US20030159152A1 - Fast motion trick mode using dummy bidirectional predictive pictures - Google Patents

Abstract

The invention concerns a method (200or300) and system (100) for performing a trick mode operation on a video signal containing a plurality of progressively scanned original pictures. The method (200) includes the step of selectively skipping (214) at least one of the original pictures to convert the video signal to a trick mode video signal in response to a trick mode command and the step of selectively inserting (216) at least one dummy bidirectional predictive picture in the trick mode video signal. In addition, the method (300) can include the step of monitoring (316) the trick mode video signal so that the dummy bidirectional predictive picture is selectively inserted when the bit rate exceeds a predetermined threshold. Display indicators of certain pictures in the trick mode video signal can also be modified (226) (328) to reflect an intended display order.

Description

CROSS REFERENCE TO RELATED APPLICATIONS
• This is a non-provisional application of provisional application serial No. 60/334,914 filed Oct. 23, 2001.[0001]
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
• (Not Applicable)[0002]
BACKGROUND OF THE INVENTION
• 1. Technical Field[0003]
• The inventive arrangements relate generally to video systems and more particularly to video systems that record or play back digitally encoded video sequences.[0004]
• 2. Description of Related Art[0005]
• Digital televisions (DTV) and high-definition televisions (HDTV) are gaining popularity in today's consumer electronics marketplace. Many purchasers of these types of televisions also buy digital video recorders or players, such as digital video disc (DVD) recorders or players, for purposes of viewing previously recorded programs or recording their favorite programs. Notably, the combination of a DTV (or an HDTV) and a digital video recorder or player can be an integral part of a home theater entertainment system.[0006]
• A digital video recorder or player typically contains a Moving Pictures Expert Group (MPEG) decoder to decode the digitally encoded multimedia data that is stored on the discs that the recorder or player plays. If the digital video recorder or player is connected to a conventional (non-DTV or non-HDTV) television, the digitally encoded signal will be decoded by the digital video recorder or player's MPEG decoder before being displayed on the conventional television. Significantly, however, many DTVs contain their own MPEG decoders. As such, if a digital video recorder or player is connected to a DTV, the video signal read from the disc is remotely decoded by the DTVs decoder. This configuration can be referred to as a remote decoder arrangement.[0007]
• There is, however, an important disadvantage in decoding digitally encoded signals with a remote DTV decoder. Namely, it is very difficult to perform trick modes in this type of arrangement. A trick mode can be any playback of video in which the playback is not done at normal speed or in a forward direction. Oftentimes, a trick mode involves skipping a number of pictures in a video signal such as during a fast motion trick mode. Skipping pictures in a video signal being transmitted to a remote decoder can actually increase the average bit rate of the signal. As the bandwidth between the digital video recorder or player and the DTV is limited, performing a fast motion trick mode may cause the signal to exceed the maximum bit rate limit of the transmission channel.[0008]
• For instance, in an MPEG video signal, there are three separate types of digitally encoded pictures: intra (I) pictures, predictive (P) pictures and bidirectional predictive (B) pictures. As is known in the art, I and P pictures contain relatively large amounts of encoded data, at least with respect to B pictures. During a fast motion trick mode, the first pictures in a group of pictures (GOP) to be skipped are typically the B pictures. As the B pictures are skipped, however, the average amount of encoded data for the remaining pictures, or the average number of bits per picture, in the GOP increases. Such a drawback can lead to buffer overflow and the loss of pictures during the display of the trick mode video signal. Thus, a need exists for a method and system for performing a fast motion trick mode in a remote decoder arrangement without exceeding a maximum bit rate limit and without increasing system costs or complexity.[0009]
SUMMARY OF THE INVENTION
• The present invention concerns a method of performing a trick mode on a video signal containing a plurality of progressively scanned original pictures. The method includes the steps of selectively skipping at least one of the original pictures to convert the video signal to a trick mode video signal in response to a trick mode command and selectively inserting at least one dummy bidirectional predictive picture in the trick mode video signal. The method can also include the steps of monitoring the trick mode video signal and selectively inserting at least one dummy bidirectional predictive picture in the trick mode video signal if the bit rate of the trick mode video signal exceeds a predetermined threshold.[0010]
