Mercurial > hg > nginx-site
annotate xml/en/docs/http/ngx_http_mp4_module.xml @ 33:ae5aca1efe2c
Using new <module> and <section> format in ngx_http_mp4_module.xml.
| author | Igor Sysoev <igor@sysoev.ru> |
|---|---|
| date | Fri, 30 Sep 2011 13:14:04 +0000 |
| parents | 9d3403f5204d |
| children | 666e85596e3c |
| rev | line source |
|---|---|
| 22 | 1 <?xml version="1.0"?> |
| 2 | |
| 3 <!DOCTYPE module SYSTEM "../../../../dtd/module.dtd"> | |
| 4 | |
|
33
ae5aca1efe2c
Using new <module> and <section> format in ngx_http_mp4_module.xml.
Igor Sysoev <igor@sysoev.ru>
parents:
22
diff
changeset
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5 <module name="HTTP MP4 module" |
| 22 | 6 link="/en/docs/http/ngx_http_mp4_module.html" |
| 7 lang="en"> | |
| 8 | |
|
33
ae5aca1efe2c
Using new <module> and <section> format in ngx_http_mp4_module.xml.
Igor Sysoev <igor@sysoev.ru>
parents:
22
diff
changeset
|
9 <section name="Summary"> |
| 22 | 10 |
| 11 <para> | |
| 12 The module <code>ngx_http_mp4_module</code> provides pseudo-streaming | |
| 13 server-side support for H.264/AAC files typically having filename extensions | |
| 14 <pathname>.mp4</pathname>, <pathname>.m4v</pathname>, | |
| 15 and <pathname>.m4a</pathname>. | |
| 16 </para> | |
| 17 | |
| 18 <para> | |
| 19 Pseudo-streaming works in alliance with conformant Flash players. | |
| 20 A player sends an HTTP request to the server with a start time | |
| 21 argument in the request URI’s query string (named simply | |
| 22 <parameter>start</parameter> | |
| 23 and specified in seconds), and the server responds with a stream | |
| 24 so that its start position corresponds to the requested time, | |
| 25 for example: | |
| 26 <example> | |
| 27 http://example.com/elephants_dream.mp4?start=238.88 | |
| 28 </example> | |
| 29 This allows for a random seeking at any time, or starting playback | |
| 30 in the middle of a timeline. | |
| 31 </para> | |
| 32 | |
| 33 <para> | |
| 34 To support seeking, H.264-based formats store the metadata | |
| 35 in the so-called “moov atom.” | |
| 36 It is a part of the file that holds the index information for the | |
| 37 whole file. | |
| 38 </para> | |
| 39 | |
| 40 <para> | |
| 41 To start playback, a player first needs to read metadata. | |
| 42 This is done by sending a special request with the | |
| 43 <parameter>start=0</parameter> | |
| 44 argument. Many encoding software will insert the metadata at | |
| 45 the end of the file. This is bad for pseudo-streaming: | |
| 46 the metadata needs to be located at the beginning of the file, | |
| 47 or else the entire file will have to be downloaded before it | |
| 48 starts playing. If a file is well-formed (with metadata at the | |
| 49 beginning of a file), nginx just sends back the contents of a file. | |
| 50 Otherwise, it has to read the file and prepare a new stream so that | |
| 51 metadata comes before media data. | |
| 52 This involves some CPU, memory, and disk I/O overhead, | |
| 53 so it is a good idea to | |
| 54 <a href="http://flowplayer.org/plugins/streaming/pseudostreaming.html#prepare"> | |
| 55 prepare an original file for pseudo-streaming</a>, | |
| 56 rather than having nginx do this on every such request. | |
| 57 </para> | |
| 58 | |
| 59 <para> | |
| 60 For a matching request with a non-zero | |
| 61 <parameter>start</parameter> | |
