[x264] tff vs bff

[Kurtnoise]

quoting the strings help :

--interlaced Enable pure-interlaced mode (tff)
--tff Alias for --interlaced
--bff Enable pure-interlaced mode (bff)


It's very confusing when we read this imo. So, can we have some tweakings for this please ?



coz my main goal is to know what is (are) the difference(s) between bff and tff ?

:thanks:

[Sagittaire]

Well I understand that:

--interlaced Enable pure-interlaced mode (tff)
enable interlacing with top field first by default

--tff Alias for --interlaced
exactly the same command than --interlaced

--bff Enable pure-interlaced mode (bff)
enable interlacing with bottom field first by default

In fact --interlaced command here is useless. you must just know if your interlaced source is bff or tff.

[Kurtnoise]

ok...So, "bottom Field 1st" & "top Field 1st" should be added in the comments strings help then.

[Dark Shikari]

Talk to the person who maintains that patch; it isn't in git x264.

[Gabriel_Bouvigne]

Depending on the underlying implementation, TFF vs BFF might just be a matter of signalisation. TFF just means that within a frame made of 2 fields, the top field should be displayed first, and BFF that the bottom field should be displayed first.

[nm]

Depending on the underlying implementation, TFF vs BFF might just be a matter of signalisation.
Yes, dattrax's patch that adds those parameters is only about signaling interlacing properties within the SEI info. Parameter --interlaced is the MBAFF switch in vanilla x264 and the patch adds --tff and --bff.