docs/html/http/ngx_http_mp4_module.html - nginx - Git at Google

 <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>
	<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>