qtmux: add some more documentation

gst/quicktime/gstqtmux.c

@@ -1,7 +1,9 @@
 /* Quicktime muxer plugin for GStreamer
  * Copyright (C) 2008-2010 Thiago Santos <thiagoss@embedded.ufcg.edu.br>
  * Copyright (C) 2008 Mark Nauwelaerts <mnauw@users.sf.net>
- *
+ * Copyright (C) 2010 Nokia Corporation. All rights reserved.
+ * Contact: Stefan Kost <stefan.kost@nokia.com>
+
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
@@ -62,6 +64,24 @@
  * The fragmented file features defined (only) in ISO Base Media are used by
  * ISMV files making up (a.o.) Smooth Streaming (ismlmux).
  *
+ * A few properties (<link linkend="GstQTMux--movie-timescale">movie-timescale</link>,
+ * <link linkend="GstQTMux--trak-timescale">trak-timescale</link>) allow adjusting
+ * some technical parameters, which might be useful in (rare) cases to resolve
+ * compatibility issues in some situations.
+ *
+ * Some other properties influence the result more fundamentally.
+ * A typical mov/mp4 file's metadata (aka moov) is located at the end of the file,
+ * somewhat contrary to this usually being called "the header".
+ * However, a <link linkend="GstQTMux--faststart">faststart</link> file will
+ * (with some effort) arrange this to be located near start of the file,
+ * which then allows it e.g. to be played while downloading.
+ * Alternatively, rather than having one chunk of metadata at start (or end),
+ * there can be some metadata at start and most of the other data can be spread
+ * out into fragments of <link linkend="GstQTMux--fragment-duration">fragment-duration</link>.
+ * If such fragmented layout is intended for streaming purposes, then
+ * <link linkend="GstQTMux--streamable">streamable</link> allows foregoing to add
+ * index metadata (at the end of file).
+ *
  * <refsect2>
  * <title>Example pipelines</title>
  * |[