I use Videora AppleTV converter. It's completely free & you can just queue up all the files, it will automatically change them to the right format, retaining image & sound quality & will even load them into itunes for you.
Personally, I'd stay away from it. There are much better choices, as long as your sources are mostly MKV's; for example, MP4Tools. It just remuxes MKV's with compatible video tracks to MP4's, unlike the Videora AppleTV converter, which ALWAYS reencodes the video. With incompatible videos (Ogg Vorbis, VC-1 etc.) it'll automatically reencode the video.
Anotehr excellent choice is iFFMpeg, which, so far, I've found excellent.
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I suggest MKV2M4V (off the app store) to convert the mkv files.
iVI (off the app store) for any avi's or other formats.
MKV2M4V is decent but there certainly are much better choices. Let me cite my pros/cons section of my review:
The biggest problems
Let's start with the biggest, not-fixable problems of the app so that you don't waste more time reading this article if you see an absolute stumbling-block.
There are two of them:
- the app can't transfer (by reencoding if needed) more than two original audio tracks. This is a major problem if you want to retain, say, all the commentary tracks of a video. For example, the well-known Finnish sci-fi parody Iron Sky has two commentary tracks (Finnish and English) and two main audio tracks (one 5.1 and one 2-channel AC-3 tracks, having the same audio). This is at least three tracks if you want to preserve both commentaries, along with either of the main audio tracks.
- there is absolutely no support for embedded subtitles at all. It only supports external SRT subs, which means you need to extract them first with, say, Subler. This, should you want to use this app in batch mode, would result in a lot of additional work. (Needless to say, top remuxers like the most recommended MP4Tools and Subler both support embedded subtracks. Actually, Subler even supports their bitmap versions too both OCR'ing and pass-through'ing-wise.)
OK, these are the major problems of the app you must be aware of. Don't even think of purchasing the app if they're a problem.
Before going further and I quickly explain how the app should be used, I tell you more of the advantages / disadvantages of the app. After all, there are a lot of alternatives on the market it's better to decide if you need this app as quickly as possible.
Pros
Accepts both M4V (MP4 / MOV) and MKV input, meaning you can quickly, say, downmix the AC3 track of an already-converted M4V file now that AC3 is no longer supported in the vast majority of players.
Very easy-to-setup for batch mode (to convert more than one video at a time) unlike MP4/MKVTools, where you do have to make some additional settings. Batch mode is particularly good compared to Subler, which has very weak batch support.
Cheap (compared to almost all the other remuxers; except for, of course, the free Subler).
Cons (in addition to the ones already explained)
Somewhat slow conversion, at least compared to the, in this regard, best tools (Subler, MP4Tools, AnyVideo Converter HD). It's still way faster than, say, iVI (Pro).
No support for video conversion for non-H.264 (for example, VC-1) input, unlike with MP4/MKVTools / iVI.
Uses at least twice the movie's filesize for temp files can be an issue when, to speed things up, you use a small(er) SSD to write the target movie file to.
(more info:
https://forums.macrumors.com/threads/1504900/ )
