Squeaks/chirps in audio after converting from Mini DV as AVI

[AmRy]

Hi,

Not sure if Audio is the right place to post this, happy to have it moved, but it's an audio problem in a video so I wasn't sure.

I have Mini DV tapes from 2002 that I'm transferring via a perilously old laptop with firewire using Cyberdirector (also very old), producing AVIs which I then transfer to a newer computer and edit a bit before running a modern compression to save space etc.

I was doing this last year successfully but I've recently resumed (it's a "spare time" job) but I'm finding that whenever I convert an AVI to anything else there are these squeaky / chirp noises in the final product, often every few seconds. I tried exporting to mp4, to avi again, I tried multiple compression methods, I tried multiple programs like Handbrake, Virtualdub2, Openshot, Clipchamp, all sorts of combinations, always the same result. It's bizarre. Often there's no sign of the noise in the original AVIs, sometimes I think maybe a bit but much quieter.

I've even gone back to a clip I transferred in 2023 which I still had the original AVI and mp4, neither had the sound, but when I run the same AVI through any of these programs now the sound occurs. It's driving me nuts because there can't be a rational explanation (except there must be). Maybe the software I used in 2023 somehow filtered it out? I didn't think I was doing anything fancy and I don't remember what software I was using.

This year I even tried using ffmeg at the command line to convert direct from avi to avi and the sound still occurs. I've even tried using ffmeg and Virtualdub2 to stream out just as a wav, it still happens.

The video is PAL, I think 720x576i. The audio I'm less sure, ffmeg is telling me Lavf61.9.100, pcm_s161e, 32000Hz, 1024kb/s, I think that's the input.

With Virtualdub2 or Handbrake (I forget which, the nights of trial and error are blurring) I tried lots of different audio compression settings, bitrates etc, no difference.

I've attached two 10 second examples. It's noisy/windy anyway in the snowy one, with a motor running in the background until the last second, but the noises are clear and continue into the next few sequences (not attached). In the next attachment there's a hint that the noises align with some glitches in the video (it's an old camera and an old tape) but there are other chirps that don't seem to. And again, the noises are not in the original AVI.

I would try to post a small snippet of the original to compare with but I have no way to snip it out from the longer video, even doing so with ffmpeg introduces the sound, as heard in the attachment - it's just the original untarnished AVI just run through ffmeg with something like the following, to break it into 10 secs chunks:

ffmpeg -i goodvideo.avi -c copy -map 0 -segment_time 00:00:10 -f segment -reset_timestamps 1 badvideo%03d.avi.

I'm not doing anything analogue, this is all done on my laptop from the AVIs. It seems this will now be all through all my hours of old videos if I try to edit them or compress them. Of course my partner says move on, ignore the squeaks. I'm going to need the help of a mental health professional for that!

It's not actually through all of the videos when I convert. It was for these snow scenes. It was from footage filmed from a train journey. And on a cable car. Could there be a very low level of high pitched noise from the train car squeaking, from the cable car wheel, or in the snow from the tape mechanism in the Mini DV camera, that all the converters are amplifying? I just would've thought when I use options that I think are supposed to stream the sound straight through that it shouldn't change from what I hear on the original.

I assume the traditional way to end a post is.... please help!

[timtape]

These appear to be dropouts, possibly created at time of the recording. Especially in clip 050, sound and picture dropouts or artefacts occur simultaneously : a chirp and a lost frame at the same moment.

In very cold weather there is a lot of moisture in the air which can greatly increases drag of the tape against the camera's spinning video drum. At time of shooting the fast spinning video drum may have slowed just enough to cause these artefacts in picture and sound. Another issue can be mold forming on the tapes. The tapes are so thin and fragile that the mold can glue tape winds together causing the tape to tear itself apart as it unwinds. Also the tapes use a pure metal encased in a protective coating. Once wet, the protective coating can easily be destroyed, the exposed metal oxidises and the recording is lost.

At what tape speed were these shots recorded? Standard Play was recommended. Recording at Long Play speed was not recommended for anything important.

These tapes are tiny and so are the miniaturised cameras and players. It takes only slight internal misalignment or other small maintenance issue - for artefacts or complete loss of sound and picture to occur. For clean picture and sound, everything had to be working well at time of shooting and also now at playback. If the playback itself isnt optimal, playing the tape on another player may improve things - or make it worse! New DV cameras, players or parts havent been available for years which doesnt help matters.

