We are using two CVBS signal sources carrying teletext to test the teletext extraction of TVP5146M2，But encountered some problems as follows
The first signal source is the same as described in chapter 6.1 & 6.3 of the "ETS 300 706" standard and has the same "clock run-in (16-bit: 1010101010101010)".. This signal source TVP5146M2 can extract teletext data contentnormally.
The "clock run-in" of the second test signal has one less pulse signal "10" than the first（14bit:10101010101010）, and the teletext data in it cannot be extracted by TVP5146M2.
However, when we use an analog modulator to modulate the above two signals and receive them with the TV, the teletext carried in both signals can be parsed and displayed correctly by the TV, which shows that the signal content should be no problem.
We want to know whether the TVP5146M2 has a specific detection of the "clock run-in" pulse number, so that the teletext data in the second format cannot be detected, or there is a corresponding configuration for the TVP5146M2 to adapt the "clock run-in".