MXPA05011869A - Forward trick modes on progressive video using special groups of pictures - Google Patents

Abstract

The invention concerns a method (200) and system (100) for encoding a video signal. The method includes the steps of receiving (212) a progressive video signal and encoding (214) the progressive video signal into at least one group of pictures having at least one prediction source picture and at least one non-prediction source picture. All the non-prediction source pictures are predicted from the prediction source picture such that no non-prediction source picture is predicted from another non-prediction source picture. The method can also include the step of, in response to a forward trick mode command, modifying (217, 218) at least the number of non-prediction source pictures in the group of pictures to convert the progressive video signal to a trick mode video signal.

Description

European (AT, BE, BG, CH, CY, CZ, DE, DK, EE, ES, Fl, For two-letter codes and other abbreviations.) Refer to the "Guid- FR, GB, GR, HU, IE, IT , LU, MC, NL, PL, PT, RO, SE, YES, anee Notes on Codes and Abbreviations "appearing at the begin- SK, TR), OAPI (BF, BJ, CF, CG, Cl, CM, GA, GN , GQ, no ofeach regular issue of the PCT Gazette, GW, ML, MR, NE, SN, TD, TG). Published: - without iniemational search report and what is republished upon receipt ofthat repon TRUCKED PROGRESS MODES IN PROGRESSIVE VIDEO USING SPECIAL IMAGE GROUPS BACKGROUND OF THE INVENTION 1 . Technical Field The inventive arrangements refer, in general, to video systems, and more particularly to video systems that record or reproduce digitally encoded video sequences. 2. Description of Related Art Devices that facilitate video playback are gaining popularity in the consumer electronics market to date. For example, many consumers have purchased digital video disc players (DVDs) for the purposes of watching pre-recorded programs or recording their favorite programs. A DVD player or recorder typically contains a Motion Picture Expert Group (MPEG) decoder to decode the digitally encoded multimedia data that is stored on the discs that play the recorder or the player. The MPEG video signal to be decoded is comprised of a plurality of groups of images (GOP), each of which typically contains an intra (I) image, a plurality of predictive images (P) and a plurality of bidirectional predictive images. (B) During the reproduction of a video signal, some viewers may wish to develop certain gimmicked modes. A trick mode can be any video playback in which playback is not done at a normal speed or in a forward direction. As an example, a fast-forward trick mode can be started to allow the viewer to move through the video parts faster. To perform a fast-forward trick mode on an MPEG video signal, the DVD decoder may skip a number of images on each GOP of the video signal. The faster the trick mode, the more images in each GOP need to be skipped. Generally, B images are skipped first in successive GOPs until none of them remains, followed by P images until they are also depleted. With respect to the P images, it is necessary to first skip the P image at the end of the GOP (typically it is the last image in order of display in a GOP) followed by the immediately preceding P image in order of display. This process can continue in such a way that the image P to be skipped is the last P image in the GOP (in order of display) until there are no P. images. If desired, image 1 can also be skipped, at which point all the GOP is skipped. The principle behind this particular algorithm, in which the B images are skipped first and the P images are skipped after considering their display order, is based on the prediction schemes employed in a typical GOP. Specifically, B images are not used to predict other images, and it is useful to jump them for moderate or lower acceleration. In contrast, image I is used, both directly and indirectly, to predict all other images in the GOP; if this is the only I image in the GOP, it must be retained if any of the other images in the GOP are not skipped. If the image I were to skip without skipping any of the other images, it would be impossible to accurately predict any of the remaining images. Similarly, the P images are used to predict the other P images and the jump of a different P image to the currently last P image in the GOP would adversely affect the display of any image that follows the order of display to the P figure. jumped Although acceptable, the algorithm described above requires programming of the additional microprocessor to adjust to the particular order in which the images are skipped. In addition, this jump algorithm does not allow images to be skipped to produce optimal reproduction. For example, if a viewer wanted to play a video at twice the normal playback speed, the most desirable way to skip the images in the video would be to skip all other images. However, in a typical GOP structure, it is not possible to skip the images in this manner due to the limitations described above.

