Device that turns 30P video into 60i output - which deinterlacing method?

[daygecko]

I have a device that takes 1080p30 video and sends it over component as 1080i60. I'm recording with a Blackmagic Intensity Pro 4K using OBS which gives the options: Retro, Blend, Blend 2x, Linear, Linear 2x, Yadif, Yadif 2x. I would prefer to record the interlaced video and then let the player software deinterlace, but that's only possible with the Blackmagic software which can only do it with uncompressed Quicktime (massive files). So I want to figure out the best de-interlacing method for content that was originally 30p.

I can't find any explanation of these methods that tells me which is best for recombining lines to get back to 30p. Everything I find on the internet claims all of these methods "interpolates" but I don't think that's accurate. And I don't want interpolation, I just want the two 1920x540 frames combined back to a single 1920x1080 frame.

Thanks!

[pandy]

Don't deinterlace something not interlaced - just change flag from interlace to progressive.

[daygecko]

Don't deinterlace something not interlaced - just change flag from interlace to progressive.

The device turns the 30p content into 1080i60. There is no 1080p30 option so I need to either record it interlaced, or deinterlace it

[davexnet]

Don't deinterlace something not interlaced - just change flag from interlace to progressive.

The device turns the 30p content into 1080i60. There is no 1080p30 option so I need to either record it interlaced, or deinterlace it

Can you provide a sample? Something showing steady movement

[daygecko]

Don't deinterlace something not interlaced - just change flag from interlace to progressive.

The device turns the 30p content into 1080i60. There is no 1080p30 option so I need to either record it interlaced, or deinterlace it

Can you provide a sample? Something showing steady movement

I just got a few minutes of video with the Blackmagic software but it's 30 gigs so I tried compressing it with FFMPEG, but that messes up the interlacing. Seems like half the frames just get dropped by FFMPEG. I can't find any way to compress and keep the interlacing preserved

[davexnet]

Open the file with Avidemux, leave the video and audio (on the left) to "copy", output format to MKV.
Use the A and B buttons to mark a few seconds and save

[daygecko]

Open the file with Avidemux, leave the video and audio (on the left) to "copy", output format to MKV.
Use the A and B buttons to mark a few seconds and save

AVIdemux doesn't work, but Quicktime on Mac does. The files are still gigantic, a few seconds is 2GB because it's 1000Mbps!

I think I got the answer to my question. Weave is the method where lines are "woven" from two frames to one frame, without any kind of motion interpolation which should be ideal for 30P original video. Too bad that's not an option in OBS!

[rrats]

Open the file with Avidemux, leave the video and audio (on the left) to "copy", output format to MKV.
Use the A and B buttons to mark a few seconds and save

AVIdemux doesn't work, but Quicktime on Mac does. The files are still gigantic, a few seconds is 2GB because it's 1000Mbps!

I think I got the answer to my question. Weave is the method where lines are "woven" from two frames to one frame, without any kind of motion interpolation which should be ideal for 30P original video. Too bad that's not an option in OBS!

It is, just don't use the f-ing deinterlace option

[manono]

Yeah, really. I've used OBS and never had it make interlaced files. But why are you capping uncompressed?

[daygecko]

Yeah, really. I've used OBS and never had it make interlaced files. But why are you capping uncompressed?

Because this is the only way to capture the interlaced video in BlackMagic Media Express

That's why I want to figure out the best deinterlacing method for OBS

I did some testing with Yadif and it seems good

[pandy]

Don't deinterlace something not interlaced - just change flag from interlace to progressive.

The device turns the 30p content into 1080i60. There is no 1080p30 option so I need to either record it interlaced, or deinterlace it

And? This is not a problem, just flag video as progressive after capture - you can strip interlace flag with help of avisynth or ffmpeg.

To address your problem with real time capture and compression with ffmpeg you need to provide command line - ffmpeg can be configured in a way to deal with real time compression.

[Skiller]

Because this is the only way to capture the interlaced video in BlackMagic Media Express

The Intensity Pro 4K should work fine in VirtualDub, which lets you select lossless codecs for compression. I have a Intensity Pro (no 4K) and never use Media Express because it'll only do uncompressed which is a silly waste of space.

If a video is flagged interlaced does not mean it actually is interlaced. In the worst case scenario the fields are paired so that the resulting frame has combing but that would be easy to fix using field matching, no deinterlacing required.

