Method and system for a user to manually alter the quality of a previously encoded video sequence

• US 5,684,714 A
• Filed: 06/06/1995
• Issued: 11/04/1997
• Est. Priority Date: 05/08/1995
• Status: Expired due to Term

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation), Warner Bros Entertainment Incorporated (Warner Bros. Discovery, Inc.)
• Original Assignee: Time Warner Entertainment Company LP (Charter Communications Incorporated), Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Lehmann, David, Tsinberg, Mikhail, Unno, Hiroaki, Ng, Sheau-Bao, Mimura, Hideki, Kitamura, Tetsuya, Cookson, Christopher J., Yogeshwar, Jay, Azadegan, Faramarz, Thagard, Greg B., Rosen, Andrew Drusin
• Primary Examiner(s): Kizou, Hassan
• Assistant Examiner(s): Yao, Kwang Bin
• Application Number:
  US08/469,370
• Time in Patent Office: 882 Days
• Field of Search: 364/514 R, 364/514 A, 364/715.02, 348/405, 348/404, 348/420
• US Class Current: 370/521
• CPC Class Codes: G11B 2220/2562 DVDs [digital versatile discs]; Digital video discs; MMCDs; HDCDs
• CPC Class Codes: G11B 2220/90 Tape-like record carriers
• CPC Class Codes: G11B 2220/913 Digital audio tape [DAT] format
• CPC Class Codes: G11B 27/031 Electronic editing of digitised analogue information signals, e.g. audio or video signals
• CPC Class Codes: G11B 27/034 on discs G11B27/036, G11B27/038 take precedence
• CPC Class Codes: G11B 27/3027 used signal is digitally coded
• CPC Class Codes: G11B 27/329 on a disc [VTOC]
• CPC Class Codes: G11B 27/34 Indicating arrangements indicating means incorporated in magazine or cassette G11B23/046 and G11B23/0875; indicating measured values in general G01D
• CPC Class Codes: G11B 27/36 Monitoring, i.e. supervising the progress of recording or reproducing for digital recording G11B20/00 and s.gr.; for monitoring, testing or measuring of TV recorders of the type covered by H04N5/76 and subgroups, see H04N17/06
• CPC Class Codes: H04N 19/115 Selection of the code volume for a coding unit prior to coding
• CPC Class Codes: H04N 19/124 Quantisation
• CPC Class Codes: H04N 19/146 Data rate or code amount at the encoder output
• CPC Class Codes: H04N 19/15 by monitoring actual compressed data size at the memory before deciding storage at the transmission buffer
• CPC Class Codes: H04N 19/154 Measured or subjectively estimated visual quality after decoding, e.g. measurement of distortion use of rate-distortion criteria H04N19/147
• CPC Class Codes: H04N 19/157 Assigned coding mode, i.e. the coding mode being predefined or preselected to be further used for selection of another element or parameter
• CPC Class Codes: H04N 19/159 Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction
• CPC Class Codes: H04N 19/162 User input
• CPC Class Codes: H04N 19/17 the unit being an image region, e.g. an object
• CPC Class Codes: H04N 19/172 the region being a picture, frame or field
• CPC Class Codes: H04N 19/192 the adaptation method, adaptation tool or adaptation type being iterative or recursive
• CPC Class Codes: H04N 19/30 : using hierarchical techniques, e.g. scalability H04N19/63 takes precedence
• CPC Class Codes: H04N 19/503 : involving temporal prediction adaptive coding with adaptive selection between spatial and temporal predictive coding H04N19/107; adaptive coding with adaptive selection among a plurality of temporal predictive coding modes H04N19/109
• CPC Class Codes: H04N 19/60 : using transform coding
• CPC Class Codes: H04N 19/61 : in combination with predictive coding
• CPC Class Codes: H04N 5/9262 : using predictive coding
• CPC Class Codes: H04N 7/52 : Systems for transmission of a pulse code modulated video signal with one or more other pulse code modulated signals, e.g. an audio signal or a synchronizing signal assembling of a multiplex stream by combining a video stream with other content or additional data, remultiplexing of multiplex streams, insertion of stuffing bits into the multiplex stream, assembling of a packetised elementary stream at server side H04N21/236; disassembling of a multiplex stream, remultiplexing of multiplex streams, extraction or processing of Service Information, disassembling of packetised elementary stream at client side H04N21/434
• CPC Class Codes: H04N 9/8042 : involving data reduction
• CPC Class Codes: H04N 9/8063 : using time division multiplex of the PCM audio and PCM video signals

