[FFmpeg-devel] [PATCH v2] doc: update loglevel option documentation

Tobias Rapp t.rapp at noa-archive.com
Tue Apr 10 09:59:23 EEST 2018

Updates documentation after the changes to loglevel flag prefix parsing
in 4b736bc921ed96ad6d312ce0cbe0de29b9e3fe81.

Signed-off-by: Tobias Rapp <t.rapp at noa-archive.com>
 doc/fftools-common-opts.texi | 37 +++++++++++++++++++++++++++++--------
 1 file changed, 29 insertions(+), 8 deletions(-)

diff --git a/doc/fftools-common-opts.texi b/doc/fftools-common-opts.texi
index 185ec21..aa1bb63 100644
--- a/doc/fftools-common-opts.texi
+++ b/doc/fftools-common-opts.texi
@@ -168,14 +168,24 @@ The returned list cannot be assumed to be always complete.
 ffmpeg -sinks pulse,server=
 @end example
- at item -loglevel [repeat+]@var{loglevel} | -v [repeat+]@var{loglevel}
-Set the logging level used by the library.
-Adding "repeat+" indicates that repeated log output should not be compressed
-to the first line and the "Last message repeated n times" line will be
-omitted. "repeat" can also be used alone.
-If "repeat" is used alone, and with no prior loglevel set, the default
-loglevel will be used. If multiple loglevel parameters are given, using
-'repeat' will not change the loglevel.
+ at item -loglevel [@var{flags}+]@var{loglevel} | -v [@var{flags}+]@var{loglevel}
+Set logging level and flags used by the library.
+The optional @var{flags} prefix can consist of the following values:
+ at table @samp
+ at item repeat
+Indicates that repeated log output should not be compressed to the first line
+and the "Last message repeated n times" line will be omitted.
+ at item level
+Indicates that log output should add a @code{[level]} prefix to each message
+line. This can be used as an alternative to log coloring, e.g. when dumping the
+log to file.
+ at end table
+Flags can also be used alone by adding a '+'/'-' prefix to set/reset a single
+flag without affecting other @var{flags} or changing @var{loglevel}. When
+setting both @var{flags} and @var{loglevel}, a '+' separator is expected
+between the last @var{flags} value and before @var{loglevel}.
 @var{loglevel} is a string or a number containing one of the following values:
 @table @samp
 @item quiet, -8
@@ -201,6 +211,17 @@ Show everything, including debugging information.
 @item trace, 56
 @end table
+For example to enable repeated log output and set @var{loglevel} to
+ at code{verbose}:
+ at example
+ffmpeg -loglevel repeat+verbose -i input output
+ at end example
+Another example that disables the @code{level} prefix without affecting the
+current state of @code{repeat} flag or @var{loglevel}:
+ at example
+ffmpeg [...] -loglevel -level
+ at end example
 By default the program logs to stderr. If coloring is supported by the
 terminal, colors are used to mark errors and warnings. Log coloring
 can be disabled setting the environment variable

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