BRIEF DESCRIPTION OF THE INVENTION The present invention relates to a method for encoding a digital video signal. The method can include the steps of receiving a progressive video signal and encoding the progressive video signal in at least one group of images having at least one prediction source image and at least one non-prediction source image. All non-prediction source images are predicted from the prediction source image such that no source image of non-prediction is predicted from another source image of non-prediction. In addition, the method may include the steps of recording the progressive video signal in a storage medium and reproducing the progressive video signal. The method may also include the step of, in response to an advance trick mode command, modifying at least the number of non-prediction source images in the image group to convert the progressive video signal into a video signal in a manner tricked In one arrangement, the prediction source image may be an intra image. In addition, at least a part of the non-prediction source images may be predictive images or bidirectional predictive images. As an example, each of the bi-directional predictive images can be unidirectional bidirectional predictive images. In one aspect of the invention, the modification step may include the step of skipping at least one non-prediction source image in the image group to convert the progressive video signal into a trick-mode video signal. Alternatively, the modification step may include the step of inserting in the image group a duplicate of at least one non-prediction source image to convert the progressive video signal into a trick-mode video signal. In another aspect, the skipped non-predicted source image may be a predictive image being the last image in order of display in the group of images. In addition, the method may further include the step of converting a source image of previous immediate prediction, in the order of display in the group of images, to a predictive image unless the source image of previous non-prediction is a predictive image. . In another arrangement, each of the prediction source images and the non-prediction source images may contain a display indicator, and the method may further include the step of modifying the display indicator of at least a portion of the source images of prediction and source images of non-prediction to reflect a projected exhibition order. As an example, the display indicator can be a temporary reference field. The present invention also relates to a system for encoding a digital video signal. The system includes a processor for encoding a progressive video signal in at least one group of images having at least one prediction source image and at least one non-prediction source image. All non-prediction source images are predicted from the prediction source image such that no source image of non-prediction is predicted from another source image of non-prediction. In addition, the system includes a decoder to decode the progressive video signal. The system also includes the appropriate software and electronic circuit to implement the methods described above.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 A is a block diagram of a system that can encode a video signal in special GOPs and develop a trick mode of advanced motion, according to the inventive provisions. FIG. 1B is a block diagram of another system that can encode a video signal in special GOPs and develop a sophisticated motion-coupled mode, according to the inventive provisions. FIG. 2 is a flow diagram illustrating a method for encoding a video signal in special GOPs and developing an advanced motion trick mode used in accordance with the inventive arrangements. FIG. 3 illustrates an example of a special GOP, according to the inventive provisions. Fig. 4A illustrates an example of skipping images in the special GOP of FIG. 3, according to the inventive provisions. FIG. 4B illustrates an example of inserting duplicate images into the special GOP of FIG. 3, according to the inventive provisions. FIG. 4C illustrates another example of skipping images in the special GOP of FIG. 3, according to the inventive provisions. FIG. 4D illustrates yet another example of skipping images in the special GOP of FIG. 3 and the modification of the display indicators of any of the remaining images, in accordance with the inventive provisions.

