Frame rate conversion

[Alexstarfire]

Not sure if this is exactly a newb question, but whatever. I've been converting some anime using AviUtl .98D for a while now, and other than taking a while I haven't had any real problems. Didn't think much about it at the time, but I've got several files that have like 4x+ more frames than the other ones but run the same duration. This obviously means that the frame rate is much higher, nearly 120FPS. While converting these files I found that the output is horrible, both video problems and audio sync problems. I'm trying to figure out a way to solve this, and I haven't come up with anything yet.

I was wondering how to convert it down to 23.976 FPS like all the other files I have, and fix the audio problems I would have with down converting it. Also, is there anything else I can do to fix this problem? I know there are other conversion programs out there, but this one allows me to shrink the resolution which I need to do. It also let's me select which codec to re-encode it with.

Thanks for the help.

[freebird73717]

Sounds like variable frame rate mkv.

Look into these threads for some info.

https://forum.videohelp.com/topic333868.html?highlight=vfr%20mkv

https://forum.videohelp.com/topic331513.html?highlight=vfr%20mkv

https://forum.videohelp.com/topic333454.html?highlight=vfr%20mkv

Do a forum search for vfr mkv to get a lot more results.

[jagabo]

It's likely that the original source was a mixture of 23.976 and 29.97 fps material. 120 (119.88) fps is the least common multiple of the two (24*5, 30*4). Each frame of the 23.976 fps source is repeated 5 times, each frame of the 29.97 fps source is repeated 4 times.

There's no way to convert this to 23.976 fps without some parts becoming a little jerky. If the source is AVI and if you can live with some jerky sections you could easily do the frame rate conversion with VirtualDubMod. The audio shouldn't have to be modified.

[Midzuki]

After determining what part/s of the video source is/are in 23.976 fps and
what part/s is/are in 29.97 fps, you could use Avisynth to add blended frames
to the 23.976 fps segment(s) in order to obtain a 100% NTSC-framerate video
stream. Of course that will require a lot of hard manual work,
but perhaps that is the only way to get some acceptable output. I've had similar
problems with some downloaded .AVIs that were incorrectly converted from
23.976 fps to 29.97 fps --- namely, there was one repeated/blended frame for
every four frames, and I used an external AVS filter (DeleteEvery) to get
rid of the "garbage".

=====

[manono]

Yeah, it may be hybrid, but not necessarily. I've seen 119.8fps raws where the whole thing was 23.976fps. You can use VDub(Mod) to get rid of the dupe frames, as jagabo suggests, or AviSynth's SelectEvery(5,0)

And no one uses AviUtil anymore, not for 7-8 years or more. Time for you to learn some AviSynth, if you're to consider yourself a real anime encoder.

After determining what part/s of the video source is/are in 23.976 fps and
what part/s is/are in 29.97 fps, you could use Avisynth to add blended frames
to the 23.976 fps segment(s) in order to obtain a 100% NTSC-framerate video
stream. Of course that will require a lot of hard manual work, but perhaps that is the only way to get some acceptable output.

That's no work at all, as both Decomb and TIVTC have modes to do just that automatically. However, I'd do about anything to avoid encoding it for 29.97fps, especially if the vast majority is really 23.976fps, as is almost always the case.

[jagabo]

you could use Avisynth to add blended frames to the 23.976 fps segment(s)

I'd rather see jerky video than blended frames.

[Midzuki]

jagabo wrote:

I'd rather see jerky video than blended frames.

That's a matter of taste, naturally. Ain't much we can do while there "must" exist
some (non-trivial) difference between the framerate of the movie cameras and
the framerates of the TV sets.

=====

[Alexstarfire]

Well it's not like AviUtl doesn't work. Far be it from me to know everything, considering I don't do much converting usually.

Anyways, one of the real problems I'm starting to have is that something will play fine on my computer, but then not run proerly on the DVD player. I've converted 47 files so far, enough to completely fill 1 DVD, with 2 being those weird 119.xxx FPS files. All of them run PERFECT on my computer. There is no audio sync problems, no skipping, etc etc and apart from those 2 odd FPS files they have all been done the EXACT same way. However not all of these files are playing properly on the DVD player. There doesn't seem to be any rhyme or reason as to why this occurs. There doesn't seem to be anything specific about the ones that play right and the ones that don't. I can say however that I haven't checked all the files, and with over 900 minutes of video I'm sure you can understand why. BTW, after playing the files on the DVD player I've found that they are all worthless since it extends quite a bit off the screen. I only noticed that when the freaking subtitles ran off the screen. It's a fairly large portion that's off too. Could be up to 100 pixels or so total.