Abstract

A method and system in which a user manually changes the quality of specific time periods of encoded video. After the automatic encoding of video into a compressed digital format, a person editing the encoded video reviews the quality of the video and manually indicates that the quality of specific time periods of the video is to be altered. As the digital storage medium such as an optical disc which stores the encoded video has a finite storage capacity, the total number of bits for the encoded video and the quality of the video is limited. Consequently, in order to increase the quality for one time period, bits must be taken from other time periods. After the editor assigns the qualities to different time periods, a percentage of bits is removed from the time sequences and placed into a bit pool. The new number of bits for the various time periods are calculated using an exponential function and the bits in the bit pool are proportionally distributed to the video frames. The frames must then be checked and possibly adjusted to assure that underflow of the video buffer will not occur. After the underflow checking procedure, the video is re-encoded with an adjusted quantization in accordance with a quantizer model which will result in a picture having the calculated number of bits and a quality in accordance with the user'"'"'s selection.

Claims

1. A method of controlling quality of digitally encoded video, comprising the steps of:

encoding video into a digitally compressed format;

inputting commands by a user indicating qualities of time periods of the encoded video are to be changed;

determining numbers of bits for said time periods using the inputted commands indicating quality and a number of bits of frames of the video encoded in the digitally compressed format; and

re-encoding at least two of said time periods of the video into the digitally compressed format using the determined numbers of bits for said at least two of said time periods.

2. A method according to claim 1, wherein:

said determining step determines the numbers of bits of the re-encoded time periods so that a total number of bits for the re-encoded video is no greater than 5% more than a number of bits for corresponding frames of said encoding.

3. A method according to claim 2, wherein said determining step determines the numbers of bits for said time periods also using a storage capacity of a medium for storing the digitally compressed format video.

4. A method according to claim 1, further comprising the step of:

analyzing the determined number of bits to determine if underflow of a video buffer will occur due to the determined numbers of bits.

5. A method according to claim 4, wherein the step of analyzing analyzes an occupancy of the video buffer for frames after said time periods.

6. A method according to claim 1, wherein said determining step determines the number of bits for one of said time periods using one of the inputted commands which indicates a quality of the re-encoded video for another of said time periods.

7. A method according to claim 1, wherein said determining step determines the numbers of bits for said time periods such that a total number of bits removed from frames of the encoded video corresponds to a total number of bits added to other frames of the encoded video.

8. A method according to claim 1, further comprising the step of:

transferring data representing the video in the digitally compressed format to a storage medium.

9. A method according to claim 8, wherein said step of transferring data includes creating an optical disc containing said data.

10. A method according to claim 9, wherein said step of transferring data includes pressing an optical disc.

11. A method according to claim 1, wherein after the step of inputting commands by the user, said determining step is performed automatically without user intervention.

12. A method according to claim 1, further comprising the step of:

obtaining said video to be encoded in the digitally compressed format using a camera.

