Sony’s X-OCN (X–Original Camera Negative) is a new type of codec from Sony. Currently it is only available via the R7 recorder which can be attached to a Sony PMW-F5, F55 or the new Venice cinema camera.
It is a truly remarkable codec that brings the kind of flexibility normally only available with 16 bit linear raw files but with a files size that is smaller than many conventional high end video formats.
Currently there are two variations of X-OCN.
X-OCN ST is the standard version and then X-OCN LT is the “light” version. Both are 16 bit and both contain 16 bit data based directly on what comes off the cameras sensor. The LT version is barely distinguishable for a 16 bit linear raw recording and the ST version “visually lossless”. Having that sensor data in post production allows you to manipulate the footage over a far greater range than is possible with tradition video files. Traditional video files will already have some form of gamma curve as well as a colour space and white balance baked in. This limits the scope of how far the material can be adjusted and reduces the amount of picture information you have (relative to what comes directly off the sensor) .
Furthermore most traditional video files are 10 bit with a maximum of 1024 code values or levels within the recording. There are some 12 bit codecs but these are still quite rare in video cameras. X-OCN is 16 bit which means that you can have up to 65,536 code values or levels within the recording. That’s a colossal increase in tonal values over traditional recording codecs.
But the thing is that X-OCN LT files are a similar size to Sony’s own XAVC-I (class 480) codec, which is already highly efficient. X-OCN LT is around half the size of the popular 10 bit Apple ProRes HQ codec but offers comparable quality. Even the high quality ST version of X-OCN is smaller than ProRes HQ. So you can have image quality and data levels comparable to Sony’s 16 bit linear raw but in a lightweight, easy to handle 16 bit file that’s smaller than the most commonly used 10 bit version of ProRes.
But how is this even possible? Surely such an amazing 16 bit file should be bigger!
The key to all of this is that the data contained within an X-OCN file is based on the sensors output rather than traditional video. The cameras that produce the X-OCN material all use bayer sensors. In a traditional video workflow the data from a bayer sensor is first converted from the luminance values that the sensor produces into a YCbCr or RGB signal.
So if the camera has a 4096×2160 bayer sensor in a traditional workflow this pixel level data gets converted to 4096×2160 of Green plus 4096×2160 of Red, plus 4096×2160 of Green (or the same of Y, Cb and Cr). In total you end up with 26 million data points which then need to be compressed using a video codec.
However if we bypass the conversion to a video signal and just store the data that comes directly from the sensor we only need to record a single set of 4096×2160 data points – 8.8 million. This means we only need to store 1/3rd as much data as in a traditional video workflow and it is this huge data saving that is the main reason why it is possible for X-OCN to be smaller than traditional video files while retaining amazing image quality. It’s simply a far more efficient way of recording the data from a bayer camera.
Of course this does mean that the edit or playback computer has to do some extra work because as well as decoding the X-OCN file it has to be converted to a video file, but Sony developed X-OCN to be easy to work with – which it is. Even a modest modern workstation will have no problem working with X-OCN. But the fact that you have that sensor data in the grading suite means you have an amazing degree of flexibility. You can even adjust the way the file is decoded to tailor whether you want more highlight or shadow information in the video file that will created after the X-OCN is decoded.
Why isn’t 16 bit much bigger than 10 bit? Normally a 16 bit file will be bigger than a 10 bit file. But with a video image there are often areas of information that are very similar. Video compression algorithms take advantage of this and instead of recording a value for every pixel will record a single value that represents all of the similar pixels. When you go from 10 bit to 16 bit, while yes, you do have more bits of data to record a greater percentage of the code values will be the same or similar and as a result the codec becomes more efficient. So the files size does increase a bit, but not as much as you might expect.
