Converting 1080/25i to 1080/50i

[simon744]

Hi, everyone!! I have a lot of files, mainly satellite backhaul/fronthaul feeds at 1080/25i that I'd like to convert to 1080/50i. (or for some, to 1080/59.94i, as I have 29.97i footage too) I know I can use Handbrake with Yadif and Bob to achieve that, but I don't want to deinterlace, I need my outputs to be interlaced. I've spent hours looking for a solution, tried ffmpeg for this, but the output always ends up progressive even when I explicitly had told it to interlace or to at least preserve the interlaced frames/fields. I also used ffmpeg Clever GUI, which was a lot less confusing, and created different files each time; once, the output would be progressive, the other time, it would come out interlaced and with interleaved fields, but also have severe scanline and combing artifacts all over the place that I couldn't seem to get rid of regardless of what deinterlacing filter or just media player was used.

Here's the MediaInfo log of one of the files that I'm working with:

Video 
ID : 4113 (0x1011) 
Menu ID : 1 (0x1) 
Format : MPEG Video 
Format version : Version 2 
Format profile : Main@High 
Format settings : BVOP 
Format settings, BVOP : Yes 
Format settings, Matrix : Default 
Format settings, GOP : M=4, N=28 
Format settings, picture structure : Field 
Codec ID : 2 
Duration : 4 min 15 s 
Bit rate mode : Constant 
Bit rate : 37.5 Mb/s 
Maximum bit rate : 33.1 Mb/s 
Width : 1 920 pixels 
Height : 1 080 pixels 
Display aspect ratio : 16:9 
Frame rate : 25.000 FPS 
Color space : YUV 
Chroma subsampling : 4:2:0 
Bit depth : 8 bits 
Scan type : Interlaced 
Scan order : Top Field First 
Compression mode : Lossy 
Bits/(Pixel*Frame) : 0.724 
Time code of first frame : 02:57:46:18 
Time code source : Group of pictures header 
Stream size : 1.12 GiB (89%) 
Color primaries : BT.709 
Transfer characteristics : BT.709 
Matrix coefficients : BT.709 

And here's what I want my output to "look" like:

Video 
ID : 1 
Format : AVC 
Format/Info : Advanced Video Codec 
Format profile : High@L4.1 
Format settings : 3 Ref Frames 
Format settings, CABAC : No 
Format settings, Reference frames : 3 frames 
Codec ID : V_MPEG4/ISO/AVC 
Duration : 3 min 2 s 
Bit rate mode : Constant 
Bit rate : 31.3 Mb/s 
Width : 1 920 pixels 
Height : 1 080 pixels 
Display aspect ratio : 16:9 
Frame rate mode : Variable 
Frame rate : 50 FPS 
Original frame rate : 25 FPS 
Color space : YUV 
Chroma subsampling : 4:2:0 
Bit depth : 8 bits 
Scan type : Interlaced 
Scan type, store method : Separated fields 
Scan order : Top Field First 
Bits/(Pixel*Frame) : 0.252 
Stream size : 682 MiB (94%) 
Default : Yes 
Forced : No 
Color range : Limited 
Color primaries : BT.709 
Transfer characteristics : BT.709 
Matrix coefficients : BT.709 

I need the scan order to be "Top Fields First," and the Scan Type, store method, "Separated fields." The video needs to be losslessly re-encoded either back to source MPEG2 or to H.264.

I've also "heard" that AviSynth can do this better than ffmpeg can, but am not very familiar with it. If anybody knows of the right plugin and the right script to get this done, I'd be INFINITELY grateful to you. Just PLEASE, include all the tiny little steps so I don't get confused. Thanks a lot, in advance.

[Skiller]

25i and 50i are two terms to describe the exact same thing, so I don't understand what you are trying to archive.

25i = 50 fields in 25 interlaced frames
50i = 50 fields in 25 interlaced frames

[lollo]

Yes, the request is absolutely a non sense

[simon744]

I'm trying to increase the framerate while keeping the video interlaced.

[lollo]

With the new frames being interpolated from the existing? To what purpose?

[simon744]

With the new frames being interpolated from the existing? To what purpose?

To make the video "feel" smoother. I've seen files that were originally 29.97i converted to 59.97i and they look a lot smoother compared to what they originally were.

[lollo]

"I've seen things you people wouldn't believe..."

[simon744]

"I've seen things you people wouldn't believe..."

Okay, so, if you're going to act like a jerk, then PLEASE keep your help to yourself. Thank you!

[ProWo]

"I've seen things you people wouldn't believe..."

[lollo]

Okay, so, if you're going to act like a jerk, then PLEASE keep your help to yourself. Thank you!

Actually, who is acting like a jerk is not me. I'll STOP here. You are welcome!

[lollo]

"I've seen things you people wouldn't believe..."

In italiano suona ancora meglio: "Ho visto cose che voi umani..."

[simon744]

Okay, so, if you're going to act like a jerk, then PLEASE keep your help to yourself. Thank you!

