so that image B is placed in the encoding sequence. When the current image is encoded in direct selection unit type 109, the group forward movement vector is included in the backward reference image of the current image and is placed together with the current group if it is used for group encoding. The encoding control unit (110) and the selection unit (109) are assembled. The encoding control unit (110) determines the encoding sequence for a large number of contiguous images B placed between image I and image P so that the image B whose temporal distance from the two preceding encoded images is furthest in the display sequence is encoded with importance so that image B is placed in the encoding sequence. When the current image is encoded in direct selection unit type 109, the group forward movement vector is included in the backward reference image of the current image and is placed together with the current group if it is used for group encoding.

Claims (35)

Revised 08/03/2021 1. Image Decoding Methods for decoding encoded images, such image decoding methods include: decoding procedures for determining the motion vector for the current block to be decoded based on the motion vector of the jointly positioned block, which is a block included within the previously decoded image and jointly positioned with the current block; and decoding the current block by performing motion compensation operations on the current block in a direct format using the motion vector for the current block and a reference image corresponding to the motion vector for the current block. Specifically, the decoding procedures mentioned include: in the case where the jointly positioned block is decoded using two motion vectors and two reference images corresponding to the two motion vectors, respectively; generating two motion vectors to be used for decoding the current block by performing motion compensation operations on the current block in a direct format by scaling using the difference between the information indicating the display order of the image; one of the two motion vectors used for decoding the jointly positioned block; and decoding the current block by performing motion compensation operations on the current block in a direct format using the two motion vectors generated for the current block and two reference images corresponding to the two generated motion vectors, respectively. 1. The image decoding method under claim 1, where the previously decoded image combined with the jointly positioned block is a backward reference image to the current block. 2. The image decoding method under claim 1, where two reference images corresponding to two sequential motion vectors for the current block are the first and second reference images; the first reference image is the previously decoded image combined with the jointly positioned block; and the second reference image is one of the two reference images used for decoding the jointly positioned block and corresponds to the scaled motion vector for generating two motion vectors for the current block. 3. The image decoding method under claim 1, where, in the case where the jointly positioned block has been decoded in a direct format, two motion vectors for the current block are generated using one of the two motion vectors used for decoding the jointly positioned block. 4. The image decoding method under claim 2, where the information indicating the display order of the image is: the first information indicating the position in the display order of the image combined with the current block; the second information indicating the position in the display order of the second reference image for the current block; and the third information indicating the position in the display order of the first reference image for the current block. This is an image that includes jointly positioned blocks, and the difference between the data is the difference between the first and second data, the difference between the first and third data, and the difference between the second and third data. 5. Image Decoder, which decodes the encoded image. The aforementioned image decoder consists of: a decoding unit that operates to determine the motion vector for the current block to be decoded based on the motion vector of the jointly positioned block, which is a block included within the previously decoded image and is jointly positioned with the current block, and decodes the current block by performing motion compensation operations on the current block in a direct format using the motion vector for the current block and the reference image corresponding to the motion vector for the current block. Specifically, in the case where the jointly positioned block is decoded using two motion vectors and two reference images corresponding to the two motion vectors, respectively, the aforementioned decoding unit operates to generate two motion vectors to be used for decoding the current block by performing motion compensation operations on the current block in a direct format by adjusting the scale using the difference between the data indicating the display order of the image. One of the two motion vectors is used for decoding the jointly positioned block and to decode the current block by performing motion compensation operations on the block. Currently, in direct format, two motion vectors are generated for the current block, and two reference images corresponding to the two generated motion vectors respectively, where the previously decoded image, included with the jointly positioned block, is the backward reference image of the current block. ---------------------------------------------------------------------------------------------------- ------01/08/2018------(OCR) Page 1 of 3 pages. Claims 1. Image decoding procedure for decoding encoded images. The image decoding procedure described includes a decoding procedure for determining the motion vector for the current group to be decoded on the basis of the motion vector of the jointly positioned group, where the group included is within the previously decoded image and jointly positioned with the current group, and the current group is decoded by performing motion compensation on the current group in a direct format using the motion vector for the current group and a reference image that corresponds to the motion vector for the current group, which is specific to the decoding procedure described. In the case where the jointly positioned group is decoded using two motion vectors and two reference images that correspond to two motion vectors respectively. The creation of a long motion vector for use in decoding the current group by directly compensating for the motion of the current group by subdivision, using the difference between the information representing the display sequence of the images. One of the two motion vectors is used for decoding the co-laid group, and the decoding of the current group by directly compensating for the motion of the current group using the motion vector created for the current group and two reference images corresponding to the two motion vectors created respectively, where the previously decoded image included with the co-laid group is the reverse reference image of the current group. 