[x264-devel] VUI timing info issue

[shauli.rozen at gmail.com]

Hi all.

I think there might be a problem in the settingd of the VUI.

say we want to use - 10 fps.

We set *timing_info_present_flag = 1*

We set *num_units_in_tick = 1000*

We set *time_scale = 10000*

We set *fixed_frame_rate_flag = 1*

also

We set *pic_struct_present_flag = 0*

We set *field_pic_flag = 0*

from *table E-6* in the standard It derives ==> *DeltaTfiDivisor = 2*

I think ( and I see some players working that way ) that if a decoder

was to be working by the standard it would translate this to *5 fps rather
then 10*.

here is why:

from the standard:

When fixed_frame_rate_flag is equal to 1, for all n where n indicates the
n-th picture in output order and picture n is not

the last picture in the bitstream in output order, the value of *Dtfi,dpb( n
)* as specified in Equation C-13, shall obey the

following constraint,

*Dtfi,dpb( n )* = = *Dto,dpb( n )* / DeltaTfiDivisor (1)

*Dtfi,dpb( n )* = num_units_in_tick / time_scale. (2)

from this If we calculate *Dto,dpb( n )* we get *Dto,dpb( n )* =
(num_units_in_tick / time_scale) * 2 this is twice the *Dto,dpb( n )* we
ment

and thus half the frame rate.

Am I correct?

 ( all this is from pages 249 , 250 in *DRAFT ITU-T Rec. H.264 (2002 E) )
*

remaider - (C-13) --> Dto,dpb( n ) = to,dpb( nn ) - to,dpb( n )
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