Category Archives: Techniques

Cameras, Techniques

Recording direct to disk from a Firewire equipped camcorder

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There are mini-disk products that you can connect directly to your Firewire equipped camcorder to record direct to disk. But then tend to range in price from about $600 to $1800 depending on used vs new, capacity and vendor.

An alternative is to record direct to your notebook computer.

If you have a Macbook or Macbook Pro, a very easy way to record direct to disk is to connect the Firewire output of your camcorder to the notebook computer and then run iMovie and import from the camera.

The camera should be in its “camera” mode but does not need to be recording to tape. Whatever the camera sees will be recorded direct to disk.

This works with my Canon HV30 in HD mode and I’ve done it using both iMovie 8 and the older iMovie HD (version 6) connected to a Macbook.

On Windows, there are several software utilities available that will enable you to do the same thing. While I am typing this on a Windows desktop, I do not have a Windows notebook on which to test this out!

The main advantage to doing this is to overcome the occasional tape dropout problem that tends to plague HDV format.By recording direct to your notebook computer disk, who cares about tape dropouts! (Caution – you may want to use a longer Firewire cable to keep the notebook away from your camera mic, especially if the fan kicks on to keep the CPU cool. Not all cameras have sufficient drive signal to use a longer cable, though. So be sure to test out your configuration first!)

On SD recordings, a video dropout typically lost a single 1/30th of a second frame. If you even noticed, you could always copy an adjacent frame and no one would notice.

With HDV you can lose up to 1/2 second per dropout – and I guarantee, everyone will notice!

Two other steps to avoiding dropouts are to clean your video heads in the camera every 5 to 10 hours of recording – I use a Canon cleaning tape for about 10 seconds but I’m told most any cleaning tape is fine. The other important step is tape quality – I used to use TDK tape all the time on my SD camera with excellent results – but the SD tapes always had dropouts when recording HDV on standard TDK tape.

I switched to Panasonic AMQ (HDVM63AMQ) tapes and have now recorded probably 75 hours with excellent results on that tape. I buy mine from TapeStockOnline.com. They have consistently quick order fulfillment and decent prices. If you are used to buying standard miniDV tapes at the local discount store  you’ll find that high quality tapes for HDV are more expensive – currently $5.25 in a minimum order of 10 units.

There are other brands that cost both more or less than these but I’m sticking with what has worked well for me. Hopefully this note provides some idea for you to try if you are plagued by video dropouts!

Editing, Techniques

Why does my 30p video show up as 60i?

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I’ve seen some confusion on the online forums regarding shooting in 30p (or 24p) and then importing into a video editor.

Why does my 30p video show up as 60i in <name your editor>?

In an interleaved 60i video (normal old fashioned video), the image is scanned 60 times per second, producing one half frame at each scan (say the odd scan lines, followed by the even scan lines in the next half frame). Because movement can occur between the two half frames, you some times see interlaced jagged edges.

A better way is to take 30 still pictures per second of the entire image.

When your camera records at 30p video, it takes a single image – but splits it into two half frames and stuffs those into two 60i half frames (without any jaggies since its splitting one image in to two pieces whereas 60i creates one image from two separate pieces taken 1/60th of a second apart).

Consequently, a 30p video is stored as a 60i video. And two consecutive half frames, put together, become 30p. Your video software can’t tell the difference between between 60i and 30p.

So why do we have these strange 60i half frames? Historic reasons. The earliest TVs were not able to scan the full image top to bottom before the next image would arrive. The solution then was to draw only half the lines in each interval. Thanks to the persistence of the phosphor image of old TVs, the first lines remained glowing while the TV then scanned the alternate lines.

No one would design a TV like that today – but we’ve lived with it for many decades and it is still supported for compatibility reasons.

I can import 24p video into iMovie (or other editor) but it plays weird – why?

This depends on the camera. But it is common to store the 24p image in half frames, similar to 30p. But since 24 does not evenly divide into 60, the sequence of half frames is a little different.

In 30p, the sequence is basically 2:2:2:2:2:2 and so on where the 2 signifies 2 half frames.

In 24p, the video may be stored in various combinations such as:

2:3:3:2 or 2:3:2:3

In this way, the 24p mode uses up more half frames – consider 2 half frames and then 3 half frames. This slows down the video frames to match the 60i storage of the tape. Consequently, 24p gets mapped into a funky sequence of half frames on the 60i tape.

To a program like iMovie, this 24p footage looks just like 60i. But unfortunately, iMovie (And many other video editors) have no way of knowing that it is not really 60i footage with some frames appearing 3 times. So play back and edits produce strange artifacts.