I can't even just do small test files anymore since there have been times where the test files ran fine, but then the full video didn't. Go figure. Could that be because I'm using XviD to encode them and trying to ply them on a DivX DVD player? Or is it the program I'm using?

I'll go take a look at AviSynth and see what I can get done.

Think I can send these trouble files, the ones that aren't running properly, to one of you guys and see what you come up with. I'd only send you 2 files, 1 files with the regular 23.976 FPS and 1 file with the 119.xxx FPS. I'm sure you guys could figure it out faster than I and then point me in the right direction.

Ohh yea, I'm pretty sure it's not a variable frame rate for that 119.xxx FPS video file else the way I did it the audio would be off on my computer, which it isn't. I just used AviUtl to basically cut the frame rate in half, which I assume takes out every other frame, and the AV are just right, but it's not so great on the DVD player. Gonna try cutting it in half again and see what happens.

Anyways, thanks for the help.


EDIT: I'm gonna need a guide to AviSynth you guys. I'm looking for one, but I can't find one that's really useful. Also, I'm either really stupid or F'ed up, but I don't even see a program in the AviSynth folder. Is there not supposed to be one? In the guide I'm reading, which only uses AviSynth for one part, mentions the program, but never tells you to open it, just to modify the AVS files and such. So what exactly is AviSynth. Everything I read it making me think it's just a script and nothing more. Anyways, a newbie guide for AviSynth would be great.

[manono]

http://avisynth.org/mediawiki/Main_Page#New_to_AviSynth_-_start_here

[Alexstarfire]

Well since there is a new post I'll just make this a new post instead of an edit. After effectively converting the frame rate of the 120 FPS file to 23.976 it seems to run fine on the DVD player. That just means I'll have to run it through AviUtl twice since I can only down convert it so much at one go. That makes me wonder though. Since I'm playing it on a DVD player, should I convert it to 29.97 FPS as is NTSC standard? Or does it even matter since I'm using AVI?

Thanks for the link to the guide. I found one for "Nicky Avisynth guide" but the link was broken. Then I Googled for one and the link to that one was broken.


EDIT:*reads guide and totally doesn't get it* I understand that I can use it to apply filters and deinterlace, but is that it? It's great that it can do that, but what does it do with the file? If it's compressed does it leave it that way, or is it going to decompress it? If it would naturally decompress it is there a way to recompress, other than using a different program? From what I've read about it so far I don't see why it's any better than what I'm using. Is it faster or something?

[jagabo]

After effectively converting the frame rate of the 120 FPS file to 23.976 it seems to run fine on the DVD player. That just means I'll have to run it through AviUtl twice since I can only down convert it so much at one go.

You can do that but each conversion to a lossy codec will decrease the quality. Doing the frame rate conversion once in AVISynth will give you better results and will be twice as fast. To simply drop frames:

AVISoure("video.avi")
ChangeFPS(23.976)

If you did the conversion with VirtualDubMod you could use its template feature. Once you've created a template you just select the template and open the file -- VirtualDUbMod will automatically create the AVS script.

That makes me wonder though. Since I'm playing it on a DVD player, should I convert it to 29.97 FPS as is NTSC standard? Or does it even matter since I'm using AVI?

Either one will work. (What ends up on a standard definition screen is always 59.94 fields per second. A 23.976 fps source will go through 3:2 pulldown, a 29.97 fps source will go through 2:2 pulldown.) The deciding factor should be which gives smoother results. That will depend on what potions of the video are each of the two frame rates. If 90 percent of the video is 23.976 fps it will be better to convert it to 23.976, that way only 10 percent of the video will be jerky. And vice versa.

[Alexstarfire]

I don't understand how to do it with VirtualDubMod. I know they have the option to change the frame rate, seems simple enough, but then the audio is off. I did have the audio on direct stream copy though. I'm trying it as we speak using the full processing mode for the audio. Either way the quality loss is still not noticeable on the TV.

