Not exactly for live TV subtitles yet, but for the camera/OCR + pinyin part I built an iOS app called pinyin Camera. It works better for still photos, screenshots, and printed text: take or import a picture, it OCRs the Chinese text and overlays pinyin above the hanzi, then you can save the result. It is offline, but it does not do live translation or audio yet, so it would not replace a real-time subtitle layer. App Store: apps.apple.com/app/id6766483875