GStreamer with hardware video codecs on iOS

Update: GIT master of cerbero should compile fine with XCode 6 for x86/x86-64 (simulator) too now

In the last few days I spent some time on getting GStreamer to compile properly with the XCode 6 preview release (which is since today available as a stable release), and make sure everything still works with iOS 8. This should be the case now with GIT master of cerbero.

So much for the boring part. But more important, iOS 8 finally makes the VideoToolbox API available as public API. This allows us to use the hardware video decoders and encoders directly, and opens lots of new possibilities for GStreamer usage on iOS. Before iOS 8 it was only possible to directly decode local files with the hardware decoders via the AVAssetReader API, which of course only allows rather constrained GStreamer usage.

We already had elements (for OS X) using the VideoToolbox API in the applemedia plugin in gst-plugins-bad, so I tried making them work on iOS too. This required quite a few changes, and in the end I rewrote big parts of the encoder element (which should also make it work better on OS X btw). But with GIT master of GStreamer you can now directly use the hardware codecs on iOS 8 by using the vtdec decoder element or the vtenc_h264 encoder element. There’s still a lot of potential for improvements but it’s working.


If you compile everything from GIT master, it should still be possible to use the same application binary with iOS 7 and earlier versions. Just make sure to use “-weak_framework VideoToolbox” for linking your application instead of “-framework VideoToolbox”. On earlier versions you just won’t be able to use the hardware codecs.

Currently compiling cerbero GIT master for iOS x86 and x86-64 will fail in libffi. Only the ARM variants work. So don’t build with “./cerbero-uninstalled -c config/cross-ios-universal.cbc” but the “cross-ios-arm7.cbc”. And if you need to run bootstrap first, run it from the 1.4 branch for now and then switch back to the master branch. I’m working on fixing that next week.