Also, I figured out that I won't have to reconvert the files again to get it all to fit on the screen. Stupid DVD player has some options to change the display, but it seems that they don't work very well. It's default is set to auto fit. Why would auto fit extend the video off the screen in both the X and Y directions I don't know. Never got the Y axis to fit on the screen with the options they had, including one to fit it by the height of the video, but I did get the X axis to fit on the screen using the "original" option, the fit to screen by width didn't even display it properly. Could be because of the way it's encoded that some of them didn't work, but whatever. I'll figure that out soon enough when I burn my next disc.

I seem to have figured out everything except why certain videos that are 23.976 FPS normally don't run right. Episode #9 is the first one I noticed, happens to be my favorite episode. I'll just burn the next disc and see if everything gets solved. I have a feeling the burning software may have something to do with those random files not working right.

I'll post back once I burn the next disc after all the changes.


EDIT: Yea, changing it in VirtualDubMod, and Nandub, don't seem to work very well. I can change the frame rate, but it just makes the video like 5 as long. How do I tell it to just use every 5th frame? I know they have the frame rate decimation, but that doesn't help. I need it to actually drop 4 out of the 5 frames and I can't see how to do that.

[jagabo]

changing it in VirtualDubMod, and Nandub, don't seem to work very well. I can change the frame rate, but it just makes the video like 5 as long. How do I tell it to just use every 5th frame?

Leave the top part of the Frame Rate dialog (Source Frame Rate) unchanged. It should say ~120 fps. Tick the Convert To FPS option in the middle section (Frame Rate Conversion) and enter the desired frame rate. VirtualDub will drop frames to reduce the frame rate (or duplicate frames to increase the frame rate). The running time won't change.

Also, I figured out that I won't have to reconvert the files again to get it all to fit on the screen. Stupid DVD player has some options to change the display, but it seems that they don't work very well. It's default is set to auto fit. Why would auto fit extend the video off the screen in both the X and Y directions I don't know.

Your TV is cutting off the edges of the picture. It's called overscan and all TVs do it. If your player doesn't have options that let you adjust the size (most don't) you'll have to add borders to the video so that the borders fall in the overscan area. You can do this with VirtualDub's resize dialog.

[Alexstarfire]

Leave the top part of the Frame Rate dialog (Source Frame Rate) unchanged. It should say ~120 fps. Tick the Convert To FPS option in the middle section (Frame Rate Conversion) and enter the desired frame rate. VirtualDub will drop frames to reduce the frame rate (or duplicate frames to increase the frame rate). The running time won't change.

That's exactly what I did and it made it 5x longer. I'll try again though, cause I thought that I tried this before and it didn't do that, but IDK for sure.


EDIT: Yep, did it again and the same thing happened. Not sure what else to say.

Your TV is cutting off the edges of the picture. It's called overscan and all TVs do it. If your player doesn't have options that let you adjust the size (most don't) you'll have to add borders to the video so that the borders fall in the overscan area. You can do this with VirtualDub's resize dialog.

Well, just reducing the Y resolution made it fit on the screen. Anyways, I got it so I don't have borders and it fits on the screen. Probably not perfect, but much better than it was before.

[jagabo]

Leave the top part of the Frame Rate dialog (Source Frame Rate) unchanged. It should say ~120 fps. Tick the Convert To FPS option in the middle section (Frame Rate Conversion) and enter the desired frame rate. VirtualDub will drop frames to reduce the frame rate (or duplicate frames to increase the frame rate). The running time won't change.

That's exactly what I did and it made it 5x longer.

Always works for me:



It doesn't work well in Direct Stream Copy mode.

Does the dialog show 120 fps for your source?

[Alexstarfire]

Ok, now here's the problem. I don't have THAT option. I only have the one at the top, except they don't call it "Source rate adjustment."

I see what the problem is. You are talking about VirtualDub whereas I'm talking about VirtualDubMod and Nandub. Just downloaded VirtualDub and that option is there, couldn't have missed that. It's just not there in the other ones I'm using. I never used VirtualDub because the original files I had weren't 100% compatible with VirtualDub, but they are fine with VirtualDubMod and Nandub. The only way to make it compatible is to apparently recompress it, in my case using AviUtl. I just tried opening up my video file that I already changed the resolution on and it worked fine. The reason is probably because I recompress the audio as well. I found out that I have to if I want it to sync up properly. It's better that I do that anyways since I end up with smaller files and the same sound quality if I recompress it.