• In one arrangement, each of the plurality of original pictures can contain a display indicator, and the method can further include the step of selectively modifying the display indicator of at least a portion of the plurality of original pictures to reflect an intended display order when an original picture is skipped or when a dummy bidirectional predictive picture is inserted in the trick mode video signal. The display indicator can be a temporal reference field.[0011]
• In addition, each temporal reference field can have an integer value, and the step of selectively modifying the temporal reference field of at least a portion of the plurality of original pictures can include the step of incrementally decreasing by one the integer value of the temporal reference field of the subsequent original pictures each time an original picture is skipped. Alternatively, the selectively modifying step can include the step of incrementally increasing by one the integer value of the temporal reference field of the subsequent original pictures each time a dummy bidirectional predictive picture is inserted in the trick mode video signal.[0012]
• In one arrangement, the dummy bidirectional predictive picture can be predicted from a reference picture. Also, each dummy bidirectional predictive picture can be a one-directional predictive picture. The reference picture can be an intra picture or a predictive picture. In another arrangement, at least a portion of the trick mode video signal can be decoded by a remote decoder, and the trick mode can be a fast motion trick mode. In another aspect, the method can further include the step of, following the insertion of at least one dummy bidirectional predictive picture, skipping at least one remaining original picture if the insertion of dummy bidirectional predictive pictures in the trick mode video signal causes a playback speed of the trick mode video signal to decrease to an unacceptable level.[0013]
• The invention also concerns a method of performing a trick mode on a video signal containing a plurality of progressively scanned original pictures in which each of the plurality of progressively scanned original pictures contains a display indicator. This method includes the steps of selectively skipping at least one of the original pictures to convert the video signal to a trick mode video signal in response to a trick mode command and selectively modifying the display indicator of at least a portion of the plurality of original pictures each time an original picture is skipped. In addition, at least a portion of the trick mode video signal in this embodiment can be decoded by a remote decoder.[0014]
• The present invention also concerns a system for performing a trick mode on a video signal containing a plurality of progressively scanned original pictures. The system includes a controller for reading data from a storage medium and outputting the video signal containing the plurality of original pictures and a video processor in which the processor is programmed to selectively skip at least one of the original pictures to convert the video signal to a trick mode video signal in response to a trick mode command and selectively insert at least one dummy bidirectional predictive picture in the trick mode video signal. The system also includes suitable software and circuitry to implement the methods as described above.[0015]
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a block diagram of a system that can perform a fast motion trick mode using dummy bidirectional predictive pictures in accordance with the inventive arrangements herein.[0016]
• FIG. 2 is a flow chart that illustrates an operation of performing a fast motion trick mode using dummy bidirectional predictive pictures in accordance with the inventive arrangements.[0017]
• FIG. 3 is a flow chart that illustrates an alternative operation of performing a fast motion trick mode using dummy bidirectional predictive pictures in accordance with the inventive arrangements.[0018]
• FIG. 4 illustrates a typical group of pictures structure in an MPEG video signal.[0019]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
• A[0020]system100 for implementing the various advanced operating features in accordance with the inventive arrangements is shown in block diagram form in FIG. 1. The invention, however, is not limited to the particular system illustrated in FIG. 1, as the invention can be practiced with any other system capable of receiving a digitally encoded signal and transferring that signal to a display device. In addition, thesystem100 is not limited to reading data from or writing data to any particular type of storage medium, as any storage medium capable of storing digitally encoded data can be used with thesystem100.
• The[0021]system100 can include acontroller110 for reading data from and writing data to astorage medium112. Thesystem100 can also have asearching engine114, amicroprocessor116, atransmission buffer117 and adisplay device118. Thesearching engine114 can contain suitable software and circuitry for locating one or more particular types of pictures in a video signal read from thestorage medium112. Control and data interfaces can also be provided for permitting themicroprocessor116 to control the operation of thecontroller110 and thesearching engine114. Suitable software or firmware can be provided in memory for the conventional operations performed by themicroprocessor116. Further, program routines can be provided for themicroprocessor116 in accordance with the inventive arrangements.
