A little bit of history…
The process to create G.729 began in 1990. This coder was originally designed for wireless applications at fixed 8kbit/s output rate, not including the channel coding. The critical trade-off was between delay and complexity. After long debates in several commissions and committees finally in 1995 G.729 was put forward for decision. Initially 5ms frame size was proposed, however resulting in too much complexity. Therefore the frame size was set at 10ms. The required look ahead delay is 5ms. For computational processing 10ms can be assumed, resulting in an ideal one-way codec delay of 25ms. The complexity of the initial implemented versions of G.729 were defined by 20 MIPS and 3000 words of RAM. Compared to the G.728 the complexity, concerning the required instructions per second, was reduced by more than 30 percent. Because the coder was created for wireless channels, it needed to exhibit robustness for both bit errors and frame erasures, which initially were not met.