I suppose I could try it without changing the audio at all, but idk. If I ever figure out how to use AviSynth then I can use that to shrink the resolution of the file and change the FPS as well, so long as changing the FPS with AviSynth isn't just changing it, but rather converting it. Else I could try using AviSynth AND VirtualDub, but idk. Gotta figure out AviSynth first.

[manono]

If using VDubMod:

That'll give you 23.976fps.

[jagabo]

The Frame Rate dialog image I posted was from VirtualDubMod 1.5.10.1.

[Alexstarfire]

That's weird. My version didn't have it. Ohh well. I'll look into it later. I've already done the conversions my way, and I'm burning the disc. I'm going to sleep so I'll post on it later.

[Alexstarfire]

Ok, everything I went and changed is working flawlessly now. I'm still having trouble with the same random files that weren't working right the first time. I'm reconverting them as I type this. If that doesn't work I'll look into doing them another way.

[jagabo]

VirtualDub often has problems with VBR MP3 audio. Especially from Nandub.

[Alexstarfire]

Yes it does, but I'm not sure what you mean about it from Nandub. Haven't tried opening anything I've made with Nandub yet. Either way, I was using Nandub as a replacement for VirtualDub. I'll have to look into WirtualDubMod though since it has the frame rate conversion feature I was looking for.

Anyways, I can't seem to figure out why those certain files weren't working. Reconverting them didn't help. I also tested to see if I had problems with the original files, in which case it wouldn't be just because I compressed them, but the originals play just fine, other than running off the screen. I'll have to see if I can get AviSynth to resize the video files for me.

[jagabo]

To compensate for overscan with AVISynth you can just use the AddBorders() function. If your player keeps the aspect ratio:

AVISource("File.avi")
AddBorders(32, 0, 32, 0)

If your player always enlarges to full screen (4:3):

AVISource("File.avi")
AddBorders(32, 24, 32, 24)

You can use FitCD to generate scripts with different size borders.

[Alexstarfire]

I'm not worried about the borders. I got it working just fine without them. Not sure if it extends off the screen by 64 (?) pixels. I assume that the 32 you mention is on 2 sides of the video and not all the way around. I cut the Y resolution by 60 to 420 and the X resolution stays the same, I got the player to make it fit. Are you saying I should cut the Y resolution by 64?

Anyways, I got AviSynth to work with VirtualDubMod. Turn out Nandub isn't too useful since all the options I need are missing. The thing is that the file is nearly double the size of it's original state despite me using the exact same compression options. Not too big of a deal considering the output file plays perfectly and it's only a couple files that are like that. Is there any reason why using AviSynth and VirtualDubMod make my file so much larger than my other ones?

EDIT: uhh, I just noticed I used Fast Recompress, as some guide I was reading said. That could be why it was larger. I have 1 more file to go so I'll use the Full Processing Mode on that one and see how big the file is.


BTW, thanks for all the help you guys have given me. AviSynth can indeed be a very useful tool and is quite easy to use once you understand it's only a filetype/script and not an actual program, like being a service and not an actual product. I'm not sure if I would have been able to do this without your help.

[jagabo]

I'm not worried about the borders. I got it working just fine without them. Not sure if it extends off the screen by 64 (?) pixels. I assume that the 32 you mention is on 2 sides of the video and not all the way around. I cut the Y resolution by 60 to 420 and the X resolution stays the same, I got the player to make it fit. Are you saying I should cut the Y resolution by 64?

Every time you resize you will lose some image quality. That's whay I recommended simply adding borders -- leave the actual image intact. Adding 32 pixels to the left and right edges won't cost you any bitrate (black borders compress down to nearly nothing). If 32 is too much for you try 16. You can use any size but mutiples of 8 or 16 are best (because all the MPEG codecs break the image down into 16x16 and 8x8 blocks and work from there). If your player maintains the aspect ratio it will add borders to the top and bottom to compensate.

