Transcoder system for compressed digital video bitstreams
View Patent ↗A transcoder system for compressed digital video bitstreams comprising three frame types: I-frames, P-frames and B-frames. The system includes a picture reader decoder to ascertain the type of each frame prior to transcoding. The system also includes a T 2 transcoder for processing I-frames and P-frames, possibly excepting the last P-frame of a group-of-frames (GOP), a T 1 transcoder for processing B-frames and (optionally) the last P-frame of a GOP and a picture decision block for separating all frames into I-frames and P-frames, possibly excepting the last P-frame of a GOP for processing by the T 2 transcoder and B-frames and (optionally) the last P-frame of a GOP for processing by said T 1 transcoder. Another component is a remerge block for recombining the output of all frames from said T 1 transcoder and the T 2 transcoder into a reconstituted output bitstream, such that most of the frames are processed by the much faster T 1 transcoder, thereby achieving substantial improvement in the transcoding throughput speed while retaining a low error rate.
1. A transcoder system for achieving substantial improvement in the transcoding throughput speed of compressed digital video bitstreams comprising three frame types: I-frames P-frames and B-frames in a group-of-pictures/frames (GOP) progression, the system comprising:
a picture reader decoder to ascertain the type of each frame prior to transcoding;
a T 1 transcoder for processing B-frames and optionally the last P-frame of a GOP, at a first processing rate;
a T 2 transcoder for processing I-frames and P-frames at a second processing rate, possibly excepting the last P-frame of a GOP;
a picture decision block for separating all frames into;
I-frames and P-frames, possibly excepting the last P-frame of a GOP for processing by said T 2 transcoder; and
B-frames and optionally the last P-frame of a GOP for processing by said T 1 transcoder; and
a remerge block for recombining the output of all frames from said T 1 transcoder and said T 2 transcoder into a reconstituted output bitstream,
such that most of said output frames are processed by said T 1 transcoder, wherein said first processing rate of said T 1 transcoder is faster than said second processing rate of said T 2 transcoder thereby achieving substantial improvement in the transcoding throughput speed.
2. The system according to claim 1 , wherein two-thirds of the frames are processed by the T 1 transcoder.
3. The system according to claim 1 , wherein the application is for digital TV broadcasting.
4. The system according to claim 1 , wherein the application is for Digital Video Disc (DVD).
5. The system according to claim 1 , wherein the application is for videophone.
6. The system according to claim 1 , wherein the application is for videoconferencing.
7. The system according to claim 1 , wherein said T 1 transcoder dynamically transforms at least one the following coding parameters of compressed video:
frame rate;
spatial resolution;
video contents; and
coding standard.
8. The system according to claim 1 , wherein said transcoder is used for universal media access by Internet users with different access links and devices.
9. The system according to claim 1 , wherein said transcoder is used for universal media access by Intranet users with different access links and devices.
10. The system according to claim 1 , wherein the P-frames are switched from said T 2 transcoder to said T 1 transcoder at some point in the GOP progression as a trade off between drift error limitation and CPU utilization, such that the later the switch, the smaller the accumulation of drift errors.
11. A method for achieving substantial improvement in the transcoding throughput speed of a transcoder system for compressed digital video bitstreams comprising three frame types: I-frames, P-frames and B-frames, said system comprising:
a picture reader decoder to ascertain the type of each frame prior to transcoding;
a T 1 transcoder for processing B-frames and optionally the last P-frame of a GOP, at a first processing rate;
a T 2 transcoder for processing I-frames and P-frames at a second processing rate, possibly excepting the last P-frame of a group-of-frames (GOP);
a picture decision block for separating all frames into;
I-frames and P-frames, possibly excepting the last P-frame of a GOP for processing by said T 2 transcoder; and
B-frames and optionally the last P-frame of a GOP for processing by said T 1 transcoder; and
a remerge block for recombining the output of all frames from said T 1 transcoder and said T 2 transcoder into a reconstituted output bitstream,
such that most of said output frames are processed by said T 1 transcoder, wherein said first processing rate of said T 1 transcoder is faster than said second processing rate of said T 2 transcoder, thereby achieving substantial improvement in the transcoding throughput speed, said method comprising the steps of:
decoding to ascertain the type of each frame prior to transcoding;
separating all frames into:
I-frames and P-frames, possibly excepting the last P-frame of a GOP for processing by said T 2 transcoder; and
B-frames and optionally the last P-frame of a GOP for processing by said T 1 transcoder; and recombining the output of all frames from said T 1 transcoder and said T 2 transcoder into a reconstituted output bitstream.