If you value these tapes, you may be advised to seek expert help before continuing. Specs Bros in NJ, USA appear to be one of the best in the world.

http://www.specsbros.com/

[AmRy]

Hi timtape,

Yes there could've been a lot go wrong at the time or since, I accept that, but the mystery that I'm really trying to solve is why to the AVIs that I took from the tape mostly sound fine, but when I run any conversion the squeaks are introduced. Surely I should be able to reproduce the same quality that was in the AVIs, yet as soon as I pump them through VideoDub or Handbrake or ffmpeg or Openshot or Clipchamp, in all cases suddenly the squeak becomes very pronounced, from either non-existent or below noticing compared with the other sounds. I wonder if there's some kind of normalisation/equalisation happening, but doesn't say ffmpeg just pass the audio straight through?

Cheers,
AmRy

[timtape]

... Surely I should be able to reproduce the same quality that was in the AVIs...

You would think so. I'd be checking whether any file compression is going on post avi, including "noise reduction" or other processing. Sometimes these processes are automatically active and we need to uncheck them. Maybe problems in error correction are involved.

[Alwyn]

Definitely caused by glitches in the file. You could try a re-transfer with WinDV or Scenalyzer.

The file is being reported as 600fps by MediaInfo and DVDate; that's not right.

I'm not getting any extra or louder squeaks with VDub when saved to H264 and AAC. I'd probably just edit out the really annoying ones in a video editor.

[AmRy]

Yeah no worse but still annoying! I notice you also ended up with that comb effect (I think that's what people call the horizontal lines from interlacing). I'm surprised most video software doesn't automatically fix that up. I was finally happy on that front by using Videodub2 and adding the deinterlace filter and using yadif with final double frame rate output, saving as progressive. But then I realised I had this audio problem. Note that was NOT what I did with the attached files, they are purely the original AVIs at 720x576i run through ffmpeg to split into smaller chunks to attach.

I'd love to be able to attach the original but it's 9GB or so. Maybe I'll see if I can get it off the Mini DV again but just a short section.

Yeah I guess I can try to turn down the audio in a video editor every time there's a squeak. I think it's going to be 100 times across several hours of tapes. Guess it will test how pedantic I really am. It's just trying to rescue holiday home videos from the early 2000s, then I never want to see a Mini DV again, as good as they were at the time.

[Alwyn]

I notice you also ended up with that comb effect

Yes, I was lazy! That is interlacing; standard fare for these types of files. You're doing the right thing double-rate deinterlacing: results in much smoother motion.

[AmRy]

Good to hear someone confirm my understanding of interlacing thanks.

By the way, yes I reckon my videos were standard play, I was fussy even back then.

I just went back to the tape and copied off a short section to AVI and do the same ffmpeg command as above. Attached both. So again, original is very glitchy but doesn't have the squeaks, the version out of ffmpeg has the squeaks. Looking for an ffmpeg expert or someone who can tell me why the audio would change and if there's anything I can do to stop it. Otherwise, yes, a painful process of suppressing each squeak, 100s, across hours of video. And so frustrating when whatever I used to convert avi to mpg last year seemed to not suffer from this, nor do the original avi's.

[Bernix]

It was already said. Can you try to capture video with WinDV ? Your video is somehow special, Avidemux or Mkvtoolnix refusing to opens it as it is. While my DV video captured with WinDV has not problems.

[lollo]

You have problems in your captures.

Here the AVPS DV Analyzer reports:

dv1.txt

dv1f.txt

dv2.txt

dv2f.txt

[timtape]

The avi file's PCM audio is badly clipped (overloaded) in one section due to the low frequency wind noise into the camera mics. See the bright sections a short way into the clip. The squeaks only occur in that clipped section. Possibly any audio conversion at editing has not helped. Audio compression like mp3 doesnt like converting clipped or even close to clipped audio. You could try in your video editor reducing the gain of the original audio by say 3db and see what happens when you render to a new file. Hopefully it will be no worse than in the original camera avi.

[AmRy]

Hi all, thanks for a bunch of responses. I'll try WinDV to capture again. Failing that I can try the 3dB wind down. lollo, curious as to what errors are reported on the E4again.avi file. That's straight off the tape, is obviously flawed but doesn't have the squeaks. OK, off to try WinDV.

[AmRy]

Good news. I put WinDV on my old laptop and used that to copy some sample DV over. It divided it into each scene. I moved the files to my newer laptop and used ffmpeg to stitch them together:

ffmpeg -safe 0 -f concat -i list2.txt -c copy windv.avi

Then used Vdub2 to deinterlace and save as a more compressed file: windv2.avi

And it doesn't have the squeaks even though it's been through those steps. Hooray! I think maybe WinDV cut out the ugliest bits it didn't like?

Attached the results (note Windows Media Player doesn't like the 2nd version but VLC is fine, I assume an unsupported codec, I'll look for some other Vdub2 option later).

