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Forums Canon DSLR Cameras Canon 5D Mk II Clap-Board Audio Sync Issue

  • Canon 5D Mk II Clap-Board Audio Sync Issue

  • Joel Ninmann

    March 7, 2011 at 7:55 pm

    I have an issue with the 5D Mark II that I cannot find anyone discussing on any other message boards, which is alarming due to the scope of the issue. When using a clap-board and recording audio using the 5D’s on-board/built-in microphone, I notice an approximately two frame delay from the video showing the clap-board slamming down to the actual sound of the clap.

    Thus, on frame 1 I hear the first sound of the clap. Its not until frame 3 that I see the clap-board slamming down on the video. Thus, the audio is heard 2 frames too early. I have seen this issue on multiple shoots, in multiple situations, and with multiple frame rates. If you move further away from the built-in microphone on the 5D, the audio is heard only 1 frame too early. This makes no sense to me. Wouldn’t that be the opposite of what you’d expect? Is the 5D’s built-in microphone doing some automatic compensation for distance to cause this? Has anyone else seen this issue on the 5D? Does it occur on the 7D or other HDSLR’s with built-in microphones?

    Please download the below video file for a reference. The first shot is a close-up. If you run it through Premiere, Final Cut, or another editor where you can hear audio at the frame level, you will notice the clap sounding 2 frames before the clap-board slams down. The next shot is a medium close-up. It has the same 2 frame delay on the clap board video. Next is a medium shot, and then a medium long shot where the clap board video is only delayed by 1 frame.

    https://dl.dropbox.com/u/11690716/sync-test.mov

    I shot the above file at 30P (29.97) 1920×1080 on a 5D Mark II (latest firmware 2.0.8) with a 50mm lens. Shutter was 1/60. Audio was set to automatic levels. I transcoded the files from the camera to Apple ProRes 422 via Final Cut Pro 7.0.3 and the Canon EOS movie plugin E1. The file above was compressed via Apple Compressor to H.264 1500 kbps 1920×1080 29.97P for video, and 48.000 256 kbps audio.

    Obviously this is a huge issue, since most people use syncing software like Pluraleyes to sync using the built-in microphone on the 5D as a reference. If this reference is off by 2 frames, then every sync will as well.

  • Angelo Lorenzo

    March 9, 2011 at 6:10 am

    I have roughly two years of 5D footage and I’ve never had a sync issue with a clap board and dual system audio (no drift through 10 minute interview clips etc), but the delay you are seeing is par for the course with dual system.

    The reason for this is even at 29.97fps your still seeing posterization in time. The “delay” may mean one frame is slightly before the clap, and one frame is when the clapper is firmly closed. The actual clap is happening in the time between those frames.

    A camera may do 24, 25, 30, 60 frames a second, but the camera’s audio is sampling 48,000 times a second.

  • Paul Kondo

    March 24, 2011 at 10:54 pm

    Joel,

    The good news is that you aren’t crazy. I’m getting the same issue. The bad news is that I don’t know what’s causing it. I swear that this was not always a problem. It’s only been in the last couple of months.

    Someone mentioned a solution that didn’t work for me – changing the Easy Setup in FCP before importing to the frame rate of your clips.

    I thought that maybe it was the newer version of the plugin so I went back to an older version. That didn’t seem to do anything. If I look at the original clip off the card, it’s in sync. Then I wondered if it was some ProApps update that did it. But I just can’t imagine after tons of googling that there aren’t a bunch of other people with this same issue.

    If you ever find out the problem, please post it here and I will do the same. I’m going to be talking to some people this weekend that may have seen this problem. Hopefully they’ll have an answer.

    Paul

  • David Michael

    March 25, 2011 at 2:17 pm

    I came here to post this exact thing.

    I’m syncing sound from a 24p 5D shoot and I’m probably just going to scrap the in camera audio – but I noticed that sound mark is a frame or 2 ahead of the visual marker. If I was syncing audio without a guide audio track, it would be a frame off of what the camera would have recorded.

    I’m thinking I’ll just sync to the clap – like I would on any other project, but it is pretty annoying. And it makes me question my syncing practices. Should the audio clap come a frame ahead of the visual clap? Does FCP process audio frames differently than video frames?

    See, my world is upside down. Post back if you discover anything.

    -David

  • Joel Ninmann

    March 29, 2011 at 6:58 pm

    *** UPDATE ***

    I have tested this video delay with a Fostex PD-4 DAT tape recorder. The Fostex will play a reference tone when you flip a switch to the right. I set this reference tone to a level of -12 dB and the tone played through the Fostex’s on-board speakers. Once again, if you play the file back using an editing program that allows you to playback at the frame-by-frame level, you will notice the video delayed by approximately 2 to 3 frames. The sound of me flipping the switch on the Fostex is heard along with the start of the reference tone on frame 1, then on frame 3 or 4 the LEDs of the level bars begin to materialize on the Fostex’s monitor screen.

    Can we honestly simply chalk this up to the 5D processing the video and audio at different rates? I know the 5D was not designed and built to be a professional video camera with timecode and everything, but if Canon is marketing this thing to professionals (as I’ve seen in their commercials), then they need to address the lack of on-board reference audio sync. What does everyone else think? Can someone test this with a 7D at 720/60P?

