System and method for optimized channel switching in digital television broadcasting

• US 8,843,990 B1
• Filed: 04/25/2003
• Issued: 09/23/2014
• Est. Priority Date: 04/25/2002
• Status: Active Grant

• Current Assignee: TiVo Corporation (Adeia Inc.)
• Original Assignee: Visible World Incorporated (Comcast Corporation)
• Inventors: Haberman, Seth, Niemeijer, Gerrit, Booth, Richard L., Jansen, Alex, Biemans, Michael-Dennis
• Primary Examiner(s): Bruckart, Benjamin R
• Assistant Examiner(s): Bantamoi, Anthony
• Application Number:
  US10/423,280
• Time in Patent Office: 4,169 Days
• Field of Search: 725/136, 725/38, 725/90
• US Class Current: 725/136
• CPC Class Codes: H04N 21/42638 involving a hybrid front-end, e.g. analog and digital tuners
• CPC Class Codes: H04N 21/4382 Demodulation or channel decoding, e.g. QPSK demodulation analog front ends or means for connecting modulators, demodulators or transceivers to a transmission line H04L27/0002
• CPC Class Codes: H04N 21/4384 involving operations to reduce the access time, e.g. fast-tuning for reducing channel switching latency
• CPC Class Codes: H04N 21/44004 involving video buffer management, e.g. video decoder buffer or video display buffer
• CPC Class Codes: H04N 5/50 Tuning indicators; Automatic tuning control

Abstract

A system and method for masking/reducing the switch time from an analog or digital television channel to another digital television channel and back. Various optimizations which may be used individually or in combination to minimize the potential disruption to the viewer. This optimization is especially important when the channel switch is made automatically by the receiver, such as the case where the presentation of one television program is temporarily continued on another channel.

Claims

1. A broadcast television receiver configured to perform switching between broadcast television programming and dedicated digital streams carrying personalized messages, the receiver comprising:

a tuner operable to tune to a selected channel, from among a plurality of channels received by the receiver, and produce an intermediate frequency signal;

a digital demodulator configured to receive and demodulate the intermediate frequency signal produced by the tuner to produce a digital signal;

a digital demultiplexer configured to receive and demultiplex the digital signal output by the digital demodulator to produce an encoded digital video stream and an encoded digital audio stream;

a first buffer configured to receive and output the encoded digital video stream produced by the digital demultiplexer;

a second buffer configured to receive and output the encoded digital audio stream produced by the digital demultiplexer;

a digital video decoder configured to receive the encoded digital video stream output by the first buffer and produce a decoded digital video stream;

a digital audio decoder configured to receive the encoded digital audio stream output by the second buffer and produce a decoded digital audio stream; and

a controller operable to control the operation of the receiver,

wherein the controller is configured to automatically execute a channel change from a first channel to a second channel, wherein a first video frame, in presentation order, of the encoded digital video stream from the second channel is configured to have a reduced VBV delay;

responsive to at least one of a cue-tone and a time-based switching instruction, the controller leaves at least one of the digital video decoder and the digital audio decoder playing;

causing the tuner to switch from the first channel to the second channel while preventing output from the tuner from being presented by the receiver, and causing the first and second buffers to continue to output at least one of the encoded digital video stream and the encoded digital audio stream until the first and second buffers are empty, respectively, presenting at least one of the encoded digital video stream and the encoded digital audio stream via the receiver during the channel change;

wherein the second channel is an MPEG-encoded digital channel comprising a control message, the control message being sent to the receiver prior to the execution of the channel change, the second channel configured such that, after the channel change is executed, the first buffer receives an encoded digital video stream from the second channel that begins with an MPEG I-frame.

2. The receiver of claim 1, further comprising a descrambler configured to descramble the encoded digital video stream, if the encoded digital video stream is scrambled.

3. The receiver of claim 1, wherein the second channel is a digital channel and, after the channel change is executed, the first buffer receives an encoded digital video stream from the second channel.

4. The receiver of claim 3, wherein the VBV delay of the first video flame is reduced by increasing a video bitrate of the encoded digital video stream.

5. The receiver of claim 3, wherein the VBV delay of the first video flame is reduced by reducing a maximum VBV buffer size of an encoder of the digital video stream.

