[FFmpeg-user] Weird results with drawtext

[Cecil Westerhof]

Paul B Mahol <onemda at gmail.com> writes:

> On Sat, Sep 18, 2021 at 6:07 PM Cecil Westerhof via ffmpeg-user <
> ffmpeg-user at ffmpeg.org> wrote:
>
>> I have several of the following (simplified):
>>     drawtext=
>>        enable     = 'between(t, 105, 115)':
>>        text       = 'speaker':
>>        y          = main_h - (text_h * 4),
>>     drawtext=
>>        enable     = 'between(t, 105, 115)':
>>        text       = 'subject':
>>        y          = main_h - (text_h * 2.2),
>>
>> I have been carefully tweaking to get them on the correct place.
>> But when I was satisfied and generated all eight places where I wanted
>> to have them the placement of the speaker and subject text is on
>> different heights. Sometimes one or the other is different, sometimes
>> both and sometimes they are the same.
>>
>> Is this a bug, or am I doing something wrong?
>>
>
> Make sure you do not use subsampled pixel formats.

What do you mean with that?


Maybe better to give the whole drawtext:
    drawtext=
       box        = 1                           :
       boxborderw = 6                           :
       boxcolor   = black at 0.5                   :
       fontcolor  = white                       :
       fontfile   = FreeSerifBold.ttf           :
       fontsize   = 64                          :
       x          = ((main_w - text_w) / 2)     :
       enable     = 'between(t, 105, 115)':
       text       = 'speaker':
       y          = main_h - (text_h * 4),
    drawtext=
       box        = 1                           :
       boxborderw = 6                           :
       boxcolor   = black at 0.5                   :
       fontcolor  = white                       :
       fontfile   = FreeSerifBold.ttf           :
       fontsize   = 64                          :
       x          = ((main_w - text_w) / 2)     :
       enable     = 'between(t, 105, 115)':
       text       = 'subject':
       y          = main_h - (text_h * 2.2),


I tried to find a regularity. For a moment it seemed to be related to
the number of words (while sounding strange), but that was not the
case.

But it has to do with the text. By the second speaker the subject was
placed lower. When I put there the same subject the subject is placed
correctly.

-- 
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof