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+<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"><title>HTTP MP4 Module</title></head><body><center><h3>HTTP MP4 Module</h3></center><center><h4>Summary</h4></center><p>
+The module <code>ngx_http_mp4_module</code> provides pseudo-streaming
+server-side support for H.264/AAC files typically having filename extensions
+<code>.mp4</code>, <code>.m4v</code>,
+and <code>.m4a</code>.
+</p><p>
+Pseudo-streaming works in alliance with conformant Flash players.
+A player sends an HTTP request to the server with a start time
+argument in the request URI’s query string (named simply
+<code>start</code>
+and specified in seconds), and the server responds with a stream
+so that its start position corresponds to the requested time,
+for example:
+<blockquote><pre>
+http://example.com/elephants_dream.mp4?start=238.88
+</pre></blockquote>
+This allows for a random seeking at any time, or starting playback
+in the middle of a timeline.
+</p><p>
+To support seeking, H.264-based formats store the metadata
+in the so-called “moov atom.”
+It is a part of the file that holds the index information for the
+whole file.
+</p><p>
+To start playback, a player first needs to read metadata.
+This is done by sending a special request with the
+<code>start=0</code>
+argument.  Many encoding software will insert the metadata at
+the end of the file.  This is bad for pseudo-streaming:
+the metadata needs to be located at the beginning of the file,
+or else the entire file will have to be downloaded before it
+starts playing.  If a file is well-formed (with metadata at the
+beginning of a file), nginx just sends back the contents of a file.
+Otherwise, it has to read the file and prepare a new stream so that
+metadata comes before media data.
+This involves some CPU, memory, and disk I/O overhead,
+so it is a good idea to
+<a href="http://flowplayer.org/plugins/streaming/pseudostreaming.html#prepare">
+prepare an original file for pseudo-streaming</a>,
+rather than having nginx do this on every such request.
+</p><p>
+For a matching request with a non-zero
+<code>start</code>
+argument, nginx will read metadata from the file, prepare the
+stream starting from the requested offset, and send it to a client.
+This has the same overhead as described above.
+</p><p>
+If a matching request does not include the
+<code>start</code>
+argument, there is no overhead, and the file is just sent as a static resource.
+Some players also support byte-range requests, and thus do not require
+this module at all.
+</p><p>
+This module is not built by default, it should be enabled with the
+<code>--with-http_mp4_module</code>
+configuration parameter.
+
+If you were using the third-party mp4 module, be sure to disable it.
+</p><p>
+A similar pseudo-streaming support for FLV files is provided by the module
+<a href="ngx_http_flv_module.html">ngx_http_flv_module</a>.
+</p><a name="example"></a><center><h4>Example Configuration</h4></center><p><blockquote><pre>
+location /video/ {
+    mp4;
+    mp4_buffer_size     1m;
+    mp4_max_buffer_size 5m;
+}
+</pre></blockquote></p><a name="directives"></a><center><h4>Directives</h4></center><hr><a name="mp4"></a><strong>syntax</strong>:
+         <code>mp4</code><br><strong>default</strong>:
+      <strong>none</strong><br><strong>context</strong>:
+      <code>location</code><br><p>
+Turns on module processing in a surrounding location.
+</p><hr><a name="mp4_buffer_size"></a><strong>syntax</strong>:
+         <code>mp4_buffer_size <code><i>size</i></code></code><br><strong>default</strong>:
+      <code>mp4_buffer_size 512K</code><br><strong>context</strong>:
+      <code>http</code>, <code>server</code>, <code>location</code><br><p>
+Sets the initial size of a memory buffer used to process MP4 files.
+</p><hr><a name="mp4_max_buffer_size"></a><strong>syntax</strong>:
+         <code>mp4_max_buffer_size <code><i>size</i></code></code><br><strong>default</strong>:
+      <code>mp4_max_buffer_size 10M</code><br><strong>context</strong>:
+      <code>http</code>, <code>server</code>, <code>location</code><br><p>
+During metadata processing, a larger buffer may become necessary.
+Its size cannot exceed the specified <code><i>size</i></code>,
+or else nginx will return the server error
+500 (Internal Server Error),
+and log the following:
+<blockquote><pre>
+"/some/movie/file.mp4" mp4 moov atom is too large:
+12583268, you may want to increase mp4_max_buffer_size
+</pre></blockquote></p></body></html>