• It should be understood that all or portions of the[0022]searching engine114 and themicroprocessor116 can be avideo processor120 within contemplation of the present invention. Further, all or portions of thecontroller110, the searchingengine114, themicroprocessor116 and thetransmission buffer117 can be abitstream source122 within contemplation of the present invention. In one arrangement, thedisplay device118 can contain its own decoder (not pictured) for decoding all or a portion of any video signal read from thestorage medium112 and processed by thebitstream source122. In this particular arrangement, the decoder (not shown) in thebitstream source122 typically does not decode the video signal read from thestorage medium112. This particular embodiment can be referred to as a remote decoder arrangement. It should be noted, however, that the invention is not limited to this arrangement, as the invention can be practiced in other suitable systems.
• In operation, the[0023]controller110 can read a video signal containing a plurality of progressively scanned original pictures from thestorage medium112. For convenience, the phrase “progressively scanned original pictures” will be shortened to “original pictures” throughout the application. In one arrangement, if themicroprocessor116 receives a trick mode command such as a fast motion command, then themicroprocessor116 can signal the searchingengine114 to locate one or more suitable original pictures in the trick mode video signal for purposes of skipping such a picture. Once located, the microprocessor can selectively skip at least one of the original pictures to convert the video signal to a trick mode video signal. The skipped pictures will not be decoded nor will they be displayed during the trick mode.
• In addition, during the trick mode command, the[0024]microprocessor116 can signal the searching engine to locate another set of one or more suitable original pictures for purposes of inserting dummy bidirectional predictive (dummy B) pictures into the trick mode video signal. A dummy B picture is a B picture that can be predicted from certain pictures and whose motion vectors and discrete cosine transform (DCT) coefficients are set to zero or not encoded. Once a suitable original picture is located, the searchingengine114 can signal themicroprocessor116, and themicroprocessor116 can generate a corresponding dummy B picture predicted from the located original picture. Themicroprocessor116 can then selectively insert at least one of the corresponding dummy B pictures such that the dummy B picture is sent to thetransmission buffer117 and on to thedisplay device118. In this arrangement, the dummy B pictures can be used to repeat original pictures such that the dummy B picture is transmitted to thedisplay device118 and displayed.
• In another aspect of the invention, the[0025]microprocessor116 can monitor the bit rate of the trick mode video signal. If the bit rate of the trick mode video signal exceeds a predetermined threshold, then themicroprocessor116, in conjunction with the searchingengine114, can perform the selectively inserting step discussed above in which at least one dummy B picture can be inserted in the trick mode video signal.
• In another arrangement, the[0026]microprocessor116 can modify certain portions of information contained within one or more of the plurality of original pictures contained in the trick mode video signal to reflect an intended display order. This modification step can be performed whether original pictures are skipped or dummy B pictures are inserted in the video signal. The overall operation of the invention will be discussed in greater detail below.
FAST MOTION TRICK MODE USING DUMMY BIDIRECTIONAL PREDICTIVE PICTURES
• FIG. 2 is a flowchart illustrating a[0027]method200 that demonstrates one way to operate in a trick mode such as a fast motion trick mode using dummy B pictures. In one arrangement, the invention can be practiced in a remote decoder arrangement. For purposes of the invention, a remote decoder arrangement can be any system in which at least a portion of the pictures in a video signal can be decoded by a decoder that is external to and not under the control of a bitstream source that is providing the pictures to the decoder. As an example, the bitstream source can be an optical storage medium player or recorder that reads multimedia data from an optical storage medium and transfers this data over a transmission channel to a digital television, which contains its own decoder. It is understood, however, that the invention is not limited to this example or even a remote decoder arrangement, as the invention can be practiced in any other suitable system or arrangement.
• At[0028]step210, a video signal containing a plurality of progressively scanned original pictures can be read. Atstep212, a trick mode command can be received. For purposes of the invention, the trick mode command can be any command in which one or more of the original pictures are to be skipped, including a fast motion command such as fast forward or fast reverse. As shown atstep214, at least one of the original pictures can be selectively skipped. This selective skipping of pictures converts the video signal to a trick mode video signal.
