In certain contexts, transcoding is evil. Sometimes people wish to convert one lossy file format to another, say MP3 to OGG Vorbis for the sake of consistancy. All too often folks don't realize that this results in decreased quality, no matter what bitrate the resulting file is encoding at. If you share transcoded music files with people, they will be very angry at you. Sometimes transcoding is necessary, for example when the source is compressed in a lossy format. This holds true for operations like compressing a DVD down to one or two CD's. For most forms of lossy compression, results will always be best if the highest quality input is used.