So, X-OCN, out of the gate, only needs to store 1/3rd of the data points of a similar traditional RGB or YCbCr codec. Increasing the bit depth from the typical 10 bit bit depth of a regular codec to the 16 bits of X-OCN does then increase the amount of data needed to record it. But the use of a clever algorithm to minimise the data needed for those 16 bits means that the end result is a 16 bit file only a bit bigger than XAVC-I but still smaller than ProRes HQ even at it’s highest quality level.
With the first of the production Venice cameras now starting to find their way to some very lucky owners it’s time to take a look at some features that are not always well understood, or that perhaps no one has told you about yet.
Dual Native ISO’s: What does this mean?
An electronic camera uses a piece of silicon to convert photons of light into electrons of electricity. The efficiency at doing this is determined by the material used. Then the amount of light that can be captured and thus the sensitivity is determined by the size of the pixels. So, unless you physically change the sensor for one with different sized pixels (which will in the future be possible with Venice) you can’t change the true sensitivity of the camera. All you can do is adjust the electronic parameters.
With most video cameras the ISO is changed by increasing the amount of amplification applied to the signal coming off the sensor. Adding more gain or increasing the amplification will result in a brighter picture. But if you add more amplification/gain then the noise from the sensor is also amplified by the same amount. Make the picture twice as bright and normally the noise doubles.
In addition there is normally an optimum amount of gain where the full range of the signal coming from the sensor will be matched perfectly with the full recording range of the chosen gamma curve. This optimum gain level is what we normally call the “Native ISO”. If you add too much gain the brightest signal from the sensor would be amplified too much and exceed the recording range of the gamma curve. Apply too little gain and your recordings will never reach the optimum level and darker parts of the image may be too dark to be seen.
As a result the Native ISO is where you have the best match of sensor output to gain. Not too much, not too little and hopefully low noise. This is typically also referred to as 0dB gain in an electronic camera and normally there is only 1 gain level where this perfect harmony between sensor, gain and recording range is achieved, this becoming the native ISO.
Side Note: On an electronic camera ISO is an exposure rating, not a sensitivity measurement. Enter the cameras ISO rating into a light meter and you will get the correct exposure. But it doesn’t really tell you how sensitive the camera is as ISO has no allowance for increasing noise levels which will limit the darkest thing a camera can see.
Tweaking the sensor.
However, there are some things we can tweak on the sensor that effect how big the signal coming from the sensor is. The sensors pixels are analog devices. A photon of electricity hits the silicone photo receptor (pixel) and it gets converted into an electron of electricity which is then stored within the structure of the pixel as an analog signal until the pixel is read out by a circuit that converts the analog signal to a digital one, at the same time adding a degree of noise reduction. It’s possible to shift the range that the A to D converter operates over and the amount of noise reduction applied to obtain a different readout range from the sensor. By doing this (and/or other similar techniques, Venice may use some other method) it’s possible to produce a single sensor with more than one native ISO.
A camera with dual ISO’s will have two different operating ranges. One tuned for higher light levels and one tuned for lower light levels. Venice will have two exposure ratings: 500 ISO for brighter scenes and 2500 ISO for shooting when you have less light. With a conventional camera, to go from 500 ISO to 2500 ISO you would need to add just over 12dB of gain and this would increase the noise by a factor of more than 4. However with Venice and it’s dual ISO’s, as we are not adding gain but instead altering the way the sensor is operating the noise difference between 500 ISO and 2500 ISO will be very small.
You will have the same dynamic range at both ISO’s. But you can choose whether to shoot at 500 ISO for super clean images at a sensitivity not that dissimilar to traditional film stocks. This low ISO makes it easy to run lenses at wide apertures for the greatest control over the depth of field. Or you can choose to shoot at the equivalent of 2500 ISO without incurring a big noise penalty.
One of Venice’s key features is that it’s designed to work with Anamorphic lenses. Often Anamorphic lenses are typically not as fast as their spherical counterparts. Furthermore some Anamorphic lenses (particularly vintage lenses) need to be stopped down a little to prevent excessive softness at the edges. So having a second higher ISO rating will make it easier to work with slower lenses or in lower light ranges.