• In one arrangement, the first original pictures to be skipped can be B pictures. Referring to FIG. 4, a typical group of pictures (GOP)[0029]400 in display order is shown. The subscript numbers indicate when each picture will be displayed—relative to the other pictures in the GOP—at a normal playback speed. This GOP400 can be one of many GOPs in a video signal. Although the invention is not limited to this particular GOP structure, the GOP400 will serve to illustrate how a fast motion trick mode can be performed. For example, if a fast forward playback of 3× is desired (1× represents normal playback), then all the B pictures in the GOP400 can be skipped. Thus, for this particular GOP, only the picture I₂and the P pictures will be transmitted and/or decoded and displayed.
• For a faster trick mode speed, some of the P pictures can be skipped and at certain speeds, the entire GOP[0030]400 (including picture I₂) may be skipped. If P pictures are to be skipped, those of skill in the art will realize that it would be preferable to first skip the P pictures towards the end of the GOP. In this example, picture P₁₄would be skipped first and then picture P₁₁would be skipped and so on. Skipping pictures in this manner can preserve the proper decoding sequence necessary to decode those pictures that will be displayed during the trick mode.
• As discussed earlier, however, skipping pictures in a GOP can cause the average bit rate of the trick mode video signal to increase. In fact, such an increase may exceed tolerable limits in the transmission channel carrying the trick mode video signal. Referring back to[0031]flowchart200 in FIG. 2, it can be determined whether at least one dummy B picture is to be inserted in the trick mode video signal, as shown atdecision block216. If not, theflowchart200 can continue atstep224, which will be explained below. If yes, then atstep218, at least one dummy B picture can be so inserted. Inserting dummy B pictures into the trick mode video signal can help lower the bit rate of such a signal.
• As previously explained, a dummy B picture is a B picture that can be predicted from certain pictures and whose motion vectors and discrete cosine transform (DCT) coefficients are set to zero or not encoded. As such, a dummy B picture contains very little information. A dummy B picture's primary purpose is to duplicate or repeat the picture from which it was predicted using very few bits. Thus, as dummy B pictures are placed into a fast motion trick mode video signal, the average number of bits per picture in the GOP decreases thereby lowering the average bit rate.[0032]
• A picture from which a dummy B picture is predicted is commonly referred to as a reference picture, and any number of the original pictures can be reference pictures. In one arrangement, the reference picture can be either an I picture or a P picture. To illustrate an example of the insertion of dummy B pictures in a trick mode video signal, attention is once again directed to the GOP[0033]400 in FIG. 4. If all the B pictures are skipped and pictures P₁₄and P₁₁are skipped (a playback speed of 5×), then any number of dummy B pictures can be inserted into the trick mode video signal to help lower the bit rate. These dummy B pictures can be predicted from either picture I₂, P₅or P₈.
• The addition of dummy B pictures into the trick mode video signal will decrease the playback speed of the trick mode. In one arrangement of the invention, at[0034]decision block220, it can be determined whether the insertion of the dummy B pictures has slowed the fast motion playback to an unacceptable level. Referring to the above example of a playback speed of 5×, if two dummy B pictures are inserted into the trick mode video signal, then the playback speed will drop to 3×. If the decrease in playback speed is tolerable, then the process can continue to step224. If this slowdown is unacceptable, then atstep222, one or more of the remaining original pictures can be skipped.
• In one arrangement, an unacceptable slowdown can be a decrease in playback speed of roughly thirty percent from the intended trick mode playback speed. Of course, the invention is by no means limited to this particular factor, as other variations in the playback speed can be considered unacceptable. Following the insertion of the two dummy B pictures, pictures P[0035]₅and P₈can be skipped thereby increasing the playback speed back to 5×. In this embodiment, it is preferable to avoid skipping a reference picture from which the dummy B pictures are predicted.
• The insertion of dummy B pictures can also reduce the choppiness of the display of the trick mode video signal, which can be particularly troublesome at a very fast motion trick mode. For example, referring back to GOP[0036]400 in FIG. 4, if a 15× playback is to be performed (either in a forward or a reverse direction), then only picture I₂will be decoded and displayed. This algorithm also applies to any other GOPs in the trick mode video signal. Thus, only the I pictures in subsequent GOPs for a fast forward trick mode and preceding GOPs for a fast reverse trick mode will be decoded and displayed. Such a display, however, can be very choppy and may cause an uncomfortable viewing experience, as jumping from I picture to I picture at a high rate may be difficult to follow because of scene changes or sudden appearances and disappearances of moving objects in the display.
