Document stream specifier syntax change from 46cbe4ab5c

Fixes #11248.

Changelog

@@ -32,6 +32,15 @@ version 7.1:
 - LCEVC enhancement data exporting in H.26x and MP4/ISOBMFF
 - LCEVC filter
 - MV-HEVC decoding
+- minor stream specifier syntax changes:
+    - when matching by metadata (:m:<key>:<val>), the colon character
+      in keys or values now has to be backslash-escaped
+    - in optional maps (-map ....?) with a metadata-matching stream specifier,
+      the value has to be separated from the question mark by a colon, i.e.
+      -map ....:m:<key>:<val>:? (otherwise it would be ambiguous whether the
+      question mark is a part of <val> or not)
+    - multiple stream types in a single specifier (e.g. :s:s:0) now cause an
+      error, as such a specifier makes no sense
 
 
 version 7.0:

doc/ffmpeg.texi

@@ -2129,7 +2129,7 @@ Set the size of the canvas used to render subtitles.
 @section Advanced options
 
 @table @option
-@item -map [-]@var{input_file_id}[:@var{stream_specifier}][:@var{view_specifier}][?] | @var{[linklabel]} (@emph{output})
+@item -map [-]@var{input_file_id}[:@var{stream_specifier}][:@var{view_specifier}][:?] | @var{[linklabel]} (@emph{output})
 
 Create one or more streams in the output file. This option has two forms for
 specifying the data source(s): the first selects one or more streams from some

doc/fftools-common-opts.texi

@@ -78,7 +78,8 @@ Match the stream by stream id (e.g. PID in MPEG-TS container).
 @item m:@var{key}[:@var{value}]
 Matches streams with the metadata tag @var{key} having the specified value. If
 @var{value} is not given, matches streams that contain the given tag with any
-value.
+value. The colon character ':' in @var{key} or @var{value} needs to be
+backslash-escaped.
 @item disp:@var{dispositions}[:@var{additional_stream_specifier}]
 Matches streams with the given disposition(s). @var{dispositions} is a list of
 one or more dispositions (as printed by the @option{-dispositions} option)