| 62 argument, nginx will read metadata from the file, prepare the | |
| 63 stream starting from the requested offset, and send it to a client. | |
| 64 This has the same overhead as described above. | |
| 65 </para> | |
| 66 | |
| 67 <para> | |
| 68 If a matching request does not include the | |
| 69 <parameter>start</parameter> | |
| 70 argument, there is no overhead, and the file is just sent as a static resource. | |
| 71 Some players also support byte-range requests, and thus do not require | |
| 72 this module at all. | |
| 73 </para> | |
| 74 | |
| 75 <para> | |
| 76 This module is not built by default, it should be enabled with the | |
| 77 <command>--with-http_mp4_module</command> | |
| 78 configuration parameter. | |
| 79 <note> | |
| 80 If you were using the third-party mp4 module, be sure to disable it. | |
| 81 </note> | |
| 82 </para> | |
| 83 | |
| 84 <!-- | |
| 85 <para> | |
| 86 A similar pseudo-streaming support for FLV files is provided by the module | |
| 87 <a href="/en/docs/http/ngx_http_flv_module.xml">ngx_http_flv_module</a>. | |
| 88 </para> | |
| 89 --> | |
| 90 | |
| 91 </section> | |
| 92 | |
| 93 | |
|
33
ae5aca1efe2c
Using new <module> and <section> format in ngx_http_mp4_module.xml.
Igor Sysoev <igor@sysoev.ru>
parents:
22
diff
changeset
|
94 <section id="example" name="Usage example"> |
| 22 | 95 |
| 96 <para> | |
| 97 <example> | |
| 98 location /video/ { | |
| 99 mp4; | |
| 100 mp4_buffer_size 1m; | |
| 101 mp4_max_buffer_size 5m; | |
| 102 } | |
| 103 </example> | |
| 104 </para> | |
| 105 | |
| 106 </section> | |
| 107 | |
| 108 | |
|
33
ae5aca1efe2c
Using new <module> and <section> format in ngx_http_mp4_module.xml.
Igor Sysoev <igor@sysoev.ru>
parents:
22
diff
changeset
|
109 <section id="directives" name="Directives"> |
| 22 | 110 |
| 111 <directive name="mp4"> | |
| 112 <syntax>mp4</syntax> | |
| 113 <default/> | |
| 114 <context>location</context> | |
| 115 | |
| 116 <para> | |
| 117 Turns on module processing in a surrounding location. | |
| 118 </para> | |
| 119 | |
| 120 </directive> | |
| 121 | |
| 122 | |
| 123 <directive name="mp4_buffer_size"> | |
| 124 <syntax>mp4_buffer_size <argument>size</argument></syntax> | |
| 125 <default>mp4_buffer_size 512K</default> | |
| 126 <context>http</context> | |
| 127 <context>server</context> | |
| 128 <context>location</context> | |
| 129 | |
| 130 <para> | |
| 131 Sets the initial size of a memory buffer used to process MP4 files. | |
| 132 </para> | |
| 133 | |
| 134 </directive> | |
| 135 | |
| 136 | |
| 137 <directive name="mp4_max_buffer_size"> | |
| 138 <syntax>mp4_max_buffer_size <argument>size</argument></syntax> | |
| 139 <default>mp4_max_buffer_size 10M</default> | |
| 140 <context>http</context> | |
| 141 <context>server</context> | |
| 142 <context>location</context> | |
| 143 | |
| 144 <para> | |
| 145 During metadata processing, a larger buffer may become necessary. | |
| 146 Its size cannot exceed the specified <argument>size</argument>, | |
| 147 or else nginx will return | |
| 148 <http-error code="500" text="Internal Server Error"/>, | |
| 149 and log the following: | |
| 150 <example> | |
| 151 "/some/movie/file.mp4" mp4 moov atom is too large: | |
| 152 12583268, you may want to increase mp4_max_buffer_size | |
| 153 </example> | |
| 154 </para> | |
| 155 | |
| 156 </directive> | |
| 157 | |
| 158 </section> | |
| 159 | |
| 160 </module> |