[FFmpeg-devel] [PATCH 1/2] Set subtitle track dimensions for mov_text to display the subtitles properly

Niklesh Lalwani niklesh.lalwani at iitb.ac.in
Thu Jun 11 20:41:24 CEST 2015

Ok so it goes like this.

We first find out the height and width of the video stream from the header
box. The dimensions of the text track (subtitle track) is then set (in
pixels). Here, we have used the width equal to the width of the video, and
height equal to 1/10 of the video height.
The write matrix specifies the coordinate origin and the translation values
from the origin, ie, where to place the subtitle track. Here, we have set
tx = 0; and ty = 9/10 of the video track height.
There is also a text box inside this subtitle area, inside which the text
is rendered. For now, this is set equal to the the subtitle track

Philip, please correct me if I am wrong.



On Thu, Jun 11, 2015 at 11:09 PM, Nicolas George <george at nsup.org> wrote:

> Le tridi 23 prairial, an CCXXIII, Philip Langdale a écrit :
> > Yeah. I sent this to Niklesh to unblock his other work, but we need a
> proper
> > approach to setting the dimensions and this isn't it.
> Can you (or Niklesh) describe exactly the factors that guide the geometry
> of
> the text on screen? IIRC, in the original thread, there was mention of a
> matrix on top of the video resolution.
> Regards,
> --
>   Nicolas George
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