It prints the message to stderr, optionally colorizing it.
@param avcl A pointer to an arbitrary struct of which the first field is a
pointer to an AVClass struct.
@param level The importance level of the message expressed using a @ref
lavu_log_constants "Logging Constant".
@param fmt The format string (printf-compatible) that specifies how
subsequent arguments are converted to output.
@param vl The arguments referenced by the format string.
Default logging callback
It prints the message to stderr, optionally colorizing it.
@param avcl A pointer to an arbitrary struct of which the first field is a pointer to an AVClass struct. @param level The importance level of the message expressed using a @ref lavu_log_constants "Logging Constant". @param fmt The format string (printf-compatible) that specifies how subsequent arguments are converted to output. @param vl The arguments referenced by the format string.