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href="deprecation_policy.html">Dependency Deprecation Policy</a></li><li class="chapter-item expanded "><a href="other/running_synapse_on_single_board_computers.html">Running Synapse on a Single-Board Computer</a></li></ol>
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<h1 id="media-repository"><a class="header" href="#media-repository">Media Repository</a></h1>
<p><em>Synapse implementation-specific details for the media repository</em></p>
<p>The media repository</p>
<ul>
<li>stores avatars, attachments and their thumbnails for media uploaded by local
users.</li>
<li>caches avatars, attachments and their thumbnails for media uploaded by remote
users.</li>
<li>caches resources and thumbnails used for
<a href="development/url_previews.html">URL previews</a>.</li>
</ul>
<p>All media in Matrix can be identified by a unique
<a href="https://spec.matrix.org/latest/client-server-api/#matrix-content-mxc-uris">MXC URI</a>,
consisting of a server name and media ID:</p>
<pre><code>mxc://<server-name>/<media-id>
</code></pre>
<h2 id="local-media"><a class="header" href="#local-media">Local Media</a></h2>
<p>Synapse generates 24 character media IDs for content uploaded by local users.
These media IDs consist of upper and lowercase letters and are case-sensitive.
Other homeserver implementations may generate media IDs differently.</p>
<p>Local media is recorded in the <code>local_media_repository</code> table, which includes
metadata such as MIME types, upload times and file sizes.
Note that this table is shared by the URL cache, which has a different media ID
scheme.</p>
<h3 id="paths"><a class="header" href="#paths">Paths</a></h3>
<p>A file with media ID <code>aabbcccccccccccccccccccc</code> and its <code>128x96</code> <code>image/jpeg</code>
thumbnail, created by scaling, would be stored at:</p>
<pre><code>local_content/aa/bb/cccccccccccccccccccc
local_thumbnails/aa/bb/cccccccccccccccccccc/128-96-image-jpeg-scale
</code></pre>
<h2 id="remote-media"><a class="header" href="#remote-media">Remote Media</a></h2>
<p>When media from a remote homeserver is requested from Synapse, it is assigned
a local <code>filesystem_id</code>, with the same format as locally-generated media IDs,
as described above.</p>
<p>A record of remote media is stored in the <code>remote_media_cache</code> table, which
can be used to map remote MXC URIs (server names and media IDs) to local
<code>filesystem_id</code>s.</p>
<h3 id="paths-1"><a class="header" href="#paths-1">Paths</a></h3>
<p>A file from <code>matrix.org</code> with <code>filesystem_id</code> <code>aabbcccccccccccccccccccc</code> and its
<code>128x96</code> <code>image/jpeg</code> thumbnail, created by scaling, would be stored at:</p>
<pre><code>remote_content/matrix.org/aa/bb/cccccccccccccccccccc
remote_thumbnail/matrix.org/aa/bb/cccccccccccccccccccc/128-96-image-jpeg-scale
</code></pre>
<p>Older thumbnails may omit the thumbnailing method:</p>
<pre><code>remote_thumbnail/matrix.org/aa/bb/cccccccccccccccccccc/128-96-image-jpeg
</code></pre>
<p>Note that <code>remote_thumbnail/</code> does not have an <code>s</code>.</p>
<h2 id="url-previews"><a class="header" href="#url-previews">URL Previews</a></h2>
<p>See <a href="development/url_previews.html">URL Previews</a> for documentation on the URL preview
process.</p>
<p>When generating previews for URLs, Synapse may download and cache various
resources, including images. These resources are assigned temporary media IDs
of the form <code>yyyy-mm-dd_aaaaaaaaaaaaaaaa</code>, where <code>yyyy-mm-dd</code> is the current
date and <code>aaaaaaaaaaaaaaaa</code> is a random sequence of 16 case-sensitive letters.</p>
<p>The metadata for these cached resources is stored in the
<code>local_media_repository</code> and <code>local_media_repository_url_cache</code> tables.</p>
<p>Resources for URL previews are deleted after a few days.</p>
<h3 id="paths-2"><a class="header" href="#paths-2">Paths</a></h3>
<p>The file with media ID <code>yyyy-mm-dd_aaaaaaaaaaaaaaaa</code> and its <code>128x96</code>
<code>image/jpeg</code> thumbnail, created by scaling, would be stored at:</p>
<pre><code>url_cache/yyyy-mm-dd/aaaaaaaaaaaaaaaa
url_cache_thumbnails/yyyy-mm-dd/aaaaaaaaaaaaaaaa/128-96-image-jpeg-scale
</code></pre>
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