Methods and apparatus for transcoding progressive I-slice refreshed MPEG data streams to enable trick play mode features on a television appliance
View Patent ↗Progressive I-slice refreshed MPEG data streams are transcoded to I-frame based MPEG data streams to enable trick play modes on a television appliance, such as pause, scan forward, scan backward, jump, or still frame displays for use, e.g., in film indexing (chapters). A progressive I-slice refreshed MPEG data stream 10 having I-slices distributed over multiple P-frames is received by a television appliance 300 . The P-frames are decoded at decoder 220 to recover the I-slices which make up a complete I-frame. The recovered I-slices are assembled (e.g., by processor 230 ) into a complete I-frame. The complete I-frame is encoded at an encoder 250 . A selected P-frame in the MPEG data stream is replaced with the encoded I-frame (e.g., via multiplexer 255 ) to provide an encoded I-frame based data stream 200 . The I-frame based data stream is stored (e.g., in memory 240 ) for trick play mode use.
1. A method for transcoding progressive I-slice refreshed MPEG data streams to enable trick play mode features on a television appliance, comprising the steps of: receiving at the appliance a progressive I-slice refreshed MPEG data stream having I-slices distributed over multiple P-frames; decoding the P-frames to recover the I-slices which make up a complete I-frame; assembling the recovered I-slices into a complete I-frame; encoding the complete I-frame; replacing a selected P-frame in the MPEG data stream with the encoded I-frame to provide an I-frame based MPEG data stream; and storing the I-frame based MPEG data stream for trick play mode use.
2. A method in accordance with claim 1 , comprising: storing each recovered I-slice in memory as each P-frame is decoded until all I-slices required to assemble a complete I-frame are recovered from the decoded P-frames.
3. A method in accordance with claim 1 , comprising: storing the received progressive I-slice refreshed MPEG data stream.
4. A method in accordance with claim 1 , wherein the I-frame based data stream is stored on one of a personal versatile recorder (PVR), a digital video recorder, a set-top terminal, a digital television, or a personal computer.
5. A method in accordance with claim 1 , wherein: a number N of P-frames are decoded to recover the I-slices which make up the complete I-frame; and the encoded I-frame is inserted into the MPEG data stream in place of Nth P-frame.
6. A method in accordance with claim 5 , wherein: one or more additional P frames are decoded to recover additional I-slices; the additional I-slices allow assembly of additional complete I-frames; and said additional complete I-frames are insertable after encoding into the MPEG data stream at a programmable rate.
7. A method in accordance with claim 1 , comprising: inserting additional I-frames into the I-frame based data stream at a programmable interval.
8. A method in accordance with claim 1 , wherein the encoded I-frame replaces the selected Pframe at least once per refresh cycle.
9. A method in accordance with claim 1 , wherein the trick play mode features comprise at least one of pause, scan forward, scan backward, jump, and still frame display.
10. A method in accordance with claim 1 , comprising: determining whether the data stream is an I-frame based MPEG data stream or a progressive I-slice refreshed MPEG data stream, such that, in the event that the data stream is an I-frame based MPEG data stream, the data stream is stored for trick play mode use without further processing.
11. A method in accordance with claim 1 , comprising: determining whether the data stream is an I-frame based MPEG data stream or a progressive I-slice refreshed MPEG data stream; and in the event that the data stream is an I-frame based MPEG data stream, inserting additional I-frames into the data stream prior to storing the data stream for trick play mode use.
12. A method in accordance with claim 1 , wherein the television appliance is one of a personal versatile recorder (PVR), a digital video recording device, a set-top terminal, a digital television, or a personal computer.
13. A method in accordance with claim 1 , wherein: the P-frames are re-encoded using motion estimation techniques in order to remove the I-slices.
14. A television appliance capable of transcoding progressive I-slice refreshed MPEG data streams to enable trick play mode features, comprising: a receiver for receiving a progressive I-slice refreshed MPEG data stream having I-slices distributed over multiple P-frames; a decoder for decoding the P-frames to recover the I-slices which make up a complete I-frame; a processor associated with the decoder for assembling the recovered I-slices into a complete I-frame; an encoder for encoding the complete I-frame; and a multiplexer for replacing a selected P-frame in the MPEG data stream with the encoded I-frame to provide an encoded I-frame based MPEG stream; wherein: said I-frame based data MPEG stream is stored on a storage device for trick play mode use.
15. An appliance in accordance with claim 14 , comprising: memory for storing each recovered I-slice as each P-frame is decoded until all I-slices required to assemble a complete I-frame are recovered from the decoded P-frames.
16. An appliance in accordance with claim 14 , comprising: memory for storing the received progressive I-slice refreshed MPEG data stream.
17. An appliance in accordance with claim 14 , wherein said storage device is external to said television appliance.
18. An appliance in accordance with claim 14 , wherein: a number N of P-frames are decoded to recover the complete I-frame; and the encoded I-frame replaces the Nth P-frame.
19. An appliance in accordance with claim 18 , wherein: one or more additional P frames are decoded to recover additional I-slices; the additional I-slices allow assembly of additional complete I-frames; and said additional complete I-frames are insertable after encoding into the MPEG data stream at a programmable rate.
20. An appliance in accordance with claim 14 , wherein: additional I-frames are inserted into the I-frame based data stream at a programmable interval.
21. An appliance in accordance with claim 14 , wherein the encoded I-frame replaces the selected P-frame at least once per refresh cycle.
22. An appliance in accordance with claim 14 , wherein the trick play mode features comprise at least one of pause, scan forward, scan backward, jump, and still frame display.
23. An appliance in accordance with claim 14 , wherein the receiver determines whether the data stream is an I-frame based MPEG data stream or a progressive I-slice refreshed MPEG data stream, such that, in the event that the data stream is an I-frame based MPEG data stream, the data stream is stored in the storage device for trick play mode use without further processing.
24. An appliance in accordance with claim 14 , wherein: the receiver determines whether the data stream is an I-frame based MPEG data stream or a progressive I-slice refreshed MPEG data stream; and in the event that the data stream is an I-frame based MPEG data stream, the processor inserts additional I-frames into the data stream prior to storage of the data stream for trick play mode use.
25. An appliance in accordance with claim 14 , wherein the appliance is one of a personal versatile recorder (PVR), a digital video recording device, a set-top terminal, a digital television, or a personal computer.
26. An appliance in accordance with claim 14 , wherein: the encoder re-encodes the P-frames using motion estimation techniques in order to remove the I-slices.