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NOTE: This question is superceded by this new one, please do not answer below this post.

What happened?

  • [Edit] DVB file ('file1') in TS format of H.264/AC3@50i cannot be properly remuxed into any of the following formats: isom/mp4; QuickTime MOV; Matroska

  • Another DVB file ('file2') in TS format of MPEG-2/[email protected] can be properly remuxed into any of the following formats: MPEG; isom/mp4. QuickTime MOV and Matroska are not tried.

  • [Update] Still another one in TS format of H.264/[email protected] can be properly remuxed into isom/mp4 without a hitch, not requiring any ffmpeg switches other than -i, -c copy.

Technical details

  • FFMpeg reports millions of the following error messages, with or without any possible combination of these switches: -fflags +genpts, -fflags +igndts, -fflags +discardcorrupt

    • Command line is ffmpeg.exe -fflags +igndts -fflags +genpts -fflags +discardcorrupt -i INPUT -c copy -format mp4 OUTPUT
    • Error Message 1:
      [mp4 @ address] pts has no value
      Last message repeated xxx times
    • Error Message 2:
      [mp4 @ address] Non-monotonous DTS in output stream 0:0. Previous ... Current ... Changing to ... , blah blah

  • AVIDemux completes operation with wrong metadata and faulty playback. File properties and playback behaviour resembles that created by FFMpeg

    • Frame-rate becomes variable, should be 50i
    • Average frame-rate is not the correct value, showing very strange numbers
    • Playback frame-rate is abnormal, oscillating btw. 59.94 and 39.xx

  • [Edit] MP4box reports the following warnings for 2 times, and produces jagged picture with wrong frame-rate as mentioned above. If you view the resultant video very carefully you will see the image with many blocks; this is not found in the original file.

    • Command line is mp4box.exe -fps 50 -add "INPUT#video" OUTPUT
    • Error Message:
      [MPEG-2 TS] PID xx PCR discontinuity signaled but diff is small (diff xx us - PCR diff xx vs prev PCR diff 0) - ignore it

My questions, in detail

1 What on earth is "DTS" and "PTS"? They seem to be obsructing a successful remux.
2 Is this due to corrupted file or software bug (see https://trac.ffmpeg.org/ticket/4768 and https://trac.ffmpeg.org/ticket/502)?
3 If this is a software bug what are the work-arounds?
4 Any workable solution that remuxes MPEG Transport Streams to MP4 are welcome. MPEG-TS takes up too much overhead and are not well supported across platforms and systems.

Diagnostic Information
- MediaInfo dump of file1, file2, and file1 remuxed into mp4 by FFMpeg
http://pastebin.ca/3966322

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  • 2
    What does corrupted playback mean - decoding errors? Is the playback speed always wrong or it varies?
    – Gyan
    Commented Jan 31, 2018 at 16:33
  • @Mulvya, playback speed is always wrong; frame image seems fine; the decoder can work but apparently the file isn't usable.
    – user786008
    Commented Feb 1, 2018 at 3:24
  • Does a TS to TS remux preserve playback rate? The store method of file1 is unusual. Try with ffmbc. If you can't compile, get an older binary from videohelp.com/software/ffmbc
    – Gyan
    Commented Feb 1, 2018 at 5:53
  • @Mulvya , TS→TS remux works in FFMpeg with the following options specified: -mpegts_service_type advanced_codec_digital_hdtv -mpegts_m2ts_mode false -mpegts_flags system_b; works in FFMbc with -fflags +genpts specified. TS→mp4 succeeded in FFMbc (0.7.2) with -fflags +genpts -f mp4 specified. The ffmbc hack worked for this file and some others, the rest still failed. The issue appears to be centered around timestamping. A new question has been posted to supercede this one.
    – user786008
    Commented Feb 4, 2018 at 13:20

1 Answer 1

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0

To answer part of your question (and add a couple of other abbreviations you will run into):

  • PTS = Presentation Time Stamp
  • DTS = Decode Time Stamp
  • PCR = Program Clock Reference
  • SCR = System Clock Reference

MPEG elementary streams reorder the frames for transmission. The PTS indicates the order that the frames should be re-assembled into. The DTS lets the decoder know if a frame needs to be decoded earlier than it is displayed (because a P or B frame references it). The PCR or SCR are the time scale that the PTS and DTS reference.

tstools and other transport stream analyzers can help you determine if the PCR/PTS/DTS issue is in the source file or not.

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2
  • The links you've provided are just fabulous! However, I'm getting more confused after reading the PDF pp. 43-44. Although the PTS may not be monotonous as a result of bidirectional encoding, this should not cause frustrations for a proper (de)muxer because (i) the stream is transmitted and received according to the DTS which has to be (a) monotonous and (b) <= PTS-1, and (ii) every field has to have a meaningful PTS. If the million "pts has no value" and "non-monotonous DTS" in FFMpeg are real, how possible could it be to have a flawless playback of the original ts file (which I have)?
    – user786008
    Commented Feb 1, 2018 at 4:11
  • It definitely isn't likely for there to be a source problem that isn't picked up during playback and only happens during transcode. But when I want to be sure about something in a transport stream, I run it through an analyzer. Sometimes you pick up on something that is subtlety wrong that one decoder can correct that another chokes on.
    – Michael Liebman
    Commented Feb 1, 2018 at 21:08

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