6. The receiver of claim 1, wherein a quantity of encoded digital video stream data in the first buffer is maximized to cover a maximum amount of switching time required by the tuner.

7. The receiver of claim 1, further comprising:

a video renderer configured to receive the decoded digital video stream produced by the digital video decoder and produce a displayable video signal; and

an audio renderer configured to receive the decoded digital audio stream produced by the digital audio decoder and produce an audio signal for output to a speaker.

8. The receiver of claim 7, wherein a level of an audio signal from the first channel is decreased before the channel change is executed, and a level of an audio signal from the second channel is increased after the channel change is executed.

9. The receiver of claim 1, wherein the tuner is further operable to produce an analog signal if the selected channel is an analog channel, the receiver further comprising:

an analog video processor configured to receive and convert the analog signal produced by the tuner into a displayable video signal; and

an analog audio processor configured to receive and convert the analog signal produced by the tuner to produce an audio signal for output to a speaker.

10. The receiver of claim 9, wherein the analog signal produced by the tuner bypasses the first buffer to reach the analog video processor.

11. The receiver of claim 1, wherein the digital video stream comprises MPEG-encoded video.

12. The receiver of claim 1, wherein the digital audio stream comprises MPEG-encoded audio or AC-3 encoded audio.

13. A method of executing a channel change in a broadcast television receiver configured to perform switching between broadcast television programming and dedicated digital streams carrying personalized messages, the method comprising:

tuning a tuner to a first channel, from among a plurality of channels received by the receiver, and the tuner being configured to produce an intermediate frequency signal;

demodulating the intermediate frequency signal to produce a digital signal;

demultiplexing the digital signal to produce an encoded digital video stream and an encoded digital audio stream;

storing the encoded digital video stream in a first buffer;

storing the encoded digital audio stream in a second buffer;

decoding the encoded digital video stream from the first buffer to produce a decoded digital video stream;

decoding the encoded digital audio stream from the second buffer to produce a decoded digital audio stream;

a controller automatically executes a channel change from the first channel to a second channel, wherein a first video frame, in presentation order, of the encoded digital video stream from the second channel is configured to have a reduced VBV delay;

responsive to at least one of a cue-tone and a time-based switching instruction, the controller leaves at least one of the digital video decoder and the digital audio decoder playing;

switching the tuner from the first channel to the second channel while preventing output from the tuner from being presented by the receiver,

causing the first and second buffers to continue to output at least one of the encoded digital video stream and the encoded digital audio stream until the corresponding first and second buffers are empty, respectively,

presenting at least one of the encoded digital video stream and the encoded digital audio stream via the receiver during the channel change, wherein the second channel is an MPEG-encoded digital channel comprising a control message, the control message being sent to the receiver prior to the execution of the channel change, the second channel configured such that, after the channel change is executed, the first buffer receives an encoded digital video stream from the second channel that begins with an MPEG 1-frame.

14. The method of claim 13, further comprising descrambling the encoded digital video stream, if the encoded digital video stream is scrambled.

15. The method of claim 13, wherein the second channel is a digital channel and, after the channel change is executed, the first buffer receives an encoded digital video stream from the second channel.

16. The method of claim 15, wherein the VBV delay of the first video frame is reduced by increasing a video bitrate of the encoded digital video stream.

17. The method of claim 15, wherein the VBV delay of the first video frame is reduced by reducing a maximum VBV buffer size of an encoder of the digital video stream.

18. The method of claim 13, wherein a quantity of encoded digital video stream data in the first buffer is maximized to cover a maximum amount of switching time required by the tuner.

19. The method of claim 13, further comprising:

rendering the decoded digital video stream to produce a displayable video signal; and

rendering the decoded digital audio stream to produce an audio signal for output to a speaker.

20. The method of claim 19, further comprising:

decreasing a level of an audio signal from the first channel before the channel change is executed; and

decreasing a level of an audio signal from the second channel after the channel change is executed.

