A lossy AUDIO is encoded at 192 kbps by default. The Audio Quality setting also offers 320 kbps for the best quality and 128 kbps for a smaller file. A lossless AUDIO (WAV, FLAC) ignores the bitrate and keeps every sample.
Several files in one job need a paid plan. Free use is one file per conversion, one conversion an hour. On a paid plan you can add several files to one job, then download each result on its own or all of them in one ZIP.
It depends on the size and length of the file. Small documents and images are usually ready quickly. Long videos take the longest, because most video conversions re-encode every frame.
Yes. Uploaded MP4 files are processed on our own conversion servers, no person reviews them, and they are never shared. The upload and the converted AUDIO are both deleted automatically about 24 hours after the conversion, which leaves time to download the result. See /privacy/ for the full policy.
Usually the MP4 carries more than one audio track and the one that was converted is silent or secondary. The converter picks one audio track automatically, normally the main one, and this page has no setting to choose a different track. If the wrong one comes out, remux the MP4 with the track you want first (VLC or ffmpeg can do this) and convert it again.
