Mercurial > hg > nginx-site
annotate xml/en/docs/http/ngx_http_mp4_module.xml @ 151:0188d11c77dd
Initial translation of the ngx_http_flv_module documentation.
| author | Ruslan Ermilov <ru@nginx.com> |
|---|---|
| date | Tue, 25 Oct 2011 18:00:49 +0000 |
| parents | 682163f2b298 |
| children | 4c6d2c614d2c |
| rev | line source |
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| 22 | 1 <?xml version="1.0"?> |
| 2 | |
| 3 <!DOCTYPE module SYSTEM "../../../../dtd/module.dtd"> | |
| 4 | |
| 89 | 5 <module name="Module ngx_http_mp4_module" |
| 22 | 6 link="/en/docs/http/ngx_http_mp4_module.html" |
| 7 lang="en"> | |
| 8 | |
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9 <section id="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 | |
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14 <path>.mp4</path>, <path>.m4v</path>, and <path>.m4a</path>. |
| 22 | 15 </para> |
| 16 | |
| 17 <para> | |
| 88 | 18 Pseudo-streaming works in alliance with conforming Flash players. |
| 22 | 19 A player sends an HTTP request to the server with a start time |
| 20 argument in the request URI’s query string (named simply | |
| 21 <parameter>start</parameter> | |
| 22 and specified in seconds), and the server responds with a stream | |
| 23 so that its start position corresponds to the requested time, | |
| 24 for example: | |
| 25 <example> | |
| 26 http://example.com/elephants_dream.mp4?start=238.88 | |
| 27 </example> | |
| 28 This allows for a random seeking at any time, or starting playback | |
| 29 in the middle of a timeline. | |
| 30 </para> | |
| 31 | |
| 32 <para> | |
| 33 To support seeking, H.264-based formats store the metadata | |
| 34 in the so-called “moov atom.” | |
| 35 It is a part of the file that holds the index information for the | |
| 36 whole file. | |
| 37 </para> | |
| 38 | |
| 39 <para> | |
| 40 To start playback, a player first needs to read metadata. | |
| 41 This is done by sending a special request with the | |
| 42 <parameter>start=0</parameter> | |
| 43 argument. Many encoding software will insert the metadata at | |
| 44 the end of the file. This is bad for pseudo-streaming: | |
| 45 the metadata needs to be located at the beginning of the file, | |
| 46 or else the entire file will have to be downloaded before it | |
| 47 starts playing. If a file is well-formed (with metadata at the | |
| 48 beginning of a file), nginx just sends back the contents of a file. | |
| 49 Otherwise, it has to read the file and prepare a new stream so that | |
| 50 metadata comes before media data. | |
| 51 This involves some CPU, memory, and disk I/O overhead, | |
| 52 so it is a good idea to | |
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53 <link |
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54 url="http://flowplayer.org/plugins/streaming/pseudostreaming.html#prepare"> |
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55 prepare an original file for pseudo-streaming</link>, |
| 22 | 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 | |
| 54 | 77 <code>--with-http_mp4_module</code> |
| 22 | 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 <para> | |
| 85 A similar pseudo-streaming support for FLV files is provided by the module | |
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86 <link doc="ngx_http_flv_module.xml">ngx_http_flv_module</link>. |
| 22 | 87 </para> |
| 88 | |
| 89 </section> | |
| 90 | |
| 91 | |
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92 <section id="example" name="Example Configuration"> |
| 22 | 93 |
| 94 <para> | |
| 95 <example> | |
| 96 location /video/ { | |
| 97 mp4; | |
| 98 mp4_buffer_size 1m; | |
| 99 mp4_max_buffer_size 5m; | |
| 100 } | |
| 101 </example> | |
| 102 </para> | |
| 103 | |
| 104 </section> | |
| 105 | |
| 106 | |
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107 <section id="directives" name="Directives"> |
| 22 | 108 |
| 109 <directive name="mp4"> | |
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110 <syntax/> |
| 22 | 111 <default/> |
| 112 <context>location</context> | |
| 113 | |
| 114 <para> | |
| 115 Turns on module processing in a surrounding location. | |
| 116 </para> | |
| 117 | |
| 118 </directive> | |
| 119 | |
| 120 | |
| 121 <directive name="mp4_buffer_size"> | |
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122 <syntax><argument>size</argument></syntax> |
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123 <default>512K</default> |
| 22 | 124 <context>http</context> |
| 125 <context>server</context> | |
| 126 <context>location</context> | |
| 127 | |
| 128 <para> | |
| 129 Sets the initial size of a memory buffer used to process MP4 files. | |
| 130 </para> | |
| 131 | |
| 132 </directive> | |
| 133 | |
| 134 | |
| 135 <directive name="mp4_max_buffer_size"> | |
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parents:
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136 <syntax><argument>size</argument></syntax> |
|
c76a257f3fd4
The directive name is now automatically printed in <default> and <syntax>.
Ruslan Ermilov <ru@nginx.com>
parents:
89
diff
changeset
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137 <default>10M</default> |
| 22 | 138 <context>http</context> |
| 139 <context>server</context> | |
| 140 <context>location</context> | |
| 141 | |
| 142 <para> | |
| 143 During metadata processing, a larger buffer may become necessary. | |
| 144 Its size cannot exceed the specified <argument>size</argument>, | |
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145 or else nginx will return the server error |
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146 <http-status code="500" text="Internal Server Error"/>, |
| 22 | 147 and log the following: |
| 148 <example> | |
| 149 "/some/movie/file.mp4" mp4 moov atom is too large: | |
| 150 12583268, you may want to increase mp4_max_buffer_size | |
| 151 </example> | |
| 152 </para> | |
| 153 | |
| 154 </directive> | |
| 155 | |
| 156 </section> | |
| 157 | |
| 158 </module> |