In music, transcription is the practice of notating a piece or a sound which was previously unnotated and/or unpopular as a written music, for example, a jazz improvisation or a video game soundtrack. When a musician is tasked with creating sheet music from a recording and they write down the notes that make up the piece in music notation, it is said that they created a musical transcription of that recording. Transcription may also mean rewriting a piece of music, either solo or ensemble, for another instrument or other instruments than which it was originally intended. The Beethoven Symphonies transcribed for solo piano by Franz Liszt are an example. Transcription in this sense is sometimes called arrangement, although strictly speaking transcriptions are faithful adaptations, whereas arrangements change significant aspects of the original piece. Further examples of music transcription include ethnomusicological notation of oral traditions of folk music, such as Béla Bartók's and Ralph Vaughan Williams' collections of the national folk music of Hungary and England respectively. The French composer Olivier Messiaen transcribed birdsong in the wild, and incorporated it into many of his compositions, for example his Catalogue d'oiseaux for solo piano. Transcription of this nature involves scale degree recognition and harmonic analysis, both of which the transcriber will need relative or perfect pitch to perform. In popular music and rock, there are two forms of transcription. Individual performers copy a note-for-note guitar solo or other melodic line. As well, music publishers transcribe entire recordings of guitar solos and bass lines and sell the sheet music in bound books. Music publishers also publish PVG (piano/vocal/guitar) transcriptions of popular music, where the melody line is transcribed, and then the accompaniment on the recording is arranged as a piano part. The guitar aspect of the PVG label is achieved through guitar chords written above the melody. Lyrics are also included below the melody. Adaptation Some composers have rendered homage to other composers by creating "identical" versions of the earlier composers' pieces while adding their own creativity through the use of completely new sounds arising from the difference in instrumentation. The most widely known example of this is Ravel's arrangement for orchestra of Mussorgsky's piano piece Pictures at an Exhibition. Webern used his transcription for orchestra of the six-part ricercar from Bach's The Musical Offering to analyze the structure of the Bach piece, by using different instruments to play different subordinate motifs of