COMBINING DUAL ISO WITH 1 STOP ND’s.
Next it’s worth thinking about how you might want to use the cameras ND filters. Film cameras don’t have built in ND filters. An Arri Alexa does not have built in ND’s. So most cinematographers will work on the basis of a cinema camera having a single recording sensitivity.
The ND filters in Venice provide uniform, full spectrum light attenuation. Sony are incredibly fussy over the materials they use for their ND filters and you can be sure that the filters in Venice do not degrade the image. I was present for the pre-shoot tests for the European demo film and a lot of time was spent testing them. We couldn’t find any issues. If you introduce 1 stop of ND, the camera becomes 1 stop less sensitive to light. In practice this is no different to having a camera with a sensor 1 stop less sensitive. So the built in ND filters, can if you choose, be used to modify the base sensitivity of the camera in 1 stop increments, up to 8 stops lower.
So with the dual ISO’s and the ND’s combined you have a camera that you can setup to operate at the equivalent of 2 ISO all the way up to 2500 ISO in 1 stop steps (by using 2500 ISO and 500 together you can have approximately half stops steps between 10 ISO and 650 ISO). That’s an impressive range and at no stage are you adding extra gain. There is no other camera on the market that can do this.
On top of all this we do of course still have the ability to alter the Exposure Index of the cameras LUT’s to offset the exposure to move the exposure mid point up and down within the dynamic range. Talking of LUT’s I hope to have some very interesting news about the LUT’s for Venice. I’ve seen a glimpse of the future and I have to say it looks really good!
The raw and X-OCN material from a Venice camera (and from a PMW-F55 or F5 with the R7 recorder) contains a lot of dynamic metadata. This metadata tells the decoder in your grading software exactly how to handle the linear sensor data stored in the files. It tells your software where in the recorded data range the shadows start and finish, where the mid range sits and where the highlights start and finish. It also informs the software how to decode the colors you have recorded.
I recently spent some time with Sony Europe’s color grading guru Pablo Garcia at the Digital Motion Picture Center in Pinewood. He showed me how you can manipulate this metadata to alter the way the X-OCN is decoded to change the look of the images you bring into the grading suite. Using a beta version of Black Magic’s DaVinci Resolve software, Pablo was able to go into the clips metadata in real time and simply by scrubbing over the metadata settings adjust the shadows, mids and highlights BEFORE the X-OCN was decoded. It was really incredible to see the amount of data that Venice captures in the highlights and shadows. By adjusting the metadata you are tailoring the the way the file is being decoded to suit your own needs and getting the very best video information for the grade. Need more highlight data – you got it. Want to boost the shadows, you can, at the file data level before it’s converted to a traditional video signal.
It’s impressive stuff as you are manipulating the way the 16 bit linear sensor data is decoded rather than a traditional workflow which is to decode the footage to a generic intermediate file and then adjust that. This is just one of the many features that X-OCN from the Sony Venice offers. It’s even more incredible when you consider that a 16 bit linear X-OCN LT file is similar in size to 10 bit XAVC-I(class 480) and around half the size of Apples 10 bit ProRes HQ. X-OCN LT looks fantastic and in my opinion grades better than XAVC S-Log. Of course for a high end production you will probably use the regular X-OCN ST codec rather than the LT version, but ST is still smaller than ProRes HQ. What’s more X-OCN is not particularly processor intensive, it’s certainly much easier to work with X-OCN than cDNG. It’s a truly remarkable technology from Sony.
Next week I will be shooting some more test with a Venice camera as we explore the limits of what it can do. I’ll try and get some files for you to play with.
So here it finally is. Sony’s latest digital cinema camera and finally it has a name rather than a number and it’s called Venice.
