These are a couple of free droplets for converting AVCHD/MTS video files into MP4 files, and then possibly compress them further. They only run on Mac OS X.
[2014-12-18, updated 2015-03-14.]
These droplets come with absolutely no warranty and with no support!
Although no warranty and support, they are fully open so you can open the scripts they contain and change them to suit your purposes. In addition, since nothing is locked, you can scrutinize their contents to verify that there is no malware.
These script applications are simple AppleScript applications that simply call the command line utility
ffmpeg, which is embedded into the script apps.
ffmpeg is a free tool that is exceptionally powerful, but working with video files from the command line in a terminal is tedious, to say the least, and that is why I wrote these small script apps to make simple tasks very simple to accomplish — just drag&drop, no windows or tedious configurations. For details of
ffmpeg, see http://www.ffmpeg.net and http://www.ffmpeg.org
These script applications are simply packaged as zip-files. To download, just click on the link. To use them, drop files onto them and they will create new files. Or double click on them and they will ask you for a file.
Since these apps are not signed with an Apple certificate, you may see the following on first launch: "... can't be opened because it is from an unidentified developer". Then, just control click on the app and choose Open, then click on Open. Next time you can use it as normal without being haunted by this warning.
ffmpeg, which is embedded into this app. You can throw a whole bunch of MTS files onto it to convert them all in a batch.
In camcorders, an MTS file is the "real" video file inside an AVCHD container, but digital cameras that record video in AVCHD format will usually just output the actual MTS file, which will have either .mts or .m2ts as file extension. Mac OS X (at least 10.10 or earlier) will not work directly with these MTS files. Luckily, however, the encoding used in these MTS files is H.264, which is the same as in MP4 files, and AVCHD and MP4 are simply containers for various streams, so it is possible to losslessly convert an MTS file (AVCHD) into an MP4 file (except for the audio, since the containers usually use different encoding for the audio).
In this script app, the H.264 video stream of an MTS file (file extension .mts or .m2ts) will be copied into an MP4 container, making it a standard format and coding for MP4 files. It assumes that the MTS file uses progressive encoding, which makes it compatible with standard MP4 streams. It provably works very well for streams with either 25 fps or 50 fps. Although it "works" with interlaced streams, the result may not be want you wanted or expected.
The audio stream is converted from the native AVCHD format AC3 (Dolby AC-3) into AAC, which is the standard audio encoding for MP4 files. This makes it easy to use the MP4 file in all kinds of applications, such as import into a PDF using Acrobat. (If we did not convert the audio stream, i.e kept it as AC3, then Acrobat would not be able to play the sound when this MP4 file is imported into Acrobat.)
ffmpeg, which is embedded into this app.
It will ask you for the desired number of Mbits/s used to encode the H.264 video stream into a new MP4 container. The audio stream is simply copied to the new stream.
The name of the new file is the same as the input file, but with the text "-XXMbps" tacked on to the file name just before the file extension, where "XX" is the number of Mbits/s. In case the target file exists, it will be overwritten.