Logs

Top-level build scripts print only the progress of the build to the console. Actual build output is redirected to the build.log file. If you encounter an error it is the first file to look at. It will show you why the build has failed.

On some occasions, the details inside build.log are not enough to understand the root cause of the failure. On those occasions you should look inside the configuration log file (config.log) of the library compiled at that moment. This file has a path like src/LIBRARY/config.log for all libraries except ffmpeg. For ffmpeg, its path is src/ffmpeg/ffbuild/config.log.

It is possible to follow the build progress from build.log too by filtering INFO events like below.

tail -f build.log | grep INFO

INFO: Using SDK 14.4 by Xcode provided at /Applications/Xcode.app/Contents/Developer
INFO: Build options: --full --rebuild-gnutls --rebuild-lame --rebuild-fontconfig --rebuild-freetype --rebuild-expat
INFO: Disabled armv7 architecture which is not supported on SDK 14.4
INFO: Disabled armv7s architecture which is not supported on SDK 14.4
INFO: Disabled i386 architecture which is not supported on SDK 14.4
INFO: Disabled arm64-mac-catalyst architecture which can not co-exist with arm64 in the same framework bundle.
INFO: Disabled arm64-simulator architecture which can not co-exist with arm64 in the same framework bundle.
INFO: Disabled x86-64-mac-catalyst architecture which can not co-exist with x86-64 in the same framework bundle.
INFO: Building ffmpeg-kit v4.4-9-gf84880f for iOS: Fri Mar 19 22:36:46 GMT 2021
INFO: Downloading source code of ffmpeg and enabled external libraries.