Informs the encoder that the GOP length has changed. If the on-going GOP is longer than the new iGopLength, the encoder restarts the GOP immediately. Otherwise, the encoder restarts the GOP when it reaches the new length. The iGopLength argument must be between 1 and 1,000, inclusive.
If successful, returns true. If unsuccessful, returns false. Call AL_Encoder_GetLastError to get the error code.