2. The image decoding process specified in claim 1, where two reference images corresponding to the two motion vectors respectively for the current group are the first and second reference images. The first reference image is the previously decoded image included with the co-laid group, and the second reference image is one of the two reference images used for decoding the co-laid group and corresponds to the subdivided motion vector for creating the motion vector. 3. Image decoding procedure according to claim 1, page 2 of 3 pages, where in the case where the combined group is decoded directly, two motion vectors for the current group are generated using one of the two motion vectors used for the combined group. 4. Image decoding procedure according to claim 2, where the information representing the display order of the images is information one representing the position in the display order of the image included in the current group, information two representing the position in the display order of the second reference image for the current group, and information three representing the position in the display order of the first reference image for the current group that is also included in the combined group, and the difference between the information is the difference between information one and information two, the difference between information one and information two, and the difference between information two and information two. 5. Image decoding device that decodes the encoded image. The aforementioned image decoding device consists of a decoding unit that operates to determine the motion vector for the current group to be decoded. Based on the motion vectors of the collaborating group, which is a group included within the previously decoded image and collaborating with the current group, and to decode the current group by directly compensating for the movement of the current group using the motion vector for the current group and the reference image corresponding to the motion vector for the current group, specifically in the case where the collaborating group is decoded using two motion vectors and two reference images corresponding to two motion vectors, respectively, the decoding unit mentioned operates to generate two motion vectors to be used for decoding the current group by directly compensating for the movement of the current group by subdivision, using the difference between the information representing the display sequence of one of the motion vectors used for decoding the collaborating group, and to decode the current group by directly compensating for the movement of the current group using the two motion vectors generated for the current group and the reference image corresponding to the motion vector generated, respectively. Page 3 of 3 pages, where the previously decoded image mentioned, included with the collaborating group, is an image. Referring back to the current group 6. The storage medium on which the program for decoding the encoded image is stored. The program mentioned enables the computer to perform decoding using one of the image decoding methods described in claims 1 through 4. 1. The video encoding process for image data corresponds to the images being used to create the video and generates bit strings. The video encoding process consists of encoding steps for encoding the current image as one of three images: Image I, Image P, and Image B. Image I contains a group which is a prediction between images encoded using a single-reference prediction model that uses the previously encoded image as the first reference image, and Image B contains a group which is a prediction between images encoded using a double-reference prediction model that uses the previously encoded image as the first and second reference images. The encoding steps include control steps for determining the encoding order, which differs from the display order for the adjacent Image B, placed between Image I and Image P. 2. The video encoding process under claim 1, where the encoding process still includes a selection step for selecting the reference image closest to image B in the display order as at least one of the first reference images and the second reference image for encoding image B. 3. The video encoding procedure under claim 1, in which, during the control procedure, the encoding sequence for image B is determined so that image B, which is furthest from the previously encoded image in the display sequence, is encoded in order of importance. 4. The video encoding procedure under claim 1, in which, during the control procedure, the encoding sequence for image B is determined so that image B which is closest to the previously encoded image in the display sequence is encoded with priority. 5. Video encoding methods pursuant to claim 3 or claim 4, where distance is the difference specified by the information displayed in the sequence of image displays. 6. Video Encoding Process: The video encoding process involves encoding image data that corresponds to the image being video recorded and generating bit strings. The video encoding process consists of encoding steps for encoding the current image B, which contains a group predicted between the encoded images using a paired prediction reference that uses the previously encoded image as the first and second reference images. In this encoding step, the current group A in the current image B is encoded directly, where motion compensation for the current group A is performed using the motion vector of the current group A derived from the motion vector of the previously encoded group. The motion vector for motion compensation of the current group A is obtained by subdividing the motion vector dependent on the first reference image of group B, which is placed together in the second reference image, using the difference specified by the information representing the image display order. 