If you want to convert this to proper 24p footage and then edit in an editor that supports 24 frames per second see these instructions.

Cameras, Techniques

Canon XH A1 and soft focus issue

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A handful of online comments have asked about a “soft focus” issue with the Canon XH A1, a professional HD camera noted for its sharp lens! Only a few people seemed to encounter the soft focus problem – and usually dealt with it by manually focusing instead of using the auto-focus. But no one seemed to identify the root cause problem and the correct solution.

Until now.

Yesterday, I encountered soft focus and it took quite a bit of testing today to locate the cause of the problem and to identify a solution.

I was video taping a marching band competition (mostly in the rain – such fun) and noticed that the camera, which was set to auto focus, was usually slightly out of focus. Even when I manually set the focus and then turned auto focus back on, the camera would shift back out of focus just enough to produce a soft image appearance.

In the interim, I set focus to manual and peaking and magnification on and manually set the focus. But when I offloaded to the computer and blew up the images, I could see that the images were still not sharp.

What was going on?

After shooting a bunch of test images on both an XH A1 and an HV30  – and finding the little HV30 to have sharper images, I knew something was not right.

After a few hours of experimenting, I found the problem – and its even mentioned on page 39 of the manual. Sigh.

Here goes – yesterday, I was shooting an outdoor event, under cloudy skies in 24F mode at 1/48th of a second in Tv mode. I had the AGC set to off and gain manually set to 0 db to avoid adding any noise to the image. Previously I had shot similar events in 30p at 1/60th or 1/100th of a second exposure.

The problem turned out to be caused by not using neutral density (ND) filters resulting in a high f-stop setting auto selected by the camera.

What I did not realize is that when the AGC is set to off, the XH A1 does not advise you when the neutral density (ND) filters should be selected. Consequently, I never thought to use an ND filter.

Further, I did not have the exposure information visible on the display and did not realize the camera was trying to shoot at f-9.5 – where the lens sharpness is degraded. (I didn’t have my reading glasses on and for some reason I thought it said f-19.)

Two problems occur at a tiny aperture:

  1. The auto focus mechanism basically does not work at higher f-stops. In fact, it probably doesn’t work well above f-5.6 or so. If the camera is in full auto mode, it generally chooses excellent settings and you don’t need to worry about this.
  2. The lens sharpness is severely degraded at tiny apertures like f-9.5.

Consequently, there were two problems happening at the same time – one was the poor auto focus and the second was shooting at an f-stop where the lens produces soft images.

The solution is that when shooting in manual mode with AGC turned off, check the f-stop being set by the camera! Set the ND filter and shutter speed as required. Or, I suppose, shoot in Auto mode, with the AGC set to Auto/On as well. Then you’ll get an ND filter warning as required. You can also test your setting by turning AGC back on and see if the camera warns you to enable the ND filter. Set the ND filter and then turn AGC back off.

In my test shots, once I set the ND filter and dropped my exposure to f3.4 – from f-9.5 – the blurriness went away and sharpness was returned.

I have not yet determined the f-stop having the maximum sharpness but have seen some blog posts indicating f-4 is quite sharp.

Why shoot at 24 fps? When uploading online, this provides the highest quality image for a given bit rate. Although it may not make that much difference due to compression across frames.

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Update: July 2010

I recently ran across the same problem with my older Panasonic AG-DVC 30 SD camera.  The DVC 30 has a fake progressive mode for taking a “frame” like image versus an interlaced image. The problem is that in this particular camera, there is a resolution drop  when using the “30F” frame mode due to how Panasonic scans the pixels to create the frame. If I understand the situation correctly, this could result in a 33% resolution drop in Frame mode.  ( To my eye, it depends on the image because it typically seems less than this – and on some test shots, the 30F mode definitely looked better than a high quality de-interlace of the 60i video).

There are two possible work arounds. One is to shoot in normal 60i and get full resolution – and then use DV Film Maker in post to deinterlace the 60i to either 30p or 24p. This works quite well, although its not as good as shooting native progressive to start with.

The second method is to use the camera in 60i but manually set the shutter to 1/30th of a second. This actually produces a true full frame progressive image and is fine as long as you can use the low shutter speed. So far so good.

However, if shooting in bright light, the DVC 30 will push the f-stop as high as it can go – and sure enough, the auto focus fails and the camera is unable to obtain a clean focus.

Consequently, I’d say this problem is probably common across many cameras. The main issue with the XH A1 is that in manual gain setting mode, we no longer see the warning about the need for a neutral density filter.

