Page 249 - Video Coding for Mobile Communications Efficiency, Complexity, and Resilience

226 Chapter 9. Error-Resilience Video Coding Techniques

n n + 1 n + d − 1 n + d n + d + 1
damaged
area

prediction

(a) Error propagation in a sequence of frames

n n + 1 n + d − 1 n + d n + d + 1
INTRA
coded
blocks

tracked reference frame current frame
errors
NACK(n)
(b) INTRA refresh based on error tracking and feedback information

n n + 1 n + d − 1 n + d n + d + 1
reference frame current frame

prediction
tracked
errors

NACK(n) blocks predicted from
erro-free areas in reference
(c) Restricted prediction based on error tracking and feedback information
Figure 9.9: Error tracking techniques

coding e$ciency. In Ref. 202 Steinbach et al. propose a reduced-complexity
error-tracking algorithm that can provide a su$ciently accurate estimate of the
true error propagation. In order to reduce the loss of coding e$ciency, they
INTRA refresh only severely a ected blocks. Thus, if the process of error