D7000 video is really "jerky"/"stuttering"

jasonstone

Hey all, hoping you can help... i'd like to do more video with my D7000 of the kids etc. during events or when on holidays but i've noticed that it's always jerky when playing back in iMovie.

I know to keep the shutter speed down to 1/50 or 1/60 (i'm PAL in Europe) which I'm doing - letting it go up to like F11 to get enough DOF when the kids are moving back/forth to avoid focus issues.

Problem is that playback in iMovie is just terrible! It's kind of shudders - not stuttering playback i don't think as I've got the latest i7 iMac with 24GB ram, 3TB fusion drive, 2GB video card etc. - it's the shizzle and runs fast... so it can't be playback due to the system right?

What could I be doing wrong or where should I start looking to fix this???

thanks for any tips

cheers
Jase

ziggy53

Is the audio jerky too, or just the video?

jasonstone

just the video...

ziggy53 wrote: »

Is the audio jerky too, or just the video?

although looking at the videos now i think it might just be where theres faster movement in the videos - i.e. with my kids... less so normal, less active, action...

does that make any sense at all??

is it my technique perhaps???

ziggy53

jasonstone wrote: »

just the video...


although looking at the videos now i think it might just be where theres faster movement in the videos - i.e. with my kids... less so normal, less active, action...

does that make any sense at all??

is it my technique perhaps???

Most likely, you're not doing anything wrong.

Many, if not most, video editing software is not optimized for source video playback. You haven't mentioned your video capture settings but I would bet it's not a native frame rate or integer-fraction of your computer monitor frame rate.

What's likely happening is that your video editing software, iMovie in this case, is trying to playback the video at a similar rate to your computer monitor, but when it can't it just skips a frame every once in a while rather than try to render new frames. It's just a shortcut but probably won't affect the final project output.

As long as your project settings are correct for the intended playback device, iMovie should correctly render everything to the proper rate, and playback using a dedicated video software player or hardware video player (DVD/Blue-ray player) should be fine and smooth.

Just test a short section, maybe 5 - 10 minutes, all the way through the editing process and see if playback is good or not for the resulting file, playing in a proper software or hardware player.

If playback is not OK after output from iMovie, "then" it's time to check settings, processes and procedures.

jasonstone

Thx Ziggy, will try that out...
Although I did notice that video from m video camera (canon hf100) did play back smoother I think..

ziggy53 wrote: »

Most likely, you're not doing anything wrong.

Many, if not most, video editing software is not optimized for source video playback. You haven't mentioned your video capture settings but I would bet it's not a native frame rate or integer-fraction of your computer monitor frame rate.

What's likely happening is that your video editing software, iMovie in this case, is trying to playback the video at a similar rate to your computer monitor, but when it can't it just skips a frame every once in a while rather than try to render new frames. It's just a shortcut but probably won't affect the final project output.

As long as your project settings are correct for the intended playback device, iMovie should correctly render everything to the proper rate, and playback using a dedicated video software player or hardware video player (DVD/Blue-ray player) should be fine and smooth.

Just test a short section, maybe 5 - 10 minutes, all the way through the editing process and see if playback is good or not for the resulting file, playing in a proper software or hardware player.

If playback is not OK after output from iMovie, "then" it's time to check settings, processes and procedures.

ziggy53

jasonstone wrote: »

... although looking at the videos now i think it might just be where theres faster movement in the videos - i.e. with my kids... less so normal, less active, action...

does that make any sense at all??

is it my technique perhaps???

jasonstone wrote: »

Thx Ziggy, will try that out...
Although I did notice that video from m video camera (canon hf100) did play back smoother I think..

I think that your D7000 uses H.264/MPEG4 compression as does your camcorder.

H.264 is an MPEG4 variant, and all MPEG compressed files consist of three type of frames:

1) "I-frame", as above. These are used sparingly in MPEG files.
2) "P-frame", or "Predictive frame". These frames use visual information based on previous reference frames, but they are not complete frames themselves.
3) "B-frame", or "Bi-Directional frame", meaning that these frames use visual information from either previous or later frames. Again, these are not complete frames themselves.