13. A memory containing data structures for storing video generated according to claim 1, audio signals, and information used for processing of menus, comprising:

a data structure stored in said memory including;

a field for storing a number of menu cells, a cell being a unit of information;

a field for a start cell of a title menu;

a field for a start cell of an audio selection menu;

a field for a start cell of a menu used to select sub-picture information, the sub-picture information being used to present bit mapped information different from the video;

a field for a start cell for a menu used to select a plurality of programs, when a plurality of programs exist in the memory; and

a field for a start cell for an angle menu used to select a camera angle, when a plurality of angle views exist in the memory;

a menu cell information table containing table entries for each menu to be displayed, each of said table entries including;

a field indicating whether a menu corresponding to the table entry is a title menu, a program menu, an audio menu, a sub-picture menu, or an angle menu;

a field indicating a number of selection items;

a field describing at least a portion of a system clock reference of a start portion of the corresponding menu cell;

a field describing a start address of the corresponding menu cell; and

a field describing a number of blocks of the corresponding menu cell;

a data structure for storing information displayed for each menu;

a data structure for storing encoded audio signals; and

a data structure for storing said video generated according to claim 1.

14. A memory according to claim 13, wherein the memory is an optical disc.

15. A memory containing data structures for storing video generated according to claim 1, audio signals, and file management information, comprising:

a data structure for storing file management information, including;

a file management table storing address and size information of information in the memory;

a sequence information table storing information describing an order in which cells are reproduced, a cell being a unit of information, the sequence information table including a table entry for each sequence, each table entry including;

a field storing whether a corresponding sequence is a completion-type sequence which terminates after being reproduced, a head of a connection-type sequence which is part of sequences which are sequentially reproduced, a mid of a connection-type sequence, and an end of a connection-type sequence;

a field storing a number of cells in the corresponding sequence;

a field storing a reproduction time of the corresponding sequence; and

a field storing a sequence which is reproduced after the corresponding sequence;

a cell information table storing information describing cells, the cell information table including a table entry for each cell, each table entry including;

a field describing a reproduction time of a corresponding cell;

a field describing at least a portion of a system clock reference of the corresponding cell

a field describing an address of the corresponding cell; and

a field describing a number of logical blocks of the corresponding cell;

a data structure for storing encoded audio signals; and

a data structure for storing said video generated according to claim 1.

16. A memory according to claim 15, wherein the memory is an optical disc.

17. A memory containing data structures for storing video generated according to claim 1, audio signals, and descriptive information including timing information, comprising:

a data structure containing descriptive information, including;

a field for storing a system clock reference of the descriptive information data structure;

a field for storing a start time of a corresponding video picture which is decoded without reference to other pictures;

a field for storing a time stamp of audio information having a reproduction start time immediately before the reproduction start time of said corresponding video picture;

a field for storing an address of said audio information, a first bit indicating whether the audio information is located before or after the description information data structure; and

a field describing addresses of other descriptive information data structures occurring both before and after said descriptive information data structure;

a data structure for storing encoded audio signals; and

a data structure for storing said video generated according to claim 1.

18. A memory according to claim 17, wherein the memory is an optical disc.

19. A memory containing data structures for storing video generated according to claim 1, audio signals, and sub-picture information, comprising:

a data structure stored in said memory for storing a sub-picture unit, including;

a field for storing a sub-picture unit header;

a field for storing a bit mapped image; and

a field for storing a display control table including a plurality of table entries, each of said table entries including;

a sub-field which stores a display start time of the bit-mapped image;

a sub-field which stores an address of a subsequent table entry; and

a sub-field for storing at least one display control command selected from a group of commands which include a commands indicating a display area, pixel color, pixel contrast, and color and contrast changes of the pixels which occur as video frames are displayed;

a data structure for storing encoded audio signals; and

a data structure for storing said video generated according to claim 1.

20. A memory according to claim 19, wherein the sub-picture unit data structure comprises a plurality of packs containing information in the sub-picture unit data structure.

21. A memory according to claim 20, wherein the memory is an optical disc.

22. A method according to claim 1, further comprising the step of:

removing a section of the encoded video corresponding to said at least two of said time periods and inserting into the encoded video said at least two of said time periods of re-encoded video generated by the re-encoding step.

23. A method according to claim 1, wherein said step of encoding the video comprises:

encoding the video which is an entire program.

24. A method according to claim 23, wherein said step of encoding the video comprises:

encoding the video which is an entire program comprising a movie.

