and forward the test the status of outputs and forward it to the corresponding return FFERROR_NOT_READY If the filters stores internally one or a few frame for some it can consider them to be part of the FIFO and delay acknowledging a status change accordingly Example code
int ff_mpeg1_decode_block_intra(GetBitContext *gb, const uint16_t *quant_matrix, const uint8_t *scantable, int last_dc[3], int16_t *block, int index, int qscale)