[FFmpeg-user] Drawtext filter

[Stefano Sabatini]

On date Sunday 2011-03-27 14:27:22 +0100, Sebastian Arcus encoded:
> 
> 
> On 03/27/2011 09:23 AM, Stefano Sabatini wrote:
> >On date Saturday 2011-03-26 22:35:20 +0000, Sebastian Arcus encoded:
> >>Thanks Stefano. Any idea if the problem with the background colour
> >>option not having any effect has been solved? I tried it a while ago
> >>(about October-November 2010) - and the option to set a background
> >>colour for the text was not working at the time.
> >
> >Try it and report in case of problem.
> 
> Another problem seems to be that there is no distinction between
> required and optional arguments for the drawtext filter:

First of all:
http://ffmpeg.org/libavfilter.html#SEC19

Of course the documentation may improve, if you have suggestions, or
event better a patch, that would be much appreciated (especially if
you are a fluent English speaker).

> 1. If I use the just the "text" argument, there is an error
> complaining about not having used a "fontfile" argument.

Yes, because fontfile is mandatory.

> 2. If I use "text" and "fontfile", there is no error, but the text
> doesn't show.

You need to specify a value for text, or it will use the default value
of "".

> 3. If I use "text" and "fontfile" and "x" and "y" arguments, still
> no error and still no snow.

Same, x and y are optional, and default to 0.

> 4. If I use "text", "fontfile", "x", "y", "fontcolor" - finally the
> text shows in the video - although I haven't used "fontsize".

fontsize is optional.
 
> It would be useful if there is a full error for any compulsory
> argument missing from the command line - for the drawtext filter,
> that is. 

> Also - the text shows upside down in the video - I have no idea why.

Please provide commandline so that I can reproduce it.
 
> Should I report the above to the main bug database for ffmpeg, or
> bugs for filters go somewhere else?

https://ffmpeg.org/trac/ffmpeg, complaining here sometimes helps
because I read this list ;).