Thanks for everyone's help. Unfortunately it means I have to go back and redo a bunch of videos, but hopefully no more squeaks and hopefully the camera and tapes hold together. Still confused why the original AVI's sound ok and yet something like a simple ffmpeg split up introduces the squeak. Presumably it's really doing SOME kind of interpretation of the audio and changing something about it.

[lollo]

lollo, curious as to what errors are reported on the E4again.avi file. That's straight off the tape, is obviously flawed but doesn't have the squeaks

Still problematic:

dv3.txt

dv3f.txt

You can run AVPS DV Analyzer by yourself. Also have a look to DV rescue for more support https://mediaarea.net/DVRescue

[Bernix]

If it is visually o.k. for AmRy he may not deal with those errors. Those tapes are 22+ years old. And yes one can see those issues, but better than delete all frames which got glitch. It is possible to open in avidemux now.

[lollo]

If it is visually o.k. for AmRy he may not deal with those errors

The overall idea behind is to re-capture the problematic segment several times to (hopefully) reduce the errors. Sometime it happens, when the tape has not a clear physical defect in that portion.

[Bernix]

The overall idea behind is to re-capture the problematic segment several times to (hopefully) reduce the errors. Sometime it happens, when the tape has not a clear physical defect in that portion.

O.k. Personally i think it will be bit by bit same. For sure he can try it, if any difference in problematic parts.

[lollo]

O.k. Personally i think it will be bit by bit same.

No, not always. Have you ever captured DV tapes with DV concealment and fixed the errors?

Here the recommended flow:

• Use Scenalizer Live (or similar) to capture DV files type-1
• Run AVPS DV Analyzer on the captured stream to validate there were no transfer errors, because some of the tapes may have 1 or more frames with DV concealment
• Recapture areas with concealment until getting as many corrected blocks as possible and splice the frames together if necessary

[AmRy]

Thanks all. I can live with a few frame errors, ironically a few visual jumps seem less annoying that the audio squeaks. I'd love to have it all perfect but it's just holiday video for me and my family, I should try not to obsess with it. And I suspect either the taps or the camera are pretty awful. It may be the camera, because I've put a few tapes in and they are all glitching every few seconds now. But if some of the tapes are worse than others then I might have to try the extra tips above, including DV Rescue.

Thanks again. I'll update this thread when I've had a go at a whole tape.

[AmRy]

Hi all,

So yes I used WinDV to do better captures which then don't have the audio issues. But I have hours of old videos with tapes 20+ years old and although I could go back and try a deep level of DV rescue with multiple passes I can't really invest that much time now and should accept they are not that important. So I'm trying to move on and just let it go... but... it is very frustrating that all those videos were copied as AVI which does not have the squeaks, so I have these 12 GB files per tape that are fine but I can't do anything to them without introducing the squeaks (and I really want to compress because they LOOK fine with H.264 getting them down to 1.5 GB, saving me heaps of space on my laptop, but the squeaks come in). I just can't understand why they sound ok when the AVI is played but when I do any kind of conversion with any kind of software, or even just use ffmpeg to do a straight unfiltered copy to audio, that the squeaks are created.

Yes the tapes are damaged, yes the AVI is partially corrupt, but the AVIs play without squeaks, surely there should be a way to convert/copy the audio just as all the players are doing without the squeaks? Even if it meant dropping corrupt frames or samples. I did try running through ffmpeg and reducing the volume by 10 dB and similar with Openshot. Didn't help.

All the more frustrating that for a couple of the old tapes I went AVI to mp4 a few years ago and the squeaks did not appear. I can only assume the video editor was smart enough to ignore corrupt audio. I think it was old Microsoft Video Editor which can't be played anymore.

[AmRy]

A mini-breakthrough. I just discovered it is possible to still run the old Microsoft Photos app and its Video Editor. You go to Photos and the tools cog and down in the options you can install what it calls Legacy Photos. Once I did that and ran it I got a mostly blank window for a few minutes but eventually it ran ok. From there I ran the sample from earlier, E4again.avi, and other than some clicks in the first second or so, the audio squeaks are gone! This is exactly what I was remembering from a year or two ago. So it seems legacy Video Editor is the only program known to mankind that doesn't introduce the clicks. It also seems to handle the interlaced nature of my video fine, no comb effect seen on output. It has very few options unfortunately, and my 720x576i has to be converted to 1280x720, that was the closest match. So it all feels rather dirty, especially messing with the video dimensions, but the audio is better. I've attached the sample. I know it still has jumps and in an ideal world would be reclaimed from the tape, but I have many many hours of similar AVIs that would all need recapture.