7. Video Encoding Process: The video encoding process involves encoding image data that corresponds to the image being video-enabled and generating bitlines. The video encoding process consists of: The encoding step for encoding the current image as image B, which contains a group predicted between the encoded images using a pair of predictors that use the previously encoded image as the first and second reference images. In this encoding step, the current group A in the current image B is encoded directly, where the displacement of the current group A is compensated using the displacement vector of the current group A derived from the displacement vector of the previously encoded group. The displacement vector for compensating the displacement of the current group A is obtained by subdividing the second displacement vector that places the second reference image of the group B together in the second reference image, using the difference specified by the image display order. 8. Video Encoding Process: The video encoding process involves encoding image data that corresponds to the image being video recorded and generating bit strings. The video encoding process consists of: The encoding step for encoding the current image as image B, which contains a group predicted between the encoded images using a pair of predictors based on the previously encoded images as the first and second reference images. In this step, when the current group A in image B is encoded directly, the motion compensation for group A is performed using the motion vector of group A derived from the motion vector of the previously encoded group. If the co-encoding group B in the second reference image is previously encoded directly, the motion vector for the motion compensation of group A is obtained by subdividing the first motion vector based on the first reference image and is then used for encoding group B in the second reference image, using the difference specified by the image display order information. 9. Video Encoding Process: The video encoding process involves encoding image data that corresponds to the images used to create the video and generating bitlines. The video encoding process consists of: Encoding steps for encoding the current image as part of image P and image B. Image P has a group that is a prediction between images encoded using a single prediction reference that uses a previously encoded image as the first reference image, and image B has a group that is a prediction between images encoded using a double prediction reference that uses a previously encoded image as the first reference image and a second reference image. In the encoding step, the current group A in the current image B is encoded directly, where the displacement of the current group A is compensated for using the displacement vector of the current group A derived from the displacement vector of the previously encoded group. The displacement vector for compensating the displacement of the current group A is obtained by subdividing the first displacement vector by the second reference image of the group B placed in the later image P, time-sensitively, using the difference specified by the image display order. 10. Video Encoding Process: The video encoding process involves encoding image data that corresponds to the image being encoded as a video and generating bit strings. The video encoding process consists of: The encoding step encoding the current image as image B, which contains a group predicted between the encoded images using a pair of predictors that use the previously encoded image as the first reference image and the second reference image. In this encoding step, the current group A in the current image B is encoded directly, where motion compensation for the current group A is performed using the motion vector of the current group A derived from the motion vector of the previously encoded group. The motion compensation is performed using a motion vector obtained by subdivision. The selected motion vector is chosen from among the motion vectors of the previously encoded group, using the difference specified by the image display order, and the information specifying the selected motion vector is added to the bit string. 11. Video encoding process for encoding image data corresponding to the images being encoded in the video and creating bit strings. The video encoding process consists of: Encoding steps for encoding the current image as image B, which contains a group that is a prediction between the encoded images, using a prediction reference pair using the previously encoded image as the first reference image and the second reference image. In the encoding step, when the current group A in the current image B is encoded directly, the displacement of the current group A is performed using the displacement vector of the current group A derived from the displacement vector of the previously encoded group. The displacement vector for displacement of the current group A is obtained by subdividing the first displacement vector if the group B placed in the second reference image is encoded using at least the first displacement vector by the first reference image, and by subdividing the second displacement vector if the group B is encoded using only the second displacement vector by the second reference image, using the difference specified by the display order of the images. 12. A video encoding procedure under any of the claims in clauses 6 through 11 where the encoding procedure when the current group A is encoded by inter-image prediction with a paired prediction reference or in a direct manner, only one motion vector depending on the first reference image is stored. 13. A video encoding process pursuant to any of the claims in clauses 1 through 12 where the first reference image is identified by the first reference index for the identification of the reference image and the second reference image is identified by the second reference index for the identification of the reference image. 14. Video decoding process for decoding bit strings which are created by encoding image data corresponding to the image being used to make the video. The video decoding process consists of: a decoding step for decoding the current image by inter-image prediction using a previously decoded image as a reference image. In this decoding step, when the current image is decoded by inter-image prediction, a pair of predictions is made using a previously encoded image as the first and second reference images. A bit string containing at least the image that is temporal closest to the current image in the sequence is decoded as the first or second reference image. 