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  1. Dear all,

    I have an m2ts file with two audio streams and want to get rid of one of the audio streams. I decided to give tsMuxeR a try to achieve that, loaded the file in tsMuxeR GUI and tried to understand how demuxing works. In doing so, I stumbled across an understanding problem:

    In the "General" tab of the GUI, I can select options regarding the bit rate even when I have selected "Demux" in the "Output" section. Selecting different options there indeed alters the meta file in that situation; please see the attached screenshots for an example. I don't understand why this happens because I always thought that demuxing means splitting and extracting all streams (or only one) in unaltered form.

    At least, this is what I want to achieve: Extract all streams without any bits altered, throw away the audio stream which I want to get rid of, and remux the remaining streams.

    In that sense, I am a bit lost not only with regard to the bit rate setting, but also to the other settings which are available when demuxing (e.g. "Generate HDMV compatible TS", and the SEI, VUI and SPS/PPS thing).

    The documentation did not help. For "--demux", there is the following explanation:

    Run in demux mode : the selected audio and video tracks are stored as separate files. The output name must be a folder name. All selected effects (such as changing the level of a H264 stream) are processed. When demuxing, certain types of tracks are always changed : - Subtitles in a Presentation Graphic Stream are converted into sup format. - PCM audio is saved as WAV files.
    There is no hint about which of the other options are ignored when demuxing (e.g. bit rate options and the other options mentioned above).

    Hence the question: How should I choose the settings to make sure that I extract all streams in unaltered form?

    Thank you very much in advance!

    Image
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    [Attachment 57646 - Click to enlarge]
    Last edited by 4L7zHhiyQO3Thui6; 4th Mar 2021 at 01:51.
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  2. Member
    Join Date
    Aug 2013
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    These options belong to the "General" group and may only be relevant when you select one of the "muxing" options instead of "Demux".

    The bitrate flag and HDMV compatibility options are clearly only relevant when you select muxing to one of the TS related containers in the bottom, not for demuxing. I would assume that the application should ignore parameters not relevant for this mode (and IMHO, the GUI should have removed them from the generated command line when they are irrelevant).
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  3. OP here (had to create a new account ...)

    Thank you very much. I already suspected something like that.

    May I then ask what settings I need for muxing if the only thing I want to do is to throw away one audio track? That is, how do I remux the tracks I have demuxed before without altering anything?
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  4. Member Ennio's Avatar
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    You can do the remux in one pass. No need for demuxing first. Import your source m2ts file, check off the tracks you don't need in the list.
    Choose radiobutton "M2TS muxing". Set destination and hit "Start muxing".
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  5. Thank you very much for the answer.

    I'd like to learn a bit on the subject, so I tried demuxing first. I was curious about which files it would produce and about the size of each file.

    As per your recommendation, I now have tried remux in one pass (remux to m2ts). However, still being curious, I wanted to know whether it would reproduce the original file if I would include all streams in remuxing (instead of unchecking the audio stream I actually want to get rid of). To my surprise, the size of the remuxed file was a little bit smaller that the size of the original file, which made me wonder whether something substantial might have been lost.

    Therefore, I demuxed the original file again, and demuxed the remuxed file again. Then, I compared every stream from the original and the remuxed file. Fortunately, they were the same in every case.

    Now it seems I've only one question left (regarding subtitles), but I'll open another thread for it.

    Thanks to the tsMuxeR developer(s) and his colleagues! It's very satisfying to see how mature today's software is. The last time I was seriously looking into video conversion (about 15 years ago), most free software tools only produced nonsense, and those who didn't competed for the shortest time they could run before the next crash.
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