25. A method according to claim 1, further comprising the steps of:

determining a start point and an end point between which the encoded video is to be modified, the start point corresponding to a beginning of one of said at least two time periods and the end point corresponding to an end point of another of said at least two time periods;

reconstructing reference video before the start point; and

obtaining unencoded video including video representing the encoded video immediately after the end point,

wherein said step of re-encoding comprises;

re-encoding the unencoded video which corresponds to said at least two time periods using the reference video which has been reconstructed,

said method further comprising the step of;

replacing the encoded video immediately after the end point with the video encoded in said re-encoding step.

26. A method of controlling quality of digitally encoded video, comprising the steps of:

encoding video into a digitally compressed format;

inputting commands by a user indicating qualities of time periods of the encoded video are to be changed;

determining numbers of bits for said time periods using the inputted commands by reducing a number of bits in at least one of said time periods and increasing a number of bits in another of said time periods; and

re-encoding said time periods of the video using the determined number of bits.

27. A method according to claim 26, wherein:

said re-encoding step re-encodes the time periods of the video such that the total number of bits for the re-encoded time periods is no greater than 5% more than a number of bits resulting from said encoding.

28. A method according to claim 26, further comprising the step of:

analyzing if the determined numbers of bits will cause underflow of a video buffer to occur.

29. A method according to claim 28, wherein the step of analyzing analyzes the video buffer occupancy for frames after said time periods.

30. A method according to claim 28, further comprising, performed when said step of analyzing determines that underflow will occur, the steps of:

determining a number of bits which must be removed from the encoded frames to prevent the underflow;

removing said determined number of bits to prevent underflow for a video frame at which the underflow will occur back to a frame at which the video buffer is full.

31. A method according to claim 26, further comprising the step of:

determining re-encoding quantization values using the determined number of bits,

wherein said re-encoding step uses the determined re-encoding quantization values.

32. A method according to claim 26, further comprising the step of:

removing bits from said time periods based on a redistribution factor to create a bit pool,

wherein said step of determining a number of bits distributes the bits from the bit pool.

33. A method according to claim 26, wherein said determining step uses an exponential function to determine the number of bits for said time periods.

34. A method according to claim 26, further comprising the step of:

determining whether a buffer occupancy for a last re-encoded frame of a latest one of said time periods will cause a video buffer underflow by determining if frames subsequent to the last re-encoded frame of the latest one of said time periods will absorb a difference in buffer occupancy of the encoded and re-encoded video of the last frame of the latest one of said time periods.

35. A method according to claim 26, wherein said inputting step inputs a command indicating that one of said time periods is to have a maximum quality and said determining step allocates a maximum number of bits to a corresponding time period which is limited by a video buffer occupancy constraint and a maximum rate at which the video buffer can fill.

36. A method according to claim 26, wherein said inputting step inputs a command indicating that one of said time periods is to have a minimum quality and said determining step allocates a minimum number of bits to a corresponding time period which is limited by a previously determined minimum quality data rate.

37. A method according to claim 26, wherein said inputting step inputs a command indicating that a quality of one of said time periods is to have a similar quality for the encoding and the re-encoding.

38. A method according to claim 26, wherein said inputting step inputs quality priorities for said time periods and said determining step determines qualities of said time periods relative to each other.

39. A method according to claim 26, wherein said determining step determines the numbers of bits for said time periods such that a total number of bits removed from frames of the encoded video corresponds to a total number of bits added to other frames of the encoded video.

40. A method according to claim 26, further comprising the step of:

transferring data representing the video in the digitally compressed format to a storage medium.

41. A method according to claim 40, wherein said step of transferring data includes creating an optical disc containing said data.

42. A method according to claim 41, wherein said step of transferring data includes pressing an optical disc.

43. A method according to claim 26, wherein after the step of inputting commands by the user, said determining step is performed automatically without user intervention.

44. A method according to claim 26, further comprising the step of:

obtaining said video to be encoded in the digitally compressed format using a camera.

