here is the errors i got from them:
java.io.IOException: Failed to instantiate extractor.
java.lang.IllegalArgumentException: extractor does not contain video and/or audio tracks.
net.ypresto.androidtranscoder.engine.InvalidOutputFormatException: Audio codecs other than AAC is not supported, actual mime type: audio/3gpp
I tried to convert a whole bunch of different stuff on android, and they all failed except mp4. which does not help, because it is mp4 already. Maybe I should put this elsewhere because it is the converter that is actually failing. You can try the videos I did here: https://cinelerra-cv.org/footage.php and http://techslides.com/sample-webm-ogg-and-mp4-video-files-for-html5
here is the errors i got from them: java.io.IOException: Failed to instantiate extractor. java.lang.IllegalArgumentException: extractor does not contain video and/or audio tracks. net.ypresto.androidtranscoder.engine.InvalidOutputFormatException: Audio codecs other than AAC is not supported, actual mime type: audio/3gpp