DETAILED DESCRIPTION OF THE PREFERRED MODALITIES A system 100 is shown in the form of a block diagram in FIG. 1A to implement the different characteristics of advanced operation according to the inventive provisions. However, the invention is not limited to the particular system illustrated in the F1G. 1A, since the invention can be practiced with any other system capable of receiving a video signal, processing the signal and emitting the signal to any convenient component, such as a deployment device. In addition, the system 100 is not limited to reading data from or writing data to any particular type of storage medium, since with the system 100 any storage means capable of storing digitally encoded data can be used. The system 100 may include an encoder 1 10 for encoding an incoming video signal, and a microprocessor 112 for instructing the encoder 1 10 to encode the video signal according to different techniques, some of which will be explained later. All or parts of the encoder 1 10 and the microprocessor 1 12 can be considered as a processor 1 14 within the perspective of the present invention. The encoder 1 1 0 can be located in the same apparatus as the microprocessor 1 12 or, alternatively, it can be placed in a device that is remote from the apparatus housing the microprocessor 1 12. If the encoder 1 10 is remotely located, the encoder 1 10 is not necessarily under the control of the microprocessor 1 12. The system 1 10 may also include a controller 1 16 for reading data from and writing data to a storage medium 1 18. For example, the data may be a digitally encoded video signal. The system 100 may also have a decoder 120 for decoding the encoded video signal when it is read from the storage means 1 18 and transferring the decoded video signal to a convenient component, such as a display device. The decoder 120 can be mounted in the same apparatus that contains the encoder 1 10 (if the encoder 1 10 is not remotely located), the microprocessor 1 12 and the controller 1 16 or, as will be described below, can be mounted in a separate device. Control and data interfaces can also be provided to allow the microprocessor 1 12 to control the operation of the encoder 1 1 0 (as noted above), the controller 1 16 and the decoder 120. Suitable software or firmware can be provided in the memory for conventional operations performed by the microprocessor 1 12. In addition, program routines can be provided for the microprocessor 1 12, according to the inventive arrangements. In operation, the encoder 1 1 0 can receive and encode an incoming progressive video signal. As is known in the art, this type of video signal is comprised of images that have been progressively explored. In accordance with the inventive arrangements, the microprocessor 1 12 can instruct the encoder 1 10 to encode the incoming video signal into one or more GOPs that are particularly useful for developing tapped modes. Examples of such GOPs will be presented below. The encoder 1 10 can then transfer the encoded video signal to the controller 1 16, which can record the signal in the storage medium 1 18. In the case where the encoder 1 1 0 is remotely located, the encoder 1 10 can encoding the incoming non-progressive video signal, but the encoding instructions are not necessarily received from the microprocessor 1 12. If the microprocessor 1 12 receives a playback command, the microprocessor 1 12 can instruct the controller 1 16 to read the signal from encoded video of the storage medium 1 18. The controller 1 18 can transfer the signal to the microprocessor 1 12, which can send the signal to the decoder 120. The decoder 120 can decode the video signal and emit the signal for display in a convenient device. If the microprocessor 1 12 receives a trick-mode command, the microprocessor 1 12 can skip images in the GOPs or repeat the images of the GOPs. As alluded to above, there may be some examples in which the decoder 120 performing the decoding step is located in a device separate from the apparatus containing the microprocessor 1 12. An example of such an arrangement is illustrated in FIG. 1B in which the decoder 120 is in a deployment device 122, separated from a multimedia device 124 that can house the microprocessor 1 12. In this case, the decoder 120 may not be under the control of the microprocessor 1 12. A Such system can be referred to as a remote decoder system. However, trick modes can still be developed in this system 100, in which the microprocessor 1 12 can suppress images or insert duplicates of the images in the video signal before being decoded by the decoder 120 in the deployment device 122. It is understood that the 1 1 0 encoder in this type of system can be remotely located as well. In any of the provisions discussed in relation to FIGS. 1 A and 1 B, the GOPs created during the coding process will facilitate the effective implementation of a trickle-forward mode. The total operation of the invention will be discussed in detail below.