45. A memory containing data structures for storing video generated according to claim 26, audio signals, and information used for processing of menus, comprising:

a data structure stored in said memory including;

a field for storing a number of menu cells, a cell being a unit of information;

a field for a start cell of a title menu;

a field for a start cell of an audio selection menu;

a field for a start cell of a menu used to select sub-picture information, the sub-picture information being used to present bit mapped information different from the video;

a field for a start cell for a menu used to select a plurality of programs, when a plurality of programs exist in the memory; and

a field for a start cell for an angle menu used to select a camera angle, when a plurality of angle views exist in the memory;

a menu cell information table containing table entries for each menu to be displayed, each of said table entries including;

a field indicating whether a menu corresponding to the table entry is a title menu, a program menu, an audio menu, a sub-picture menu, or an angle menu;

a field indicating a number of selection items;

a field describing at least a portion of a system clock reference of a start portion of the corresponding menu cell;

a field describing a start address of the corresponding menu cell; and

a field describing a number of blocks of the corresponding menu cell;

a data structure for storing information displayed for each menu;

a data structure for storing encoded audio signals; and

a data structure for storing said video generated according to claim 26.

46. A memory according to claim 45, wherein the memory is an optical disc.

47. A memory containing data structures for storing video generated according to claim 26, audio signals, and file management information, comprising:

a data structure for storing file management information, including;

a file management table storing address and size information of information in the memory;

a sequence information table storing information describing an order in which cells are reproduced, a cell being a unit of information, the sequence information table including a table entry for each sequence, each table entry including;

a field storing whether a corresponding sequence is a completion-type sequence which terminates after being reproduced, a head of a connection-type sequence which is part of sequences which are sequentially reproduced, a mid of a connection-type sequence, and an end of a connection-type sequence;

a field storing a number of cells in the corresponding sequence;

a field storing a reproduction time of the corresponding sequence; and

a field storing a sequence which is reproduced after the corresponding sequence;

a cell information table storing information describing cells, the cell information table including a table entry for each cell, each table entry including;

a field describing a reproduction time of a corresponding cell;

a field describing at least a portion of a system clock reference of the corresponding cell

a field describing an address of the corresponding cell; and

a field describing a number of logical blocks of the corresponding cell;

a data structure for storing encoded audio signals; and

a data structure for storing said video generated according to claim 26.

48. A memory according to claim 47, wherein the memory is an optical disc.

49. A memory containing data structures for storing video generated according to claim 26, audio signals, and descriptive information including timing information, comprising:

a data structure containing descriptive information, including;

a field for storing a system clock reference of the descriptive information data structure;

a field for storing a start time of a corresponding video picture which is decoded without reference to other pictures;

a field for storing a time stamp of audio information having a reproduction start time immediately before the reproduction start time of said corresponding video picture;

a field for storing an address of said audio information, a first bit indicating whether the audio information is located before or after the description information data structure; and

a field describing addresses of other descriptive information data structures occurring both before and after said descriptive information data structure;

a data structure for storing encoded audio signals; and

a data structure for storing said video generated according to claim 26.

50. A memory according to claim 49, wherein the memory is an optical disc.

51. A memory containing data structures for storing video generated according to claim 26, audio signals, and sub-picture information, comprising:

a data structure stored in said memory for storing a sub-picture unit, including;

a field for storing a sub-picture unit header;

a field for storing a bit mapped image; and

a field for storing a display control table including a plurality of table entries, each of said table entries including;

a sub-field which stores a display start time of the bit-mapped image;

a sub-field which stores an address of a subsequent table entry; and

a sub-field for storing at least one display control command selected from a group of commands which include a commands indicating a display area, pixel color, pixel contrast, and color and contrast changes of the pixels which occur as video frames are displayed;

a data structure for storing encoded audio signals; and

a data structure for storing said video generated according to claim 26.

52. A memory according to claim 51, wherein the sub-picture unit data structure comprises a plurality of packs containing information in the sub-picture unit data structure.

53. A memory according to claim 52, wherein the memory is an optical disc.

54. A method according to claim 26, further comprising the step of:

removing a section of the encoded video corresponding to said time periods and inserting into the encoded video said time periods of re-encoded video generated by the re-encoding step.

