Improvement by benchmarking (Essay on automated music engraving)

#### Improvement by benchmarking

LilyPond’s output has improved gradually over time, and it continues to improve by comparing its output to hand-engraved scores.

For example, here is one line of a benchmark piece from a hand-engraved edition (Bärenreiter BA320):

and the same quotation as engraved by a very old version of LilyPond (version 1.4, May 2001):

The LilyPond 1.4 output is certainly readable, but close comparison with the hand-engraved score showed a lot of errors in the formatting details:

- there is too much space before the time signature
- the stems of the beamed notes are too long
- the second and fourth measures are too narrow
- the slur is awkward-looking
- the trill marks are too big
- the stems are too thin

(There were also two missing note heads, several missing editorial annotations, and an incorrect pitch!)

By adjusting the layout rules and font design, the output has improved considerably. Compare the same reference score and the output from the current version of LilyPond (2.26.0):

The current output is not a clone of the reference edition, but it is much closer to publication quality that the earlier output.

#### Essay on automated music engraving v2.26.0 (stable-branch).

- 1 Music engraving
  - 1.1 The LilyPond story
  - 1.2 Engraving details
    - Music fonts
    - Optical spacing
    - Ledger lines
    - Optical sizing
    - Why work so hard?
  - 1.3 Automated engraving
    - Beauty contests
    - Improvement by benchmarking
    - Getting things right
  - 1.4 Building software
    - Music representation
    - What symbols to engrave?
    - Flexible architecture
  - 1.5 Putting LilyPond to work
  - 1.6 Engraved examples (BWV 861)
- 2 Literature list
  - 2.1 Short literature list
  - 2.2 Long literature list
- Appendix A GNU Free Documentation License
- Appendix B Index