[daygecko]

Don't deinterlace something not interlaced - just change flag from interlace to progressive.

The device turns the 30p content into 1080i60. There is no 1080p30 option so I need to either record it interlaced, or deinterlace it

And? This is not a problem, just flag video as progressive after capture - you can strip interlace flag with help of avisynth or ffmpeg.

To address your problem with real time capture and compression with ffmpeg you need to provide command line - ffmpeg can be configured in a way to deal with real time compression.

The problem is I have two options:
1) Capture lossless interlaced using the Blackmagic software which is 1 gigabits per second
2) Capture de-interlaced using OBS which doesn't have the ideal option to simply recombine the video lines without any interpolation or artificial intelligence or anything like that

But I see the post below suggested Virtualdub so I'll look into that

[pandy]

The problem is I have two options:
1) Capture lossless interlaced using the Blackmagic software which is 1 gigabits per second
2) Capture de-interlaced using OBS which doesn't have the ideal option to simply recombine the video lines without any interpolation or artificial intelligence or anything like that

But I see the post below suggested Virtualdub so I'll look into that

You can use BM and ffmpeg to capture in real time lossless compression mode... but OK - from my perspective Virtualdub is pretty ancient software with own quirks to overcome...

[daygecko]

The problem is I have two options:
1) Capture lossless interlaced using the Blackmagic software which is 1 gigabits per second
2) Capture de-interlaced using OBS which doesn't have the ideal option to simply recombine the video lines without any interpolation or artificial intelligence or anything like that

But I see the post below suggested Virtualdub so I'll look into that

You can use BM and ffmpeg to capture in real time lossless compression mode... but OK - from my perspective Virtualdub is pretty ancient software with own quirks to overcome...

I've used Virtualdub before to change framerate of videos but couldn't figure it out for capture. The instructions I found were outdated apparently because the menu options are totally different. It also doesn't display my video input smoothly so I don't think it would work well.

I've used FFMPEG a lot for converting video formats and stuff like that, I haven't tried it for recording yet. By BM you mean Blackmagic right? I would capture to X264 though, so I'll have to figure that out

[pandy]

I've used Virtualdub before to change framerate of videos but couldn't figure it out for capture. The instructions I found were outdated apparently because the menu options are totally different. It also doesn't display my video input smoothly so I don't think it would work well.

I've used FFMPEG a lot for converting video formats and stuff like that, I haven't tried it for recording yet. By BM you mean Blackmagic right? I would capture to X264 though, so I'll have to figure that out

Virtualdub was designed for VfW API - it is outdated and with many limitations - you can ignore/disable preview to speedup capture and improve performance.

Real time encoding and capture is possible but this depend on your HW capabilities - definitely it is easier when hardware compression is used - NVidia NVEnc engine seem to be best for such tasks.

[daygecko]

I have gotten HDMI to work, so now there's another possibility-- Capture the raw HDMI data coming into the capture card. But is that possible? I can't find any method to do that. For at least a couple videos, I want to capture the output with total fidelity, but currently the best option I can find is Blackmagic Media Express recording to RGB 10 bit which has a massive bitrate and presumably a lot of extra data. The bitrate is so high that 1/3 of the frames get dropped during recording

[daygecko]

I read this VLC document and it seems like NONE of the options available in FFMPEG or OBS actually deinterlaces. They all do a lot of interpolating. Yadif literally throws away half the frames and just creates new data to fill in the empty lines. https://wiki.videolan.org/Deinterlacing/

OK so I'm stuck with capturing uncompressed interlaced video at 1Gbps, fine. How do I then deinterlace the video? It seems ridiculous that it would just be impossible. A lot of content is converted to interlaced for the consumer, why would converting it back to 30p be so arcane?

[poisondeathray]

If it's "30p" and the fields are aligned, you do nothing. You should see no combing if this was the case.

If fields are misaligned, then you use -vf fieldmatch . This reassembles the fields without interpolation

Do not use a "deinterlacer" (unless you can set it to "none" or "weave" )

[Skiller]

You can't really capture the raw HDMI data with the BMD Intensity, you have to choose the native format of the incoming HDMI signal yourself. I guess that's because the advertising claims something like "converts to any format you want" crap. I dislike this design choice as well but it can be overcome: choose "uncompressed 8-Bit YUV" in Media Express ("Capture file format").
Also double check you have input processing turned off in the driver's settings.

