Underwater Video Tips: Working with AVCHD 2.0 and 1080p60 or 1080p50 files in iMovie

As hardware becomes more and more powerful video format evolve to allow higher quality capture.

AVCHD is a format that still relied on interlaced video and the classic 24p until version 2.0 where higher frame rate 1080p50 and 1080p60 have become standard with a maximum bit-rate of 28 Mbps.

To date many non linear editing programs are not capable to process such files actually most of the low cost programs are not even able to import those files at all, this is quite frustrating after spending a good amount of money on a camera.

I use iMovie for all my edits as after testing programs like Adobe Premiere I did not really find them to add many benefits to justify the price and I also find them quite slow and counter intuitive so when I got my Sony RX100 I had the issue of processing AVCHD 2.0 files 1080p50.

An AVCHD container is made of streams that have a video and an audio track plus another track of text. The video is encoded in H.264 as other formats like mp4 and the audio is AC3 usually two channels. Usually video editor like files with an H.264 video track and a stereo audio track in AAC or MP3.

So if you re-wrap the information in an mp4 or mov format there is a good chance that a program like iMovie or final cut will digest it.

After various attempts I managed to find on the internet the tools I needed, I will list them here:

  1. LAME for Mp3 encoding (mandatory)
  2. FAAC for AAC encoding (optional but I have it in my build)
  3. FFMPEG
  4. Growl
  5. Clearpipe automator Action
  6. Automator FFmpeg action
  7. MTS2MP4 automator agent

For instruction on how to build your own ffmpeg (as the static builds did not work for me) look here:

http://sesam.hu/2012/09/05/installing-ffmpeg-on-os-x-mountain-lion/

Then install growl version 1.2.2 http://growl.googlecode.com/files/Growl-1.2.2.dmg

Get clearpipe, automator ffmpeg action and the mts2mp4 finder service here http://blog.laaz.org/apps/automator/ and install in sequence.

This creates the option to right click on an MTS file and re-wrap it into an Mp4, note that there are also commercial programs that do this like clipwrap and iVi however our finder service is free and quick…

I have created this little video to show how it works in practice, as you can see it swallows entire folders which is great. So here I create an output folder in the iMovie events folder so that iMovie can edit the 1080p50 file later skipping the import, this means no time is wasted and after generating thumbnails you are ready to edit your original video at high frame rate, a feature ‘officially’ not supported…this is how I edit my video natively in iMovie. If you have a GoPro that saves 1080p50 or 1080p60 mp4 files you can start from the manual creation of an event folder.

From there onwards you can import your double frame rate video into iMovie projects, that will anyway be 24,25,30 frames per second by default but can also exported in 50/60p using x264 decoder that you can find here http://www003.upp.so-net.ne.jp/mycometg3/

This means that you can process with iMovie and also final cut pro 50/60p projects with no problems!

Update for those struggling this is the link where all the files including the ffmpeg build are: https://www.dropbox.com/sh/6m4527odhpw3hcc/nHODxg3_DL I have modified the ffmpeg automator action as I was getting a problem with growl

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5 thoughts on “Underwater Video Tips: Working with AVCHD 2.0 and 1080p60 or 1080p50 files in iMovie”

  1. Hi again Interceptor121. I’ve been meaning to ask you: all this time I’ve been shooting video underwater using aperture priority to control my depth of field. My question is what is the best shutter speed to use? Related to this, when outputting my video using iMovie, what is the best frame rate?

    SInce I shoot on aperture priority, the camera sets the shutter speed for me. I usually use ISO200 on a sunny day and ISO400 when its a bit overcast of light is low.

    I have heard that setting a shutter speed of 1/60 is good for shooting video? Also, I understand that iMovie outputs at 30 fps or 25fps. Is 30 fps better?

    And I guess my last question would be: is it better to shoot on shutter speed priority or aperture priority?

    Thanks for your suggestions. Really appreciate it! :-)

    Robert

    1. Hi Robert.
      The shutter speed and frame rate are interrelated. You should first check your RX100 to find out if it is a PAL or NTSC model. PAL would offer 25/50 fps and NTSC 30/60. Shutter speed should always be twice the frame rate, the RX100 in program mode follows this rule, so for general use Program mode is fine. The camera will keep the ISO at 125 and only increase it when there is insufficient light. There are times when this does not work like when shooting macro, in that case aperture priority is preferred and you should be looking at f/8 or f/11 leaving the ISO to auto otherwise there is a risk that the camera uses incompatible shutter speeds. There is a general issue of soft corners with the RX100 however from my tests those are only resolved with aperture smaller than f/8 this for video purposes is not practical in ambient light unless it is a really bright day. So for wide angle I would leave the camera in program and apply sharpening in post processing if needed. This is how my videos are shot. I also want to confirm that those settings are specific to the RX100 other cameras with different behavior or lens may required a different approach.

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