Small incidence with proxy creation flow in MPEG2

What is your operating system?
Operating System: Ubuntu Studio 20.10
KDE Plasma Version: 5.19.5
KDE Frameworks Version: 5.74.0
Qt Version: 5.14.2
Kernel Version: 5.8.0-53-lowlatency
OS Type: 64-bit
Processors: 4 × Intel® Core™ i5-7400 CPU @ 3.00GHz
Memory: 15.6 GiB of RAM
Graphics Processor: GeForce GTX 1060 3GB/PCIe/SSE2

What is your Shotcut version (see Help > About Shotcut)? Is it 32-bit?
Shotcut versión 21.05.18

Can you repeat the problem? If so, what are the steps?
(Please be specific and use the names as seen in Shotcut, preferably English. Include a screenshot or screen recording if you can. Also, you can attach logs from either View > Application Log or right-click a job and choose View Log.)

I have a video that I want to add to my Shotcut project for sync reference.
The video has the following characteristics:

After the completion of the proxy creation, (the proxy file is created perfectly) the video is not seen because by default “none” is selected as the video track.

I have only seen this behavior in this type of MPEG2 file. The usual thing is that the video track generated by the proxy is automatically selected.

Are you sure? You said None video track is selected. Does that mean you can change it?
I have not reproduced this.

The steps I take are:
I create an SD PAL project (720x576 25 FPS Interlaced)
I drag the mpg file to the playlist.
Immediately the proxy creation starts.
I drag the file from the playlist to the timeline.
Nothing appears in the preview window.
In properties, I notice that the video track is set to “none”.
I choose the video track 450x360 hevc (proxy) and then I see the video in the preview window.
I thought that maybe a previous import of the PNG image sequence could affect it, so I created a new project from scratch and imported that video with the same result.
Even in that same project, I checked mp4 files and the created proxy automatically selected the video track.
I thought it was a problem with the source file and my solution was to disable Proxy for this type of file, so this already happened to me with the previous version.
I want to test on W10 as well.
I’ll do more checking and can even share a piece of that video here.

Yes, I can change it and continue editing.
Therefore, it is a small incidence.

I cut a small fragment of the video (keeping the same characteristics), to show the process.
This is in W10.
Once the proxy is created, the preview window is blank, because the video track is “none”.

Attached is a video (20 seconds) for test.

On Linux Ubuntu.

I reproduced it with your file. The problem is that the first track is an invalid data track. This messes up the audio and video track indices, which Shotcut requires and which are absolute values.
In other words, the video track in the source has index 1, but in the proxy it becomes 0 because it is dropped. ffprobe:

ffprobe version n4.3.2-167-g85713d85a7 Copyright (c) 2007-2021 the FFmpeg developers
  built with gcc 9 (Ubuntu 9.3.0-17ubuntu1~20.04)
  configuration: --prefix=/home/ddennedy/opt --disable-static --disable-doc --enable-gpl --enable-version3 --enable-shared --enable-runtime-cpudetect --enable-libtheora --enable-libvorbis --enable-libmp3lame --enable-libx264 --enable-libx265 --enable-libvpx --enable-libopus --enable-libjack --enable-libxcb --enable-libpulse --enable-libass --enable-libdav1d --enable-cuvid --enable-libzimg --enable-libaom --disable-decoder=libaom_av1
  libavutil      56. 51.100 / 56. 51.100
  libavcodec     58. 91.100 / 58. 91.100
  libavformat    58. 45.100 / 58. 45.100
  libavdevice    58. 10.100 / 58. 10.100
  libavfilter     7. 85.100 /  7. 85.100
  libswscale      5.  7.100 /  5.  7.100
  libswresample   3.  7.100 /  3.  7.100
  libpostproc    55.  7.100 / 55.  7.100
[mpeg @ 0x556d6d9a0d80] start time for stream 0 is not set in estimate_timings_from_pts
Input #0, mpeg, from '/home/ddennedy/net/media/unsorted/shotcut_bug/27854/Mpeg-PS Muxer (ff) DVD.mpg':
  Duration: 00:00:20.08, start: 0.000000, bitrate: 8056 kb/s
    Stream #0:0[0x1bf]: Data: dvd_nav_packet
    Stream #0:1[0x1e0]: Video: mpeg2video (Main), yuv420p(tv, bt470bg, top first), 720x576 [SAR 16:15 DAR 4:3], 25 fps, 25 tbr, 90k tbn, 50 tbc
    Side data:
      cpb: bitrate max/min/avg: 9000000/0/0 buffer size: 1835008 vbv_delay: N/A
    Stream #0:2[0x1c0]: Audio: mp2, 48000 Hz, stereo, s16p, 224 kb/s
Unsupported codec with id 100357 for input stream 0

This is the same or very similar to another bug report, and we have no solution for it yet - not easy.

Could the first track (DVD nav packet) be something that the DVD recorder built in as a navigation menu or something like that?

The alternative solution is very simple knowing the problem with my files. I only commented in case there was a bug behind it that could affect other things.
Thank you very much. :+1:

As a side effect, the video does not appear in the export. :pensive:
So there is no choice but to disable proxy for this mpeg2 video.

In release candidate 21.06.15 creating proxy with these files with the first non-video data stream (Stream 0), I managed to make the proxy work in Shotcut, by pressing the “Reset” button in the “Properties” window.
This seems like an unorthodox solution but it worked for me.

In the project there are two clips track V1 is the restored video and track V3 is the original video (Mpeg TS).

And it exported okay when you switched back to the original video files?

I just exported the V3 track (which is the one with the MPEG-TS file, although I didn’t finish the project.
I used the H.264 High Profile preset and it seems to work fine.

Is this what you are asking?

Yes, interesting. Just wanted to make sure that a project built with stream index 1 of the proxy matched up with the same stream when switching back to the original. Looks like it does.