[FFmpeg-devel] MediaCodec support
wm4
nfxjfg at googlemail.com
Tue Feb 16 10:41:05 CET 2016
On Mon, 15 Feb 2016 18:52:25 +0100
Matthieu Bouron <matthieu.bouron at gmail.com> wrote:
> Hello,
>
> The following patchset adds basic MediaCodec support to libavcodec, ie: only
> h264 is supported and the HWAccel part (Surface output) is missing.
>
> JNI comes as a dependency. The JNI support is based on the same patchset I've
> sent some time ago with some improvements.
>
> I originally developed the patch against the Ndk API (Android >= 5.0) but then
> changed my mind and go with the JNI version for two main reasons:
>
> * there are still too many android 4 devices
> * there is still needs for some jni bits as the MediaCodec Ndk API
> does not provide a way to known the codec name which is mandatory
> to workaround or blacklist some implementations (ie: do not use known
> software decoders, workaround OMX.SEC.avc.dec as it returns invalid
> stride and slice-height values, ...)
>
I guess there's no way around it.
> I decided to mimic the Ndk API minus a few differences (see
> mediacodec_wrapper.h) so it can be ported more easily to the C API in the
> future. The other reason being it is to totally hide the JNI code.
>
> The HWAccel part is on my todo list but I wanted a real use case to develop the
> API against.
>
> The development branch can be found here:
> https://github.com/mbouron/FFmpeg/tree/feature/mediacodec-support
>
> --enable-jni and --enable-mediacodec is required to build the h264_mediacodec
> decoder.
>
> av_jni_register_java_vm(vm) must called before lavc is used.
Wasn't there some sort of trick that could avoid this?
> The patchset also includes supports for Android content uris which is not
> mandatory for the mediacodec supports but helps dealing with them more
> seamlessly.
I'm still not convinced that this is necessary (custom I/O allows any
application to provide its own I/O callbacks). This would also avoid
the need for avpriv JNI API, since it'd be confined to libavcodec.
> In order to use this support, av_jni_register_application_context(env, context)
> must be called before lavf/lavu is used.
For "content URIs"?
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