The main reason for using JTV files is as you say, being able to record a program that has already started, if the program is in the time shift buffer. That is why I use the JTV format, because I do that quite often. See this for more info:
http://yabb.jriver.com/interact/index.php?topic=92387.0So the reasons for using the JTV format are;
1. Programs that started in the past can be recorded in full, as long as the program is in the Time Shift buffer. The TS format can only record from the moment you press the record button.
2. With TS format, MC is always writing JTV files for Time Shifting, and TS format files for any current recording. Not a big issue as you say with fast drives, but still something to be aware of, particularly if your hard drive is getting full.
3. With the JTV format a recording is made up of many files. If you have a power failure or a recording is interrupted for some reason, you don't lose the whole recording to file corruption. With the TS format you will lose the whole recording.
4. The JTV format can hold multiple programs in the one directory, which then share the overlap time to accommodate padding time. Only one tuner is used for recording sequential programs. I'm pretty sure that the TS format requires one tuner per program, where the programs are sequential and padding is used.
5. JTV files sizes are smaller for the same recording, because not all data in the broadcast stream is recorded. I think I read somewhere that JTV had better compression as well. JTV format "provides the smoothest playback".
6. Some hardware (Analogue tuners or capture devices) only records using MC in JTV format. (I'll let you research the details.)
7. JTV files can be played in ZoomPlayer (tested), Windows Media Player (although it doesn't recognise the format, it will play it), and Media Player Classic (untested). Basically, any DirectShow player or Editor can open and play/edit JTV files. So there is some portability.
The disadvantages of the JTV format are;
a. You can't use the MC Video Conversion tool to convert it to anything decent, and maintain the original audio. There is no demux/remux capability built into the MC conversion tool. Six channel audio is down mixed to stereo.
b. Even though MC uses Direct Show filters to show JTV recordings, there are no other applications that can use these filters to open and edit MC JTV files. VideoReDo looked at it and were/are going to do something, but nothing has happened in the last year. Apparently "Windows Movie Maker" from Vista days could edit the file (untested), but that wouldn't be a good solution. Even though a DirectShow editor should allowing editing JTV files, I never found an editor that worked. At least not a trial or free one.
c. The Rename, Move, & Copy Files function does not work well where there are two programs in the same recording directory. Well, it doesn't work at all really, and if you aren't aware that there are two programs in a directory that you try to use the RM&CF function on, you can make a real mess that needs manual repair. The RM&CF function does work when only one program is in a directory, but it still retains the original directory name that the files were originally saved in, putting it beneath any new directory structure you create.
d. You can't use third party add-ons that need to read a recording, such as Comskip, with JTV files.
e. Closed Captioning doesn't work with JTV files. I think it works with TS recordings.
The advantages of the TS format are;
I. You can still save the time shift buffer if you haven't started recording a program from the beginning, but have been sitting on the channel for a while. The whole Time Shift buffer is saved in JTV format, not TS format, rather than just the program. The saved JTV Time Shift files are independent of the file created for any recording started for the channel.
II. The file format is portable and easily editable.
III. Closed Captions can be stored in the format. I'm not exactly sure that MC does record them in the format, but if it does they are retained.
IV. The TS format records more of the broadcaster's data stream, although not all of the stream. Therefore, there could be multiple channels recorded with the TS file, which may be of some use to people.
Maybe now that we have better recording rules I won't need to do catch-up recordings so often, and can change to using the TS format. But I still browse the guide sometimes, watch something for a bit, and the decide to record the whole thing to watch later, so maybe not.