• Continuing with the example, inserting one or more dummy B pictures into the trick mode video signal either before or after each I picture, however, can enhance the display of the trick mode. For example, a number of dummy B pictures predicted from I[0037]₂can be inserted into the trick mode video signal. Because they are repeats of picture I₂, the dummy B pictures increase the amount of time the information in picture I₂is displayed thereby reducing the choppiness of the display. This insertion step can also lower the average bit rate of the trick mode video signal, as, in this example, the signal will have a relatively high bit rate because only I pictures are being transmitted.
• In one arrangement, the dummy B pictures that are inserted in the trick mode video signal can be one-directional prediction pictures. A one-directional prediction picture is predicted from merely one picture, whereas a B picture is generally predicted from two separate pictures. The one-directional dummy B pictures can either be forward predicted dummy B pictures or backward predicted dummy B pictures. If the dummy B picture is a forward predicted dummy B picture, then the dummy B picture can be predicted from a reference picture that is before (in display order) the dummy B picture. In contrast, if the dummy B picture is a backward predicted dummy B picture, then the dummy B picture can be predicted from a reference picture that follows (in display order) the dummy B picture. Because they are predicted merely from one picture, one-directional prediction dummy B pictures can be suitable for repeating or duplicating pictures.[0038]
• Because of their versatility, dummy B pictures can be inserted in almost any location in a trick mode video signal and at any suitable fast motion trick mode speed. Accordingly, the invention is in no way limited to the foregoing examples, as those skilled in the art will appreciate that there are numerous insertion sequences that can be used to lower the bit rate of a trick mode video signal or to reduce the choppiness of such a signal.[0039]
• In another embodiment, each of the plurality of original pictures can contain a display indicator. Referring back to[0040]flowchart200 in FIG. 2, as determined atdecision block224, if the display indicators of these pictures are to be selectively modified, then the display indicator of at least a portion of the plurality of original pictures can be selectively modified, as shown atstep226.
• Notably, modifying these display indicators can reflect an intended display order of the plurality of original pictures when an original picture is skipped or when a dummy B picture is inserted in the trick mode video signal. It is understood, however, that this process can be performed irrespective of whether dummy B pictures are being inserted into the trick mode video signal. Thus, the step of modifying a display indicator can be performed during a conventional fast motion trick mode in which pictures are merely skipped and no dummy B pictures are inserted into the trick mode video signal. If the display indicators are not to be modified, then the[0041]flowchart200 can continue atstep228.
• In one arrangement, the display indicator can be a temporal reference field. A temporal reference field is typically a ten bit field located in the picture header of digitally encoded pictures. Some decoders rely on the temporal reference field to determine when a particular picture in a video signal will be displayed relative to other pictures in the video signal. This field normally has an integer value.[0042]
• As an example, referring once again to FIG. 4, GOP[0043]400 contains fifteen pictures. The subscript numbers for the pictures in the GOP400 can correspond to the integer values for each respective picture's temporal reference field. For instance, the temporal reference field of picture B₀, the first picture in the GOP, can have an integer value of zero. The temporal reference field of picture B1, the next picture to be displayed, can have an integer value of one. Thus, the integer value of the temporal reference field for each subsequent picture to be displayed can be increased by one, all the way to picture P₁₄, whose temporal reference field can have an integer value of 14. For convenience, the phrase “integer value of the temporal reference field” can also be referred to as “integer value.”
