New Features
- A Tips and Tricks blog at http://blog.calibre-ebook.com [External link] to introduce less well known calibre features in a simple way
- Add a special output profile for the PocketBook 900 as it does not resize images correctly by itself
- Amazon metadata download plugin: Add option to download metadata from amazon.es
- Driver for Vizio and iRobot A9 Android tablets. Closes tickets: 854408 [External link] , 862175 [External link]
- News download: Add list of articles in the downloaded issue to the comments metadata of the generated ebook. Makes it possible to search for a particular article in the calibre library.
- Template language: Add list_equals function
- Toolbar buttons: You can now also right click the buttons to bring the popup of extra actions, in addition to clicking the small arrow next to the button.
- When switching to/starting with a library with a corrupted database, offer the user the option of rebuilding the database instead of erroring out.

Bug Fixes
- Allow user defined templates to be used in save to disk
- Content server: When a search matches no queries, do not show an error message
- Content server: When WSGI embedding fix handling of empty URL
- Do not delete the file when the user tries to add a format to a book from a file already in the books directory. Closes tickets: 856158 [External link]
- Fix incorrect display of the month September in Finnish calibre. Closes tickets: 858737 [External link]
- Fix reading metadata from filenames when the author regexp does not match anything
- Fix regression that broke clicking on the first letter of author names in the Tag Browser when grouped. Closes tickets: 860615 [External link]
- Fix regression that broke customization of Kobo device plugin
- Fix regression that cause PDF Output to generate very large files
- Fix Title Sort field not being displayed in Book details panel
- Get books: Fix getting price from Foyles
- ODT Input: Add workaround for ADE to fix centering of block level images when converting to EPUB. Closes tickets: 859343 [External link]
- Prevent renaming of languages in the Tag browser. Closes tickets: 860943 [External link]
- RTF Input: Fix spurious spaces inserted after some unicode characters. Closes tickets: 851215 [External link]

New news sources
- Den of Geek by Jaded
- Folha de Sao Paulo (full edition) by fluzao
- Gosc Niedzielny by Piotr Kontek
- Leipzer Volkszeitung by a.peter
- Republica by Manish Bhattarai
- Sign on San Diego by Jay Kindle
- Various Colombian news sources by BIGO-CAVA

Improved news sources
- American Prospect
- American Spectator
- Chicago Tribune
- Cnet
- DNA India
- Kurier
- Read It Later
- Sydney Morning Herald
- Times of India
- xkcd

Actions: toggle multichannel track metering, now in track menu
API: added SetProjectMarker3() and AddProjectMarker2() for setting custom marker colors
API: threading fixes for GetSetObjectState() and other related APIs
Directory cleanup: now looks for media references in project bay media items
Envelopes: fixed editing point values for FX wet/dry envelopes
Envelopes: pitch envelopes snap configuration (1 semitone, 50 cent, 25 cent, 10 cent, 5 cent, 1 cent, off)
Fades/crossfades: prevent unintentional crossfade edits when media items are adjacent but not crossfaded
FX: fixed possible excess midi notes on loop when PDC FX are used
FX: improved undo state tracking when copying/moving FX between tracks
FX: if project samplerate set and loading project, try to initialize loaded plug-ins at correct rate (avoid later reinit)
FX: pin mappings are now stored more safely, fix for possible race conditions
Freeze: actions to render tracks in-place with FX, then save/remove existing media and online FX
Freeze: menu actions in FX chain window to freeze track up to last selected FX
Grouping: fix for rare item group reuse bug
Media explorer: fixed crash issue when group policy prevented embedded explorer (falls back to non-explorer view)
Metering: new multichannel tracks default to multichannel metering enabled
Metering: master multichannel metering is now optional
Mixer: scroll improvements/fixes
Mixer: opening/unhiding mixer now makes last selected track visible
Mixer: restore undocked mixer window position in docked screensets
MIDI: use MIDI track name event when importing files
MIDI files: options to automatically snap time signature changes, tempo changes on file import
MIDI editor: switching sources via filter window no longer unhides all other sources
MIDI editor: undo fixes, especially related to list editor
MIDI editor: improved list view default focus, toolbar focus
MIDI editor: note properties fixed reset of combo boxes on multiple note selection
MIDI editor: inline editor marquee fix
MIDI editor: fixed bug when quantizing notes that were drawn in (not painted or recorded)
MIDI editor: fixed context menu doubleness when clicking above piano keys
MIDI editor: support painting notes in drum mode with very small grid
MIDI editor: step recording works when docked
Mouse modifiers: support ripple edit (off, one track, all tracks) while moving items
Mouse modifiers: import/export mouse modifier support (.ReaperMouseMap files)
Mouse modifiers: obey user preferences to seek playback when middle clicking ruler or arrange view
OSX: better behavior when using modal windows (such as save as with convert) when REAPER inactive
Playback: corrected minor rounding bug on playback start in certain instances
Relative snap: avoid clearing snap offset when copying media items
Render: new user setting for tail length to use in project render, stem render, track freeze
Render: fixed certain issues with filename wildcards
Scale finder: button to use selected notes in MIDI editor
Scale finder: added topmost window pin
Scrub/jog: don't snap edit cursor
Sends: shift+drag IO from unselected track to selected uses all selected tracks as receivers
SRC: fixed quality/synchronization issue (4.0x regression)
Toolbars: store toolbar assignments in screensets
Topmost pin buttons: bug fixes, buttons now remember their last states (based on window title)
Track manager, region manager, project bay: columns can be reordered
Track manager: added freeze column/button
Undo history: improved keyboard behavior (return loads state, escape when docked sets focus to arrange, other keys passed through to main)
Vertical zooming: scrollbar fixes, better behavior
Video: improved rendering accuracy, support for rendering with playrates
Video: hide topmost pin when going fullscreen
Video: updated API to support the newest FFmpeg/libav version (v53)
VST: support effSetSpeakerArrangement notifications for plug-ins