This guide details the process I've used to build Tiger-compatible Picard app bundles on macOS. There are many ways to achieve this, but I've found these steps to be the simplest and most compatible after much trial and error.

This guide was tested in a VM running Leopard. If you're using anything above Snow Leopard (Lion, Mountain Lion) you won't be able to install XCode 3, so this guide won't work.

Last updated on 2012-06-03 for Picard 1.0.

Avoid MacPorts

There are a lot of architecture issues in MacPorts that took days to debug. After working around those, Qt4 had broken functionality, such as drag and drop from Finder not working. Qt4 takes an entire day to build on my machine, whereas the precompiled Qt package from Nokia works just fine. The rest of the dependencies will be installed manually to /usr/local.

Prerequisites

• XCode 3.2.6, with the 10.4 SDK installed at /Developer/SDKs/MacOSX10.4u.sdk (it's a selectable option in the installer).
• Python 2.7.3. Since we want compatibility with Tiger/i386, make sure to install this one: python-2.7.3-macosx10.3.dmg. Use the provided Update Shell Profile.command to make this your default Python. Note: this is required. You can't use the system Python that comes with macOS! py2app won't allow you to build standalone app bundles with it.
• Qt 4.7.3. Install this one: qt-mac-carbon-opensource-4.7.3.dmg. Qt 4.8 and up no longer support 10.4/Carbon.

Set up your environment

Make sure /usr/local/bin is in your PATH, and have the following variables set in your .profile or .bash_profile (or do it manually):

      export CFLAGS="-arch i386 -isysroot /Developer/SDKs/MacOSX10.4u.sdk -mmacosx-version-min=10.4 -I/usr/local/include"
      export CXXFLAGS="$CFLAGS"
      export LDFLAGS="-arch i386 -Xlinker -headerpad_max_install_names -L/usr/local/lib"
      export MACOSX_DEPLOYMENT_TARGET="10.4"

Make sure you're using gcc 4.0.2. On Snow Leopard, I had to change the symlinks, because setting CC= didn't work for some dependencies. (I did this, but for 4.0 instead of 4.2.)

Dependencies

Now you have to install a bunch of dependencies by hand. Or, that's what you would have to do if I hadn't written this super-convenient (hacked-together) script for you: build-deps.sh. chmod +x and run from an empty directory.

I have no doubt the script will break somewhere for someone—help me fix it. :)

To enabled AcoustID fingerprinting in Picard, you also need the fpcalc binary. Download that from here and place it in /usr/local/bin.

Finally, you'll need two Python modules: py2app and mutagen. Install them manually or just use easy_install. Be sure to install them for the correct Python version!

Building Picard

Create the file build.cfg in the source directory. Mine looks like this:

      [libofa]
      libs = -arch i386 -L/usr/local/lib -lofa
      cflags = -arch i386 -I/usr/local/include

      [avcodec]
      libs = -arch i386 -L/usr/local/lib -lavcodec -lavformat -lavutil -lvorbis -lvorbisenc -logg -lmp3lame -lfaac
      cflags = -arch i386 -I/usr/local/include

      [build]
      with-directshow = False
      with-avcodec = True
      with-libofa = True 

Now we should be able to build a Picard app bundle. This requires a few commands, so I use a bash script to run them all:

      #!/bin/bash
      rm -rf build dist
      python setup.py clean
      python setup.py build_ext -i
      python setup.py py2app
      cd dist
      # Strip any non-i386 code from the app bundle
      ditto -rsrc --arch i386 MusicBrainz\ Picard.app MusicBrainz\ Picard.tmp
      rm -r MusicBrainz\ Picard.app
     mv MusicBrainz\ Picard.tmp MusicBrainz\ Picard.app

If all goes well, you'll end up with an app bundle in the dist directory. We're done! Yay!