When the target is a text file, the Burrows-Wheeler method may be used, as, for example, in bzip2, while for audio targets WavPack or FLAC can be used.
PCX and TTA are, but AAC isn't, although Apple does support one of them. PNG is, and GIF should be, but because of dithering, in practice it usually isn't. Its performance is limited by the Shannon entropy of the original source, which cannot be reduced by applying this method. When the target is a text file, the Burrows-Wheeler method may be used, as, for example, in bzip2, while for audio targets WavPack or FLAC can be used. MP3s do not use it, and it can be achieved by the LZW algorithm and Huffman coding, but not by the discrete cosine transform, which is used to make JPEG images. For ten points, what is this type of encoding that is fully reversible, ensuring that all of the original data can be recovered?
PCX and TTA are, but AAC isn't, although Apple does support one of them.
lossless compression