Pulse or digital communications – Bandwidth reduction or expansion – Television or motion video signal
Reexamination Certificate
1999-02-23
2001-05-08
Le, Vu (Department: 2613)
Pulse or digital communications
Bandwidth reduction or expansion
Television or motion video signal
Reexamination Certificate
active
06229851
ABSTRACT:
This invention relates to the looping of compressed video bitstreams.
For many years video engineers have been accustomed to splicing the beginning and end of a sequence of images together to form a looping sequence. Often a few basic rules must be followed in order to ensure that the splice point is seamless. For instance a looped interlaced video clip should contain an even number of fields; if no tricks are applied to a PAL encoded sequence it should be a multiple of 8 fields in length in order to preserve the mathematical PAL sequence.
However, in the case of bit-rate reduced video, in particular MPEG encoding, there are many more constraints to consider. Indeed, some people have claimed that it is simply not possible in general terms to loop an MPEG video bitstream.
Techniques have already been developed that make it possible to loop specially prepared sequences. However, these techniques usually demand that the precise frames to be looped are known at the time of encoding.
It is here recognised that the problem of looping can be divided into two parts.
The first part is concerned with the selection of appropriate pictures to comprise the loop. The second part of the problem concerns the harder task of ensuring that a decoder's buffer does not over- or underflow whilst replaying a looped sequence. This can arise as a consequence of the variable length encoding process.
It is an object of this invention to provide a novel technique that allows a segment from any compressed sequence to be extracted and looped by a bitstream player, avoiding decoder buffer over-/underflow and requiring no knowledge of the looping at the encoding stage.
Accordingly, the present invention consists in a method of looping a sequence of compressed video bitstream having chosen start and end points, the sequence having a decode time determined by the number of frames in the sequence and the video frame rate, wherein the bit rate at which the sequence is replayed is modified such that the time taken to replay the sequence is made equal to the decode time for the sequence.
REFERENCES:
patent: 5598352 (1997-01-01), Rosenau et al.
patent: 5740307 (1998-04-01), Lane
patent: 6031960 (2000-02-01), Lane
patent: 0656729A2 (1995-06-01), None
patent: 0742670A2 (1996-11-01), None
patent: 2242097A (1991-09-01), None
Lauderdale et al, “A new technique for transmission of pre-encoded MPEG VBR video using CBR service”, IEEE International Conference on Technologies for Tomorrow's Applications, Jun. 1996.*
S. Merrill Weiss, Switching Facilities in MPEG-2: Necessary But Not Sufficient,8012 SMPTE Journal, vol. 104, No. 12, Dec. 1995.
Kinberg Robert
Le Vu
Snell & Wilcox Limited
Venable
LandOfFree
Method and apparatus for looping of compressed video bitstreams does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for looping of compressed video bitstreams, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for looping of compressed video bitstreams will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2512492