You could try using MPEG4Modifier to change the Pixel Aspect Ratio. That might be enough to get the subtitles visible. If it works you can completely avoid resizing and reencoding. BUt many players don't pay any attention to the aspect ratio settings.

Anyways, I got AviSynth to work with VirtualDubMod. Turn out Nandub isn't too useful since all the options I need are missing. The thing is that the file is nearly double the size of it's original state despite me using the exact same compression options. Not too big of a deal considering the output file plays perfectly and it's only a couple files that are like that. Is there any reason why using AviSynth and VirtualDubMod make my file so much larger than my other ones?

EDIT: uhh, I just noticed I used Fast Recompress, as some guide I was reading said. That could be why it was larger. I have 1 more file to go so I'll use the Full Processing Mode on that one and see how big the file is.

No. File size = bitrate * running time. If you want a smaller file use a lower bitrate. If you're using target quantizer mode use a higher quantizer. The higher the quantizer the smaller the file and the worse the quality. If you used Xvid's default settings you got a constant quantizer encoding with a quantizer of 4. That's better quality (how closely the decomrpessed output matches what was input) than most files you download from the web. I usually use 3 for my own encodings.

Some notes on VirtualDub's (all versions) Video Processing Modes:

Direct Stream Copy -- simply copies the compressed data from the input to the output. The image isn't changed in any way.

Fast Recompress -- the incoming video is decompressed to whatever native form the decomrpessor outputs it. This is usually YV12 or YUY2. If you're not using VirtualDub's filtering this mode is fastest and gives the best quality.

Normal Recompress -- VirtaulDub takes data from the decompressor, YV12 or YUY2, and converts it to RGB. Filtering is not enbaled. This mode is hardly ever used.

Full Processing -- same as Normal recompress but filtering is enabled.

BTW, thanks for all the help you guys have given me. AviSynth can indeed be a very useful tool and is quite easy to use once you understand it's only a filetype/script and not an actual program, like being a service and not an actual product. I'm not sure if I would have been able to do this without your help.

AVISynth and VirtualDub are really great tools -- well worth learning how to use.

[Alexstarfire]

No. File size = bitrate * running time. If you want a smaller file use a lower bitrate. If you're using target quantizer mode use a higher quantizer. The higher the quantizer the smaller the file and the worse the quality. If you used Xvid's default settings you got a constant quantizer encoding with a quantizer of 4. That's better quality (how closely the decomrpessed output matches what was input) than most files you download from the web. I usually use 3 for my own encodings.

Well, what I'm telling you is that I have the EXACT SAME encoding settings. I have the quality target set to 3.25 for mine. I'm telling you that using the AviSynth + VirtualDub method makes my files 3-4 times bigger than just using AviUlt alone. I can say that I have a noise reduction filter set in Aviutl that I don't in VirtualDub, but I can't see how it would make THAT much difference.

[jagabo]

Have you examined the files with Gspot and verified that they both have the same frame size, frame rate, audio and video codecs? Do the files appear to have the same visual quality?

Noise reduction will usually make the file smaller. Xvid's major compression method is not to encode parts of the frame that don't change from frame to frame. More noise = more changes = bigger file. The effect is usually fairly small (single or double digit percentages) unless you are using very heavy filtering.

I don't know anything about AviUtl -- does it use Xvid's dialog for specifying the quantizer? Or does it have its own dialog? Maybe the setting isn't exactly the same thing?

[Alexstarfire]

Yep, files are very similar, I'm not talking about before and after conversions though. The files I convert are very similar though. Nearly the same # of frames, same visual quality, same frame rate, and same audio. The video codecs of some are different, not sure why (s)he chose to do that, but it's only a handful out for the 200 or so files. The ones in particular that I converted using AviSynth and VirtualDub are identical in the video codec though, Divx 3 Low-Motion.

I'll have to look into the noise reduction then. I didn't think I had it set that high, but maybe I did and didn't notice. I made sure it didn't affect the picture in a negative way. The still parts are noticeably better while the action parts are only very slightly blurred, not even noticeable.

As far as I can tell it's using XviDs dialog. They both go to the same XviD encoding properties page.

[jagabo]

I tried using AviUtl but it was all in Japanese.

[Alexstarfire]

To get it into English all you have to do is open the program, close it, open the avutl.ini file and add

[system]
resource=English

at the bottom of the file.