15. Video decoding process for decoding bitlines, which are created by encoding image data corresponding to the video image. The video decoding process consists of: a decoding step for decoding the current image by inter-image prediction using the previously decoded image as a reference image; a decoding step when the current image is a group image, which is decoded by inter-image prediction using paired predictions with the previously decoded image as the first and second reference images; and the current group A is decoded directly, where the motion compensation of the current group A is performed using the motion vector of the current group A derived from the motion vector of the previously encoded group. The motion vector for the motion compensation of the current group A is obtained by subdividing the first motion vector that depends on the first reference image of group B placed together in the second reference image using the difference specified by the information representing the display order of the images. 16. Video decoding process for decoding bitlines which are created by encoding image data corresponding to the video image. The video decoding process consists of: a decoding step for decoding the current image by predictive pairing using the previously decoded image as the reference image; a decoding step when the current image is a group image which is decoded by predictive pairing using the previously decoded image as the first and second reference images; and the current group A is decoded directly, where the motion compensation of the current group A is performed using the current group A motion vector derived from the motion vector of the previously encoded group. The motion vector for the motion compensation of the current group A is obtained by subdividing the second motion vector which depends on the first reference image of group B placed together in the second reference image using the difference specified by the information representing the display order of the images. 17. Video decoding procedures for decoding bitlines, which are created by encoding image data corresponding to the video image, consist of: a decoding step for decoding the current image by inter-image prediction using a previously decoded image as a reference image; a decoding step when the current image is a group image which is decoded by inter-image prediction using a pair of predictions that uses a previously decoded image as the first and second reference images; and the current group A is decoded directly, where the motion compensation of the current group A is performed using the motion vector of the current group A derived from the motion vector of the previously encoded group. If the co-located group B in the second reference image is previously decoded directly, the motion vector for the motion compensation of the current group A is obtained by subdividing the first motion vector based on the first reference image. This is mostly used to decode group B in the second reference image using the difference specified by the information representing the display order of the images. 18. The video decoding process for decoding bitlines is created by encoding image data corresponding to the video image. The video decoding process consists of: a decoding step for decoding the current image by inter-image prediction using a previously decoded image as a reference image; and a decoding step when the current image is a group image which is decoded by inter-image prediction using a paired reference prediction using a previously decoded image as the first and second reference images. The current group A is decoded directly, where the motion compensation of the current group A is performed using the current group A motion vector derived from the motion vector of the previously encoded group. The motion vector for the motion compensation of the current group A is obtained by subdividing the first motion vector that depends on the first reference image of group B placed together in the later image temporally using the difference specified by the information representing the display order of the images. The later image is decoded by inter-image prediction using a single reference prediction using a previously decoded image as the first reference image. 19. Video decoding procedures for decoding bitlines, which are created by encoding image data corresponding to the video image, consist of: a decoding step for decoding the current image by predicting between images using a previously decoded image as a reference image; a decoding step when the current image is a group image, which is decoded by predicting between reference images; a pair of predictors using a previously decoded image as the first reference image and a second reference image; and the current group A is decoded directly, where the motion compensation of the current group A is performed using the current group A motion vector derived from the motion vector of the previously encoded group. The motion vector for the motion compensation of the current group A is obtained by subdividing the obtained motion vector based on the bitline information representing the motion vector to be selected from among the motion vectors of the previously decoded group used, the difference specified by the information representing the image display order. 20. Video decoding process for decoding bitlines, which are created by encoding image data corresponding to the images being used to make the video. The video decoding process consists of: a decoding step for decoding the current image by inter-image prediction using a previously decoded image as a reference image; a decoding step when the current image is a group image, which is decoded by inter-image prediction using a paired prediction using a previously decoded image as the first and second reference images; and the current group A is decoded directly, where the motion compensation of the current group A is performed using the motion vector of the current group A derived from the motion vector of the previously encoded group. The motion vector for the motion compensation of the current group A is obtained by subdividing the first motion vector if the group B, which is placed in the second reference image, is decoded using at least the first motion vector dependent on the first reference image, and subdividing the second motion vector if the group B is decoded using only the second motion vector dependent on the second reference image, using the difference specified by the information representing the display order of the images. 