With reference to FIG. 2, a method 200 is illustrated which shows a way to develop a trick mode in a progressive video signal using special GOPs. The method 200 can be practiced in any convenient system capable of encoding and decoding a video signal. The method 200 may begin, as shown in step 210. In step 212, a progressive video signal may be received. As noted above, a progressive video signal contains images that have been progressively scanned. As shown in step 214, the progressive video signal may be encoded in at least one GOP having at least one prediction source image and at least one non-prediction source image. In one arrangement, all non-prediction source images can be predicted from the prediction source image, such that no source image of non-prediction is predicted from another source image of non-prediction. Referring to the F1G. 3, an example of such a process is shown. In this particular arrangement, the video signal can be encoded in one or more GOPs 300. The GOPs 300 are displayed in order of display. Each of the GOPs 300 may include at least one prediction source image 310 and at least one non-prediction source image 312. A prediction source image is an image in a GOP that is not predicted from another image, however, it is You can use it to predict other images in the GOP. In addition, a non-prediction source image can be any image in a GOP that can be predicted from a prediction source image in that GOP. As an example, the prediction source image 310 can be an I image, and the non-prediction source images 312 can be B and / or P images. Each of the non-prediction source images 312 can be predicted from the source image. prediction 310, which in this example is correlated with each of the B and P images that are predicted from the I image. Because the P images can serve as non-prediction source images 312, it should be evident that a source image of no prediction 312 is not limited to images from which other images can not always be predicted, such as images B. However, according to the inventive provisions, each of the source images of non-prediction 312 can be predicted from the 310 prediction source image only. In one arrangement, the B images can be unidirectional prediction images, such that the B images prior to, or in front of, the image 1 (in order of display) can be predicted backward of the I image, and the B images behind the image I (in order of display) can be predicted forward of the image 1. The numbers subscripts incorporated in the prediction source images 310 and the source images of non-prediction 312 can indicate the order in which they will display each of these images - in relation to the other images in the GOP - at a normal playback speed. As noted above, the GOP 300 is displayed in order of display. The order of transmission is slightly different in that the prediction source image 310, in this example, image 13, can first be transmitted to a decoder followed by the non-prediction source images 312 to be predicted from the prediction source image 310. It is important to note that the invention is not limited in any way to these particular GOPs 300, since they merely represent an example of a GOP structure in accordance with the inventive arrangements. In fact, any GOP in which all source images of non-prediction in the GOP can be predicted from a source prediction image in that GOP, is within the perspective of the inventive provisions. In addition, although only two GOPs 300 are shown in FIG. 3 in which each GOP 300 has a prediction source image 310 and six source images of non-prediction 312, it is understood that the received video signal can be encoded at any convenient number of GOPs 300 having any convenient number of prediction source images 310 and non-prediction source images 312. Also, if more than one prediction source image 310 is in the GOP 300, any B image in the GOP 300 can be predicted bi-directionally. As an example, more than one prediction source image 310 can be placed in the GOP 300 and some of the non-prediction source images 312 can be predicted from these prediction source images 310. As such, the prediction source images 31 0 can be transmitted to a decoder before the non-prediction source images 312 that are dependent on these prediction source images 310 for prediction. Referring again to method 200, in step 215, the progressive video signal containing the GOPs can be recorded in a convenient storage medium. Once recorded, the progressive video signal containing the GOPs can be played, as shown in step 216. In decision block 217 it can be determined whether the number of source images of non-prediction in the GOPs are to be modified. As an example, the modification may be developed in response to a trick-forward mode order, such as advanced fast or slow advanced. If modification is not going to occur, method 200 may continue in step 216. If so, then such a process may be developed in step 218. The operation conducted in step 218 may convert the progressive video signal to a signal of video in trick mode. Several examples are shown in FIGS. 4A-4D. With reference to FIG. 4A, each of the GOPs 300, as illustrated first in FIG. 3, it is shown with several 312 non-predicted source images removed or skipped. Specifically, the B0, B2, B and P6 images in the GOP 300 