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79 lines
2.9 KiB
Markdown
79 lines
2.9 KiB
Markdown
# Media Repository
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*Synapse implementation-specific details for the media repository*
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The media repository
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* stores avatars, attachments and their thumbnails for media uploaded by local
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users.
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* caches avatars, attachments and their thumbnails for media uploaded by remote
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users.
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* caches resources and thumbnails used for URL previews.
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All media in Matrix can be identified by a unique
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[MXC URI](https://spec.matrix.org/latest/client-server-api/#matrix-content-mxc-uris),
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consisting of a server name and media ID:
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```
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mxc://<server-name>/<media-id>
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```
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## Local Media
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Synapse generates 24 character media IDs for content uploaded by local users.
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These media IDs consist of upper and lowercase letters and are case-sensitive.
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Other homeserver implementations may generate media IDs differently.
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Local media is recorded in the `local_media_repository` table, which includes
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metadata such as MIME types, upload times and file sizes.
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Note that this table is shared by the URL cache, which has a different media ID
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scheme.
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### Paths
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A file with media ID `aabbcccccccccccccccccccc` and its `128x96` `image/jpeg`
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thumbnail, created by scaling, would be stored at:
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```
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local_content/aa/bb/cccccccccccccccccccc
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local_thumbnails/aa/bb/cccccccccccccccccccc/128-96-image-jpeg-scale
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```
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## Remote Media
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When media from a remote homeserver is requested from Synapse, it is assigned
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a local `filesystem_id`, with the same format as locally-generated media IDs,
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as described above.
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A record of remote media is stored in the `remote_media_cache` table, which
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can be used to map remote MXC URIs (server names and media IDs) to local
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`filesystem_id`s.
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### Paths
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A file from `matrix.org` with `filesystem_id` `aabbcccccccccccccccccccc` and its
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`128x96` `image/jpeg` thumbnail, created by scaling, would be stored at:
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```
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remote_content/matrix.org/aa/bb/cccccccccccccccccccc
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remote_thumbnail/matrix.org/aa/bb/cccccccccccccccccccc/128-96-image-jpeg-scale
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```
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Older thumbnails may omit the thumbnailing method:
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```
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remote_thumbnail/matrix.org/aa/bb/cccccccccccccccccccc/128-96-image-jpeg
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```
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Note that `remote_thumbnail/` does not have an `s`.
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## URL Previews
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When generating previews for URLs, Synapse may download and cache various
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resources, including images. These resources are assigned temporary media IDs
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of the form `yyyy-mm-dd_aaaaaaaaaaaaaaaa`, where `yyyy-mm-dd` is the current
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date and `aaaaaaaaaaaaaaaa` is a random sequence of 16 case-sensitive letters.
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The metadata for these cached resources is stored in the
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`local_media_repository` and `local_media_repository_url_cache` tables.
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Resources for URL previews are deleted after a few days.
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### Paths
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The file with media ID `yyyy-mm-dd_aaaaaaaaaaaaaaaa` and its `128x96`
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`image/jpeg` thumbnail, created by scaling, would be stored at:
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```
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url_cache/yyyy-mm-dd/aaaaaaaaaaaaaaaa
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url_cache_thumbnails/yyyy-mm-dd/aaaaaaaaaaaaaaaa/128-96-image-jpeg-scale
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```
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