21. A video decoding procedure under any of the claims 15 through 20 in which, in the decoding step, when the current group A is decoded by inter-image prediction with paired or direct reference predictions, only the first motion vector dependent on the first reference image is stored. 22. The video decoding procedure under any of the claims of Articles 14 through 21 where the first reference image is identified by the first reference index for the identification of the reference image and the second reference image is identified by the second reference index for the identification of the reference image. 23. Video encoding devices are used to encode image data corresponding to the images being used to create a video and generate bit strings. A video encoding device consists of: an encoding unit capable of encoding the current image as part of Image I, Image P, and Image B; Image I containing only the groups encoded within the image; Image P containing the groups encoded with inter-image prediction using a single prediction reference that uses the previously encoded image as the first reference image; and Image B containing the groups encoded with inter-image prediction using a double prediction reference that uses the previously encoded image as the first and second reference images. The encoding unit includes a control unit capable of determining the encoding order, which differs from the display order for the adjacent Image B placed between Image I and Image P. 24. Video encoding equipment is used to encode image data corresponding to the images being used to create video and generate bit strings. The video encoding equipment consists of: an encoding unit capable of encoding the current image B, which contains groups encoding predictions between images using a prediction reference pair that uses the previously encoded image as the first and second reference images. This is where the current group A in the current image B is encoded directly, where the motion compensation of the current group A is made using the motion vector of the current group A derived from the motion vector of the previously encoded group. An encoding unit that obtains the motion vector for the motion compensation of the current group A by subdividing the first motion vector based on the first reference image of group B placed together in the second reference image, using the differences identified by the information representing the display order of the images. 25. Video encoding equipment is used to encode image data corresponding to the images being used to create video and generate bit strings. The video encoding equipment consists of: an encoding unit capable of encoding the current image B, which contains groups encoding predictions between images using a prediction reference pair that uses the previously encoded image as the first and second reference images. This is where the current group A in the current image B is encoded directly, where the motion compensation of the current group A is made using the motion vector of the current group A derived from the motion vector of the previously encoded group. An encoding unit that obtains the motion vector for the motion compensation of the current group A by subdividing the second motion vector by taking the second reference image of the group B placed together in the second reference image, using the differences identified by the information representing the display order of the images. 26. Video encoding devices are used to encode image data corresponding to the images being used to create video and generate bit strings. A video encoding device consists of: an encoding unit capable of encoding the current image B, which contains groups encoding predictions between images using a prediction reference pair that uses the previously encoded image as the first and second reference images. This is where the current group A in the current image B is encoded directly, where the motion compensation of the current group A is made using the motion vector of the current group A derived from the motion vector of the previously encoded group. If the group B placed together in the second reference image is previously encoded directly, the encoding unit obtains a motion vector for compensating the motion of the current group A. The motion vector, based on the first reference image, is mostly used for encoding group B in the second reference image, using the differences specified by the information representing the display order of the images. 27. Video encoding devices are used to encode image data corresponding to the images being used to create video and generate bit strings. A video encoding device consists of: an encoding unit capable of encoding the current image as one of image P and image B. Image P contains groups encoded using a single-reference inter-image prediction encoding method, using the previously encoded image as the first reference image, and image B contains groups encoded using a double-reference inter-image prediction encoding method, using the previously encoded image as the first and second reference images. This is where the current group A in current image B is encoded directly, where the movement compensation of current group A is made using the movement vector of current group A derived from the movement vector of the previously encoded group. The encoding unit obtains the movement vector for the movement compensation of current group A by subdividing the first movement vector, which depends on the first reference image of the group B placed in the later-arriving image P, time-dependent on the difference specified by the information representing the image display order. 28. Video encoding devices are used to encode image data corresponding to the images being used to create video and generate bit strings. A video encoding device consists of: an encoding unit capable of encoding the current image B into an image B containing groups that are encoded predictively between images using a prediction reference pair that uses the previously encoded image as the first and second reference images. This is where the current group A in the current image B is encoded directly, where the motion compensation of the current group A is made using the motion vector of the current group A derived from the motion vector of the previously encoded group. The encoding unit performs the motion compensation using the derived motion vector by subdividing the selected motion vector from among the motion vectors of the previously encoded group using the differences identified by the information representing the image display order and adding the information identifying the selected motion vector to the bit string. 