on the left can be skipped, while the Bi, B4 and Pe images in the GOP 300 on the right can be skipped. Skipping of such non-prediction source images 312 may cause the reproduction rate to increase. Here, the number of non-predicted 312 source images skipped, half of all the images in the two GOPs 300, is correlated with a playback speed that is twice the normal playback speed, or 2X (1X represents playback speed normal). According to the inventive arrangements, any one of the non-prediction source images 312 in the GOPs 300 can be skipped to increase the reproduction speed of the video signal without affecting the prediction of any remaining non-prediction source image 312 in GOPs 300. This feature is made possible through the coding process described above. A step to place the 300 GOPs according to the standard MPEG, for example, will be discussed later. Of course, it is understood that the invention is not limited to the example described in relation to FIG. 4A, since the ability to skip all non-prediction source images 312 applies to any other GOP in which the non-prediction source images 312 are predicted from a prediction source image 310. Also, all of the GOP 300 can be skipped to produce faster playback. Referring again to FIG. 2, the modification step 21 8 may also include the step of inserting into the GOP 300 a duplicate of at least one prediction source image 310 or non-prediction source image 312 to convert the progressive video signal into a video signal of faked mode. An example of such an operation is shown in the F1G. 4B. Here, a duplicate of each prediction source image 310 and non-prediction source image 312 can be inserted into the GOP 300 (for convenience, only one GOP 300 of FIG 3 is shown). This particular example can produce a reproduction speed of Y? X. The letter subscript "d" represents the image to which it is associated as a duplicate of the preceding immediate image. Similar to 312 original non-prediction source images, duplicates of such images can be predicted from a prediction source image 310 (according to the standard MPEG, the last image in the GOP 300, the duplicate image P6d, can be predicted from the immediately preceding image P, which in this case is image P6). In addition, the original non-prediction images 312 and their duplicates can be predicted from the duplicate of a prediction source image 310. The example presented in FIG. 4B is explained as follows: all non-prediction source images 312 and their duplicates opposite (in order of display) of the original prediction source image 310, or l3 image, can be predicted from the I3 image. Additionally, the original non-prediction source images 312 and their duplicates behind the duplicate (in order of display) of the original prediction source image 310, or l3c_ image, can be predicted from the duplicated image l3d (with the exception of the duplicate image). P6d) - However, it is understood that this particular arrangement is merely an example, since the non-prediction source images 312 and their duplicates can be predicted from any other convenient prediction source image 310, including any duplicate of a source image of prediction 310. In another arrangement, one or more of the duplicate images inserted in the GOP 300 may be fictitious B or fictitious P images. A fictitious image B or fictional P is a B or P image, respectively, in which the motion vectors of the fictitious image are set to zero and their residual signal is set to zero or not encoded. For example, the duplicate of the prediction source image 310 (image 13) in the GOP 300 may be a fictitious image P instead of another image l, such as the image l3d. Similarly, the duplicate for the last non-prediction image 312 (image P6) can be a fictitious image P instead of a conventional image P, such as the image P6d- By using fictional B or P images during a trick mode it can decrease the bit rate of the video signal, which may be necessary in certain circumstances. Referring again to FIG. 2, in decision block 220, it can be determined if the last source image of non-prediction in the GOP has been skipped. Otherwise, method 200 may continue in decision block 226 through hop circle A. If yes, it may be determined in decision block 222 whether the source image of previous immediate non-prediction in order of display in the GOP , is a picture P. If so, method 200 may continue in decision block 226 through jump circle A. If it is not, then the source image of no previous immediate prediction in the GOP may be converted to an image P, as shown in step 224. An example of this operation is illustrated in the F1G. 4C. The MPEG video specifications require that the last image in a GOP be a P image or an I image. Therefore, if the P6 image in the GOP 300, a non-predicted source image 312, was skipped during a trick mode, the The last image on the GOP 300 (if it is not skipped) would be the B5 image, a standard MPEG violation. To satisfy the MPEG requirement, the previous immediate non-prediction source image 312, in this case, image B5, can be converted to an image P, or image P5. An image B can be converted to an image P by setting the following parameters for the values of the image P located in the image of the header of image B: coding_type_image; vector_to_back_full_plete; and