Package org.tukaani.xz

Class DeltaOptions

java.lang.Object
org.tukaani.xz.FilterOptions
org.tukaani.xz.DeltaOptions
All Implemented Interfaces:
Cloneable
public class DeltaOptions
extends FilterOptions
Delta filter options. The Delta filter can be used only as a non-last filter in the chain, for example Delta + LZMA2.

Currently only simple byte-wise delta is supported. The only option is the delta distance, which you should set to match your data. It's not possible to provide a generic default value for it.

For example, with distance = 2 and eight-byte input A1 B1 A2 B3 A3 B5 A4 B7, the output will be A1 B1 01 02 01 02 01 02.

The Delta filter can be good with uncompressed bitmap images. It can also help with PCM audio, although special-purpose compressors like FLAC will give much smaller result at much better compression speed.

  • Field Details

    • DISTANCE_MIN

      public static final int DISTANCE_MIN
      Smallest supported delta calculation distance.
      See Also:
      Constant Field Values

    • DISTANCE_MAX

      public static final int DISTANCE_MAX
      Largest supported delta calculation distance.
      See Also:
      Constant Field Values

  • Constructor Details

    • DeltaOptions

      public DeltaOptions()
      Creates new Delta options and sets the delta distance to 1 byte.

    • DeltaOptions

      public DeltaOptions​(int distance) throws UnsupportedOptionsException
      Creates new Delta options and sets the distance to the given value.
      Throws:
      UnsupportedOptionsException

  • Method Details

    • setDistance

      public void setDistance​(int distance) throws UnsupportedOptionsException
      Sets the delta distance in bytes. The new distance must be in the range [DISTANCE_MIN, DISTANCE_MAX].
      Throws:
      UnsupportedOptionsException

    • getDistance

      public int getDistance()
      Gets the delta distance.

    • getEncoderMemoryUsage

      public int getEncoderMemoryUsage()
      Description copied from class: FilterOptions
      Gets how much memory the encoder will need with these options.
      Specified by:
      getEncoderMemoryUsage in class FilterOptions

    • getOutputStream

      public FinishableOutputStream getOutputStream​(FinishableOutputStream out, ArrayCache arrayCache)
      Description copied from class: FilterOptions
      Gets a raw (no XZ headers) encoder output stream using these options and the given ArrayCache. Raw streams are an advanced feature. In most cases you want to store the compressed data in the .xz container format instead of using a raw stream. To use this filter in a .xz file, pass this object to XZOutputStream.
      Specified by:
      getOutputStream in class FilterOptions

    • getDecoderMemoryUsage

      public int getDecoderMemoryUsage()
      Description copied from class: FilterOptions
      Gets how much memory the decoder will need to decompress the data that was encoded with these options.
      Specified by:
      getDecoderMemoryUsage in class FilterOptions

    • getInputStream

      public InputStream getInputStream​(InputStream in, ArrayCache arrayCache)
      Description copied from class: FilterOptions
      Gets a raw (no XZ headers) decoder input stream using these options and the given ArrayCache.
      Specified by:
      getInputStream in class FilterOptions

    • clone

      public Object clone()
      Overrides:
      clone in class Object