    I recorded the below file at a distance of about 2 feet with the Canon 5D Mark II (latest firmware 2.0.8) with a 50mm lens. Shutter was 1/60. Audio was set to manual and levels set to -12 dB. I transcoded the files from the camera to Apple ProRes 422 via Final Cut Pro 7.0.3 and the Canon EOS movie plugin E1. The file below was compressed via Apple Compressor to H.264 1500 kbps 1920×1080 29.97P for video, and 48.000 256 kbps audio.

    https://dl.dropbox.com/u/11690716/fostex-sync-test.mov

  • Joel Ninmann

    March 29, 2011 at 7:02 pm

    David,

    I don’t think its from Final Cut Pro, though FCP does process video and audio slightly differently. Obviously, FCP only deals with video at a maximum of the frame-by-frame level. Audio, however, can be zoomed-in to the sub-frame level.

    Still, I can’t be sure that this issue isn’t caused by FCP unless it is tested in a different editing program. Maybe someone out there with Avid or Premiere could do so?

    I can try and wrangle a copy of Premiere around here, but it may take a little while. I’ll let you know if I do.

  • Hamish McCollester

    June 2, 2011 at 12:33 am

    Just wondering if anyone ever figured out anything further on this. I just got done syncing a three-camera (two 5Ds and a 7D) shoot. And almost EVERY clip from each camera (across four days of shooting) had the same issue…the in-camera audio preceded the visual reference by two frames…a couple seemed like they were off by one-and-a-half.

    Ultimately, not a huge problem, since I find it just as fast to sync manually in FCP, rather than using PluralEyes. But yeah… this certainly shouldn’t be happening. Does anyone have any answers? Any info would be much appreciated.

    (FYI… I shot 1080 24P, Technicolor Cinestyle, conversion to ProRes 422 via EOS FCP plugin and log and transfer.)

  • David Michael

    June 2, 2011 at 1:20 am

    I think I did get to the bottom of this, though my conclusions are based on deduction and not on fact.

    I believe the Canon cameras record audio 1 frame early on average. This problem forced me to rethink my old syncing methods though, as I noticed the 2 frame problem as well. What I decided was that hearing the sound before seeing the clap simply means the clap falls between frames. So whether or not it is closer to match the moment of clap or to the frame before are equally inaccurate. I have begun to sync most all my sound to when the slate arm in blurry instead of to the point of contact and I think this may be more accurate.

    Using pluraleyes, you can automatically match up all the clips, select all the audio and simply move it (alt+arrow) all a frame to the right in one keystroke. From there just relink each clip audio and drop in the browser.

    I did work with a Canon camera that had accurate sound sync once. I believe it was a 7D and I believe they had the audio set to 44.1khz. This could be the entire difference.

    Let me know your thoughts.

  • Hamish McCollester

    June 2, 2011 at 2:03 am

    Interesting about the 7D. We had ours set to 48khz and I noticed the same issues as the 5D — audio was generally 2 frames off.

    I appreciate your deductions and had a similar thought about things landing between frames. But having just spent a few hours syncing almost a hundred clips, my experience is that more often than not, the audio reference comes a solid two frames before the visual. But I agree, a lot are just one frame off. Not that most people are going to notice one frame out of sync in either direction, but being a perfectionist, I’m not comfortable making a blanket rule of one frame (or two frames for that matter) shift on all clips to solve the issue. But maybe the next hundred of these I have to do will push me over the edge and I’ll go with it! Very annoying little issue though.

    I wonder if shutter speed (I’m shooting at 1/50th) changes would help or at least be worth testing. If nothing else, a faster shutter speed would give a less blurred visual reference of the sticks… and that might give us a clearer answer on whether there is a one or two frame rule we can utilize…. assuming that the added variable of shutter speed doesn’t effect something else in this little mess. When I’m done with the edit job I’m on, I’ll try to do some tests and post the results.

    Oh, the hoops these DSLRs make us jump through…

  • Joel Ninmann

    June 7, 2011 at 8:38 pm

    Good to see some people are still aware of/trying to come up with a solution to this problem. Also good to hear from someone using a 7D with the same problem. Now we know it isn’t just the 5D Mark II. I suspect 48.000 has something to do with the issue, but since these cameras do not give you the option of changing sampling rate, I have no way of testing this.

    My video clap frames have been consistently 2 frames off. I have not seen many that are only 1. I also am fairly certain that shutter speed does not have an effect on this issue, especially when you consider that when shooting video on these DSLRs, the shutter is not a true mechanical shutter, but a fake/digital shutter. In my experience, changing the digital shutter speed has had no affect on this audio sync issue, but I invite people to test it out for themselves to double-check my experience.

    Even if it WERE due to shutter speed, this wouldn’t matter, because you almost never want to have a DSLR’s shutter speed (when shooting video) set to anything other than 1/30 or 1/60 (for NTSC) or 1/50 (for PAL) due to monitor/light strobing that you can get in the opposite region otherwise. Also, its been my experience that longer shutter speeds’ (e.g. 1/30) blurring effect is not a true motion blur (due to the aforementioned lack of a physical/mechanical shutter), but rather a largely displeasing-looking digital blur.

    No thank you to any shutter speed other than 1/60 for NTSC.

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