1, The full form of RED is Redundant code

In computer programming, redundant code is source code or compiled code in a computer program that is unnecessary, such as:

• recomputing a value that has previously been calculated^[1] and is still available,
• code that is never executed (known as unreachable code),
• code which is executed but has no external effect (e.g., does not change the output produced by a program; known as dead code).

A NOP instruction might be considered to be redundant code that has been explicitly inserted to pad out the instruction stream or introduce a time delay, for example to create a timing loop by “wasting time”. Identifiers that are declared, but never referenced, are termed redundant declarations.

Examples

The following examples are in C.

int foo(int iX)
{
    int iY = iX*2;

    return iX*2;
}

The second iX*2 expression is redundant code and can be replaced by a reference to the variable iY. Alternatively, the definition int iY = iX*2 can instead be removed.

2, The full form of RED is Redundant coding

RED stands for REDundant coding and it is a RTP payload format defined in RFC 2198 for encoding redundant audio or video data.

The primary motivation of sending redundant data is to be able to recover packets lost under lossy network conditions. If a packet is lost then the missing information may be reconstructed at the receiver from the redundant data that arrives in the following packet(s).

The use of RED is negotiated in the SDP as an additional payload type and when used the audio/video RTP packets are packaged using RED format with a 6 bytes header, before the primary and secondary payloads conveying the actual audio/video packet and the redundant information.

An example of a redundant information schema is ULPFEC.