I was lucky enough to be involved with Venice during the filming of the UK promo film, so I have had a little bit of a chance to play with one, seen it in action in the hands of an experienced DP (Ed Wild B.S.C.) and I have copies of the footage from it (I did the BTS film). So I have a pretty good idea of what we are dealing with…… and it’s good, it’s very, very good.
For a long time I have been saying that what we need is better pixels, not more pixels and that’s precisely what Sony have delivered in Venice. The newly developed sensor is a full frame sensor, 36mm x 24mm with 6K’s worth of horizontal pixels. This means that if you use the camera as a super 35mm camera you have 4K (and for the demo films the pre production cameras used only worked at 4K, the equivalent of 35mm 4 perf. 6K will come a little later). Venice will be able to do a huge range of resolutions and aspect ratios including Anamorphic.
Why only 6K? Well it’s down to pixel size. Bigger pixels can capture more light and they can also store more electrons before they overload. This means you get a bigger dynamic range than would typically be possible with smaller pixels. The extra light capturing capability can be used in one of 2 ways, to increase sensitivity or to decrease noise. It appears that the engineers behind Venice went for the latter, lower noise.
A lot of research was done for this camera. Engineers from Japan met with many ASC and BSC cinematographers. They talked to post houses and colourists to find out what was really needed. I know that Claudio Miranda A.S.C. played an important part in the development process, he also shot the US demo film. The end result is a pretty sensitive camera (500 ISO) with very low noise and over 15 stops of dynamic range. Yes – that’s right over 15 stops without resorting to double exposures or any other tricks!!
While the sensor isn’t a global shutter sensor it does have an extremely fast readout rate. This extra fast readout means that jello and other rolling shutter artefacts are minimised to the point where it behaves much more like a global shutter sensor. Generally speaking, the extra memory circuits needed to get a global shutter either add noise, reduce sensitivity or reduce dynamic range. So it’s not a huge surprise to see the fast read out approach. There was quite a bit of filming done with a rather lovely Lamborghini Uraco, both hand held inside the car and mounted on the front of the car. Looking at the rushes there is no sign of any noticeable rolling shutter artefacts, even the trees flashing past in the background are still nice and vertical.
A lot of the car shooting took place at dusk and an interesting thing that came out of the UK demo reel shoot was how well it performed in low light. The 500 ISO rating is deceptive, because the camera produces so little noise you can rate the camera at a higher ISO and still get good results. Most current cinema cameras don’t produce the best results unless you rate them lower than their base ISO’s. Venice is different, the base ISO is very low noise and very high dynamic range. There appears to be little need to rate it lower for even less noise, although you could if you wish. I asked Ed Wild about this and he was really pleased with Venice’s ISO rating commenting that he often had to rate cameras from other manufacturers lower than the base ISO while he felt Venice at 500 ISO worked really well and that he would even consider rating it higher if needed.
Having a low base ISO means there is less need to use large amounts of ND on outdoor shoots. But talking of ND filters one of the great features of Venice is an 8 stage, behind the lens glass ND filter system. This allows you to choose just the right amount of ND for the light levels you have with no loss of quality. During the pre-shoot test and prep day at Pinewood each stage of the ND was carefully tested for colour shifts and accuracy, no problems were found.
The lens mount on a Venice camera can be changed. It’s not a quick release mount as on the F55 or F5 cameras. It’s normally a PL mount. But the PL mount can be removed and the camera changed to a Sony E-Mount. 6 bolts remove the PL mount and a locking E mount similar to the one on the FS7 II is on the cameras body. This opens up the possibility of using a huge range of lenses, practically anything in fact as it’s easy to adapt from E-Mount to other mounts such as Canon EF for example. For the UK demo reel XTAL Anamorphics from MovieTec were used. Ultra Primes were used for the US promo film.
VENICE A Truly Modular Camera.
