50i to 24p

[temproh]

Hi,

I'm currently trying to edit a movie with Adobe Premiere. Most of the clips I'm using were shot in 24p, some of them in 50i (by accident) - is there an easy way to convert the 50i material to 24p without creating a stutter fest?

I'm kinda new to this stuff, so my apologies if this is the wrong place for my question.

Here's what MediaInfo has to say about the material:

General
Complete name : I:\!____0204_01\!____0204_01.MP4
Format : MPEG-4
Commercial name : XDCAM EX 35
Format profile : Base Media / Version 2
Codec ID : mp42
File size : 81.9 MiB
Duration : 18s 800ms
Overall bit rate mode : Variable
Overall bit rate : 36.5 Mbps
Encoded date : UTC 2013-01-10 22:06:45
Tagged date : UTC 2013-01-10 22:06:45

Video
ID : 1
Format : MPEG Video
Commercial name : XDCAM EX 35
Format version : Version 2
Format profile : Main@High
Format settings, BVOP : Yes
Format settings, Matrix : Custom
Format settings, GOP : M=3, N=12
Codec ID : 61
Duration : 18s 800ms
Bit rate mode : Variable
Bit rate : 35.0 Mbps
Width : 1 920 pixels
Height : 1 080 pixels
Display aspect ratio : 16:9
Frame rate mode : Constant
Frame rate : 25.000 fps
Standard : Component
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) : 0.675
Stream size : 78.4 MiB (96%)
Language : English
Encoded date : UTC 2013-01-10 22:06:45
Tagged date : UTC 2013-01-10 22:06:45
Color primaries : BT.709
Transfer characteristics : BT.709
Matrix coefficients : BT.709

Audio
ID : 2
Format : PCM
Format settings, Endianness : Big
Format settings, Sign : Signed
Codec ID : twos
Duration : 18s 800ms
Bit rate mode : Constant
Bit rate : 1 536 Kbps
Channel(s) : 2 channels
Sampling rate : 48.0 KHz
Bit depth : 16 bits
Stream size : 3.44 MiB (4%)
Language : English
Encoded date : UTC 2013-01-10 22:06:45
Tagged date : UTC 2013-01-10 22:06:45

[temproh]

Thanks a lot! But can you also tell me how to deinterlace the video to get 25p?

[mp3dom]

If it's true 50i (not 25PsF), deinterlacing to 25p will throw away half of the motion. You can use QTGMC for deinterlacing (it's an avisynth script which combines different plugins). You can also think of adding a small amount of motion blur just to let the motion be "smoother" to the eye.

[2Bdecided]

If the 24p footage you're matching it too was shot with a sensible shutter speed, and the 50i was shot with a higher shutter speed, you would ideally use something like MFlowBlur (from http://avisynth.org.ru/mvtools/mvtools2.html ) to add blur to the deinterlaced footage before removing frames.

i.e.
1) deinterlace to 50p (QTGMC for good results, bob for quick results)
2) add blur (gives blury 50p)
3) throw away every other frame (gives 25p)
4) slow down to 24fps

If you shoot 50i with 1/50th shutter speed, you won't need the blur.

You can use MFlowFPS to convert 50fps straight to 24fps without a speed change, but I wouldn't do it that way.

Cheers,
David.

P.S. I did it here a long time ago...
http://www.hv20.com/showthread.php?2876-Format-conversion-(50i-50p-24p-25p)-tests
...but foolishly didn't post the full script. Those functions are all out of date now anyway.

[2Bdecided]

Sorry, I don't have that script around any more (that's why I didn't post it).

I was going 50i>50p>blur>25p>24p. Working with 50 frames per second rather than 25 frames per second makes it much easier for mvtools because the motion between each frame is half as much. Still get artefact sometimes though. More visible with framerate conversion (e.g. 50>60) than with blur.

I don't have much luck using mvtools with 25p or 30p content either. Sorry.

Cheers,
David.

[nhope]

If it's needed, extra motion blur can be introduced right inside QTGMC.

I have a guide on using QTGMC here (http://www.bubblevision.com/underwater-video/Vegas-YouTube-Vimeo.htm). Section 4.3 is about motion blur. The guide is as relevant to Premiere Pro as it is to Sony Vegas, since the Debugmode Frameserver can be installed in both.

[2Bdecided]

Thanks for that - hadn't spotted that in QTGMC!

I don't agree with the definition of shutter angle though - I've posted in the QTGMC thread.

Cheers,
David.