55. A method according to claim 26, wherein said step of encoding the video comprises:

encoding the video which is an entire program.

56. A method according to claim 55, wherein said step of encoding the video comprises:

encoding the video which is an entire program comprising a movie.

57. A method according to claim 26, further comprising the steps of:

determining a start point and an end point between which the encoded video is to be modified, the start point corresponding to a beginning of said one of said time periods and the end point corresponding to an end point of said another of said time periods;

reconstructing reference video before the start point; and

obtaining unencoded video including video representing the encoded video immediately after the end point,

wherein said step of re-encoding comprises;

re-encoding the unencoded video which corresponds to said one and said another time periods using the reference video which has been reconstructed,

said method further comprising the step of;

replacing the encoded video immediately after the end point with the video encoded in said re-encoding step.

58. A method of determining if a re-encoded video of a time period of a video will result in a video buffer underflow condition for video subsequent to the time period, comprising the steps of:

determining a buffer occupancy corresponding to a video frame of original encoded video;

determining a buffer occupancy corresponding to said video frame of re-encoded video, said video frame of the re-encoded video being a last frame of the re-encoded video;

determining a minimum allowable video buffer occupancy of said video frame of the re-encoded video so that the video buffer underflow condition will not occur for video frames subsequent to said video frame; and

reducing a number of bits of ending frames of said re-encoded video so that said video frame of the re-encoded video will have at least the minimum allowable buffer occupancy.

59. A method according to claim 58, wherein said determining step determines the minimum allowable buffer occupancy by determining a number of bits of video frames after said frame which can be absorbed to prevent underflow.

60. A method according to claim 58, wherein said reducing step reduces the number of bits from said frame of said re-encoded video back to a frame of said re-encoded video where the video buffer was full.

61. A system for controlling quality of digitally encoded video, comprising:

means for encoding video into a digitally compressed format;

means for inputting commands by a user indicating qualities of time periods of the encoded video are to be changed;

means for determining numbers of bits for said time periods using the inputted commands indicating quality and a number of bits of frames of the video encoded in the digitally compressed format; and

means for re-encoding at least two of said time periods of the video into the digitally compressed format using the determined numbers of bits for said at least two of said time periods.

62. A system according to claim 61, wherein:

said determining means determines the numbers of bits of the re-encoded time periods so that a total number of bits for the re-encoded video is no greater than 5% more than a number of bits for corresponding frames of said encoding.

63. A system according to claim 62, wherein said determining means determines the numbers of bits for said time periods also using a storage capacity of a medium for storing the digitally compressed format video.

64. A system according to claim 61, further comprising:

means for analyzing the determined number of bits to determine if underflow of a video buffer will occur due to the determined numbers of bits.

65. A system according to claim 64, wherein the means for analyzing analyzes an occupancy of the video buffer for frames after said time periods.

66. A system according to claim 61, wherein said determining means determines the number of bits for one of said time periods using one of the inputted commands which indicates a quality of the re-encoded video for another of said time periods.

67. A system according to claim 61, wherein said determining means determines the numbers of bits for said time periods such that a total number of bits removed from frames of the encoded video corresponds to a total number of bits added to other frames of the encoded video.

68. A system according to claim 61, further comprising:

means for transferring data representing the video in the digitally compressed format to a storage medium.

69. A system according to claim 68, wherein said means for transferring data includes means for creating an optical disc containing said data.

70. A system according to claim 69, wherein said means for transferring data includes means for pressing an optical disc.

71. A system according to claim 61, wherein after the inputting of commands by the user, said determining means operates automatically without user intervention.

72. A system according to claim 61, further comprising:

a camera for obtaining said video to be encoded in the digitally compressed format.

73. A system according to claim 61, further comprising:

means for removing a section of the encoded video corresponding to said at least two of said time periods and inserting into the encoded video said at least two of said time periods of re-encoded video generated by the means for re-encoding.

