Method and system for fast digital channel change utilizing time-stamp management
A video stream demultiplxer receives video streams comprising a selected current content channel and one or more adjacent content channels. Time stamp management is concurrently performed on the adjacent content channels while decoding the selected current content channel. Timing information such as Decoding Time Stamp (DTS) and Presentation Time Stamp (PTS) values, and/or random access points (RAPs) may be determined for pictures stored for the selected current content channel and the adjacent content channels. The determined timing information is utilized to determine a Program Clock Reference (PCR) value for each of the selected current channel and the adjacent channels for channel monitoring. A timebase, derived from a PCR rate that is determined based on the determined PCR value, is determined for decoding the selected current content channel. An adjacent content channel, which is primed during decoding of the selected current content channel, may be directly decoded for display if selected.
1. A method, comprising:
receiving, by a video decoding system, a first coded picture of a first content channel and a second coded picture of a second content channel adjacent to the first content channel, the second content channel selected for decoding;
storing the received coded picture of the first content channel, in a first coded data buffer of the video decoding system, while decoding the second coded picture of the second content channel,
determining, by a video primer of the video decoding system, that a Presentation Time Stamp (PTS) of the stored coded picture of the first content channel is greater than a current Program Clock Reference (PCR) value;
responsive to the determination, maintaining the stored coded picture of the first content channel in the first coded data buffer;
subsequently determining, by the video primer, that the PTS of the stored coded picture of the first content channel is not greater than a second current PCR value of the first content channel; and
responsive to the determination that the PTS of the stored coded picture is not greater than the second current PCR value, discarding the stored coded picture of the first content channel from the first coded data buffer.
2. The method of claim 1 , further comprising:
decoding the stored coded picture of the first content channel in the first coded data buffer, responsive to a subsequent determination that a difference between the PTS of the stored coded picture of the first content channel and the PCR value of the first content channel is less than a predetermined threshold.
3. The method of claim 1 , further comprising:
receiving a request to change to the first content channel; and
providing the stored coded picture of the first content channel from the first coded data buffer to a decoder of the video decoding system for immediate decoding and display, responsive to the request.
4. The method of claim 1 , further comprising:
determining timing information for the first content channel and the selected current content channel.
5. The method of claim 4 , wherein the timing information comprises a Decoding Time Stamp (DTS) value, a PTS value, or one or more random access points (RAPs).
6. The method of claim 1 , further comprising identifying a timebase for the selected current content channel based on a PCR rate.
7. The method of claim 6 , further comprising decoding the selected current content channel utilizing the identified timebase.
8. The method of claim 1 , further comprising:
storing a received second coded picture of a third content channel, adjacent to the selected current content channel or the first content channel, in a second coded data buffer of the video decoding system;
determining, by the video primer, that a Presentation Time Stamp (PTS) of the stored second coded picture is greater than the current Program Clock Reference (PCR) value; and
responsive to the determination, maintaining the stored second coded picture of the third content channel in the second coded data buffer.
9. A system, comprising:
a first coded data buffer configured to store a received coded picture of a first content channel, adjacent to a selected current content channel; and
a video primer configured to determine that a Presentation Time Stamp (PTS) of the stored coded picture is greater than a current Program Clock Reference (PCR) value, and responsive to the determination, maintain the stored coded picture in the first coded data buffer; and
a decoder configured to decode the selected current content channel responsive to a determination that a difference between a PTS of a coded picture of the selected current content channel and the current PCR value is less than a predetermined threshold, by the video decoding system, while maintaining the stored coded picture in the first coded data buffer, responsive to the determination that the PTS of the stored coded picture is greater than a current PCR value;
wherein the video primer is further configured to:
determine that the PTS of the stored coded picture is not greater than a second current PCR value, and
discard the stored coded picture from the first coded data buffer, responsive to the determination that the PTS of the stored coded picture is not greater than the second current PCR value.
10. The system of claim 9 , wherein the decoder is further configured to decode the stored coded picture in the first coded data buffer, responsive to a subsequent determination that a difference between the PTS of the stored coded picture and the PCR value is less than the predetermined threshold.
11. The system of claim 9 , further comprising:
a user interface for receiving a request to change to the first content channel; and
a decoder configured to decode the stored coded picture from the first coded data buffer for display, responsive to the request.
12. The system of claim 9 , wherein the video primer is further configured to:
determine timing information for the first content channel and the selected current content channel.
13. The system of claim 12 , wherein the timing information comprises a Decoding Time Stamp (DTS) value, a PTS value, or one or more random access points (RAPs).
14. The system of claim 9 , wherein the video primer is further configured to identify a timebase for decoding the selected current content channel based on a PCR rate.
15. The system of claim 9 , further comprising a second coded data buffer configured to store a received second coded picture of a second content channel, adjacent to the selected current content channel or the first content channel; and
wherein the video primer is further configured to determine that a Presentation Time Stamp (PTS) of the stored second coded picture is greater than the current Program Clock Reference (PCR) value, and responsive to the determination, maintain the stored second coded picture in the second coded data buffer.
16. A method, comprising:
receiving a plurality of content channels, by a video decoding system, each content channel comprising a bitstream of encoded pictures, each content channel adjacent to at least one other content channel of the plurality of content channels;
decoding, by a decoder of the video decoding system, a first encoded picture of a first content channel of the plurality of content channels, responsive to a selection of the first content channel by a user of the video decoding system and responsive to a difference between a Presentation Time Stamp (PTS) of the first encoded picture and a current Program Clock Reference (PCR) value being less than a predetermined threshold;
storing, by the video decoding system in a first coded data buffer, a second encoded picture of a second content channel adjacent to the first content channel;
maintaining the second encoded picture in the first coded data buffer, by a video primer of the video decoding system, while a PTS of the second encoded picture is greater than the current PCR value;
subsequently determining, by the video primer, that the PTS of the second encoded picture is not greater than a second current PCR value; and
responsive to the determination that the PTS of the second encoded picture is not greater than the second current PCR value, discarding the second encoded picture from the first coded data buffer.