• When an original picture is skipped or if a dummy B picture is inserted in the trick mode video signal, however, the display order according to the temporal reference fields of the original pictures is no longer valid. Accordingly, the integer value of the temporal reference fields of the original pictures that follow the inserted dummy B pictures or skipped original pictures can be modified to indicate a proper display order. For example, if pictures B[0044]₉and B₁₀are skipped, then the integer values of those original pictures that follow can be decreased by a value of two. So, the integer value of the temporal reference field of picture P₁₁can be modified from eleven to nine, the integer value of the temporal reference field of picture B₁₂can be modified from twelve to ten and so on. This modification process can continue until the end of the GOP400 is reached and can ensure that the remaining pictures in the GOP400 will be displayed in a proper order. Thus, each time an original picture in a GOP is skipped, the integer values of the temporal reference fields of the remaining pictures in that GOP can be decreased by a value of one.
• In addition, if dummy B pictures are inserted into the trick mode video signal, then the integer value of the temporal reference fields of the original pictures that follow can be increased by an appropriate value to reflect an intended display order. As an example, if all the B pictures and the last two P pictures in the GOP[0045]400 are skipped, then only picture I₂, P₅and P₈would remain. To reflect an intended display order, the integer value of the temporal reference field for picture I₂can be modified from two to zero, the integer value for P₅can be modified from five to one and the integer value for P₈can be modified from eight to three.
• If, for example, four dummy B pictures are inserted into the trick mode video signal following picture I[0046]₂, the integer values for the remaining P pictures would be as follows: the integer value for P₅can be modified from one back to five (the integer value prior to the initiation of the trick mode) and the integer value for P₈can be modified from two to seven. As a result, each time a dummy B picture is inserted in the trick mode video signal, the integer value of the temporal reference fields of the following remaining original pictures can be increased by an integer value of one.
• The step of modifying the integer values of the temporal reference fields of the non-skipped pictures in other GOPs in the trick mode video signal can be carried out in accordance with these examples. It must be noted, however, that the invention is not limited to these particular examples, as other ways to modify the integer values of the relevant temporal reference fields to reflect an intended display order can be performed in any other suitable fashion. Moreover, it should be noted that the invention is not limited to the use of a temporal reference field, as any other suitable display indicator can be modified to reflect an intended display order in either of the embodiments discussed above. Referring back to the[0047]method200 in FIG. 2, once the display indicator has been selectively modified, the process can continue atdecision block228. If the trick mode is to continue, then the trick mode can continue atstep214. If not, normal playback can resume atstep230.
• Referring to FIG. 3, a flowchart represents an[0048]alternative method300 to the trick mode discussed with respect to themethod200. As shown inflowchart300, steps310-314 are identical to steps210-214 in themethod200 and, accordingly, warrant no discussion here. Atstep316, during the trick mode command, the bit rate of the trick mode video signal can be monitored. Monitoring the bit rate of the trick mode video signal may be necessary during a fast motion trick mode because, as mentioned earlier, skipping pictures may result in an increased average bit rate. In certain cases, this increased bit rate may exceed the maximum allowable bit rate for the transmission channel that is carrying the video signal. For purposes of the invention, this maximum allowable bit rate for the transmission channel can be referred to as a predetermined threshold.
• At[0049]decision block318, it can be determined whether the bit rate of the trick mode video signal has exceeded this predetermined threshold. If the bit rate has not reached the predetermined threshold, then theflowchart300 can continue atdecision block326. Referring back to step318, if the bit rate has exceeded the predetermined threshold, then dummy B pictures can be inserted in the trick mode video signal, as shown atstep320. Also, if desired, following the insertion of the dummy B pictures, one or more of the remaining original pictures can be skipped to increase the playback speed, as shown atsteps322 and324. In addition, the display indicators of at least a portion of the original pictures can be modified, as shown atsteps326 and328.
• The procedures shown in[0050]steps320,322,324,326 and328 are similar to the corresponding procedures illustrated in themethod200 of FIG. 2. Thus, the insertion of dummy B pictures can occur based on the monitoring of the bit rate of the trick mode video signal and can be performed if this bit rate exceeds a predetermined threshold. Atdecision block330, it can be determined whether the trick mode is to continue. If yes, then themethod300 can resume atstep314. If not, normal playback can resume atstep322.
• Although the present invention has been described in conjunction with the embodiments disclosed herein, it should be understood that the foregoing description is intended to illustrate and not limit the scope of the invention as defined by the claims.[0051]