Still I'd give VirtualDub another shot if I was you. Works perfectly fine for me with my Intensity Pro and I can choose any lossless codec I like for capturing.

[pandy]

OK so I'm stuck with capturing uncompressed interlaced video at 1Gbps, fine. How do I then deinterlace the video? It seems ridiculous that it would just be impossible. A lot of content is converted to interlaced for the consumer, why would converting it back to 30p be so arcane?

How do you know if this video is interlaced - are you checking fields dependency or there is something else to detect interlace?

[daygecko]

If it's "30p" and the fields are aligned, you do nothing. You should see no combing if this was the case.

If fields are misaligned, then you use -vf fieldmatch . This reassembles the fields without interpolation

Do not use a "deinterlacer" (unless you can set it to "none" or "weave" )

Thanks, and I also saw your other reply on the old thread I bumped about deinterlacing, I will respond to that post too

I concluded that FFMPEG can't handle the video without deinterlacing because I compressed it using HEVC_NVENC expecting the video to stay interlaced, but the result had combing effects. So I concluded that FFMPEG was dropping half the frames and leaving only half the lines. I tried it again with Yadif deinterlacing and it looked fine, but now I know that Yadif throws away half the frames and just interpolates in-between lines.

I'll try -vf fieldmatch

I found this explanation of it http://underpop.online.fr/f/ffmpeg/help/fieldmatch.htm.gz

[daygecko]

OK so I'm stuck with capturing uncompressed interlaced video at 1Gbps, fine. How do I then deinterlace the video? It seems ridiculous that it would just be impossible. A lot of content is converted to interlaced for the consumer, why would converting it back to 30p be so arcane?

How do you know if this video is interlaced - are you checking fields dependency or there is something else to detect interlace?

It's a cablebox that can only output 1080i

[manono]

It's a cablebox that can only output 1080i

Which, by itself, means nothing. That only tells you it was encoded as interlaced, not what the content is like. There's often a difference. If you don't see any interlacing, it's not interlaced.

[daygecko]

It's a cablebox that can only output 1080i

Which, by itself, means nothing. That only tells you it was encoded as interlaced, not what the content is like. There's often a difference. If you don't see any interlacing, it's not interlaced.

It does mean something-- If I'm recording from the box, I need to record interlaced or deinterlaced.

For interlaced recording I can use Blackmagic Media Express but only uncompressed formats are available.

I can create compressed recordings with OBS but it doesn't support interlaced. I originally recorded with no deinterlacing and this was the result https://www.youtube.com/watch?v=H2lGEZOOHwI&lc=Ugz72vLhL_bCnsCPWV94AaABAg
You can see the combing effects

Some shows like sports are real 1080i 60fps but most seem to be 1080p30

[manono]

It's a cablebox that can only output 1080i

You capture what is broadcast. You don't ever want to deinterlace anything while capturing. If it has to be done for one reason or another, do it later.

You can see the combing effects

Yes, that's a true interlaced source. But, as I mentioned earlier, the content can easily be progressive. This isn't. Why didn't you deinterlace it before uploading it? Interestingly, the lower resolution versions on YouTube have been deinterlaced.

Some shows like sports are real 1080i 60fps but most seem to be 1080p30

Some channels (especially sports channels) broadcast 720p 60fps, some 1080i 30fps (including a lot of progressive content). If your cable box hands you anything 1080i 60fps, they're upscaling the original broadcast. In the US anyway, with only a very few exceptions.

CBS and NBC chose 1080i ,Fox and ABC and ESPN are all 720p ,PBS is mostly 1080i but not all of it and the cable channels are all over the map with cable channels like HBO. SHOW,History ,the Discovery network channels ,Velocity ,CNN and so on at 1080i while Fox news ,Disney/ABC/ESPN co. network,channels are 720p .

https://e-cards-greetings.com/qa/what-resolution-is-tv-broadcast-in.html

[daygecko]

It's a cablebox that can only output 1080i

You capture what is broadcast. You don't ever want to deinterlace anything while capturing. If it has to be done for one reason or another, do it later.

You can see the combing effects

Yes, that's a true interlaced source. But, as I mentioned earlier, the content can easily be progressive. This isn't. Why didn't you deinterlace it before uploading it? Interestingly, the lower resolution versions on YouTube have been deinterlaced.