It's not so much this sample that I was trying to rescue, it's just the only short example I can upload here. I tested this on a much longer video, also filmed in windy conditions, which had a click just about every single second, and legacy Video Editor handled it fine. The downside is I don't get quite the space savings of staying at 720x576 and say H.264 compression. Feels so much cleaner using VirtualDub2 or Handbrake to deinterlace and maintain video dimensions, but the audio squeaks every second are a showstopper. Would still love an audio expert to give me a tip that let's me use ffmeg or handbrake or vdub instead. Surely Microsoft isn't superior to those!

[AmRy]

Just a bit more to confuse me. I just noticed that one of my original AVIs, when played through VLC, has the squeaks in it too. But not if played through Media Player. If I process it through Video Editor to produce an mp4 then the squeaks are not there whether I play on VLC or Media Player.

I think I'll just run all my AVIs through Video Editor, produce as 1280x720 (the smallest setting it allows whilst being bigger than than the originals, so hopefully not losing anything) and thus get decent audio and about 3x smaller files than the AVIs. I'll keep the AVIs on external HDD but keep the mp4s as my laptop version to watch. All a bit of an unsatisfactory mystery but I have a reasonable way forward.

[timtape]

Be careful in analyzing the playback on different players. They may not handle artefacts identically, having different thresholds for example. One may not drop frames, leaving in audio and video glitches, while another may drop the problem audio and the video frames, giving a first impression that they've fixed the problem or improved it. You may have to choose what seems the least objectionable to you and your audience.

[Bernix]

Source as you said should be PAL 25i. Why is it now 30fps? You did it or program itself?

[pcspeak]

If the clips were mine, and there was no voice dialogue I wished to keep, I would substitute the audio track for something more pleasing.
Cheers.

[AmRy]

@pcspeak, yes there could be some cases I could do that if all else fails.

@timtape, yeah good point, it seems this whole issue is as much about how various software interprets errors and decides how to output them. Even in converters with passthrough they presumably notice an error and don't pass through exactly even if told to. And then the players have similar variety in interpretation.

@Bernix, Legacy Photo Editor gives you no control, it chooses 30 fps. It fixes my audio issues but gives me little control over anything else. I'm trying to learn to live with it! But even then, some of my videos are so messed up that Legacy Photo Editor hangs or crashes rather than convert them, even though various players manage to play them. In these cases I either convert first (like with Handbrake) and cop the audio clicks or I just leave as AVI. I'm now doing a mix, trying to save a few 10s of GB with Legacy Photo Editor conversions and keeping a few as AVI.

Also playing around with Audacity click removal, doesn't do a great job, and the clicks seem to appear in both channels of the original stereo, often when other sounds such as voice are present, so not easily separated and removed. Also tried the free Adobe AI audio cleanup but that got rid of all environmental sounds as well, very voice focussed.

Currently doing the Adobe Audition free trial and selecting a squeak and running auto heal. Working well! Except I can't really listen to hours and hours and try to spot the squeak, select just that and auto heal. I was hoping I could auto heal a whole video at once but it didn't work. Will keep playing with various tools within this app.

[dellsam34]

That DV Analyzer one time showed me NTSC frame rate for a PAL DV at 25 fps, I don't trust it anymore.

[dellsam34]

and my 720x576i has to be converted to 1280x720, that was the closest match.

This is a huge mistake, if you must resize, resize to 1440x1080. Resizing 576 lines to 720 is a complete destruction.

[AmRy]

Specifically on 1280x720 vs 1440x1080, ok. Mostly I had done the latter. Actually MS Video Editor calls it 1920x1080 but I think it's at least being smart enough to effectively maintain the original 4:3 and adds the borders to fill it out to the 16:9. I can then run Handbrake with H.264 to remove the borders and improve the compression, getting back to 1440x1080 and files that are about 1/4 the original AVI, which saves me a lot of disk space.


It's all definitely very very sub-optimal. I'm on my precious summer holiday break and going to come out the other side feeling more stressed than I came into it, like I spent days of effort for a poor result. All because of these audio chirps that (in almost all cases) are not audible on the original AVI.

The rate is as much as 2 chirps per second on some tapes for extended periods, particularly when there was a lot of wind, more annoying than slight loss of video quality using legacy Video Editor to avoid it. I just need to accept the slightly degraded video and keep the original AVIs on external HDD (x2 for safe keeping). Maybe in 10 years I can process them again and tell some AI to remove the chirps. (It seems we're almost there with some apps but things that work perfectly in some cases, in other situations kill the voices or other sounds).

[AmRy]

I had a thought. Since Microsoft Video Editor does the audio ok but mangles the video, and everything else like Handbrake and Virtual Dub can do the video but introduces the audio clicks, I should do it both ways then use ffmpeg (or many other apps) to extract the good audio and put it on the good video. This suddenly seems obvious! I'll give it a go.