static int aac_sync(uint64_t state, AACAC3ParseContext *hdr_info, int *need_next_header, int *new_frame_start) { GetBitContext bits; int size, rdb, ch, sr; union { uint64_t u64; uint8_t u8[8]; } tmp; tmp.u64 = be2me_64(state); init_get_bits(&bits, tmp.u8+8-AAC_HEADER_SIZE, AAC_HEADER_SIZE * 8); if(get_bits(&bits, 12) != 0xfff) return 0; skip_bits1(&bits); /* id */ skip_bits(&bits, 2); /* layer */ skip_bits1(&bits); /* protection_absent */ skip_bits(&bits, 2); /* profile_objecttype */ sr = get_bits(&bits, 4); /* sample_frequency_index */ if(!ff_mpeg4audio_sample_rates[sr]) return 0; skip_bits1(&bits); /* private_bit */ ch = get_bits(&bits, 3); /* channel_configuration */ if(!ff_mpeg4audio_channels[ch]) return 0; skip_bits1(&bits); /* original/copy */ skip_bits1(&bits); /* home */ /* adts_variable_header */ skip_bits1(&bits); /* copyright_identification_bit */ skip_bits1(&bits); /* copyright_identification_start */ size = get_bits(&bits, 13); /* aac_frame_length */ if(size < AAC_HEADER_SIZE) return 0; skip_bits(&bits, 11); /* adts_buffer_fullness */ rdb = get_bits(&bits, 2); /* number_of_raw_data_blocks_in_frame */ hdr_info->channels = ff_mpeg4audio_channels[ch]; hdr_info->sample_rate = ff_mpeg4audio_sample_rates[sr]; hdr_info->samples = (rdb + 1) * 1024; hdr_info->bit_rate = size * 8 * hdr_info->sample_rate / hdr_info->samples; *need_next_header = 0; *new_frame_start = 1; return size; }