Virtualdub2 showing gray artifacting with MPG2

[rmiller3]

I've attached an example screenshot of virtualdub2 showing gray artifacting when opening mpg2 files (my old capture card saves in this format). If I use virtualdub to save the new compression, the artifacting persists if I don't crop it out. Not every frame is corrupted.

This problem doesn't persist in VirtualDubMpg, so I can continue using that, but does anyone know why virtualdub2 and virtualdubmpg behave differently in this space?

Someone posted about a similar problem in this 3 year old thread: https://forum.videohelp.com/threads/398027-VirtualDub2-has-video-that-grey-s-up


[Attachment 76084 - Click to enlarge]

Thanks! I'm also curious what other (free) pieces of software people use for frame by frame editing.

[Sharc]

I suspect that you are getting these garbled frames only when doing random seeking and hitting a P or B frame which cannot be decoded as its own. It will probably return to normal when you step forward to the next keyframe (I-frame), or by pressing SHIFT-> (right) key in Vdub which moves to the next keyframe.

[DB83]

Even if the above is not the case, there is no reason why vdub2 should not play mpeg2 without artifacts.

Just did a quick test with one of my own mpeg2 captures. No issues. No idea why vdubmpg differs from vdub2. Always thought that vdub2 was a natutal progression and with addit codecs.


Could it be that your video has a low bitrate, lack of TBC etc. Or vdubmpg having more tolerance or not using so much cpu as vdub2.

[Sharc]

I'm also curious what other (free) pieces of software people use for frame by frame editing.

Try Avidemux.
When you seek and jump forward/backwards at at random in the timeline it will always stop at I-frames only, never at P or B frames.
Vdub2 stops at any frame. Maybe vdubmpg was smarter in this respect. Maybe the GOP size has an impact as well.

[Hunk91]

I had the same issue. In order to open it without any problem, I open my Mpeg2 video file with an avisynth script (so you must install Avisynth). A simple FFMpegSource2 will help.

[poisondeathray]

You can also try the vdub2 mpeg2 input driver

In the open file dialog box, there is a drop down menu. The default is "all media file types" which is the ffmpeg based caching input driver .

"mpeg2 files" uses the mpeg-2 plugin (v4.5 )

You can check what input driver is being used by file=>file information when a file has been opened

[rgr]

I've attached an example screenshot of virtualdub2 showing gray artifacting when opening mpg2 files (my old capture card saves in this format). If I use virtualdub to save the new compression, the artifacting persists if I don't crop it out. Not every frame is corrupted.

Use other Input Driver.

[lordsmurf]

DVD-Video VOB files, and DVB TS files, are not pure MPEG. Extra junk in the signal parses badly.

Those files cannot simply be rename .mpg/.mpeg to make it a pure MPEG.

Perhaps that's the issue?

[rmiller3]

You can also try the vdub2 mpeg2 input driver

In the open file dialog box, there is a drop down menu. The default is "all media file types" which is the ffmpeg based caching input driver .

"mpeg2 files" uses the mpeg-2 plugin (v4.5 )

You can check what input driver is being used by file=>file information when a file has been opened

This seems to have worked, though I haven't tried editing / compressing.

Specifically these worked: MPEG-2, MIDX
This one shows the corruption: FFMpeg: Video

and furthermore, FFMpeg is not an option in VirtualDubMpg so it probably forces to MPEG-2.


I wonder why FFMpeg doesn't work as well.

I suspect that you are getting these garbled frames only when doing random seeking and hitting a P or B frame which cannot be decoded as its own. It will probably return to normal when you step forward to the next keyframe (I-frame), or by pressing SHIFT-> (right) key in Vdub which moves to the next keyframe.

I thought maybe it was something like that but it's not a single frame of corruption. I have one example where it's 7 frames of corruption in a row, plus if I compress it to another format, the corruption persists. Again, this is not the case with VirtualDubMpg which is weird to me.

Note: If I press shift+right or left in vdub2, it just moves one frame. In the frame bar it shows a "K" on most frames.
[Attachment 76113 - Click to enlarge]. In virtualdubMpg shift+right seems to work properly (and the frames it jumps to are marked as "I").

Could it be that your video has a low bitrate, lack of TBC etc. Or vdubmpg having more tolerance or not using so much cpu as vdub2.

Well the frame is permanently garbled in vdub2, so while it's possible the video is of poor quality, I doubt the cpu thought is it. (The video source is a diamond TV tuner card...I need to find a better capture solution too obviously ).