MP4 headaches

[Mabel]

The MTS-files produced by my (Sony) video-camera's play lousily, or not at all, on all but one of our windows-computers and play without sound on our android tablet. Clearly, a conversion is in order, but to what format? After lots of experimenting I choose MP4, as produced by my video-edidor (Vegas) as well as by the conversion program Freemake. The resulting files play smoothly and with synchronous sound on all our devices and with any player.
So far so good, but every such conversion means a loss of quality and since I discovered (thanks to this forum) that my MTS-files in fact contain a video-stream encoded with MPEG-4v2 I wondered whether the conversion could be done losslessly. I used ffmpeg, through the GUI Avidemux, to produce, within a second or so, an MP4-file. Indeed, something has been gained by this step since the file now plays on all our devices. BUT the movie plays jerkily
So I downloaded the analysing program Gspot to find out what the differences are between the files produced by Vegas or Freemake and that produced by ffmpeg. To my dismay, all the parameters found by Gspot are exactly the same for all three files. Yet, there clearly is a crucial difference.
I'm at a loss here; is this a bug in ffmpeg? I was ready to believe that, until I took into account the MP4-video's produced by my Canon photo camera. According to Gspot, these files too have virtually the same form and contents; yet these files too play jerkily on all our computers. I have to 'convert' them first as described above - only then will they play smoothly. I do not even understand what 'conversion' means in this case, as I set everything to 'use original' and the input and output formats are, according to Gspot, virtually the same.
This, in my opinion, makes it less likely that it's just a bug in ffmpeg which is bugging me. Apparently, a video-file can have other properties or qualities which determine whether it plays smoothly or jerkily.
Does anyone recognise this and can anyone enlighten me about the cause?
And, in a more practical vein, can someone say anything about the possibility of losslessly converting my problematic MTS files and my jerkily playing MP4 files to a format which plays well on all our computers?

Mabel
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PS: The files playing well on all our systems is described by Gspot as:
"mp42: MP4v2 [ISO 1446-14] - isom MP4 base media v1 [ISO 14496-12.2003]; codec: avc1, name H.264/MPEG-4/AVC". The files produced by avidemux, which play jerkily, are described in EXACTLY the same way.
The MP4-files produced by our Canon photo-camera are described by Gspot as:
"mp42: MP4v2 [ISO 1446-14] - avc1: MP4-base w/AVC ext [ISO 14496-12.2005]; codec: avc1, name H.264/MPEG-4/AVC"
That's allmost identical, but they play jerkily.
Gspot gives a lot of other parameters (resolution, frame rate etc.) but these are identical for all files.

[redwudz]

You might try the MediaInfo program instead of Gspot as it may not do well with some formats. Gspot hasn't been updated since 2007.

But another member may be able to give you more information on the conversions.

[Baldrick]

Have you tried remux with mp4box? Or a gui for it like mymp4boxgui. Add the mts and make a mp4.

[Mabel]

Thanks very much for the tip about Mediainfo; it's very good and very up-to-date it seems to me. Not only does it read the MTS-format well (which Gspot does not) but also it immediately spotted the difference in the two MP4-files: the re-packaged files are interlaced, the converted files are not. I should have guessed it was something like that, because I had read about interlaced video.
So I now understand that the lossless conversion I hoped for is impossible. I am reasonably content with the conversions though, and for the video's I edit with Vegas some quality loss seems inevitable anyway. My original question is thus solved; yet I'm left with a new one:
I can see why interlacing was invented. But I don't really understand why it has to be discarded when playing movies on a computer, as every article on the subject seems to tell me. Why can't I play interlaced video's on my computers with all the advantages (smoother movement without loss in resolution)? Maybe it requires more CPU-power? But they play lousily even on my (rather powerful) desktop!
Meanwhile, I'll sure try out MP4box - thanks a lot for that tip, too!
Mabel

[jagabo]

So I now understand that the lossless conversion I hoped for is impossible.

You can't come to that conclusion yet. It's certainly possible to remux interlaced h.264 into an MP4 container. Try YAMB or Mp4Muxer. You may need to demux the audio and video streams before using those tools to remux to MP4. Also try remuxing to MKV with Mkvtoolnix. Playback support for MKV isn't quite as widespread as MP4 but Mkvtoolnix is a much better muxing tool.

[Mabel]

It's certainly possible to remux interlaced h.264 into an MP4 container.

I'm pleasantly surprised. From the article at www.100fps.com, which looked very comprehensive, I seemed to understand that de-interlacing necessarily involves compromises. But on reflexion I may have been too hasty in concluding that this amounts to a 'lossy' conversion. Thanks for telling me.
So now I have 3 more programs to play around with! I hope I can find the time and I'll post the results.
(I can't help wondering though, why finding the ideal procedure takes me such an inordinate amount of time. I can't be the only one with this problem, surely: these MTS-files seem to be rather common on modern video-camera's and devices like windows-computers and android tablet are not that rare either. So, did I miss something?)
Mabel

[hech54]

I should have guessed it was something like that, because I had read about interlaced video.

Despite all of the talk that shows up about this subject.....it's usually NEVER your problem and RARELY worth even mentioning as a posssible cause for a video file problem.

[jagabo]

I can't help wondering though, why finding the ideal procedure takes me such an inordinate amount of time. I can't be the only one with this problem, surely: these MTS-files seem to be rather common on modern video-camera's and devices like windows-computers and android tablet are not that rare either. So, did I miss something?)

It seems that every piece of hardware and software does something different in transport streams (MTS, M2TS, TS, etc.). They are amongst the most problematic containers.