Actually, who is acting like a jerk is not me. I'll STOP here. You are welcome!

When was I mean to you again? I'm politely asking for help, and you are being rude instead of telling me what is what.

[lollo]

When was I mean to you again? I'm politely asking for help, and you are being rude instead of telling me what is what.

I did not want to be rude, I just thought that Skiller's answer was clear and final.

[simon744]

When was I mean to you again? I'm politely asking for help, and you are being rude instead of telling me what is what.

I did not want to be rude, I just thought that Skiller's answer was clear and final.

Thank you, but you were in fact rude. I'm sorry if I was rude, too.

I'm just talking about something I saw myself and continue to see regularly.

Here's the MediaInfo log of one example:

Video 
ID : 1 
Format : AVC 
Format/Info : Advanced Video Codec 
Format profile : High@L4.1 
Format settings : 3 Ref Frames 
Format settings, CABAC : No 
Format settings, Reference frames : 3 frames 
Codec ID : V_MPEG4/ISO/AVC 
Duration : 3 min 2 s 
Bit rate mode : Constant 
Bit rate : 31.3 Mb/s 
Width : 1 920 pixels 
Height : 1 080 pixels 
Display aspect ratio : 16:9 
Frame rate mode : Variable 
Frame rate : 59.940 (60000/1001) FPS 
Original frame rate : 29.970 (30000/1001) FPS 
Color space : YUV 
Chroma subsampling : 4:2:0 
Bit depth : 8 bits 
Scan type : Interlaced 
Scan type, store method : Separated fields 
Scan order : Top Field First 
Bits/(Pixel*Frame) : 0.252 
Stream size : 682 MiB (94%) 
Default : Yes 
Forced : No 
Color range : Limited 
Color primaries : BT.709 
Transfer characteristics : BT.709 
Matrix coefficients : BT.709 

Clearly, the bitrate of this file initially wasn't 59.94fps, but now it is, and the video's interlaced too, which isn't typical. I'm just curious as to how was that achieved?

[lollo]

Post the sample please

[simon744]

I don't have the before, and am not sure if the metadata would be preserved if I were to try cutting the video myself, so am sending a link to the file:

https://5qwt55-my.sharepoint.com/:v:/g/personal/dream66_5qwt55_onmicrosoft_com/EerRVaJ...43I8A?e=Oe3QY8

P.S. I don't do torrents from the scene or something haha, this file's from Sharemania where people post backhauls of awards shows, performances, etc.

[jagabo]

That video has interlaced frames and is encoded interlaced at 29.97 fps. MediaInfo shows the frame rate as variable but every frame has the same duration ~33 ms. MediaInfo also shows the frame rate as 59.95 fps -- but it is reporting the field rate, not the frame rate. This is how you can tell:

Scan type, store method                  : Separated fields

When decompressed pairs of fields are woven together int frames, so 59.94 fields per second becomes 29.97 frames per second. So the video is 29.97i.

Played back correctly you get smooth motion with 59.94 different pictures per second. It does not play correctly in my browser (Firefox). But after downloading the video and playing it with MPCHC it plays properly.

[lollo]

I don't have the before, and am not sure if the metadata would be preserved if I were to try cutting the video myself, so am sending a link to the file

Thanks.

Master jagabo already said everything. Once more, "I've seen things you people wouldn't believe..."

[simon744]

That video has interlaced frames and is encoded interlaced at 29.97 fps. MediaInfo shows the frame rate as variable but every frame has the same duration ~33 ms. MediaInfo also shows the frame rate as 59.95 fps -- but it is reporting the field rate, not the frame rate. This is how you can tell:

Scan type, store method                  : Separated fields

When decompressed pairs of fields are woven together int frames, so 59.94 fields per second becomes 29.97 frames per second. So the video is 29.97i.

Played back correctly you get smooth motion with 59.94 different pictures per second. It does not play correctly in my browser (Firefox). But after downloading the video and playing it with MPCHC it plays properly.

Thank you very much!! That was very clear, and gave me a better understanding. Now what am interested in is how do I go on about processing/encoding the 25i and 29.97i files in my possession to be like that one, as in having a field rate that's double the frame rate? All for the video to be smoother? And WITHOUT DE-INTERLACING.

[simon744]

I don't have the before, and am not sure if the metadata would be preserved if I were to try cutting the video myself, so am sending a link to the file

Thanks.

Master jagabo already said everything. Once more, "I've seen things you people wouldn't believe..."

Thanks for your help, and again sorry for the misunderstanding we first had.

I'm no expert at this, just trying to learn, though slowly.

[lollo]

Thanks for your help, and again sorry for the misunderstanding we first had.

No problem at all

[jagabo]

Now what am interested in is how do I go on about processing/encoding the 25i and 29.97i files in my possession to be like that one, as in having a field rate that's double the frame rate?

Since 25p (or 25p frames encoded as 25i) only have 25 different pictures per second. Simply duplicating frames to make 50p or 60p will not give you smooth motion. You have to create new frames with motion interpolation. There are various methods of doing this but they sometimes generate gross distortions. You can try FrameRateConverter(), InterFrame(), or RIFE() in AviSynth. Topaz and Vegas have such features.

