For all supported file types, Assets Server generates previews to display in the Web clients and in API clients. The previews are all based on lightweight Web formats and can therefore be quickly displayed and navigated.
Generated previews
The following table shows the file formats that are generated for the various types of files:
| File type | Preview file format |
|---|---|
| Images and PDFs | JPEG |
| Videos | mp3 |
| Audio files |
|
| Most documents | HTML |
Default preview formats
Previews of an asset can be requested by using the asset ID or the assetPath, using the following syntax:
- Example using the asset ID:
http://demo.assets-server.com/preview/5LMAQTW9qfhANn7f6JJVpl
- Example using the assetPath:
http://demo.assets-server.com/preview/Demo%20Zone/Images/Travel/Architecture/Domein%20Hofstade.jpg
The default previews are equal to the previews in Assets.
| File type | Preview format |
|---|---|
| Images | maxWidth_1600_maxHeight_1600.jpg |
| PDF or PowerPoint | maxWidth_1600_maxHeight_1600_page_0.jpg |
| Videos | maxWidth_480_maxHeight_360.mp4 |
| Audio files |
|
Customized preview formats
By altering the preview URL, customized preview formats can be requested from the server such as a smaller JPEG preview, a different page of a PDF or a video preview in FLV format.
Note: Custom preview formats are not supported for HTML previews.
If these previews have not been generated yet, they will be generated on-the-fly by the server and stored in the Assets Server Shared Data/renditionFileStore folder.
- Example using the asset ID:
http://demo.assets-server.com/preview/5LMAQTW9qfhANn7f6JJVpl/previews/maxWidth_1600_maxHeight_1600.jpg
- Example using the assetPath:
http://demo.assets-server.com/preview/Demo%20Zone/Images/Travel/Architecture/Domein%20Hofstade.jpg/previews/maxWidth_1600_maxHeight_1600.jpg
- Default preview with different extension:
preview.tiff
- Smaller preview for use on a Web page:
maxWidth_500_maxHeight_350.jpg
- Preview for page 3 of a PDF or slide 3 of a PowerPoint:
maxWidth_1600_maxHeight_1600_page_3.jpg
- HD (720p) preview for a video:
maxWidth_1280_maxHeight_720.mp4
- Flash video format preview:
maxWidth_640_maxHeight_480.flv
Using a custom file name
By default the file name of the requested image contains the parameters as supplied in the URL.
Example: maxWidth_1600_maxHeight_1600.jpg
To use a custom file name, add the following to the end of the URL:
file name/*/extension
- Examples using the asset ID:
http://demo.assets-server.com/preview/5LMAQTW9qfhANn7f6JJVpl////my-custom-name.jpg
http://demo.assets-server.com/preview/5LMAQTW9qfhANn7f6JJVpl/*/my-custom-name.jpg
- Example using the assetPath:
http://demo.assets-server.com/preview/5LMAQTW9qfhANn7f6JJVpl/previews/maxWidth_1600_maxHeight_1600.jpg////my-custom-name.jpg
http://demo.assets-server.com/preview/5LMAQTW9qfhANn7f6JJVpl/previews/maxWidth_1600_maxHeight_1600.jpg/*/my-custom-name.jpg
Changing the file name separator
In case a different separator needs to be used (for example by changing it back to 4 forward slashes), add the following property to the cluster-config.properties file:
downloadUrlFilenameSeparator=
Example: downloadUrlFilenameSeparator=////
Supported properties
maxWidth and maxHeight
- Description: Sets the maximum width and/or height of the preview. The aspect ratio will always remain the same. If the original asset fits within the supplied dimensions, the original width and height will be used for generating the preview. It is allowed to just supply one of the dimensions.
- Applicable file types: Images, videos, PDFs, presentations and layouts.
- Value: numeric.
- Example:
maxWidth_800_maxHeight_600.jpg
cropWidth and cropHeight
- Description: Sets the width and/or height (in pixels) to which an image should be cropped.
- Note: Because the image processing engine on MacOS does not support cropping, this functionality only works on Windows and Linux servers; it does not work on a MacOS server.
- Applicable file types: Images.
- Value: numeric.
- Example:
cropWidth_500_cropHeight_400.jpg
With crop offset (see below):
cropWidth_500_cropHeight_400_cropOffsetX_750_cropOffsetY_800.jpg
cropOffsetX and cropOffsetY
- Description: Sets the crop x and/or y offset in pixels (from the top left corner).
- Note: Because the image processing engine on MacOS does not support cropping, this functionality only works on Windows and Linux servers; it does not work on a MacOS server.
- Applicable file types: Images.
- Value: numeric.
- Example:
cropOffsetX_750_cropOffsetY_800.jpg
With crop width and height (see above):
cropWidth_500_cropHeight_400_cropOffsetX_750_cropOffsetY_800.jpg
scale
- Description: Sets the width and height of the preview relative to the original size. The scale is in percentages from 1 to 100. If used in combination with maxWidth or maxHeight the image will be scaled with a maximum size.
- Applicable file types: Images.
- Value: 1 – 100.
- Example:
scale_50.jpg
PPI / DPI
- Description: The pixels per inch / dots per inch can be set to any desired value. When not set, the original PPI / DPI value of the file will be used. .
- Applicable file types: Images.
- Value: numeric.
- Example:
maxWidth_800_maxHeight_600_ppi_72.jpg
compression
- Description: TIFF compression.
- Applicable file types: Images.
- Value: uncompressed, packBits, LZW, ZIP and JPEG.
- Example:
maxHeight_600_compression_packBits.tiff
quality
- Description: JPEG compression quality 1 - 100.
- Applicable file types: JPEG images.
- Value: 1 – 100.
- Example:
scale_75_quality_12.jpg
maxLength
- Description: Limits the length of audio previews. The value is in milliseconds.
- Applicable file types: Audio files.
- Value: numeric.
- Example:
maxLength_60000.mp3
page
- Description: The page of the PDF or presentation to create a preview from. The value can range from 1 to the number of pages in the document. The preview will always have .jpg as extension.
- Applicable file types: PDFs, presentations and layouts.
- Value: numeric.
- Example:
maxWidth_1600_maxHeight_1600_page_3.jpg
embedMetadata
- Description: When set to true the metadata embedded in the original asset will be embedded in the generated preview. Note that for certain file types the embedding of metadata is not supported, for example for PNG files. By default the original metadata is not embedded.
- Applicable file types: Images, PDFs, presentations and layouts.
- Value: true or false
- Example:
maxWidth_800_maxHeight_600_ppi_72_embedMetadata_true.jpg
Extensions
- Description: The extension of the generated preview can be different from the original.
- Applicable file types: Images, PDFs, presentations and layouts.
- Value:
- Images: jpg, png, tiff
- Videos: flv, mp4
- Audio files: mp3, flv
- PDF, presentation, layout: jpg
- Example:
maxWidth_800_maxHeight_600.png
embedColorProfile
- Description: When set to true the color profile that is used to generate the preview is included.
- Applicable file types: Images.
- Value: true or false
- Example:
maxWidth_1600_maxHeight_1600_embedColorProfile_true.jpg
background
- Description: Sets the background color for transparent images. If not specified, the output of PNG and TIFF images will be transparent.
- Applicable file types: Images.
- Value: An RGB hex triplet.
- Example:
maxWidth_800_maxHeight_600_background_F0F0F0.jpg
Comment
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