[FFmpeg-devel] [PATCH] drawtext: Allow textfile path to be expanded per frame

David Andreoletti david at andreoletti.net
Tue May 19 15:36:15 EEST 2020


Manolis: drawtext's text expansion section [0] does not mention the special
variable %{frame_num} has 0 paddable. When I tested locally (on master), it is
not 0 padded.

Running through different scenario, I recommend the expanded file path to not
contain 0 padded frame number:- if automatic padding is specified, then video
with no total frame known (live stream) would be problematic- if manually
padding is specified, it would complicate drawtext's textfile options parsing:
support for 0 padded %{frame_num} and possibly other custom formatting when
other supported %{....} variables are expanded.
For a first improvement to an existing functionality, I would prefer to keep it
simple and focused :-)

[0]https://ffmpeg.org/ffmpeg-filters.html#Text-expansion






On Tue, May 19, 2020 9:34 AM, Manolis Stamatogiannakis mstamat at gmail.com  wrote:
Hi David,




Not a full review, but a minor point that popped in mind.




It is common to pad serially numbered files with 0. E.g. if you have <1000

files, the 9th file will be named file009.txt.

Is this case handled by the expansion? Or is it assumed that the text file

numbers are not zero-padded?




If it the latter is the case, it would be good to make that explicit in the

documentation.

Of course, accounting for padding would be better, but this may not be

straightforward without adding more code.




Regards,

Manolis




On Tue, 19 May 2020 at 06:10, David Andreoletti <david at andreoletti.net>

wrote:




> Hi ffmpeg maintainers / community,

> New contributor here. The patch [0] for the drawtext filter was submitted

> some

> time ago now but has been reviewed yet. It seems there is no official

> maintainer

> for this filter (as per the MAINTAINERS file)

> What should be done to have it reviewed ?

>

> [0]

>

>
https://patchwork.ffmpeg.org/project/ffmpeg/patch/20200511143159.19390-1-david@andreoletti.net/

>

> Regards,

> David Andreoletti

>

>

>

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