In the case of the DVC 30, a simple solution would be to use an external ND filter.

Update November 2010

I shot an event, outdoors, under stadium lighting, at night. For some of this event, I used f1.6 aperture and 0 db gain. The image looked fine in the viewfinder. However, after watching on the computer, I discovered some of the shots did quick small jumps out of focus and then back in focus. Really ugly stuff. What’s going on?

In low light conditions, the “Instant Auto-Focus” feature often starts doing a hunt and seek. Therefore, DO NOT use I.A.F. mode in low light. Either use the standard through-the-lens autofocus, or use manual focus.

Some of the event I shot at +6 db gain and I did not seem to have the focus problem there. Again, in low light:

– don’t use I.A.F., use standard auto focus or manual focus

– if you use auto focus, probably best to add sufficient gain

The problem with gain is that it adds some noise, although nothing to worry about at +6 db.

Bottom line

Focus on the XH A1 is a complicated affair!

Editing, Techniques

The Mac, AVCHD and 24p

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The only workable solution I have found for editing 24p video from my Canon HG10 (AVCHD) on Mac OS X is to:

1. Use iMovie 9 to import and transcode the AVCHD video to Quicktime AIC video files. Keep in mind that 24p on the Canon and some other cameras is actually stuffed into the 60i interlaced video stream. So you can import into iMovie even though iMovie does not know what to do with the 24p frames. (Note  – I only have Final Cut Pro 5 which does not support AVCHD. The newer versions, 6 and 7, do support AVCHD directly, although as best I can tell, they do not support the 24p stuffed into 60i video streams directly. So you still have to do the next step.)

2. Use the free JES Deinterlacer’s inverse telecine feature to remove the 2:3:3:2 pulldown from the previously converted AIC file. Just look in your Movies Events folder and let JES Deinterlacer process the imported movie clips. Let JES transcode the input back out to AIC files.

3. At this point, you now have 24p AIC files. You’ll need to run Final Cut Pro to do a good job of editing 24p because Final Cut Express doesn’t do 24 fps timelines. In FCP, set your timeline compression sequene to use the AIC compressor – that way you don’t have to render the AIC files to some other format. Drag your inverse telecined 24p files into Final Cut and have fun editing.

Timewise, this process is actually pretty fast. AIC files do “explode” to about 3 to 5 times larger though, than their original AVCHD format. The newer versions of Final Cut support ProRes422, which is a more compact compressor with excellent quality. But if you don’t yet have FCP 6 or 7, that option is not available.

So why go through this trouble to edit 24p? For me, I like progressive images much more than interlaced. However, 24p enables shooting at 1/24th or 1/48th shutter speeds, making it ideal for low light situations.

Update: VoltaicHD’s problems, noted in the next paragraph, have since been fixed. More here – VoltaicHD now works fine on the HG-10 and presumably more cameras too.

Update: Cineform Neo Scene, for both Windows and Mac, appears to do AVCHD conversion and 24p pulldown removal for 24p embedded in 60i streams. Costs $129.

Other options? I’ve tried VoltaicHD, whcih is recommended by many for transcoding AVCHD files to AIC on the Mac (both Intel and PPC versions). VoltaicHD includes a 24p feature that is supposed to remove the pulldown. But based on my testing with the Canon HG10, it only works some of the time. Some clips are successully processed while others have no pulldown removal. I’ve done many experiments with the settings and have concluded that VoltaicHD probably only works on pulldown removal on the 3 specific cameras they list on their website, even though the underlying data formats should be identical. Thus, don’t buy VoltaicHD for the 24p feature unless your camera is specifically listed.

Editing, Techniques

Working with AVCHD on the Mac

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I do nearly all of my video editing now on a Mac so this post is about processing AVCHD files on the Mac.

Easiest Import

The easiest way to deal with AVCHD is to let iMovie (latest version) import and transcode to the Apple Intermediate Codec (AIC). If you want, you can then edit in iMovie. If you wish to edit in older versions of Final Cut Express or Final Cut Pro, you can import the Quicktime .mov files created by iMovie. Set your timeline sequence encoding to the Apple Intermediate Codec. You can now edit copy your clips direct to the time line, edit as much as you want.

Converting AVCHD to HDV Format

If you must edit both original AVCHD video and HDV video into a single time line and do not want to spend lots of time rendering video clips from AIC into your HDV timeline, then it may be useful to convert AVCHD direct to HDV. If you do not need to merge with HDV footage, then you will not want to do this at all!

