JamieG Analysis

Canon has slated the release of a new camera that will put H.264/AVC into the spot light recently.  I have written much over the years about how H.264 will eventually take over as the standardised codec of choice. The Canon HG20/HG21 is the camera that will make consumers love AVC.

See Gizmoto review here.

The thing that makes the HG20 special is that it supports a more realistic bitrate for the AVCHD codec.  Most of the recent cameras from Sony and other brand have only supported up to 16mbit.  The Canon unit will support AVCHD up to 24 mbit. This is a huge difference as, the picture quality is greatly improved for shooting more demanding video.  This is more then a typical consumer quality camera.

For example, the new Sony EX1 and EX3, $10,000 (On average) cameras are the hottest prosumer cameras around right now.  And for good reason.  The build and tactile interface is fantastic for one.  Plus the quality of the 35mbit MPEG2 is stunning.  Build quality means nothing unless you can capture a great picture.  MPEG2 at 35mbit does just that.

Now, looking at AVCHD (H.264) at 24mbit.  Yes, it is not as high as 35mbit, but it is well known that the newer technology of H.264 is up to 2 times as efficent.  2×24mbit(H.264) = 48mbit(MPEG2) in quality.

I personally do not thing it is twice as good, but one could expect it to match 35mbit easily.

So we now have $1500 consumer cameras matching the quality of $10,000 prosumer cameras.  Thats big news to anyone who shoots video on a day to day basis.

The other huge advantage is that storing/archiving your content is easier as at 24mbit over, 35mbit, is a major advantage.  This may not sound like a big issue, but video files pile up fast, and it is not unusual to have 10-100 of terrabytes of video.

Standard are very important

Finally, the long term advantage. AVC is a SMPTE specifications which takes it into the future.  For example. support for up to 4k resolutions, 4:2:2, 4:4:4 and 10, 12 bit colour.  No other SMPTE standard codec supports these characteristics.  People talk about the RED all the time using the RED codec.  I find it a sign of ignorance that they do not understand the advantages of supporting standards based codecs.  H.264 at High 4:4:4 12bit 4k is positioned to become tiff/tga of video. A file format anything can read.

An example of this is that DCI (Digital Cinema Initiative) have standardised that a Digital Film Master has to be supplied in 16bit 2K or 4K TIFF files with uncompressed 48kHz 24 bit stems (audio file for each channel, usually 6 (5.1)).  This standard is based on open file formats and not proprietary RedCode or ProRES for example.

The Bad

There is one major issue with AVCHD.  Its not easy to edit.  As it is a complex codec with long GOP (Group of pictures) When a editing system requests a certain image while playing a time line or rendering a timeline, it needs to go to the nearest I-Frame or full frame before the frame it wants, then calculate down to the exact frame.  Very inefficent.  Faster computers with more memory will make this less of an issue in the future, but in real terms, it is usually best to transcode the content to a more editable format whitch also keeps all the quality.  For example, ProRES for Final Cut Pro.  This will, of cause, mean the video content will take up many, many ties the amount of disk space compared to the original.  This is common in editing work flows. For example EXCAM (Sony EX1) and RedCode (RED cameras).

AVC also have other iterations of its codec to make it easy to edit.  An example of this AVC-Intra used by Panasonic in their t hi-enf ENG range of cameras.  This is similar to the old MPEG2-I-frame codecs.  Its just a H.264 I-frame codec.  As it is I-frame only, it runs at much higher bitrates such as 50 and 100mbit.

The Road ahead

AVCHD still has a road ahead.  H.264 is said to have up to 2 times the efficiency then MPEG2.  In my experience I do not find this to be the case.  But like DV and MPEG2 based codec cameras when they where first released, the real time codec implementation was always very version 1.0 and over time improved As such, I expect AVC to also improve in real time camera capturing in the future.