Claims (28)

What is claimed is:

1. A method of performing a trick mode on a video signal containing a plurality of progressively scanned original pictures, comprising the steps of:

in response to a trick mode command, selectively skipping at least one of the original pictures to convert the video signal to a trick mode video signal; and gcc

selectively inserting at least one dummy bidirectional predictive picture in the trick mode video signal.

2. The method according toclaim 1, further comprising the steps of:

monitoring the trick mode video signal; and

implementing the step of selectively inserting at least one dummy bidirectional predictive picture in the trick mode video signal if the bit rate of the trick mode video signal exceeds a predetermined threshold.

3. The method according toclaim 1, further comprising the step of selectively modifying a display indicator of at least a portion of the plurality of original pictures to reflect an intended display order when an original picture is skipped or when a dummy bidirectional predictive picture is inserted in the trick mode video signal.

4. The method according toclaim 3, wherein the display indicator is a temporal reference field.

5. The method according toclaim 4, comprising the step of incrementally decreasing by one each integer value of the temporal reference field each time an original picture is skipped.

6. The method according toclaim 4, comprising the step of incrementally increasing by one each integer value of the temporal reference field each time a dummy bidirectional predictive picture is inserted in the trick mode video signal.

7. The method according toclaim 1, comprising the step of predicting each dummy bidirectional predictive picture from a reference picture.

8. The method according toclaim 1, wherein each dummy bidirectional predictive picture is a one-directional predictive picture.

9. The method according toclaim 7, wherein the reference picture is an intra picture.

10. The method according toclaim 7, wherein the reference picture is a predictive picture.

11. The method according toclaim 1, comprising the step of decoding at least a portion of the trick mode video signal by a remote decoder.

12. The method according toclaim 1, wherein the trick mode is a fast motion trick mode.

13. The method according toclaim 1, wherein the method further comprises the step of, following the insertion of at least one dummy bidirectional predictive picture, skipping at least one remaining original picture if the insertion of dummy bidirectional predictive pictures in the trick mode video signal causes a playback speed of the trick mode video signal to decrease to an unacceptable level.

14. In a remote decoder arrangement, a method of performing a trick mode on a video signal containing a plurality of progressively scanned original pictures, wherein each of the plurality of progressively scanned original pictures contains a display indicator, comprising the steps of:

in response to a trick mode command, selectively skipping at least one of the original pictures to convert the video signal to a trick mode video signal;

monitoring a bit rate of the trick mode video signal; selectively inserting at least one dummy bidirectional predictive picture in the trick mode video signal if the bit rate exceeds a predetermined threshold; and

selectively modifying the display indicator of at least a portion of the plurality of original pictures to reflect an intended display order when an original picture is repeated or when a dummy bidirectional predictive picture is inserted in the trick mode video signal.

