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1. WO2002025949 - SYSTEM AND METHOD OF PROCESSING MPEG STREAMS FOR FILE INDEX INSERTION

Note: Text based on automatic Optical Character Recognition processes. Please use the PDF version for legal matters

[ EN ]

C A I M S

1. A method for automatic insertion of a compressed GOP offset table within a previously encoded MPEG video file, for frame accurate random access of each individual video frame by an
MPEG player/decoder in play-from-offset mode, comprising the following steps:
(a) creating a compressed GOP offset table having an
entry for each GOP header of every video packet of the
MPEG video file, for obtaining accurate GOP header SMPTE timecode and address offsets; and
(b) modifying the MPEG video file by inserting the
compressed GOP offset table before the MPEG video file as at least one padding packet, while maintaining the MPEG video file's original frame presentation,
thereby preserving the MPEG compliance and compressed
audio/video data of the MPEG video file.

2. The method according to claim 1, further comprising a step for estimating a number of padding packets needed for the GOP
offset table, thereby limiting the MPEG video file reading to a single read.

3. The method according to claim 1, wherein at least one
compressed GOP offset table padding packet being preceded by a pack header having a system clock reference (SCR) , and further comprising: a standard PES header, an offset table signature, a starting timecode field, and a starting GOP address field.

4. The method according to claim 3 , wherein each said GOP header entry further comprises: a field for number of frames within a prior GOP, and a field for a GOP address offset having an
offset address of the pack header corresponding to the GOP header, for re-synchronizing an MPEG player/decoder clock
prior to decoding of the GOP offset table, and for
reconstructing the timecode and address offset of each GOP header during decompression and decoding by the MPEG
player/decoder, by adding the number of frames and address offset of each GOP header entry to the starting timecode and starting GOP address, respectively, and for allowing random access of each individual video frame in play-from-offset
mode.

5. The method according to claim 3, further comprising a step for adjusting the SCR backwards in time, after the GOP offset
table insertion, for maintaining proper- system timing.

6. A system for automatic insertion of a compressed GOP offset table within a previously encoded MPEG video file, for frame accurate random access of each individual video frame by an
MPEG player/decoder in play-from-offset mode, comprising:
a computer coupled to an electronic storage device for storing the MPEG video file;
programming means, performed by the computer, for creating a compressed GOP offset table having an entry for each GOP
header of every video packet of the MPEG video file, for obtaining accurate GOP header SMPTE timecode and address
offsets; and
programming means, performed by the computer, for
modifying the MPEG video file by inserting the compressed

GOP offset table before the MPEG video file as at least one padding packet, while maintaining the MPEG video
file's original frame presentation,
thereby preserving the MPEG compliance and compressed
audio/video data of the MPEG video file.

7. The system according to claim 6, further comprising a means for estimating a number of padding packets needed for the GOP offset table, thereby limiting the MPEG video file reading to a single read.

8. The system according to claim 6, wherein at least one
compressed GOP offset table padding packet being preceded by a pack header having a system clock reference (SCR) , and further comprising: a standard PES header, an offset table signature, a starting timecode field, and a starting GOP address field.

9. The system according to claim 8, wherein each said GOP header entry further comprises : a field for number of frames within a prior GOP, and a field for a GOP address offset having an
offset address of the pack header corresponding to the GOP
header, for re-synchronizing an MPEG player/decoder clock
prior to decoding of the GOP offset table, and for
reconstructing the timecode and address offset of each GOP header during decompression and decoding by the MPEG
player/decoder, by adding the number of frames and address offset of each GOP header entry to the starting timecode and starting GOP address, respectively, and for allowing random access of each individual video frame in play-from-offset
mode.

10. The system according to claim 8, further comprising a means for adjusting the SCR backwards in time, after the GOP offset table insertion, for maintaining proper system timing.

11. A computer program product stored on a computer usable medium comprising computer readable program means for causing a
computer to perform method steps for automatic insertion of a compressed GOP offset table within a previously encoded MPEG video file, for frame accurate random access of each
individual video frame by an MPEG player/decoder in play-from- offset mode, the MPEG video file stored in an electronic
storage device coupled to the computer, the method comprising the following steps :

(a) creating a compressed GOP offset table having an entry for each GOP header of every video packet of the MPEG video file, for obtaining accurate GOP header SMPTE timecode and address offsets; and
(b) modifying the MPEG video file by inserting the compressed GOP offset table before the MPEG video file as at least one padding packet, while maintaining the MPEG video file's
original frame presentation,
thereby preserving the MPEG compliance and compressed
audio/video data of the MPEG video file.

12. Computer program product according to claim 11, further
comprising a step for estimating a number of padding packets needed for the GOP offset table, thereby limiting the MPEG video file reading to a single read.

13. Computer program product according to claim 11, wherein at least one compressed GOP offset table padding packet being preceded by a pack header having a system clock reference
(SCR) , and further comprising: a standard PES header, an
offset table signature, a starting timecode field, and a
starting GOP address field.

14. Computer program product according to claim 13 , wherein each said GOP header entry further comprises : a field for number of frames within a prior GOP, and a field for a GOP address
offset having an offset address of the pack header
corresponding to the GOP header, for re-synchronizing an MPEG player/decoder clock prior to decoding of the GOP offset
table, and for reconstructing the timecode and address offset of each GOP header during decompression and decoding by the
MPEG player/decoder, by adding the number of frames and
address offset of each GOP header entry to the starting
timecode and starting GOP address, respectively, and for allowing random access of each individual video frame in play- from-offset mode.

15. Computer program product according to claim 13 , further
comprising a step for adjusting the SCR backwards in time, after the GOP offset table insertion, for maintaining proper system timing.