Media Galleries API Metadata: Add audio video metadata extractor.

chrome/common/extensions/api/media_galleries.idl

Index: chrome/common/extensions/api/media_galleries.idl
diff --git a/chrome/common/extensions/api/media_galleries.idl b/chrome/common/extensions/api/media_galleries.idl
index 79c724e3fd9b51b4c19f9fefbdf128263a05ae51..a274c635d13e056d0c71ba2744f0ae58fbfa73ae 100644
--- a/chrome/common/extensions/api/media_galleries.idl
+++ b/chrome/common/extensions/api/media_galleries.idl
@@ -69,6 +69,24 @@ namespace mediaGalleries {
   dictionary MediaMetadata {
     // The browser sniffed mime type.
     DOMString mimeType;
+    
+    // Defined for images and video. In pixels.
+    long? height;
+    long? width;
+    
+    // Defined for audio and video.
+    long? durationSeconds;

[acolwell GONE FROM CHROMIUM, 2014/01/03 19:14:04]

nit: Consider using a double since time in HTMLMediaElements are represented as
doubles. Also s/durationSeconds/duration/ to match the HTMLMediaElement field
that would have a equivalent value if you actually loaded the file.

[tommycli, 2014/01/03 23:08:36]

Done.

+    
+    // FFmpeg-defined generic fields.

[acolwell GONE FROM CHROMIUM, 2014/01/03 19:14:04]

I don't think it is wise to expose these fields in terms of what FFmpeg returns.
These seem more like ID3 type fields so you should probably reference
appropriate parts of that spec for each one so these values are well defined.

Another reason to not bind this to FFmpeg is that FFmpeg isn't used on Android.

[Lei Zhang, 2014/01/03 23:00:15]

Chrome extensions and apps are not available on mobile platforms either, FWIW.

[tommycli, 2014/01/03 23:08:36]

Comment might be misleading. FFmpeg inspired the tag names, but we could
implement this with an alternate backend also.

On 2014/01/03 19:14:04, acolwell wrote:

+    DOMString? album;
+    DOMString? artist;
+    DOMString? comment;
+    DOMString? copyright;
+    long? disc;
+    DOMString? genre;
+    DOMString? language;
+    DOMString? title;
+    long? track;
   };
 
   callback MediaMetadataCallback = void (MediaMetadata metadata);