Not only can the lens mount be changed but the entire front part of the camera can be changed by removing just 4 screws. Venice is built as a modular camera and the front part of the camera that contains the sensor and ND filters is a removable module (no need for lab conditions or clean rooms to remove the module). This means that in the future Sony could release new sensor options for Venice. Maybe a higher resolution sensor, a monochrome sensor or a high speed sensor. Removing the front sensor module from the camera allows easy access to the cameras internal near silent fan so that it can be cleaned or replaced should that become necessary. All of the cameras electronics are in sealed compartments for dust and moisture protection and rubber seals are installed around any openings such as the SxS card access door. In addition if you do use the AXS-R7 recorder to record Raw/X-OCN this too is weather sealed.
Venice records to SxS cards and with the AXS-R7 attached to AXS cards. You can record XAVC, ProRes HD, ProRes Proxy, as well as Raw/X-OCN. The XAVC recording option allows you to record direct to compact but high quality ready to go files or to record lower resolution proxy files. X-OCN gives a 16 bit linear workflow with raw type performance but without massive files. There is very little difference between X-OCN and Sony 16 bit linear raw and different versions of X-OCN work at different bit rates so you can pick and choose the right balance of image quality against file size for each project.
For Venice Sony have developed new colour science that is designed to emulate film. Looking at the rushes from the camera it really looked nice without any grading. The images contain lots of lush colours. You could see amazing subtle tonal information in the leaves and trees in the shots. Skin tone highlights roll of in a particularly pleasing way.
One of the biggest criticisms of the PMW-F55 and F5 cameras when they were launched was that they were too complex to drive. The F55 menu system is very large containing many, many pages of settings and adjustments. This is a cinema camera without a lot of the fancy modes that cameras like the F5 or F55 have so the menus are simpler straight away. A lot of time was spent trialling different menu structures to determine the easiest and friendliest structure. At the press event during the hands on session most people found it quite easy to navigate around the menus. But really the way the side panel and the quick menu is set up means you won’t need to dive into the main menu very often.
The camera body is a bit bigger than an F55/F5 and a lot smaller and lighter than an F65. On the right side of the camera there is the main LCD display, which is very similar to the one on the F55/F5 with 6 hot keys around it and a rotary menu dial. This is actually quite similar to the F55’s new Quick Menu system and easy to master. All the key functions and setup options are just a couple of button presses away. This is the main display and where most of the cameras settings can be changed. It’s on the right side so the AC or DIT can get at it and see it easily. Pressing the user button turns 5 of the 6 buttons around the LCD into user assignable buttons (the 6th button is used to set the assignable functions).
On the left side of the camera there is a small information display that shows the frame rate, shutter speed, ND, ISO and white balance.
The white balance of the camera can be dialled in manually unlike the F55 you are no longer tied to 3 presets. You can now dial in the white balance you want down to 1 kelvin increments. Once you have set your white balance you can include your new custom setting in the preset list for quick recall at any time.
The camera can run off either 12V or 24V and it has an internal 24V inverter so that when using a 12V power source such as a V-Mount battery you still get 24V out of the industry standard 24V lemo connectors.
Venice is a modular camera system with various upgrade options. The base camera comes as a 4K super 35mm camera. the 6K option, anamorphic options (6K full frame and 4K 35mm) and other options will be available as option licences. These licences can be purchased as weekly, monthly or permanent options depending on your needs.
What about the picture? I spent a couple of days looking at footage from this camera both in my own grading suite and at Sony’s Pinewood facility during the production of the BTS film. I also saw it projected at the press day and it looks good. One problem today is that there are so many very good and very capable cameras that it’s tough to really pinpoint things that make one stand out as better than another. What I have found to be very pleasing from Venice is the skin tones. Sony have introduced new colour science and colour management for Venice and I think it looks really good. Even before grading, just looking at the clips on a monitor with S-Log3 gamma the pictures have a wonderful rich look. It’s worth noting that the cameras used for both the US and EU launch films were hand made pre-production units and the engineers are still learning how to fully exploit the new sensors in these cameras. So we can only expect them to get better between now and when they become available to buy.
