Update CHANGELOG for v2.2.1

Change-Id: Iedd53d423b5c71ab8aba8b671ca8fa4ad3ab933b

CHANGELOG.md

@@ -3,6 +3,24 @@
 - Disable bundled binutil and gold on Linux by default. There may be a slight
   increase in binary link time.
 
+## [2.2.1] - 2018-09-20
+### Added
+- Added support for seek preroll in AAC and other audio codecs (#452). This also
+  addressed 'Unexpected seek preroll for codecs ...' warnings.
+- Computes and sets VP9 Level in the codec config if it is not already set
+  (#469). This fixed VP9 in ISO-BMFF files generated by FFmpeg v4.0.2 or earlier
+  which does not have level set in the codec config.
+
+### Fixed
+- Added a workaround for TS contents with dts moving backwards (#451). So
+  instead of generating a sample with negative duration, which ExoPlayer does
+  not handle, use an arbitrarily short duration instead.
+- Fixed pattern signaling in seig for key rotation with cbcs (#460).
+- Fixed incorrect segment name with $Time$ in segment_template (#472). This
+  resulted in the first segment being overwritten and led to playback problems.
+- Fixed TTML text input passthrough in DASH (#478). This is a regression
+  introduced in v2.2.0.
+
 ## [2.2.0] - 2018-08-16
 ### Added
 - EditList support in ISO-BMFF in both input and output (#112).
@@ -414,6 +432,7 @@ First public release.
 - Added mpd_generator driver program to generate mpd file from packager generated
   intermediate files.
 
+[2.2.1]: https://github.com/google/shaka-packager/compare/v2.2.0...v2.2.1
 [2.2.0]: https://github.com/google/shaka-packager/compare/v2.1.1...v2.2.0
 [2.1.1]: https://github.com/google/shaka-packager/compare/v2.1.0...v2.1.1
 [2.1.0]: https://github.com/google/shaka-packager/compare/v2.0.3...v2.1.0