ROKU detect only one audio channel with MP4 container ( MP4 H264 with 2 audio channels in AAC EN/FR ) ROKU detect the two audio channels with MKV container ( MKV H264 with 2 audio channels in AAC EN/FR )
so, with MKV container I can select French speaking or English speaking. but not support in MP4
I believe you mean streams, not channels. If that's a question, then yes and no. There is (was?) a way to choose the language of the audio stream in an MP4, but not via the remote. You have (had?) to select the language before you start playing the video. Since the roVideoXxx components are going away, I don't know if it's possible with the roSG stuff or not. In short, if you want to be able to switch languages/streams easily, use MKV.
I don't know if it's worth mentioning, but if using a MP4 container, you had to choose the language of the stream. There was no way to choose between two streams of the same language. MKV doesn't have that limitation (except on a RokuTV, but that's a topic for another thread).