15. A method of performing a trick mode on a video signal containing a plurality of progressively scanned original pictures, wherein each of the plurality of progressively scanned original pictures contains a display indicator, comprising the steps of:

in response to a trick mode command, selectively skipping at least one of the original pictures to convert the video signal to a trick mode video signal; and

selectively modifying the display indicator of at least a portion of the plurality of original pictures to reflect an intended display order each time an original picture is skipped.

16. The method according toclaim 15, comprising the step of decoding at least a portion of the trick mode video signal by a remote decoder.

17. A system for performing a trick mode on a video signal containing a plurality of progressively scanned original pictures, comprising

a controller for reading data from a storage medium and outputting the video signal containing the plurality of original pictures; and

a video processor, wherein the processor is programmed to:

in response to a trick mode command, selectively skip at least one of the original pictures to convert the video signal to a trick mode video signal; and

selectively insert at least one dummy bidirectional predictive picture in the trick mode video signal.

18. The system according toclaim 17, wherein the video processor is further programmed to:

monitor the trick mode video signal; and

selectively insert at least one dummy bidirectional predictive picture in the trick mode video signal if the bit rate of the trick mode video signal exceeds a predetermined threshold.

19. The system according toclaim 17, wherein each of the plurality of original pictures contains a display indicator and the video processor is further programmed to modify selectively the display indicator of at least a portion of the plurality of original pictures to reflect an intended display order when an original picture is skipped or when a dummy bidirectional predictive picture is inserted in the trick mode video signal.

20. The system according toclaim 19, wherein the display indicator is a temporal reference field.

21. The system according toclaim 20, wherein each temporal reference field has an integer value and the video processor is further programmed to modify selectively the temporal reference field of at least a portion of the plurality of original pictures by incrementally decreasing by one the integer value of the temporal reference field each time an original picture is skipped.

22. The system according toclaim 20, wherein each temporal reference field has an integer value and the video processor is further programmed to modify selectively the temporal reference field of at least a portion of the plurality of original pictures by incrementally increasing by one the integer value of the temporal reference field each time a dummy bidirectional predictive picture is inserted in the trick mode video signal.

23. The system according toclaim 17, further comprising a remote decoder, wherein the remote decoder decodes at least a portion of the trick mode video signal.

24. The system according toclaim 17, wherein the trick mode is a fast motion trick mode.

25. The system according toclaim 17, wherein the video processor is further programmed to, following the insertion of at least one dummy bidirectional predictive picture, skip at least one remaining original picture if the insertion of dummy bidirectional predictive pictures in the trick mode video signal causes a playback speed of the trick mode video signal to decrease to an unacceptable level.

26. A remote decoder system for performing a trick mode on a video signal containing a plurality of progressively scanned original pictures, wherein each of the plurality of progressively scanned original pictures contains a display indicator, comprising:

a controller for reading data from a storage medium and outputting the video signal containing the plurality of original pictures; and

a video processor, wherein the processor is programmed to:

in response to a trick mode command, selectively skip at least one of the original pictures to convert the video signal to a trick mode video signal;

monitor a bit rate of the trick mode video signal;

selectively insert at least one dummy bidirectional predictive picture in the trick mode video signal if the bit rate exceeds a predetermined threshold; and

selectively modify the display indicator of at least a portion of the plurality of original pictures to reflect an intended display order when an original picture is skipped or when a dummy bidirectional predictive picture is inserted in the trick mode video signal.

27. A system for performing a trick mode on a video signal containing a plurality of progressively scanned original pictures, wherein each of the plurality of progressively scanned original pictures contains a display indicator, comprising:

a controller for reading data from a storage medium and generating the video signal containing the plurality of original pictures; and

a video processor, wherein the processor is programmed to:

in response to a trick mode command, selectively repeat at least one of the original pictures to convert the video signal to a trick mode video signal; and

selectively modify the display indicator of at least a portion of the plurality of original pictures each time an original picture is skipped.

28. The system according toclaim 27, further comprising a remote decoder, wherein the remote decoder decodes at least a portion of the trick mode video signal.

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