Forward error correction for media transmission

A computer readable medium, excluding carrier waves, having computer executable instructions stored thereon for constructing encoded data packets of a media signal for transmission to a decoder, comprising instructions for:

• segmenting a real-time media signal into sequential frames of data;
• determining for each frame a variable number N, wherein N is at least two, of bitrate representations and a set of N bitrates, each bitrate representing a different signal quality, by evaluating signal characteristics of the media signal in combination with an available transmission bandwidth, and wherein N is selected to minimize a rate distortion of an encoding of the media signal in view of expected network packet losses;
• encoding every frame of the media signal at each of the N bitrates to construct N representations of each frame of the media signal;
• after each frame of the media signal is encoded into N bitrate representations, constructing an encoded data packet by combining a highest available bitrate representation of the current frame, and a single lower bitrate representation of each of as many of the preceding N−1 sequential frames as are available;
• and transmitting each encoded data packet to a decoder as soon as each data packet is constructed.

A method for encoding a media signal to be transmitted across a lossy network transmission channel, comprising:

• receiving rate/distortion parameters of a media signal;
• receiving bandwidth and loss characteristics of a lossy network transmission channel;
• evaluating the distortion parameters, the bandwidth and the loss characteristics to determine a variable number of bitrate representations to be used for encoding each frame of the media signal, wherein the variable number is two or more, and wherein the variable number is selected to minimize a rate distortion of an encoding of the media signal in view of the loss characteristics;
• allocating the bandwidth in a set of bitrates corresponding to the variable number of bitrate representations, said set of bitrates including representing a range of bitrates from highest to lowest;
• using an encoder device for every frame of the media signal, encoding a representation of that frame at every bitrate of the set of bitrates;
• and as each frame of the media signal is encoded, constructing a composite data packet that includes a single bitrate representation of the current frame encoded at the highest bitrate of the set of bitrate representations, and as many of the preceding sequential frames as are available up to a maximum number of frames equal to the variable number of bitrate representations, each preceding sequential frame encoded at next lower one of the set of bitrate representations.