[simon744]

Now what am interested in is how do I go on about processing/encoding the 25i and 29.97i files in my possession to be like that one, as in having a field rate that's double the frame rate?

Since 25p (or 25p frames encoded as 25i) only have 25 different pictures per second. Simply duplicating frames to make 50p or 60p will not give you smooth motion. You have to create new frames with motion interpolation. There are various methods of doing this but they sometimes generate gross distortions. You can try FrameRateConverter(), InterFrame(), or RIFE() in AviSynth. Topaz and Vegas have such features.

But looks like none of these will get me what I need. Anyways, thanks a lot for your help!

[jagabo]

Now what am interested in is how do I go on about processing/encoding the 25i and 29.97i files in my possession to be like that one, as in having a field rate that's double the frame rate?

Since 25p (or 25p frames encoded as 25i) only have 25 different pictures per second. Simply duplicating frames to make 50p or 60p will not give you smooth motion. You have to create new frames with motion interpolation. There are various methods of doing this but they sometimes generate gross distortions. You can try FrameRateConverter(), InterFrame(), or RIFE() in AviSynth. Topaz and Vegas have such features.

But looks like none of these will get me what I need.

Once you double the frame rate with a motion interpolation it's easy to convert that back to interlaced video with smooth motion.

[simon744]

Now what am interested in is how do I go on about processing/encoding the 25i and 29.97i files in my possession to be like that one, as in having a field rate that's double the frame rate?

Since 25p (or 25p frames encoded as 25i) only have 25 different pictures per second. Simply duplicating frames to make 50p or 60p will not give you smooth motion. You have to create new frames with motion interpolation. There are various methods of doing this but they sometimes generate gross distortions. You can try FrameRateConverter(), InterFrame(), or RIFE() in AviSynth. Topaz and Vegas have such features.

But looks like none of these will get me what I need.

Once you double the frame rate with a motion interpolation it's easy to convert that back to interlaced video with smooth motion.

Thank you very much! Looks like AviSynth will be of most help to me. Do you happen to know which of the plugins you have mentioned will be best for this and what scripts should I run to increase the frame/field rate and then interlace? I'm not familiar with AviSynth.

[_Al_]

So , how to load that posted video into avisynth/vapoursynth so it's 30i?

[jagabo]

After making it 60p use:

AssumeTFF()
SeparateFields()
SelectEvery(4,0,3)
Weave()

Then encode interlaced, top field first.

[jagabo]

Assuming the frames are already progressive and you want to double the frame rate, a full script might look like:

LWlibavVideoSource("filename.ext")
InterFrame(cores=4) # defaults to double frame rate
AssumeTFF()
SeparateFields()
SelectEvery(4,0,3)
Weave()

or:

LWlibavVideoSource("filename.ext")
FrameRateConverter() # defaults to double frame rate
AssumeTFF()
SeparateFields()
SelectEvery(4,0,3)
Weave()

or:

LWlibavVideoSource("filename.ext")
z_ConvertFormat(pixel_type="RGBPS", colorspace_op="709:709:709:l=>rgb:709:709:f")
Rife(gpu_thread=1, model=6, sc=true, sc_threshold=0.12) # defaults to double frame rate
z_ConvertFormat(pixel_type="YUV420P8", colorspace_op="rgb:709:709:f=>709:709:709:l")
AssumeTFF()
SeparateFields()
SelectEvery(4,0,3)
Weave()

The first two have lots of variables you can use to tune the results, bias toward blending or distortion, speed vs. quality, etc. The last one usually gives the best quality.

But why would you want interlaced video when you can just leave your video at 50p or 60p and have smooth motion with no interlace artifacts, reduced resolution, and worse encoding?

And as I mentioned before, motion interpolation like this often creates very ugly artifacts. I don't really recommend it.

[_Al_]

thanks, I manage to load it as 60p by ffms2, as you mentioned, then at the end actually output it as 60p :

from havsfunc import QTGMC
import vapoursynth as vs
from vapoursynth import core
clip = core.ffms2.Source("Bebe Rexha - I'm A Mess.mkv", fpsnum=60000, fpsden=1001)
clip = clip.std.SeparateFields(tff=True)
clip = clip.std.SelectEvery(cycle=4, offsets=[0, 3])
clip = clip.std.DoubleWeave(tff=True)
clip = clip.std.SelectEvery(cycle=2, offsets=0)
clip = QTGMC(clip, TFF=True)
clip.set_output()

[lollo]

And as I mentioned before, motion interpolation like this often creates very ugly artifacts. I don't really recommend it.

That's what I tried to suggest to OP in post #5 https://forum.videohelp.com/threads/411010-Converting-1080-25i-to-1080-50i?p=2703524&v...=1#post2703524

I failed to understand he has no knowledge on the matter, so your detailed explanation should convince him now. Thanks.