back_code_f. Additionally, the following variable length codes can be set for macro_type! Oque for the values of the image P: cant_macroblock; forward_macrobmovement_macrob! Oque; backward_macroblock movement; macroblock pattern; intra_macroblock; temporary_space_weight_code_flag; and permissible temporal_heavy_classes. This process can instruct a decoder to decode the image as an image P. As such, according to the inventive provisions, the last image in a GOP 300 can be skipped without violating the MPEG requirement that the last image in a GOP be an image P. As another example, referring to FIG. 4A, the image B5 in both GOPs 300, can be converted into a P image to conform to the standard MPEG. Referring again to method 200 of FIG. 2, the prediction source images and the non-prediction source images may contain an exhibition indicator. As determined in decision block 226 of hop circle A, if the display indicators of these images are not to be modified, then such a process may be developed in step 228. Remarkably, modifying these display indicators may reflect a Projected display order of source prediction images and source images of non-prediction when any of these images is skipped or duplicated. If the display indicators are not to be modified, then method 200 may be stopped at step 230. In one arrangement, the display indicator may be a temporary reference field. A temporal reference field is typically a ten-bit field located in the image header of digitally encoded images. Some decoders depend on the temporal reference field to determine when a particular image in a video signal will be displayed in relation to other images in the video signal. This field normally has an integer value.

As an example, referring again to FIG. 3, each GOP 300 contains seven images. The sub-index numbers for the images in each GOP 300 may correspond to the integer values for each time reference field of the respective image. For example, the time reference field of the first non-prediction source image 312, or image B0, may have an integer value of zero, which indicates that this particular image will be the first in each GOP 300 to be displayed. The temporal reference field of the B-i image, the next image to be displayed, may have an integer value of one. Therefore, the integer value of the time reference field for each subsequent image to be displayed may be larger by one, up to the image P6, whose temporal reference field may have an integer value of 6. For convenience, the phrase "value whole of the temporal reference field "can also be referred to as" whole value ". When, for example, a source image of non-prediction 312 is skipped, however, the order of display according to the original temporary reference fields is no longer valid. Accordingly, the integer value of the temporal reference fields of the prediction source images 310 and the non-prediction source images 312 that follow the skipped image can be modified to indicate an appropriate display order. This feature is also applicable if the duplicates of the 31 0 prediction source images or the non-prediction source images 312 are inserted into the GOP 300.

As an example, if the image B. in the GOP 300 on the right it is skipped, then the integer values of the prediction source images 31 0 and the non-prediction source images 312 that follow this image can be decreased by a value of one. Therefore, the integer value of the temporal reference field of the image B2 can be modified from two to one, the integer value of the temporal reference field of the image l3 can be modified from three to two, and so on. This modification process can continue until the end of the GOP 300 is reached and can ensure that the remaining images in the GOP 300 will be displayed in an appropriate order. Therefore, each time a prediction source image 310 or a non-prediction source image 312 in a GOP is skipped, the integer values of the temporal reference fields of the remaining images in that GOP following the skipped image are they can decrease by a value of one. The final result is illustrated in the F1G. 4D, where the new integer values are shown, the skipped image B-? it is represented by a striped outline and the previous integer values are in parentheses. In a similar manner, whenever a duplicate of a prediction source image 310 or a non-prediction source image 312 is inserted into a GOP 300, the integer values of the images following the inserted duplicates may be increased by a value of one. It is understood that the invention is not limited to these particular examples, since other forms may be developed, in any other convenient way, to modify the integer values of the relevant temporal reference fields to reflect a projected display order. Furthermore, it should be noted that the invention is not limited to the use of a temporary reference field, since any other convenient display indicator may be modified to reflect a projected display order in any of the modes discussed above. Referring again to FIG. 2, the method 200 can be stopped in step 230. Although the present invention has been described in conjunction with the embodiments described herein, it is to be understood that the aforementioned description is intended to illustrate and not limit the scope of the invention as it is defined through the claims.

