Audio-Video Rendering Speed Control for Digital TV Zapping
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Solution Overview
Problem
Digital television zapping times are increased due to the need for decoding I pictures and network unreliability, resulting in delays between stream reception and rendering, which existing methods like rapid I picture finding and unicast burst push methods fail to adequately address without impacting the sender.
Innovation Solution
A method at the receiver that starts receiving and rendering audio-video streams at a slower speed and gradually accelerates to standard speed, allowing early rendering of discrete samples and synchronizing continuous samples with discrete samples when feasible, without affecting the sender.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the receiver waits for I pictures to start decoding the program, then the decoding accuracy is improved, but the zapping time increases
Solution Approach 1:
The receiver performs preliminary actions by decoding P and B pictures before the I picture is fully decoded. The system starts rendering the program stream immediately upon receiving the first picture (I, P, or B) without waiting for the I picture to complete decoding, thereby reducing zapping time while maintaining decoding accuracy through progressive decoding of subsequent pictures.
2Reliability
If additional buffers are added at the decoder to compensate network delivery unreliability, then the network reliability is improved, but the time between reception and rendering increases
Solution Approach 1:
The system performs preliminary rendering actions by starting to render pictures as soon as they are received, without waiting for network reliability compensation. The receiver decodes and renders P and B pictures in advance, reducing the time between reception and rendering while maintaining network reliability through selective buffering only when necessary.
3Manufacturing precision
If the receiver starts rendering at standard rendering speed, then the rendering quality is improved, but the zapping time increases
Solution Approach 1:
The system dynamically adjusts the rendering speed based on the decoding progress. Initially, the receiver renders at a slower speed to accommodate the progressive decoding of P and B pictures, then transitions to standard rendering speed once the I picture is fully decoded and the buffer is sufficient, thereby maintaining rendering quality while reducing zapping time.
4Loss of time
If rapid I picture finding methods are used, then the zapping time is reduced, but the device complexity increases
Solution Approach 1:
The receiver performs self-service by utilizing its existing decoding capabilities to decode P and B pictures without requiring additional external assistance or complex mechanisms. The system leverages the standard MPEG decoding process to achieve rapid picture finding and rendering, reducing zapping time while avoiding increased device complexity.
Data Source
AI summary
The present invention relates to a method at a receiver for playing a stream comprising a set of video samples and a set of audio samples, said audio samples and said video samples being adapted to be rendered at a standard rendering speed in a synchronized manner, comprising at the receiver the steps of starting the reception of the stream, starting the rendering of the video samples at a speed slower than the standard rendering speed and accelerating the rendering speed up to the standard rendering speed. The invention also concerns methods for an early rendering of audio samples, when the stream comprises a set of audio samples, wherein the audio and video samples are adapted to be rendered at a standard rendering speed in a synchronized manner.