74. A system according to claim 61, wherein said means for encoding the video comprises:

means for encoding the video which is an entire program.

75. A system according to claim 74, wherein said means for encoding the video comprises:

means for encoding the video which is an entire program comprising a movie.

76. A system according to claim 61, further comprising:

means for determining a start point and an end point between which the encoded video is to be modified, the start point corresponding to a beginning of one of said at least two time periods and the end point corresponding to an end point of another of said at least two time periods;

means for reconstructing reference video before the start point; and

means for obtaining unencoded video including video representing the encoded video immediately after the end point,

wherein said means for re-encoding comprises;

means for re-encoding the unencoded video which corresponds to said at least two time periods using the reference video which has been reconstructed,

said system further comprising;

means for replacing the encoded video immediately after the end point with the video encoded by said re-encoding.

77. A system for controlling quality of digitally encoded video, comprising:

means for encoding video into a digitally compressed format;

means for inputting commands by a user indicating qualities of time periods of the encoded video are to be changed;

means for determining numbers of bits for said time periods using the inputted commands by reducing a number of bits in at least one of said time periods and increasing a number of bits in another of said time periods;

means for re-encoding said time periods of the video using the determined number of bits.

78. A system according to claim 77, wherein:

said re-encoding means re-encodes the time periods of the video such that the total number of bits for the re-encoded time periods is no greater than 5% more than a number of bits resulting from said encoding.

79. A system according to claim 77, further comprising:

means for analyzing if the determined numbers of bits will cause underflow of a video buffer to occur.

80. A system according to claim 79, wherein the means for analyzing analyzes the video buffer occupancy for frames after said time periods.

81. A system according to claim 79, further comprising:

means for determining a number of bits which must be removed from the encoded frames to prevent the underflow; and

means for removing said determined number of bits to prevent underflow for a video frame at which the underflow will occur back to a frame at which the video buffer is full.

82. A system according to claim 77, further comprising:

means for determining re-encoding quantization values using the determined number of bits,

wherein said re-encoding means uses the determined re-encoding quantization values.

83. A system according to claim 77, further comprising:

means for removing bits from said time periods based on a redistribution factor to create a bit pool,

wherein said means for determining a number of bits distributes the bits from the bit pool.

84. A system according to claim 77, wherein said determining means uses an exponential function to determine the number of bits for said time periods.

85. A system according to claim 77, further comprising:

means for determining whether a buffer occupancy for a last re-encoded frame of a latest one of said time periods will cause a video buffer underflow by determining if frames subsequent to the last re-encoded frame of the latest one of said time periods will absorb a difference in buffer occupancy of the encoded and re-encoded video of the last frame of the latest one of said time periods.

86. A system according to claim 77, wherein said inputting means inputs a command indicating that one of said time periods is to have a maximum quality and said determining means allocates a maximum number of bits to a corresponding time period which is limited by a video buffer occupancy constraint and a maximum rate at which the video buffer can fill.

87. A system according to claim 77, wherein said inputting means inputs a command indicating that one of said time periods is to have a minimum quality and said determining step allocates a minimum number of bits to a corresponding time period which is limited by a previously determined minimum quality data rate.

88. A system according to claim 77, wherein said inputting means inputs a command indicating that a quality of one of said time periods is to have a similar quality for the encoding and the re-encoding.

89. A system according to claim 77, wherein said inputting means inputs quality priorities for said time periods and said determining means determines qualities of said time periods relative to each other.

90. A system according to claim 77, wherein said determining means determines the numbers of bits for said time periods such that a total number of bits removed from frames of the encoded video corresponds to a total number of bits added to other frames of the encoded video.

91. A system according to claim 77, further comprising:

means for transferring data representing the video in the digitally compressed format to a storage medium.

92. A system according to claim 91, wherein said means for transferring data includes means for creating an optical disc containing said data.

93. A system according to claim 92, wherein said means for transferring data includes means for pressing an optical disc.

94. A system according to claim 77, wherein after the inputting of user commands by the inputting means, said determining means operates automatically without user intervention.

