/**
* decode palette from the input stream
*
* @param pic SubPicture object containing info about the current caption
* @return
* @throws CoreException
*/
private Palette decodePalette(SubPictureBD pic) throws CoreException {
boolean fadeOut = false;
int paletteIndex;
List<PaletteInfo> paletteInfos = pic.getPalettes().get(pic.getImageObject().getPaletteID());
if (paletteInfos == null) {
throw new CoreException("Palette ID out of bounds.");
}
Palette palette = new Palette(256, Core.usesBT601());
// by definition, index 0xff is always completely transparent
// also all entries must be fully transparent after initialization
try {
for (PaletteInfo paletteInfo : paletteInfos) {
int index = paletteInfo.getPaletteOffset();
for (int i = 0; i < paletteInfo.getPaletteSize(); i++) {
// each palette entry consists of 5 bytes
paletteIndex = buffer.getByte(index);
int y = buffer.getByte(++index);
int cr, cb;
if (configuration.isSwapCrCb()) {
cb = buffer.getByte(++index);
cr = buffer.getByte(++index);
} else {
cr = buffer.getByte(++index);
cb = buffer.getByte(++index);
}
int alpha = buffer.getByte(++index);
int alphaOld = palette.getAlpha(paletteIndex);
// avoid fading out
if (alpha >= alphaOld) {
if (alpha
< configuration
.getAlphaCrop()) { // to not mess with scaling algorithms, make transparent
// color black
y = 16;
cr = 128;
cb = 128;
}
palette.setAlpha(paletteIndex, alpha);
} else {
fadeOut = true;
}
palette.setYCbCr(paletteIndex, y, cb, cr);
index++;
}
}
if (fadeOut) {
logger.warn("fade out detected -> patched palette\n");
}
return palette;
} catch (FileBufferException ex) {
throw new CoreException(ex.getMessage());
}
}
