design: draft-metadata: add missing markup & drop needless escaping

Additionally:

- Grammar improvements
- Remove reference to WONTFIX bug

markdown/design/draft-metadata.md

@@ -8,81 +8,81 @@ proposes some additions.
 The paragraphs below list supported native metadata standards sorted by
 type and then in alphabetical order. Some standards have been extended
 to support additional metadata. GStreamer already supports all of those
-to some extend. This is showns in the table below as either \[--\],
+to some extend. This is showns in the table below as either `[--]`,
-\[r-\], \[-w\] or \[rw\] depending on read/write support (08.Feb.2010).
+`[r-]`, `[-w]` or `[rw]` depending on read/write support (08.Feb.2010).
 
 ### Audio
 - mp3
-  * ID3v2: \[rw]
+  * ID3v2: `[rw]`
      * http://www.id3.org/Developer_Information
-  * ID3v1: [rw] 
+  * ID3v1: `[rw]`
     * http://www.id3.org/ID3v1
-  * XMP: \[--] (inside ID3v2 PRIV tag of owner XMP)
+  * XMP: `[--]` (inside ID3v2 PRIV tag of owner XMP)
     * http://www.adobe.com/devnet/xmp/
 - ogg/vorbis
-  * vorbiscomment: \[rw] 
+  * vorbiscomment: `[rw]`
     * http://www.xiph.org/vorbis/doc/v-comment.html
     * http://wiki.xiph.org/VorbisComment
 - wav
-  * LIST/INFO chunk: \[rw]
+  * LIST/INFO chunk: `[rw]`
     * http://www.sno.phy.queensu.ca/~phil/exiftool/TagNames/RIFF.html#Info
     * http://www.kk.iij4u.or.jp/~kondo/wave/mpidata.txt
-  * XMP: \[--]
+  * XMP: `[--]`
     * http://www.adobe.com/devnet/xmp/
 
 ### Video
 - 3gp
-  * {moov,trak}.udta:  \[rw]
+  * {moov,trak}.udta:  `[rw]`
      * http://www.3gpp.org/ftp/Specs/html-info/26244.htm
-  * ID3V2: \[--]
+  * ID3V2: `[--]`
      * http://www.3gpp.org/ftp/Specs/html-info/26244.htm
      * http://www.mp4ra.org/specs.html#id3v2
 - avi
-  * LIST/INFO chunk: \[rw]
+  * LIST/INFO chunk: `[rw]`
     * http://www.sno.phy.queensu.ca/~phil/exiftool/TagNames/RIFF.html#Info
     * http://www.kk.iij4u.or.jp/~kondo/wave/mpidata.txt
-  * XMP: \[--] (inside "_PMX" chunk)
+  * XMP: `[--]` (inside "_PMX" chunk)
     * http://www.adobe.com/devnet/xmp/
 - asf
   * ??:
-  * XMP: \[--]
+  * XMP: `[--]`
     * http://www.adobe.com/devnet/xmp/
-- flv \[--]
+- flv `[--]`
   * XMP: (inside onXMPData script data tag)
     * http://www.adobe.com/devnet/xmp/
 - mkv
-  * tags: \[rw]
+  * tags: `[rw]`
     * http://www.matroska.org/technical/specs/tagging/index.html
 - mov
-  * XMP: \[--] (inside moov.udta.XMP_ box)
+  * XMP: `[--]` (inside moov.udta.XMP_ box)
     * http://www.adobe.com/devnet/xmp/
 - mp4
-  * {moov,trak}.udta: \[rw]
+  * {moov,trak}.udta: `[rw]`
     * http://standards.iso.org/ittf/PubliclyAvailableStandards/c051533_ISO_IEC_14496-12_2008.zip
-  * moov.udta.meta.ilst: \[rw]
+  * moov.udta.meta.ilst: `[rw]`
     * http://atomicparsley.sourceforge.net/
     * http://atomicparsley.sourceforge.net/mpeg-4files.html
-  * ID3v2: \[--]
+  * ID3v2: `[--]`
     * http://www.mp4ra.org/specs.html#id3v2
-  * XMP: \[--] (inside UUID box)
+  * XMP: `[--]` (inside UUID box)
     * http://www.adobe.com/devnet/xmp/
 - mxf
   * ??
 
 ### Images
 - gif
-  * XMP: \[--]
+  * XMP: `[--]`
     * http://www.adobe.com/devnet/xmp/
 - jpg
-  * jif: \[rw] (only comments)
+  * jif: `[rw]` (only comments)
-  * EXIF: \[rw] (via metadata plugin)
+  * EXIF: `[rw]` (via metadata plugin)
     * http://www.exif.org/specifications.html
-  * IPTC: \[rw] (via metadata plugin)
+  * IPTC: `[rw]` (via metadata plugin)
     * http://www.iptc.org/IPTC4XMP/
-  * XMP: \[rw] (via metadata plugin)
+  * XMP: `[rw]` (via metadata plugin)
     * http://www.adobe.com/devnet/xmp/
 - png
-  * XMP: \[--]
+  * XMP: `[--]`
     * http://www.adobe.com/devnet/xmp/
 
 ### further Links:
@@ -93,14 +93,14 @@ http://wiki.creativecommons.org/Tracker_CC_Indexing
 ## Current Metadata handling
 
 When reading files, demuxers or parsers extract the metadata. It will be
-sent a GST\_EVENT\_TAG to downstream elements. When a sink element
+sent a `GST_EVENT_TAG` to downstream elements. When a sink element
-receives a tag event, it will post a GST\_MESSAGE\_TAG message on the
+receives a tag event, it will post a `GST_MESSAGE_TAG` message on the
 bus with the contents of the tag event.
 
