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A Priority Based Buffer Management Method to Reduce the Delay of Channel Switch for DTV

IP.com Disclosure Number: IPCOM000202021D
Publication Date: 2010-Dec-01
Document File: 3 page(s) / 61K

Publishing Venue

The IP.com Prior Art Database


Disclosed is a Buffer Management Method for Digital TV system to reduce the delay of channel switch. Compare with other solution, this disclosure leverage an systematic buffer management method to sore relevant information in advance. These information can help to reduce latency in stream data buffer time, video decode and display buffer time with limited software and hardware penalty.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 55% of the total text.

Page 01 of 3

A Priority Based Buffer Management Method to Reduce the Delay of Channel Switch for DTV

Digital TV is much more popular in recent couple years. DTV signal can be transferred by Cable, Satellite, or Internet (IPTV), but the television content is always packet as a stream data (TS stream in DVB system)

with compression standard

(MPEG2/4, H.264). The channel capacity and content quality is better than traditional Analog TV system. But the one disadvantage is "longer delay to switch the program channel". The user always need to wait almost 1 second or more with blank screen to switch to next program channel. This let the user uncomfortable compare with analog CATV system.

This solution leverage an systematic Buffer Management Method to store relevant information in advance. These information can help to reduce latency in below parts:
1. Stream Data Buffer time;

Video Decode Frame Buffer time

Video Decode and Display Buffer

It can help to minimize the latency of channel switch with limited software and hardware penalty.

Where introduced switch delay in DTV?

The long delay of channel switch in DTV system can be introduced by below parts :

Analog Tuner Switch Time

     - For Cable or Satellite based DTV transmission system, it always need a analog tuner to demodulate the signal. Change from one frequency point to another and lock/sync the signal are introduced latency. (Tuner re-configuration time + Signal lock time + data sync time)

2. Stream Data Buffer Time -

As compressed video packed as stream data in DTV system

                                             , it is always need time to buffer a specific stream data (PID) from one steam.


Video Decode and Display Buffer Time

- Frame need to be decode by decompression engine.
- The decoded images will be stored in display buffer

Analysis on Above Parts,

reduce the over latency. The only hardware penalty is need additional memory

space than traditional solution.




Video Decode Frame Buffer Time


                         (MPEG2/4, H.264) is common in modern DTV system. In order to compress the video content, the compression standard identify a serial frame (I frame, P frame, B frame) to perform the algorithm. It always need to decode the video from I frame as beginning, other frames will be dropped without relative I frame.


Video compression technique

we can managed related memory buffers carefully to


Page 02 of 3


Forecast method on next switch to channel

Another assumption is the system will have a forecast on next switched channel

These are several ways to perform the forecast, for examples:
- In general, Switch Up and Switch Down is the most operation to perform the switch channel. so the nearby channels will be set as forecast targets. If current at Channel 16, then Channel 15 and 17 have high possibility to be switched to.



will be set as forecast target. If just jumped from Chan...