21. A non-transitory computer-readable medium comprising computer executable instructions for performing a method of executing a channel change in a broadcast television receiver configured to perform switching between broadcast television programming and dedicated digital streams carrying personalized messages, the method comprising:

tuning a tuner to a first channel, from among a plurality of channels received by the receiver, and the tuner being configured to produce an intermediate frequency signal;

demodulating the intermediate frequency signal to produce a digital signal;

demultiplexing the digital signal to produce an encoded digital video stream and an encoded digital audio stream;

storing the encoded digital video stream in a first buffer;

storing the encoded digital audio stream in a second buffer;

decoding the encoded digital video stream from the first buffer to produce a decoded digital video stream;

decoding the encoded digital audio stream from the second buffer to produce a decoded digital audio stream; and

a controller automatically executes a channel change from the first channel to a second channel, wherein a first video frame, in presentation order, of the encoded digital video stream from the second channel is configured to have a reduced VBV delay;

responsive to at least one of a cue-tone and a time-based switching instruction, the controller leaves at least one of the digital video decoder and the digital audio decoder playing;

switching the tuner from the first channel to the second channel while preventing output from the tuner from being presented by the receiver, and

causing the first and second buffers to continue to output at least one of the encoded digital video stream and the encoded digital audio stream until the corresponding first and second buffers are empty, respectively,

presenting at least one of the encoded digital video stream and the encoded digital audio stream via the receiver during the channel change, wherein the second channel is an MPEG-encoded digital channel comprising a control message, the control message being sent to the receiver prior to the execution of the channel change, the second channel configured such that, after the channel change is executed, the first buffer receives an encoded digital video stream from the second channel that always begins with an MPEG I-frame.

22. The non-transitory computer-readable medium of claim 21, wherein the method further comprises descrambling the encoded digital video stream, if the encoded digital video stream is scrambled.

23. The non-transitory computer-readable medium of claim 21, wherein the second channel is a digital channel and, after the channel change is executed, the first buffer receives an encoded digital video stream from the second channel.

24. The non-transitory computer-readable medium of claim 23, wherein the VBV delay of the first video frame is reduced by increasing a video bitrate of the encoded digital video stream.

25. The non-transitory computer-readable medium of claim 23, wherein the VBV delay of the first video frame is reduced by reducing a maximum VBV buffer size of an encoder of the digital video stream.

26. The non-transitory computer-readable medium of claim 21, wherein a quantity of encoded digital video stream data in the first buffer is maximized to cover a maximum amount of switching time required by the tuner.

27. The non-transitory computer-readable medium of claim 21, wherein the method further comprises:

rendering the decoded digital video stream to produce a displayable video signal; and

rendering the decoded digital audio stream to produce an audio signal for output to a speaker.

28. The non-transitory computer-readable medium of claim 27, wherein the method further comprises:

decreasing a level of an audio signal from the first channel before the channel change is executed; and

decreasing a level of an audio signal from the second channel after the channel change is executed.

29. A broadcast television receiver configured to perform switching between broadcast television programming and dedicated digital streams carrying personalized messages, the receiver comprising:

a tuner receiving a plurality of channels, the plurality of channels including at least one analog channel and one dedicated digital stream carrying personalized messages;

a digital demodulator configured to receive and demodulate the analog channel to produce a digital signal;

a digital demultiplexer configured to receive and demultiplex the digital signal output by the digital demodulator to produce an encoded digital stream;

a buffer configured to receive and output the encoded digital stream produced by the digital demultiplexer;

a digital decoder configured to receive the encoded digital stream output by the buffer and produce a decoded digital stream; and

a controller configured to automatically execute a channel change from the analog channel to the dedicated digital stream, wherein a first video frame, in presentation order, of the encoded digital video stream from the dedicated digital stream is configured to have a reduced VBV delay;

responsive to a time-based switching instruction, the controller leaves the digital decoder playing;

causing the tuner to switch from the analog channel to the dedicated digital channel while preventing output from the tuner from being presented by the receiver, and

causing the buffer to continue to output the encoded digital stream during the channel change until the buffer is empty, thereby presenting the encoded digital video stream via the receiver during the channel change,

wherein the dedicated digital channel comprising a control message, the control message being sent to the receiver prior to the execution of the channel change, wherein the first frame of the dedicated digital channel received at the buffer is an MPEG I-frame.