Filters

Configuring filters that process data during I/O operation (H5Z)

• H5Z_FILTER_AVAIL — Determines whether a filter is available. 
• H5Z_GET_FILTER_INFO — Retrieves information about a filter
• H5Z_REGISTER — Registers a new filter with the HDF5 library
• H5Z_UNREGISTER — Unregisters a filter.

HDF5 supports a filter pipeline that provides the capability for standard and customized raw data processing during I/O operations. HDF5 is distributed with a small set of standard filters such as compression (gzip, SZIP, and a shuffling algorithm) and error checking (Fletcher32 checksum). For further flexibility, the library allows a user application to extend the pipeline through the creation and registration of customized filters.

The flexibility of the filter pipeline implementation enables the definition of additional filters by a user application. A filter

• is associated with a dataset when the dataset is created,
• can be used only with chunked data 
  (i.e., datasets stored in the H5D_CHUNKED storage layout), and
• is applied independently to each chunk of the dataset.

The HDF5 library does not support filters for contiguous datasets because of the difficulty of implementing random access for partial I/O. Compact dataset filters are not supported because it would not produce significant results.

Filter identifiers for the filters distributed with the HDF5 Library are as follows:

Custom filters that have been registered with the library will have additional unique identifiers.

See HDF5 Dynamically Loaded Filters for more information on how an HDF5 application can apply a filter that is not registered with the HDF5 library.