Network architecture¶

Frame format¶

The application foreseen aims at transmitting video streams, so we choose to use the MPEG-4/H264 coding standard, and the adapted codec x264 for video compression/decompression. The associated frame format MP4 is used for the encapsulation of multimedia data type. As a result of this encapsulation, we will transmit longer frames, containing not only data bits, but encaplsulation bits (header, footer...). Therefore, we must consider a higher bit rate than the effective video bit rate.

Protocol stack¶

We define here a first sketch for the protocol stack, in particular the transport and network protocols that would best fit this application:

• Transport layer:

1. the transmission content is video stream, and our application requires real time performance. Therefore the Real Time transport protocol (RTP) seems adapted for the project. In fact RTP adds a header to UDP packets, which specifies the transported media type and format (codec) and numbers the packets to handle losses.

2. the real time constraint also imposes to minimize the packet transmission time. The solution for that is to use UDP transport protocol, which avoids the ACK process and thus is faster than TCP.

• Network layer: the use of IP is likely to be well adapted to our application: it is mostly associated with RTP for video streaming.