Insufficient decode buffer size when using H264

[nanang]

With default H264 codec settings, i.e: level=3.0 and size=720x480, when receiving video with resolution 704x576, there will be no incoming video shown and repeated error messages in the log:

Error: not enough buffer for decoded frame (supplied=x, required=y)
codec decode() error: Size is too short (PJ_ETOOSMALL) [err:70019]

Initially, it is the application that should set the expected maximum size of the incoming video via H264 codec param, as described in this wiki. However, since #1622, the lib is equipped with such auto-adjust mechanism if the configured size is too small, unfortunately there is a bug in the auto-adjustment code, as described in ​the original report, this ticket should fix this bug.

Thanks Bill Gardner for the report.

[nanang]

In 4854:

Fix #1769: Fixed maximum size/resolution calculation of H264 video in decoding direction.