Convert MOV to AAC

That is why this pair exists at all. QuickTime is the master format of broadcast and advertising: an agency delivers MOV, a post house sends MOV, a station’s ingest sheet describes MOV, and the picture specification runs to ProRes profiles and colour ranges. The audio line beneath it is usually one word long.

The trouble is that the one word is ambiguous. AAC is a codec, not a file, and it can be delivered as a stream on its own, inside an M4A, inside the MP4 that carries the picture, or as a track in the MOV you already have. All four are honestly described as "AAC audio", and only one of them is what this page writes.

It is an elementary stream in ADTS framing: the compressed audio frames, each with a small header stating the sample rate, the channel configuration and the profile, laid end to end with nothing wrapped around them. There is no index, no metadata area, no duration field and no place to put a title.

The absence is the design. A stream is meant to be read from any point and appended to indefinitely, which is what a segmenter, a broadcast encoder or a piece of embedded firmware needs. It is also why players estimate the duration and seek approximately: there is nothing in the file that says how long it is.

If the specification names ADTS, an elementary stream, a transport stream or a segmenter, this is the file. If it names a bitrate and a channel configuration and nothing about a container, it probably still is.

If it says "AAC 192 kbps stereo" in a list next to a picture specification, it almost certainly means the audio track inside the deliverable rather than a separate file — and sending a loose .aac will come back. If it says M4A, or lists a container at all, use the M4A route instead, which produces a file with a duration, an index and somewhere to put a name. Asking the recipient costs one email and saves a rejected delivery.

A MOV master frequently already carries AAC, and it would be reasonable to expect the stream to be lifted out untouched. It is not. The audio is decoded and encoded again, which puts a second generation of lossy compression on something that was signed off in the first.

For a working file that is fine. For a deliverable it is a question worth asking, because "the audio as approved" and "an AAC encode of the audio as approved" are different claims. Where the exact stream matters, export from the system that produced the master — a professional application can copy the track without touching it, and a browser cannot.

The picture is the reason. Broadcast and advertising masters are ProRes, and no browser exposes a ProRes decoder, so the conversion stops with a message saying nothing in the file could be converted and that it may use a codec this browser cannot read.

That is a decoder problem rather than a fault, and it is a good indication of which files this page suits. It works on the H.264 or HEVC versions that circulate for review and approval; it does not work on the ProRes master sitting on the shared drive. For that one, the audio export belongs in the application that can open it.

The control offers three bands rather than a field, and they resolve to 96, 128 and 192 kilobits a second. The reason the numbers are those and not others is that the encoder snaps to a set of accepted rates, so an in-between request lands on the nearest one.

If your specification names a rate, check the output rather than assuming. A sheet asking for 320 kilobits of AAC cannot be satisfied here at all, and one asking for 128 is satisfied by the balanced band exactly. Sample rate and channel count are carried across from the master unchanged, which is usually the other half of the requirement.

An ADTS file holds exactly one audio track, so a master with a stereo mix, a music-and-effects track and a described-audio track gives you the first of the three. On a broadcast deliverable that is a significant omission and it is silent — nothing tells you the other tracks existed.

Everything outside the audio goes too: the picture, the timecode track, subtitle tracks and every piece of metadata the master carried. If the delivery needs more than one audio track, this page cannot produce it and no converter that writes a single-track format can.

Feeding a packager that will segment it for HLS. Handing audio to a hardware encoder or a broadcast chain that reads ADTS and rejects containers. Testing a decoder in firmware. Supplying an app build whose asset loader expects raw frames. In all of those the absence of a container is the requirement.

What it is not right for is anybody who is going to open it. A .aac will play in VLC and be refused by a surprising amount of ordinary software, it shows no name, and it reports a duration that may be wrong. If a person is the recipient, convert to M4A instead and spend the extra kilobyte on a container.

The whole conversion runs in this tab, on your processor, using codecs the operating system already exposes. Nothing carrying the master is transmitted anywhere, which the network tab will confirm while a file is converting.

On unaired work that is not a nicety. Advertising masters, embargoed programming and anything under a non-disclosure agreement should not pass through a converter chosen from a search result, and the free ones that do this job are exactly that. The 100 MB free ceiling means this suits review copies rather than masters in any case.