screenshot: make screenshot filenames configurable

This adds the --screenshot-template option, which specifies a template
for the filename used for a screenshot. The '%' character is parsed as
format specifier. These format specifiers insert metadata into the
filename. For example, '%f' is replaced with the filename of the
currently played file.

The following format specifiers are available:

%n      Insert sequence number (padded with 4 zeros), e.g. "0002".
%0Nn    Like %n, but pad to N zeros (N = 0 to 9).
        %n behaves like %04n.
%#n     Like %n, but reset the sequence counter on every screenshot.
        (Useful if other parts in the template make the resulting
        filename already mostly unique.)
%#0Nn   Use %0Nn and %#n at the same time.
%f      Insert filename of the currently played video.
%F      Like %f, but with stripped file extension ("." and rest).
%p      Insert current playback time, in HH:MM:SS format.
%P      Like %p, but adds milliseconds: HH:MM:SS.mmmm
%tX     Insert the current local date/time, using the date format X.
        X is a single letter and is passed to strftime() as "%X".
        E.g. "%td" inserts the number of the current day.
%{prop} Insert the value of the slave property 'prop'.
        E.g. %{filename} is the same as %f. If the property doesn't
        exist or is not available, nothing is inserted, unless a
        fallback is specified as in %{prop:fallback text}.
%%      Insert the character '%'.

The strings inserted by format specifiers will be checked for
characters not allowed in filenames (including '/' and '\'), and
replaced with the placeholder '_'. (This doesn't happen for text that
was passed with the --screenshot-template option, and allows specifying
a screenshot target directory by prefixing the template with a relative
or absolute path.)

1 files changed, 1 insertions, 0 deletions

diff --git a/options.h b/options.h
index 670c3ac6e5..f667031595 100644
--- a/options.h
+++ b/options.h
@@ -86,6 +86,7 @@ typedef struct MPOpts {
     int screenshot_jpeg_quality;
     int screenshot_png_compression;
     char *screenshot_filetype;
+    char *screenshot_template;
 
     int audio_output_channels;
     int audio_output_format;