Toast 10 from Roxio is the only product that has successfully done the transcoding from AVCHD to HDV (for me). Toast can import your AVCHD files directly from the camera and then re-encode into HDV file format. You do lose some quality (but not very much that most people would actually notice) by re-encoding into HDV.

UPDATE 2009: The Toast 10 product has been riddled with bugs (defects). The company  came out with a 10.0.2 fix release five months later but much is still broken. Worse, the AVCHD conversion feature in Toast 10 DOES NOT WORK. Their decoder gets the video and audio out of synchronization. It does not matter whether you convert from AVCHD to AIC or to HDV. The synchronization will be off. Roxio knows about the problem but after many months has not yet produced a fix. I recommend that you do not purchase Roxio Toast 10 at this time. (Its now 2012 as I revise this text – presumably this has been fixed but I have not gone back to check.)

24p

If you have a consumer camera with 24p capability, you probably cannot directly edit the 24p video without first doing a conversion. But before you consider shooting in 24p, ask yourself if you’d be better off shooting 30p progressive? If you have sort of last year’s Canon camera (HV20, HG10, HG20), you can, in fact, shoot 30p progressive using a simple trick:  Use the Program mode and the Tv selection to set your shutter speed. Set the shutter to 1/30th of second. Your camera now records in 30p mode! This is because the camera actually contains a progressive imaging system-with a 1/30th second shutter speed, both “fields” of the 60i video are recorded without any field shifts. You get perfect 30p, as long as the 1/30th of a second shutter speed is acceptable. (Most 24p is shot at 1/48th or 1/24th of a second. Many people like the blurred motion effect of the slow shutter speeds. Your choice). This trick actually works on a wide variety of older cameras too. If you have a newer camera with true 30p, you may wish to use 30p for all your shooting since it can be directly processed for online or Apple TV/XBox360/PS3 viewing without having to de-interlace.

If you do use the 30p trick, just import your video as 60i and edit as usual. That’s all there is too it.

But if you choose to use 24p, then you must do a “reverse telecine” (or sometimes called “de-telecine” or “inverse telecine”) step to convert the recorded 24p to a true 24p that can be edited in Final Cut Pro. (Final Cut Express and iMovie do not edit 24p video).

VoltaicHD ($35) claims to do the conversion but the demo version did not do so successfully for me. However, if it works, you can use VoltaicHD to import and do telecine removal in one step, producing the AIC files for editing. If it worked, this would be my preferred solution.

HandBrake (see next section) also claims to do reverse telecine conversion but it failed to do so properly on my HG10 video stream. However, its output format is MP4 which is not ideal for video editing.

JES De-Interlacer does do reverse telecine and does it properly and very well (and also does excellent de-interlacing as well as several other features). And its FREE! To use, first import the 24p AVCHD files in iMovie. Then, find the converted files (.mov) in your Movies Events folder. Run JES-Deinterlacer, select all of your input files, and the options page, select the “inverse telecine” option. On the output page, specify a folder to store the converted files – and set your output file format to AIC (Photo JPEG is also very good). Then let it run to convert the input files, producing a new set of output files.

You can then import the output files to Final Cut and begin editing.

You can also see why editing 24p is viewed as somewhat difficult!

Update Fall 2012

Since this post was originally written, another popular solution has emerged called Neo Scene which converts videos to the Cineform codec (now owned by GoPro). Neo Scene converts your AVCHD into the Cineform codec – files do become much larger but editing becomes much quicker and smoother. The Cineform codec is better suited for editing than is AVCHD and many editing programs can play Cineform coded video in real time, smoothly.

I do not – yet – own this product but have used the trial version and have used the free GoPro Studio (which also uses Cineform but does not support so many cameras). Cineform really works.

Cineform can also handled 24p files embedded in a 60i video stream. Versions are available for both Windows and Mac, and based on my experiments on Windows – Cineform coded files work fine in Sony Vegas Movie Studio 11 and in Magix Movie Edit Pro latest versions.

Converting Camera Video Files Direct to MP4 Format

Plug in your camera and copy the files from the camera to your hard disk. (You can also use iMovie’s Archive feature to do this for you).

Then, run the HandBrake program. It can read AVCHD files and convert directly to MP4 files. HandBrake is quite fast and can be configured to re-size your images to 1280×720, as well as de-interlacing (if you did not shoot in progressive). HandBrake is probably the fastest (and FREE!) utility for converting your camera files direct to MP4 files for viewing XBox360’s, Apple TV etc.

Toast 10 can also do the AVCHD to MP4 conversion in one step.