Will I be getting one? Probably not. This is a wonderful camera and I would love to own one, but Venice will be more expensive than the F55 and probably not the best investment for me at least. However I fully intend to get my grubby fingers on one as soon as possible to learn all of it’s in’s and out’s as I hope to use a Venice for some short films I have planned. This is a serious Alexa or Red alternative It has image quality to rival or better almost any other digital cinema camera, but that does come at a price, although it’s no more expensive than any other comparable camera.
The estimated price for the base camera is expected to be around €37,000. Full frame and anamorphic options will be payable options, with the full-frame option costing a approx €4,000 and the anamorphic costing a approx €6,000. it should be available from around February 2018.
This time last year I was just starting to earn about a new codec from Sony called XOCN (eXtended Original Camera Negative). XOCN is currently only available with the Sony F5/F55 and the new AXS-R7 raw recorder. Sony’s original R5 raw recorder takes 16 bit sensor data and applies a very mild amount of compression before recording the sensor data as linear raw. I have never seen any compression artefacts when using the 16 bit linear raw and it really is an amazing format to work with. So much so that I will always use it whenever possible.
But now as well as 16 bit linear raw the R7 can record 16 bit linear XOCN. Now, I’ll be completely honest here, I’m really not sure what the difference is between raw and XOCN. As far as I can tell XOCN is very, very similar to raw but sufficiently different to raw to avoid infringing on patents held by other manufacturers for compressed raw. XOCN is more highly compressed than Sony’s raw, but in every test I’ve done I have found it hard to spot any compression problems or any significant difference between XOCN and the original 3:1 raw.
So, I hear you ask…. “If it’s really that good what don’t we just do away with XAVC and use XOCN?” Well that is a good question. It all depends on processing power. XAVC is a traditional codec so inside the codec is a normal video image, so the only thing a computer has to do to play it back is uncompress the codec. XOCN is a compressed wrapper that contains sensor data, in order to view the image the computer has to uncompress the data and then it has to construct the image from the data. So you need a really good graphics card in a decent computer to work with XOCN. But if you do have a decent edit or grading workstation you should find XOCN straight forward to work with, it doesn’t require specialist cards to accelerate the decoding as Red raw does.
The key benefit that XOCN brings over traditional video is that it is 16 bit. 10 bit video is pretty good. In a 10 bit video you have almost 1000 tonal values, not bad when you consider that we have been using 8 bit for decades with only 235 shades. But 16 bit brings the potential for a whopping great 65,535 shades. This starts to make a big difference when you are extensively manipulating the image in post production. Any of you that are in to photography will know that you can push and pull a 16 bit raw photograph far, far further than an 8 bit jpeg. 16 bit video is no different.
But what’s really amazing about XOCN is you get almost all the benefits of linear raw but in a file size smaller than the same resolution 10 bit ProResHQ. If you use XOCN-LT the files are roughly half the size of ProResHQ. This means your media lasts a sensible amount of time and backups, transfers and archiving are all much easier, much faster than with uncompressed raw. Sony’s 3:1 compressed raw from the R5 has always been pretty easy to deal with. XOCN is even easier. Using XOCN-LT you can squeeze well over 2 hours of 16bit 4K on to a 512GB AXS card! In fact the file sizes are only marginally larger than XAVC class 480.
The reduction in data rates becomes really significant if you shoot at high frame rates. As 50p and 60p productions become more common XOCN allows production companies to shoot 60fps with the benefits of 16 bit data but with files sizes barely any bigger than 24fps ProResHQ. If you have a Sony PMW-F55 you can shoot at 120fps in 4K using XOCN and the files are twice as big as 24fps raw.
For further information on XOCN please take a look at this page from Sony, it’s very informative and has a very good example of why 16 bit data is important, especially if you are shooting for HDR.