95. A system according to claim 77, further comprising:

a camera for obtaining said video to be encoded in the digitally compressed format.

96. A system according to claim 77, further comprising:

means for removing a section of the encoded video corresponding to said time periods and inserting into the encoded video said time periods of re-encoded video generated by the means for re-encoding.

97. A system according to claim 77, wherein said means for encoding the video comprises:

means for encoding the video which is an entire program.

98. A system according to claim 97, wherein said means for encoding the video comprises:

means for encoding the video which is an entire program comprising a movie.

99. A system according to claim 77, further comprising:

means for determining a start point and an end point between which the encoded video is to be modified, the start point corresponding to a beginning of said one of said time periods and the end point corresponding to an end point of said another of said time periods;

means for reconstructing reference video before the start point; and

means for obtaining unencoded video including video representing the encoded video immediately after the end point,

wherein said means for re-encoding comprises;

means for re-encoding the unencoded video which corresponds to said one and said another time periods using the reference video which has been reconstructed,

said system further comprising;

means for replacing the encoded video immediately after the end point with the video encoded by said means for re-encoding.

100. A system for determining if re-encoded video of a time period of a video will result in a video buffer underflow condition for video subsequent to the time period, comprising:

means for determining a buffer occupancy corresponding to a video frame of original encoded video;

means for determining a buffer occupancy corresponding to said video frame of re-encoded video, said video frame of the re-encoded video being a last frame of the re-encoded video;

means for determining a minimum allowable video buffer occupancy of said video frame of the re-encoded video so that the video buffer underflow condition will not occur for video frames subsequent to said video frame; and

means for reducing a number of bits of ending frames of said re-encoded video so that said video frame of the re-encoded video will have at least the minimum allowable buffer occupancy.

101. A system according to claim 100, wherein said determining means determines the minimum allowable buffer occupancy by determining a number of bits of video frames after said frame which can be absorbed to prevent underflow.

102. A system according to claim 100, wherein said means for reducing reduces the number of bits from said frame of said re-encoded video back to a frame of said re-encoded video where the video buffer was full.

103. A system for encoding video, comprising:

a video source;

a video encoder connected to the video source;

an intermediate storage device, connected to the video encoder;

a user input device;

a display;

a controller, connected to the user input device, the display, and the video encoder, which commands the video encoder to perform a first encoding of video from the video source and store the first encoding in the intermediate storage device, and commands the video encoder to re-encode sections of the video to have quality based on quality selections input by the user input device.

104. A system for encoding video according to claim 103, wherein:

said controller commands the video encoder to re-encode the video such that the total number of bits for the re-encoding does not exceed the number of bits of the first encoding by more than 5%.

105. A system for encoding video according to claim 103, wherein:

said controller controls the video encoder for the re-encoding such that a number of bits removed from time periods of the encoding correspond to a number of bits added to time periods of the encoding.

106. A system for encoding video according to claim 103, wherein said controller controls the video encoder for the re-encoding automatically without user intervention after the user inputs the quality selections by the user.

107. A method for controlling quality of digitally encoded video, comprising the steps of:

encoding video into a digitally compressed form;

inputting commands by a user indicating qualities of time periods of the encoded video are to be changed;

creating a pool of bits by removing bits from the encoded video; and

redistributing the pool of bits in accordance with the commands indicating qualities of the time periods.

108. A method according to claim 107, wherein the step of inputting commands comprises:

inputting a command which indicates that a period of time is not to have the quality thereof changed.

109. A system for controlling quality of digitally encoded video, comprising:

means for encoding video into a digitally compressed form;

means for inputting commands by a user indicating qualities of time periods of the encoded video are to be changed;

means for creating a pool of bits by removing bits from the encoded video; and

means for redistributing the pool of bits in accordance with the commands indicating qualities of the time periods.

110. A system according to claim 109, wherein the means for inputting commands comprises:

means for inputting a command which indicates that a period of time is not to have the quality thereof changed.