29. A video decoding device is responsible for decoding bitlines, which are created by encoding image data corresponding to the video image. A video decoding device consists of: a decoding unit capable of decoding the current image by inter-image prediction using previously decoded images as reference images; a reference pair using the previously decoded image as the first and second reference images; and a bitline decoding unit containing at least the images temporally closest to the current image in the display sequence as the first and second reference images. 30. A video decoding device is used to decode bitlines created by encoding image data corresponding to the video image. The video decoding device consists of: a decoding unit capable of decoding the current image by inter-image prediction using a previously decoded image as a reference image; where the current image is a group image decoded by inter-image prediction using a pair of prediction references that use the previously decoded image as the first reference image and the second reference image, and the current group A is decoded directly, where motion compensation for the current group A is performed using the motion vector of the current group A derived from the motion vector of the previously decoded group. The decoding unit obtains the motion vector for motion compensation of the current group A by subdividing the first motion vector based on the first reference image of the group B in the second reference image used, the difference identified by the information representing the display order of the images. 31. A video decoding device is used to decode bitlines created by encoding image data corresponding to the video image. The video decoding device consists of: a decoding unit capable of decoding the current image by prediction between images using the previously decoded image as a reference image, where the current image is a group image that is decoded by prediction between images. Based on paired predictions using the previously decoded image as the first reference image and the second reference image, the current group A is decoded directly, where motion compensation for the current group A is performed using the motion vector of the current group A derived from the motion vector of the previously decoded group. The decoding unit obtains the motion vector for motion compensation of the current group A by subdividing the second motion vector based on the second reference image of the co-located group B. In the second reference image, the difference specified by the information representing the display order of the images is used. 32. Video decoding devices are used to decode bitlines created by encoding image data corresponding to the video image. A video decoding device consists of: a decoding unit capable of decoding the current image by inter-image prediction using a previously decoded image as a reference image. This occurs when the current image is a group image decoded by inter-image prediction using a pair of predictions that uses the previously decoded image as the first reference image and the second reference image, and the current group A is decoded directly, where motion compensation for the current group A is made by placing the motion vector of the current group A derived from the motion vector of the previously decoded group. If the co-decoded group B in the second reference image is previously decoded directly, the decoding unit obtains a motion vector for motion compensation of the current group A by dividing the first motion vector based on the first reference image. This is mostly used for decoding group B in the second reference image using the difference specified by the information representing the display order of the images. 33. Video decoding devices are used to decode bitlines created by encoding image data corresponding to the video image. A video decoding device consists of: a decoding unit capable of decoding the current image by inter-image prediction using a previously decoded image as a reference image; where the current image is a group image decoded by inter-image prediction using a pair of prediction references, with the previously decoded image as the first and second reference images, and the current group A is decoded directly, where motion compensation for the current group A is made using the motion vector of the current group A derived from the motion vector of the previously decoded group. The decoding unit obtains the motion vector for motion compensation of the current group A by subdividing the first motion vector based on the first reference image of the co-laid group B in the subsequent image in a time-dependent manner, using the difference identified by the information representing the display order of the images. The subsequent image is decoded by inter-image prediction using a single prediction reference, with the previously decoded image as the first reference image. 34. Video decoding devices are used to decode bitlines created by encoding image data corresponding to the video image. A video decoding device consists of: a decoding unit capable of decoding the current image by prediction between images using a previously decoded image as a reference image; where the current image is a group image decoded by prediction between images using a pair of prediction references that use the previously decoded image as the first reference image and the second reference image, and the current group A is decoded directly, where motion compensation for the current group A is performed using the motion vector of the current group A derived from the motion vector of the previously decoded group. The decoding unit obtains the motion vector for motion compensation of the current group A by subdividing the motion vector based on the information obtained from the bitline specifying the motion vector to be selected from among the motion vectors of the previously decoded group, using the difference specified by the information representing the display order of the images. 35. A recording medium for storing bit strings created by encoding image data corresponding to a video image, where the bit strings are encoded using a video encoding process as provided by one of the claims 1 through 13.