IFF library

Portamos includes a small IFF support library under the dev.rambris.iff package. It provides:

• IFF ILBM read/write via javax.imageio (Java’s standard ImageIO API)
• IFF 8SVX read/write via javax.sound.sampled (Java’s standard audio API)

Both providers are registered automatically through the Java SPI mechanism when portamos is on the classpath. No explicit registration code is needed.

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IFF ILBM images

IFF ILBM is the native image format on the Commodore Amiga. Portamos reads and writes indexed-colour ILBM images (with CMAP palette), including ByteRun1 compressed BODY data.

Reading an ILBM file

Use the standard ImageIO API:

import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;

BufferedImage image = ImageIO.read(Path.of("sprite.iff").toFile());
// image type is BufferedImage.TYPE_BYTE_INDEXED

Writing an ILBM file

import javax.imageio.ImageIO;
import javax.imageio.ImageWriter;
import javax.imageio.stream.FileImageOutputStream;
import dev.rambris.iff.imageio.IlbmWriteParam;

BufferedImage image = ...; // must be TYPE_BYTE_INDEXED

Iterator<ImageWriter> writers = ImageIO.getImageWritersByFormatName("ilbm");
ImageWriter writer = writers.next();

IlbmWriteParam param = (IlbmWriteParam) writer.getDefaultWriteParam();
// param.setCompressionMode(ImageWriteParam.MODE_EXPLICIT);
// param.setCompressionType("ByteRun1");

try (var out = new FileImageOutputStream(Path.of("output.iff").toFile())) {
    writer.setOutput(out);
    writer.write(null, new IIOImage(image, null, null), param);
}

Supported format names for ImageIO: "ilbm", "iff".

IlbmUtility

IlbmUtility provides convenience methods for working with Amiga screen geometry and palette data:

import dev.rambris.iff.IlbmUtility;

// Convert a BufferedImage.TYPE_BYTE_INDEXED to an IlbmImage model
IlbmImage ilbm = IlbmUtility.fromBufferedImage(image);

// Convert back
BufferedImage result = IlbmUtility.toBufferedImage(ilbm);

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IFF 8SVX audio

IFF 8SVX is the native mono audio format on the Commodore Amiga. Portamos reads and writes 8SVX files as 8-bit signed PCM streams via the Java Sound API.

Reading an 8SVX file

import javax.sound.sampled.AudioSystem;
import javax.sound.sampled.AudioInputStream;

AudioInputStream audio = AudioSystem.getAudioInputStream(Path.of("sample.8svx").toFile());
// audio.getFormat() returns 8-bit signed PCM at the sample's native frequency
byte[] pcmData = audio.readAllBytes();

Writing an 8SVX file

import javax.sound.sampled.AudioSystem;
import javax.sound.sampled.AudioFormat;
import javax.sound.sampled.AudioInputStream;
import dev.rambris.iff.audio.Svx8AudioFileTypes;

AudioFormat format = new AudioFormat(8363f, 8, 1, true, false);
byte[] pcmData = ...; // 8-bit signed PCM samples

AudioInputStream audio = new AudioInputStream(
    new ByteArrayInputStream(pcmData), format, pcmData.length);

AudioSystem.write(audio, Svx8AudioFileTypes.SVX8, Path.of("output.8svx").toFile());

The Svx8AudioFileTypes.SVX8 constant identifies the 8SVX file type to the AudioSystem.

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Low-level IFF parsing

For custom IFF chunk handling, use IffReader and IffWriter directly:

import dev.rambris.iff.IffReader;
import dev.rambris.iff.IffId;

byte[] raw = Files.readAllBytes(Path.of("custom.iff"));
IffReader reader = new IffReader(raw);

reader.read((id, data) -> {
    System.out.printf("Chunk %s: %d bytes%n", id, data.length);
    return true; // return false to stop
});

import dev.rambris.iff.IffWriter;
import dev.rambris.iff.FourCC;

IffWriter writer = new IffWriter();
writer.beginGroup(FourCC.of("FORM"), FourCC.of("MYTP"));
writer.writeChunk(FourCC.of("DATA"), myPayload);
writer.endGroup();

byte[] iff = writer.toBytes();