Android: Creating an OMX component for a video decoder

Question

I have a new task of integrating a decoder(HEVC) from FFMPEG to Android's Stagefright. To do this, i first need to created an OMX component, My next thing is to register my codec in media_codecs.xml and then the OMX component registration in OMXCore.

Is there any guide or steps to create an OMX component for a video decoder? Secondly, this decoder plays only elementary streams (.bin or .h265 files) so there is no container format here.

Can anyone provide some steps or guidelines to be followed while creating the OMX component for a video codec. Any sort of pointers will be really helpful to me.

Thanks in advance.

Answer 1

In general, you could follow the steps pointed in this question for integrating a decoder into OMX Core.

HEVC is not yet part of the OMX IL specification. Hence, you would have to introduce a new role like video_decoder.hevc for your component while registering in media_codecs.xml. Please do check that your OMX core can support this new role.

If you are trying to play only elementary streams, you can consider modifying the stagefright command line utility to read the elementary stream data and feed the decoder.

Another option is to modify the current recordVideo utility to read a frame data and create a decoder instead of the encoder. With these, I presume you should be able to play your decoder from command line.

EDIT: If you wish to build a new OMX component, I would recommend that you could refer to the Bellagio Component Writers Guide which should give good information on how to build an OMX component. This gives a pretty comprehensive guide to build a new component. Please do ensure that you are able to identify the dependencies with the Bellagio implementation and your core implementation.

Also, you could look at other public domain OMX implementations as here: http://androidxref.com/4.4.2_r1/xref/hardware/ti/omap4xxx/domx/ http://androidxref.com/4.4.2_r1/xref/hardware/qcom/media/mm-video-v4l2/vidc/

I feel Bellagio could work as a good starting reference if you haven't build an OMX component earlier. The sources for Bellagio are available on Sourceforge.