Some shows like sports are real 1080i 60fps but most seem to be 1080p30

Some channels (especially sports channels) broadcast 720p 60fps, some 1080i 30fps (including a lot of progressive content). If your cable box hands you anything 1080i 60fps, they're upscaling the original broadcast. In the US anyway, with only a very few exceptions.

CBS and NBC chose 1080i ,Fox and ABC and ESPN are all 720p ,PBS is mostly 1080i but not all of it and the cable channels are all over the map with cable channels like HBO. SHOW,History ,the Discovery network channels ,Velocity ,CNN and so on at 1080i while Fox news ,Disney/ABC/ESPN co. network,channels are 720p .

https://e-cards-greetings.com/qa/what-resolution-is-tv-broadcast-in.html

When I say 1080i 60fps I'm referring to each of the interlaced halves as a frame. I know some people say 1080i30

The clip on Youtube was recorded with OBS which doesn't support interlaced recording and also doesn't have real deinterlacing. From the VLC document above, it seems that linear, yadif, and blend just throw away half the data and interpolate between lines. I don't know what retro does


[Attachment 63106 - Click to enlarge]

[daygecko]

I think for deinterlacing with FFMPEG, BWDIF may be the best option. I tried it on an uncompressed clip from Blackmagic Media Express and it came out looking really nice with 60 frames https://ffmpeg.org/ffmpeg-filters.html#bwdif


From that description it seems smart enough to adapt to interlaced vs progressive content and the render rate is 1/2 real time with my 8 core CPU, so it must be doing some advanced stuff


I guess if it were an option in OBS it would be too slow, so maybe Yadif 2X is a good alternative since unlike Yadif 1x it doesn't just discard data

[poisondeathray]

I think for deinterlacing with FFMPEG, BWDIF may be the best option. I tried it on an uncompressed clip from Blackmagic Media Express and it came out looking really nice with 60 frames https://ffmpeg.org/ffmpeg-filters.html#bwdif


From that description it seems smart enough to adapt to interlaced vs progressive content and the render rate is 1/2 real time with my 8 core CPU, so it must be doing some advanced stuff


I guess if it were an option in OBS it would be too slow, so maybe Yadif 2X is a good alternative since unlike Yadif 1x it doesn't just discard data

bwdif is quite a bit faster than yadif for me. There might be some other conversions "underneath the hood" or bottlenecks for you, such as pixel type (RGB30 ?) , or I/O bottlenecks

bwdif only weaves properly, when there is no motion . There is still some degredation on progressive content (it doesn't field match) . Some types of progressive content are not degraded as noticably, but others will be severely degraded compared to fieldmatching

Yadif 2x retains the original fields, so you can reconstruct the original progressive frames later if you had to (you discard the interpolated fields that yadif generated , and weave the original ones)

[daygecko]

I think for deinterlacing with FFMPEG, BWDIF may be the best option. I tried it on an uncompressed clip from Blackmagic Media Express and it came out looking really nice with 60 frames https://ffmpeg.org/ffmpeg-filters.html#bwdif


From that description it seems smart enough to adapt to interlaced vs progressive content and the render rate is 1/2 real time with my 8 core CPU, so it must be doing some advanced stuff


I guess if it were an option in OBS it would be too slow, so maybe Yadif 2X is a good alternative since unlike Yadif 1x it doesn't just discard data

bwdif is quite a bit faster than yadif for me. There might be some other conversions "underneath the hood" or bottlenecks for you, such as pixel type (RGB30 ?) , or I/O bottlenecks

bwdif only weaves properly, when there is no motion . There is still some degredation on progressive content (it doesn't field match) . Some types of progressive content are not degraded as noticably, but others will be severely degraded compared to fieldmatching

Yadif 2x retains the original fields, so you can reconstruct the original progressive frames later if you had to (you discard the interpolated fields that yadif generated , and weave the original ones)

Interesting... From the multiple descriptions I've read on various websites, yadif fills in the missing lines, so if you do 2X it does that for every "field" but also keeps the original lines as they are. Is that correct? So to reconstruct the original data you would take the original lines out of the 60p video and then interleave those back together. So I guess it's "lossless" but still easy to record and view.

Does BWDIF not keep the original lines?