Claims (24)

1. CLAIMS 1. A method for encoding a digital video signal, comprising the steps of: receiving a progressive video signal; and, encoding the progressive video signal in at least one group of images having at least one prediction source image and at least one non-prediction source image, wherein all non-prediction source images are predicted from the source image of prediction in such a way that no source image of non-prediction is predicted from another source image of non-prediction. The method according to claim 1, further comprising the steps of: recording the progressive video signal in a storage medium; and, play the progressive video signal. The method according to claim 1, further comprising the step of, in response to a trick-forward mode command, modifying at least the number of non-prediction source images in the group of images to convert the video signal progressive in a trick-mode video signal. 4. The method according to claim 1, characterized in that the prediction source image is an intra image. The method according to claim 1, characterized in that at least a part of the non-prediction source images are bidirectional predictive images. 6. The method according to claim 1, characterized in that at least a part of the non-prediction source images are predictive images. The method according to claim 5, characterized in that each of the bi-directional predictive images is a bidirectional unidirectional predictive image. The method according to claim 3, characterized in that said step of modifying comprises the step of skipping at least one source image of non-prediction in the group of images to convert the progressive video signal into a video signal in a faked fashion . The method according to claim 3, characterized in that said modification step comprises the step of inserting in the image group a duplicate of at least one non-prediction source image to convert the progressive video signal into a video signal in a tricked way The method according to claim 8, characterized in that the source image of skipped prediction is a predictive image that is the last image in order of display in the group of images, and wherein said method further comprises the step of converting. a source image of no previous immediate prediction in order of display in the group of images, in a predictive image unless the source image of no previous immediate prediction is a predictive image. eleven . The method according to claim 3, characterized in that each of the prediction source images and the non-prediction source images contain an exhibition indicator and the method further comprises the step of modifying the display indicator of at least a portion of the prediction source images and the non-prediction source images to reflect a projected exhibition order. The method according to claim 1, characterized in that the display indicator is a temporary reference field. 13. A system for encoding a progressive video signal, comprising: a processor for encoding a progressive video signal in at least one group of images having at least one prediction source image and at least one non-prediction source image, where all the non-prediction source images are predicted from the prediction source image such that no source image of non-prediction is predicted from another source image of non-prediction; and, a decoder to decode the group of images. The system according to claim 13, further comprising a controller for recording the progressive video signal in a storage medium and reproducing the progressive video signal. 15. The system according to claim 13, characterized in that the processor is further programmed to, in response to an advance trick mode command, modify at least the number of non-prediction source images in the image group to convert the progressive video signal into a video signal of faked mode. 16. The system according to claim 13, characterized in that the prediction source image is an intra image. The system according to claim 13, characterized in that at least a part of the non-prediction source images are bidirectional predictive images. 18. The system according to claim 13, characterized in that at least a part of the non-prediction source images are predictive images. 19. The system according to claim 17, characterized in that each of the bidirectional predictive images is a bidirectional unidirectional predictive image. The system according to claim 15, characterized in that the processor is further programmed to skip at least one non-prediction source image in the group of images to convert the progressive video signal into a trick-mode video signal. twenty-one . The system according to claim 15, characterized in that the processor is further programmed to insert in the group of images a duplicate of at least one non-prediction source image for converting the progressive video signal into a trick-mode video signal. 22. The system according to claim 20, characterized in that the source image of skipped prediction is a predictive image that is the last image in order of display in the group of images, and wherein the processor is also programmed to convert a source image of no previous immediate prediction in order of display in the group of images, in a predictive image unless the source image of no previous immediate prediction is a predictive image. The system according to claim 15, characterized in that each of the prediction source images and the non-prediction source images contain an exhibit indicator and the processor is further programmed to modify the display indicator of at least a part of the prediction source images and the non-prediction source images to reflect a projected exhibition order. 24. The system according to claim 23, characterized in that the display indicator is a temporary reference field.