GH2 24p Cadence "judder"...

[Eric Olson]

Originally Posted by Steven Bills

https://vimeo.com/37309808

PS: That's as smooth a pan as I have ever done, and it still looks choppy!

The Vimeo file is 30p. The judder is either because you edited 24p on a 30p timeline or because Vimeo converted it to 30p after uploading. This is an example of how 24p looks when played back at 30p using duplicate frames.

[Steven Bills]

@Eric: I made sure that I was editing the video at 23.976 fps. Could this actually be my problem?? Should I be editing at an even 24p rather than 23.976?

Also, is vimeo converting my 24p stuff to 30p?!?

And I am not sure I like the look of the 1/30 SS stuff...

SB

[David Grinnell]

Originally Posted by Don Litten

David, is that a hack or stock?

Hacked but the only thing I did was boost the bit rate from 22000000 to 42000000

[William Hohauser]

It's doubtful that any hack would help much with judder. Generally the hacks are dealing with bit rate increases that don't change the limitations of capturing movement with a limited number of frames per second.

1/30 shutter speed certainly would reduce judder as the image smear connects the frames better. It certainly makes the pan shots posted earlier smoother. However we start to enter a realm of issues caused by slow shutter speeds which start to translate to slower frame rates. Essentially frame rates slower than 18 frames impart a dreamlike quality to movement. 1/30 shutter speed works with modest subject motion but fast motion starts to look odd.

[Eric Olson]

Originally Posted by Steven Bills

@Eric: I made sure that I was editing the video at 23.976 fps. Could this actually be my problem?? Should I be editing at an even 24p rather than 23.976? Also, is vimeo converting my 24p stuff to 30p?!?

Using 23.976 fps is correct, but there is something wrong with your workflow. The streaming video file on Vimeo is 30p and has the exact 4:5 cadence that you get by duplicating one frame out of every 4 to fit 24p into 30p. Here is the output from mediainfo for your Vimeo file:

General
Complete name                    : 37309808-hd.flv
Format                           : MPEG-4
Format profile                   : Base Media
Codec ID                         : isom
File size                        : 2.31 MiB
Duration                         : 7s 367ms
Overall bit rate                 : 2 634 Kbps
Encoded date                     : UTC 2012-02-22 14:08:24
Tagged date                      : UTC 2012-02-23 14:08:24

Video
ID                               : 1
Format                           : AVC
Format/Info                      : Advanced Video Codec
Format profile                   : High@L3.1
Format settings, CABAC           : Yes
Format settings, ReFrames        : 4 frames
Codec ID                         : avc1
Codec ID/Info                    : Advanced Video Coding
Duration                         : 7s 367ms
Bit rate mode                    : Variable
Bit rate                         : 2 477 Kbps
Maximum bit rate                 : 3 890 Kbps
Width                            : 1 280 pixels
Height                           : 720 pixels
Display aspect ratio             : 16:9
Frame rate mode                  : Constant
Frame rate                       : 30.000 fps
Color space                      : YUV
Chroma subsampling               : 4:2:0
Bit depth                        : 8 bits
Scan type                        : Progressive
Bits/(Pixel*Frame)               : 0.090
Stream size                      : 2.18 MiB (94%)
Writing library                  : Vimeo Encoder
Encoded date                     : UTC 2012-02-22 14:08:24
Tagged date                      : UTC 2012-02-22 14:08:24

Audio
ID                               : 2
Format                           : AAC
Format/Info                      : Advanced Audio Codec
Format profile                   : LC
Codec ID                         : 40
Duration                         : 7s 82ms
Bit rate mode                    : Variable
Bit rate                         : 157 Kbps
Maximum bit rate                 : 180 Kbps
Channel(s)                       : 2 channels
Channel positions                : Front: L R
Sampling rate                    : 44.1 KHz
Compression mode                 : Lossy
Stream size                      : 136 KiB (6%)
Encoded date                     : UTC 2012-02-22 14:08:24
Tagged date                      : UTC 2012-02-22 14:08:24

I would recommend checking the original file you uploaded with mediainfo.

http://mediainfo.sourceforge.net/en

[Sanjin Svajger]

Originally Posted by Eric Olson

Using 23.976 fps is correct, but there is something wrong with your workflow.

Definitely something wrong with his workflow.

[Steve Montoto]

Workflow aside. Just thought I would chime in and give you guys a link that shows some really good motion characteristics using 1/40 and a Orion hack for the gh2 that is optimized for the motion.

https://vimeo.com/35999739

The guy is really helpful and is a font of information. I think the motion looks as smooth as most of the high end cameras Ive seen.

Maybe the hack can help some?

[Steven Bills]

Steve, I'll have to look into that hack and those settings some...

But since the last few posts have talked about workflow, I thought I'd chime in again with another video. This was shot at 24p at 1/50, edited at 23.976, and rendered at 23.976.

https://vimeo.com/38299244

Let me know what you think, and if you still see some judder.

SB

[Steve Montoto]

Yes, I see the judder your talking about. I would look into the hack I mentioned for the smoother motion and see if that helps some. I usually try to avoid panning as much as possible or I do it really slow.

I remember when I used to export 1280x720 h.264 and upload to vimeo I would get color and motion issues. Someone told me to start using 1280x720 Windows Media Video file output 10k bitrate and I havent
noticed anything weird going on anymore with colors either. I don't know if its due to the way vimeo handles re-compression or what but its worth looking into. Its all I use now and Ive been very happy.

P.S. I am definitely no expert, just my experiences and talking to various people.

[Eric Olson]

Originally Posted by Steven Bills

Let me know what you think, and if you still see some judder.

Vimeo has converted your 23.976 fps .wmv file to a 30 fps .flv file. The original file does not have judder, but the streaming video has the same judder as before. I don't know why Vimeo is messing with the frame rate. Try uploading a .mp4 file instead.

[Eric Olson]

I converted your .wmf file to .mp4 with ffmpeg

http://ffmpeg.org/

using the command

ffmpeg -sameq -i 88459348.wmv -y 88459348.mp4

and then uploaded it. Vimeo had no trouble creating a proper 23.976 fps .flv file for streaming.

judder test on Vimeo

[Sanjin Svajger]

Originally Posted by Eric Olson

Vimeo had no trouble creating a proper 23.976 fps .flv file for streaming.

Now your talking! That looks as it should. Problem solved!:)

[Steve Montoto]

woops. I missed that you already were using a .wmv file. Anyway I am glad it worked out for you. I use TMPGENC, so I don't know how much is/if any difference with the various encoders.

Cheers!

[Steven Bills]

So I hacked my GH2 last night after reading the post above. I will do some tests and post again! Except this time I will upload an mp4 instead of a wmv.

Does anyone know if anybody else has had this 24p --> 30p problem with vimeoo??

SB

[Steven Bills]

Okay so here is a test with the Quantum v9b hack (the hack which was mentioned above).

Settings are the same as before, except I uploaded an mp4 file to vimeo instead of a wmv, thus (hopefully) preventing the 24p --> 30p conversion.

Let me know what you think.

24p Cadence Judder test 3 on Vimeo

SB