[FFmpeg-user] Subtitle Timing: Clock Timestamps vs. Frame Timestamps

[jeremie bergeron]

I'm not trying to edit the subtitle, so no, it doesn't really help me.

I want to know if the player must use the Clock Timestamps or Frame
Timestamps to know when to display the subtitle.

Le ven. 4 avr. 2025 à 14:10, Mark Filipak <markfilipak.trash at gmail.com> a
écrit :

> On 04/04/2025 10.16, jeremie bergeron wrote:
> > Hi,
> >
> > This is not strictly an FFmpeg question but rather a general video
> > processing question regarding when subtitles should be rendered.
> >
> > In this discussion, we are debating whether subtitles should be displayed
> > based on *clock timestamps* or *frame timestamps (PTS)*.
> > Let's say I have a video with those timestamps:
> >
> >     -
> >
> >     Frame 0: 0 ms
> >     -
> >
> >     Frame 1: 42 ms
> >     -
> >
> >     Frame 2: 83 ms
>
> ... continues
>
> >     Frame 9: 375 ms
>
> ... continues
>
> >     Frame 20: 834 ms
>
> > Now, let's consider a subtitle that starts at *400 ms* and ends at *860
> ms*.
>
> Subtitle Edit (https://www.nikse.dk/subtitleedit) has a tool called
> "Beautify time codes". The tool
> snaps subtitle times to the elapsed-time equivalents of frame PTSes. So
> your 0:0.400..0:0.860
> subtitle would snap to 0:0.375..0:0.834.
>
> Hope this helps.
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