Since only the I-frames are complete, all other frames have to be generated from either prior frames or surrounding frames. This makes for more compact files (higher compression), but at the expense of lost information (which may, or may not, be visually significant). All of this processing means that more powerful computers have to be used for both playback and editing of MPEG files too.

MPEG files are generally recommended for distribution, but not for acquisition or editing. (Modern camcorders do a commendable job using H.264 for acquisition, however.)

Your camcorder may do a better job of utilizing the available bandwidth for recording, since it's designed for video acquisition, so it may produce video files with somewhat easier files to play. This may be very important with video segments which contain rapid motion, which produce relatively complicated IPB sequences. Action sequences, video pans and moving water, also place the highest load on your computer.

If you really need to find an exact cause, there is specialized software available to analyse the video streams from your files, but I'm only aware of the Windows versions.

DavidTO

I wonder if it's not just a high shutter speed rather than playback issues that's causing the stuttering. Is it struggling to playback? Or is the playback not as smooth as you would expect? Have you tried viewing it by other means to narrow down the cause? Open it in QT Player, see if it happens there? Export it as a smaller file size and see if it's still present.

jasonstone

Actually the shutter speed was either 1/50 or 1/60 as I'm aware of the issue with high shutter speed and juddering video...

I just don't think it's playback as the machine is very quick and has plenty of ram and a fast HD etc.

I'll try viewing it in QT and even export the movie to a M4V and see if that's better - will try it out tonight

thx for all the help everyone - I really appreciate it

DavidTO wrote: »

I wonder if it's not just a high shutter speed rather than playback issues that's causing the stuttering. Is it struggling to playback? Or is the playback not as smooth as you would expect? Have you tried viewing it by other means to narrow down the cause? Open it in QT Player, see if it happens there? Export it as a smaller file size and see if it's still present.

jasonstone

Thanks for the info Ziggy, it definitely is H.264/MPEG-4 Advanced Video Coding as a MOV
But I know that Apple licensed the H264 codec for iChat (years ago) and that it was then built into OS X - so I would hope that H264 playback is optimised on a fast new iMac

Anyway - as DavidTO put - maybe it's just the playback engine in Lightroom 4??

Thanks for the help - will eventually get there

ziggy53 wrote: »

I think that your D7000 uses H.264/MPEG4 compression as does your camcorder.

H.264 is an MPEG4 variant, and all MPEG compressed files consist of three type of frames:

1) "I-frame", as above. These are used sparingly in MPEG files.
2) "P-frame", or "Predictive frame". These frames use visual information based on previous reference frames, but they are not complete frames themselves.
3) "B-frame", or "Bi-Directional frame", meaning that these frames use visual information from either previous or later frames. Again, these are not complete frames themselves.

Since only the I-frames are complete, all other frames have to be generated from either prior frames or surrounding frames. This makes for more compact files (higher compression), but at the expense of lost information (which may, or may not, be visually significant). All of this processing means that more powerful computers have to be used for both playback and editing of MPEG files too.

MPEG files are generally recommended for distribution, but not for acquisition or editing. (Modern camcorders do a commendable job using H.264 for acquisition, however.)

Your camcorder may do a better job of utilizing the available bandwidth for recording, since it's designed for video acquisition, so it may produce video files with somewhat easier files to play. This may be very important with video segments which contain rapid motion, which produce relatively complicated IPB sequences. Action sequences, video pans and moving water, also place the highest load on your computer.

If you really need to find an exact cause, there is specialized software available to analyse the video streams from your files, but I'm only aware of the Windows versions.

jasonstone

Thanks David and Ziggy for the help - I believe that the playback problem is isolated to Lightroom. I copied the .mov file into iMovie and also opened it in QT and it plays back much much smoother - so looks like I wasn't doing anything (well much anyway) wrong... just need to use a different program

I'm a little ashamed that I didn't think to try that before :dgrin

tsk1979

Try using VLC and enable hardware acceleration. VLC can use GPU(Graphics card) for displaying videos, so even on slower computers videos will play without stutter etc.,