Losing frames, sync issues when filtering/muxing in Hybrid?

[VHS_UK]

Ever since learning how to filter VHS capture using Hybrid, I been having problem regarding audio and video not syncing together and even losing frames during the process. This happens when converting from .avi to .mkv or anything that involves muxing, I think also ffmpeg might be involved. For example, I had a 50 mins long video that was 38,311 frames, after doing the converting and filtering, it lost 183 frames and is now 38128 frames. After several tests I did with the help of Selur, ticking CFR Output or Prefer .avi source for .avi input settings seems to mitigate the async and reduce amount of frame loss but it not 100% synced.

I had a long troubleshoot with Selur over at his forums and was still unable to solve it. I did browse to see if someone else had the same problem and I think the links below are all related to the problem I am having now. I can't be the only one who is having this problem.

It very frustrating that after solving one problem regarding filtering VHS capture, another one comes up and this one is the biggest I faced and I have no clue what to do to solve it, all I want to do is filter my capture through Hybrid and not have sync issue or frame loss. Is it cause by the unstable frames coming from the VHS capture or a video process issue with ffmpeg or something?

I linked both the Selur's forum and some links I found of people having similar problems below.


https://forum.selur.net/thread-2500.html

https://superuser.com/questions/4361...es-out-of-sync
https://video.stackexchange.com/ques...-losing-frames
https://video.stackexchange.com/ques...-losing-frames
https://gitlab.com/mbunkus/mkvtoolnix/-/issues/2777

[lollo2]

What happens of you just run ffmpeg from a command line?

[VHS_UK]

You mean

ffmpeg.exe  -i "F:\VHS\Broken Silence - Waste Not Want Not.avi" -c copy -vsync vfr "F:\VHS\Broken Silence - Waste Not Want Not ffmpeg.mkv"

?

It still loses frames and become out of sync, that was one of the last test I did.

[lollo2]

OK. Sorry, I do not know how to help; I encoded hundreds of captures with ffmepg command line and never had loss of frames or asynch audio/video.

The version I use: ffmpeg-20200831-4a11a6f-win32-static

The command I use:

ffmpeg.exe -i input.avs -c:v libx264 -crf 17 -preset slow -aspect 4:3 -c:a aac -b:a 128k output.mp4

[traal]

I had a sync issue once when trying to transcode a VFR video. But HuffYUV doesn't support VFR, does it?

[VHS_UK]

Quote:

Originally Posted by lollo2

OK. Sorry, I do not know how to help; I encoded hundreds of captures with ffmepg command line and never had loss of frames or asynch audio/video.

The version I use: ffmpeg-20200831-4a11a6f-win32-static

The command I use:

ffmpeg.exe -i input.avs -c:v libx264 -crf 17 -preset slow -aspect 4:3 -c:a aac -b:a 128k output.mp4

It isn't exactly a command line, it doing it on Hybrid. Whenever I do a job on it, I lose some frames and cause the video and audio to not be synced. I wonder lordsmurf would be able to help since he has been using Hybrid.

[lollo2]

Why do you not try outside Hybrid?

[VHS_UK]

Because it has all the functions and setup just like the command version and a lot easier using a GUI based interface than a command-based, I'm not very good with command prompt.

Edit: Forgot to add this link in the OP.

https://video.stackexchange.com/ques...es-with-ffmpeg

[lollo2]

I did not mean to leave Hybrid, just an experiment to isolate the problem

[VHS_UK]

How do I ping lordsmurf to a forum? I just think he the best to ask about this problem when using hybrid or any form of muxing (if that the right term to use).

[lordsmurf]

Say my name 3 times.

Encoders can't lose frames like a capture. Those process whatever gets input. The issue has to be with the captures, perhaps NTSC/PAL or frame rate issues in the capture or encoder settings.

BTW, for video topics, StackExchange is 99%+ useless. (In general, it's worthless, but especially for these sorts of topics.)

One of your posts is about muxing. Are you saying you believe this is due muxing? If so, don't use MKV for a test.

As selur stated first, it's a source issue. Back up, go over that.

selur also made a good point about frame count reporting. The source file may be reporting wrong.

There are some Avisynth scripts for dropped frames detection. Not exacting, but can possibly pinpoint error spots on the source. PVAstrumento used to remove bad frames, when audio was disjointed, but I forget what formats that old tool supports.

I concur with selur. It's the capture source file that is bad. Back up. What hardware, software, settings? Did you pay attention to the dropped frames counter, possibly the audio resync % during capture.

[VHS_UK]

Well, I capture using a JVC HR-S9700EK, via VC500 USB on a Windows 11 custom desktop. Well it can be muxing that caused it since the problem occurs even when doing filters with .avi as the output.

[lordsmurf]

You're already off to a bad start.

VC500 = a variable card, due to long life, multiple production versions. All kinds of reported and verified issues, be it AGC, drivers, and more. So if it lost frames, even lost without reporting, I'd not be shocked, though that exact issues has not been reported before. The card was only loosely suggested (mostly sanlyn), with flaws seen by many others (myself included).

Win11 = at least as bad as Win10, that is to say awful OS for capturing.

Good JVC VCR.

And the external frame TBC? If none, probably your issue right there.

[VHS_UK]

I don't have an external frame, haven't done a Windows XP build yet. maybe the VC500 is the culprit. The exact problem I'm having is that the video scrubber when playing the original and the filtered aren't in the right place.

Edit: Quick question, my JVC VCR has a digital screen that show the timestamps of where the tape is. When I fast forward, the time counter follows where the tape is. But when I do rewind, it doesn't keep track of it. I think I broke something because I was trying to find a certain part in the VHS I was pressing forward and rewind in quick combination, do you think that might of caused some problems?

Edit 2: I think it happened depending on the tape quality.

[lordsmurf]

I think you're playing Clue, and have a whole room of culprits.

VCR issue, eh... hard to say. Can it lead to issue that lead to dropped frames, especially without frame TBC? Yes. But I just don't see that as likely. And even if so, TBC would probably smooth that over, in terms of the capture files.

[VHS_UK]

I can't seem to find any good TBC for sale though. All the ones such as the AVT-871 are all the faulty black boxes.

[lordsmurf]

You didn't check the marketplace forum.

http://www.digitalFAQ.com/forum/marketplace/