4K codecs - the good, the big and the ugly. Part 2

The first part of this blog looked at the file sizes of a 1 second 4K video clip using various QuickTime codecs. This part looks at the image quality of the codecs that use an efficient lossy compression system. Some codecs can compress an image and uncompress it without any loss of information (lossless compression), but these produce extremely large file sizes and I have left them out of this test as they should, in theory, show no difference to the original.   

The codecs compared here are GoPro's Cineform, Avid's DNxHD, MJPEG A, MJPEG B, MPEG 4 and Photo JPEG. Here is the table of file sizes for the various versions I made:

File sizes of 4K 1 second clip

Here is the link to the 1 second clip at HD 1920x1080 size in the MPEG 4 codec at 90%.

I made 2 JPEG (100%) stills of the first frame of the clip. One is the full size 4K image and the other is a 640x360 pixel crop with the image zoomed up to 200%. The cropped image is the top of the tower with the crane by the side. All the images are shown below, but I also made a stack of the crops in Photoshop and sliced out the layers for a comparison. 

Quality of various codecs 90% quality. 200% zoom and cropped

I haven't included MJPEGB here because it is no different from MJPEGA, but both MJPEGs show a large variation in the original colour, lifting the gamma significantly. All the other codecs were consistent and matched the uncompressed version.


The original purpose of this test was to see if the Avid DNxHD codec was suitable for 4K use but when I saw how poor the quality was I looked at all the other codecs to see what was wrong. You can see from the sliced picture how blurred the image of the crane has become, but the MPEG4 version is as sharp as the Photo JPEG image below. I was surprised when I looked at the file size how much DNxHD was compressing the image because I hadn't seen such degradation when editing high definition material and the file size is larger than MPEG4. I rendered out this clip in 1920x1080 with the codecs again set to 90% quality. The DNxHD clip was 44 MB in size and the MPEG4 was only 14 MB in size.

To be precise the HD version of the DNxHD codec was 44,808 KB in size which is exactly the size of the 4K version, which gave the solution. The DNxHD codec is only designed for the 1920x1080 video space and when the image dimension goes beyond that the pixels are duplicated (or more) to fill in the gaps, hence why it is blurred and the file size doesn't increase.

I think this is a mistake and Avid should limit the dimension the codec can produce, like H.264 does. Or it should ignore file size and produce a similar quality of image that the other codecs show here. I assume Avid will come up with a native 4K codec very soon which can be used in the next generation of cameras such as the Blackmagic Design Cinema Camera and their edit tools.

Meanwhile the best solution for moving 4K videos around the web appears to be MPEG 4 because it scales well, reproduces the original colour and is the smallest of all the options. However I hope that the GoPro Cineform codec becomes more widely used (and free) as it is robust and platform agnostic. And of course we wait for the launch of H.265 which is likely to be the choice of the broadcast world.

For videographers producing 4K clips the only solution is to use a lossless codec 

Here are the JPEG images of all the test clips. Please download them to compare.

Cineform 90%

Cineform 90% crop with 200% zoom

Avid DNxHD 90%

Avid DNxHD 90% crop with 200% zoom

MPEG A 90%

MPEG A 90% crop with 200% zoom

MPEG 4 90%

MPEG 4 90% crop with 200% zoom

Photo JPEG 90%

Photo JPEG 90% crop with 200% zoom

Useful software for videographers and photographers - Part 1

Over the years I have purchased or downloaded for free many small pieces of software to achieve specific results or solutions. Some are used a couple of times and then deleted, others, like Christmas dogs, stay with me forever. I thought I would run through some of them here as they may prove useful to you one day.

MPEG Streamclip by Squared 5 is one of the best known video converters and despite owning powerful conversion software by Avid, Apple and Adobe, this is the one I use the most. Firstly it produces files that are universally playable and recommended by stock sites. Secondly it can convert sections of a DVD to a QT file that can be imported to Avid. Thirdly it is quick to use and the presets are logical. Finally it is very small programme that has little impact on computer resources.

MPEG Streamclip options

Most editors know that attaching Apple formatted drives to a Windows PC just doesn't work unless you install Mediafour's Mac Drive which allows you to be totally agnostic about the drive format. But another of the company's software, Disk Aware has been the find of the year for me. Disk Aware analyses every folder and file on a drive and presents it as a list arranged in size order and also as a colour-coded wheel which shows you the relative size of the files and folders. Simply click on a segment and analyse the next layer down.

DiskAware - The Wheel

The programme only costs $10 per computer but it can analyse any drive: internal, external, flash and even network drives. It enables easy clearing up of drives and lets you work out why all your storage has disappeared. 

One tool I used for a while, dropped and have returned to is IrfanView, the strangely named freeware viewer for PCs. One of the more recent improvements is IrfanView Thumbnails which you get when you install the complete set of plugins and I place as a shortcut on the desktop. It opens up an explorer window with a light grey background to distinguish it from Windows Explorer. Open up a folder containing mixed media and almost immediately it is populated with thumbnails which can be set to many sizes, not just Window's three. 

IrfanView Thumbnails of text, video and .psd

Thumbnails are shown for videos (with filmstrip icon), stills (even Photoshop) and text. PDFs are not shown however. One of the most useful tools is the ability to save those thumbnails as separate images for putting into a spreadsheet for example. Hovering over a thumbnail reveals information about the file itself such as dimensions, although for video only the dimensions of the thumbnail itself are shown. Like most features of IrfanView they are a work in progress, but the ability to see thumbnails from both videos and Photoshop files make it worth having.

In Part 2 I look at a a couple of sound tools, a backup programme and a couple of tools for uploading and managing material at iStock and Smugmug.

What can you shoot these days? Part 1

This is not a blog decrying the lack of targets for blood-lust hungry hunters but is about how you cannot film or photograph anything these days without written permission. Watch any news footage or television programme shot in the previous millennium and there were practically no restrictions on what you were allowed to cover - kids, iconic buildings, film stars, even the Queen was fair game.

Much of the work I produce is sold through stock libraries and each one has its own different rules and all of them have release forms available when you can identify someone within the picture or video. iStock is one of the most restrictive of all the stock libraries, possibly because it is owned by the omnipotent Getty Images. Material I have supplied but has been rejected for copyright issues include The Eiffel Tower at night (the light show is the problem), Sydney Opera House, a night time shot of London when a logo appeared over a total of 12 pixels (out of 5,800,000 or so) and macro shots of the Queen's image on a coin.

A photo of the "Boris" bikes in central London, which look great in their rack, was rejected because the bikes feature Barclays Bank logo. I Photoshopped the logo out, re-submitted and got it rejected again because the London Underground logo appeared in the background.

Timelapse footage of a glorious sunset behind the Millennium Wheel was rejected by iStock (although accepted by three other libraries) because it featured, yup, the Millennium Wheel.

I can see both sides of the coin (but I can't photograph it) and in ten years iStock have over 100 million images downloaded from their site, so they must be doing something right and their quality control is amazingly good. My concern (apart from not being able to get my images and video out to the iStock customers) is that the rich heritage that still and moving images have developed over the last 200 years may be eroded.

Fotolia and Shutterstock have a more relaxed attitude to copyright issues and search engines such as Google Images will find you almost anything, but would you feel happy using a photo sourced here in a TV programme that is being transmitted world-wide?

Without a court case to clarify each case, photographers and film makers will never be certain what they can shoot but one thing is clear, copyright free imagery is becoming an endangered species.