PowerShell

Compress Large Binary File in Blocks

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Compresses a large binary file in blocks. PowerShell

Add-Type -Path "C:\chilkat\ChilkatDotNet47-x64\ChilkatDotNet47.dll"

$success = $false

# This example assumes the Chilkat API to have been previously unlocked.
# See Global Unlock Sample for sample code.

$facSrc = New-Object Chilkat.FileAccess
$facDest = New-Object Chilkat.FileAccess

# Open a large binary file for reading.
$success = $facSrc.OpenForRead("qa_data/bmp/big.bmp")
if ($success -eq $false) {
    $($facSrc.LastErrorText)
    exit
}

# If we compress in 64K chunks, find out how many blocks there will be.
$blockSize = 65536
$numBlocks = $facSrc.GetNumBlocks($blockSize)

# Open an output file for the compressed data.
$success = $facDest.OpenForWrite("c:/temp/qa_output/compressedBmp.dat")
if ($success -eq $false) {
    $($facDest.LastErrorText)
    exit
}

$compress = New-Object Chilkat.Compression
$compress.Algorithm = "deflate"

# Assuming numBlocks > 1
$compress.FirstChunk = $true
$compress.LastChunk = $false

$i = 0
while ($i -lt $numBlocks) {
    $fileBytes = $facSrc.ReadBlock($i,$blockSize)
    $compressedBytes = $compress.CompressBytes($fileBytes)

    $facDest.FileWrite($compressedBytes)

    $i = $i + 1

    $compress.FirstChunk = $false
    if ($i -eq ($numBlocks - 1)) {
        $compress.LastChunk = $true
    }

}

$facSrc.FileClose()
$facDest.FileClose()

$("Finished compressing file.")