Remuxing TS to MP4 (question about MediaInfo stats)

[MGRV]

Someone gave me a few videos in TS format. I'm not too familiar with it, and while I've generally had no problems playing them, there's an application I use to stream from my hard drive to the TV that doesn't seem to like it. So I wanted to remux them to a more convenient format such as MP4 or MKV and throw away the TS files. What I don't understand is, generally when I remux a video it's very easy to see with MediaInfo that the stream stats are exactly the same. But it seems to be different with TS (the listed stats are different altogether, making it hard to compare, i.e. you don't see Video Bitrate, but Maximum Bitrate). I used Avidemux with Copy in both streams so I know it's not reencoding anything, plus it was done fairly quickly, but is there any way to do it properly and know I haven't messed up? I notice different overall bitrates in my resulting files, too. I converted a TS file to MP4, then converted that MP4 to a new TS just to test (it was fairly bigger than the original). I also tried VLC's Convert option. Every time the bitrate (and some other info) comes out different, though I've read I should take some of those stats with a grain of salt. I've used ffmpeg in the past for this type of thing but honestly, I trusted it did what it had to do and never thought about it much.

Anyway, I guess the basic question is: what is a safe way you would recommend to remux these videos? What's with the different filesizes/stats, should I worry about any of that at all?

Thanks in advance!

[LigH.de]

Convenient media formats often have a header which collects all necessary data so that a player knows what to expect before the playback starts. But they also contain one movie only, usually. A player does not have to expect the need to adapt to new content in the middle of the playback.

The MPEG-2 Transport Stream format ([M2]TS) is a streaming oriented format which contains only the most important attributes once in a while, and the rest is collected during playback. This enables e.g. entering a programme in the middle or switching between several programmes in a short time, as to be expected in e.g. Digital Video Broadcasts (DVB) in television sets.

MediaInfo reads only headers. To know all details of a TS, it would need to read deeper into the contained streams, possibly even have to start the decoding of content, which would not be its intended purpose.

The fact that the Blu-ray disc standard chose M2TS as well (with its tiny packets of 192 bytes, in contrast to e.g. DVD Video which uses Program Streams with packets as big as media sectors of 2048 bytes) was surprising to many people... but both M2TS and M2PS are packet oriented, supporting optional and skippable multiplexed content parts in some ways. Matroska may support some of these features too, but it is not a standard accepted widely by the media industry.

[MGRV]

Thanks for your reply. So, I understand what you explained accounts for the differences I see using MediaInfo (even between different converted MP4s with TS as source). I suppose I can do without the benefits of TS over other formats that you described, since I won't do much with them but play them either in my PC or streaming it to a TV.

As I mentioned, I've done some remuxing in the past with ffmpeg, but didn't know what I was doing. I just knew that if I could check that the average bitrate, encoder, etc. matched, I was safe. What had me wondering now is the fact that every conversion seems to result in a different filesize, too. Granted, not too big of a difference, but it made me wonder if I could be missing something or doing anything wrong. By the way, aside from Avidemux and VLC, I also tried with my old method, but ffmpeg threw an error:

[mp4 @ 0000023fd753f200] Malformed AAC bitstream detected: use the audio bitstream filter 'aac_adtstoasc' to fix it ('-bsf:a aac_adtstoasc' option with ffmpeg)
av_interleaved_write_frame(): Operation not permitted
[mp4 @ 0000023fd753f200] Malformed AAC bitstream detected: use the audio bitstream filter 'aac_adtstoasc' to fix it ('-bsf:a aac_adtstoasc' option with ffmpeg)

Would Avidemux be a proper way to convert them? Would you recommend any other tool?

[LigH.de]

The MP4 container has its limits, especially supporting only specified content formats. You may not be able to store everything supported in a TS container (Blu-ray has its extensions...) in an MP4. And if you can, it may be advisable that MP4Box was the last multiplexer creating your final MP4 file (unfortunately, on its own it is a CLI tool, you may need an additional GUI for it).

If you have the choice, MKV is the more generic container (supporting the largest variety of contents, usuallly), and MKVtoolnixGUI may be a more user-friendly multiplexer at first hand. Test your player. As long as you play on a PC only, it would be the no-brainer.

[MGRV]

Yes, most of the times I just play stuff on a PC. There's one application I use sometimes to cast to the TV that doesn't seem to work with TS files (but has no problem with MKV), that's really the only reason I'm remuxing them. If MKV is a better alternative I'll use it instead, I don't know why I went for MP4, I was hesitant between those two formats and just picked the latter for no reason. I've just used MKVtoolnixGUI to convert one of the TS files to MKV, I'll keep it as my go-to option. Thanks again!