-Elements receiving GST\_EVENT\_TAG events can mangle them, mux them into
+Elements receiving `GST_EVENT_TAG` events can mangle them, mux them into
 the buffers they send or just pass them through. Usually is muxers that
 will format the tag data into the form required by the format they mux.
-Such elements would also implement the GstTagSetter interface to receive
+Such elements would also implement the `GstTagSetter` interface to receive
 tags from the application.
 
 ```
@@ -118,8 +118,8 @@ GstEvent(tag) over GstPad from upstream element --> sink       src
                                                     +----------+
 ```
 
-The data used in all those interfaces is GstTagList. It is based on a
+The data used in all those interfaces is `GstTagList`. It is based on a
-GstStructure which is like a hash table with differently typed entries.
+`GstStructure` which is like a hash table with differently typed entries.
 The key is always a string/GQuark. Many keys are predefined in GStreamer
 core. More keys are defined in gst-plugins-base/gst-libs/gst/tag/tag.h.
 If elements and applications use predefined types, it is possible to
@@ -130,15 +130,15 @@ and mapped metadata.
 
 ### Unknown/Unmapped metadata
 
-Right now GStreamer can lose metadata when transcoding, remuxing
+Right now GStreamer can lose metadata when transcoding and/or remuxing
-content. This can happend as we don’t map all metadata fields to generic
+content. This can happens as we don’t map all metadata fields to generic
 ones.
 
-We should probably also add the whole metadata blob to the GstTagList.
+We should probably also add the whole metadata blob to the `GstTagList`.
-We would need a GST\_TAG\_SYSTEM\_xxx define (e.g.
+We would need a `GST_TAG_SYSTEM_xxx` define (e.g.
-GST\_TAG\_SYSTEM\_ID3V2) for each standard. The content is not printable
+`GST_TAG_SYSTEM_ID3V2`) for each standard. The content is not printable
 and should be treated as binary if not known. The tag is not mergeable -
-call gst\_tag\_register() with GstTagMergeFunc=NULL. Also the tag data
+call `gst_tag_register()` with `GstTagMergeFunc=NULL`. Also the tag data
 is only useful for upstream elements, not for the application.
 
 A muxer would first scan a taglist for known system tags. Unknown tags
@@ -146,9 +146,9 @@ are ignored as already. It would first populate its own metadata store
 with the entries from the system tag and the update the entries with the
 data in normal tags.
 
-Below is an initial list of tag systems: ID3V1 - GST\_TAG\_SYSTEM\_ID3V1
+Below is an initial list of tag systems: `ID3V1` - `GST_TAG_SYSTEM_ID3V1`
-ID3V2 - GST\_TAG\_SYSTEM\_ID3V2 RIFF\_INFO -
+`ID3V2` - `GST_TAG_SYSTEM_ID3V2` `RIFF_INFO` -
-GST\_TAG\_SYSTEM\_RIFF\_INFO XMP - GST\_TAG\_SYSTEM\_XMP
+`GST_TAG_SYSTEM_RIFF_INFO` XMP - `GST_TAG_SYSTEM_XMP`
 
 We would basically need this for each container format.
 
@@ -157,14 +157,14 @@ See also <https://bugzilla.gnome.org/show_bug.cgi?id=345352>
 ### Lost metadata
 
 A case slighly different from the previous is that when an application
-sets a GstTagList on a pipeline. Right elements consuming tags do not
+sets a `GstTagList` on a pipeline. Right elements consuming tags do not
 report which tags have been consumed. Especially when using elements
 that make metadata persistent, we have no means of knowing which of the
 tags made it into the target stream and which were not serialized.
 Ideally the application would like to know which kind of metadata is
 accepted by a pipleine to reflect that in the UI.
 
-Although it is in practise so that elements implementing GstTagSetter
+Although it is in practise so that elements implementing `GstTagSetter`
 are the ones that serialize, this does not have to be so. Otherwise we
 could add a means to that interface, where elements add the tags they
 have serialized. The application could build one list from all the tag
@@ -172,7 +172,7 @@ messages and then query all the serialized tags from tag-setters. The
 delta tells what has not been serialized.
 
 A different approach would be to query the list of supported tags in
-advance. This could be a query (GST\_QUERY\_TAG\_SUPPORT). The query
+advance. This could be a query (`GST_QUERY_TAG_SUPPORT`). The query
 result could be a list of elements and their tags. As a convenience we
 could flatten the list of tags for the top-level element (if the query
 was sent to a bin) and add that.
@@ -180,9 +180,9 @@ was sent to a bin) and add that.
 ### Tags are per Element
 
 In many cases we want tags per stream. Even metadata standards like
-mp4/3gp metadata supports that. Right now GST\_MESSAGE\_SRC(tags) is the
+mp4/3gp metadata supports that. Right now `GST_MESSAGE_SRC(tags)` is the
 element. We tried changing that to the pad, but that broke applications.
-Also we miss the symmetric functionality in GstTagSetter. This interface
+Also we miss the symmetric functionality in `GstTagSetter`. This interface
 is usually implemented by
 elements.
 
@@ -190,5 +190,3 @@ elements.
 
 <https://bugzilla.gnome.org/buglist.cgi?query_format=advanced;short_desc=tag;bug_status=UNCONFIRMED;bug_status=NEW;bug_status=ASSIGNED;bug_status=REOPENED;bug_status=NEEDINFO;short_desc_type=allwordssubstr;product=GStreamer>
 
-Add GST\_TAG\_MERGE\_REMOVE
-<https://bugzilla.gnome.org/show_bug.cgi?id=560302>