《电影与数字时代》杂志关于 ALEXA SUP 9.0 的访谈(上)

在电影业备受欢迎的《电影与数字时代》期刊二月号中,约翰·福尔(Jon Fauer,ASC)采访了 ARRI 摄影机系统产品经理马克•西普曼-穆勒(Marc Shipman-Mueller)和 ARRI 数字流程解决方案部门主任亨宁•雷德莱恩(Henning Rädlein)。他们探讨了 ALEXA 最新的软件升级包(SUP)9.0 版,并详细描述了如何将升级包运用到片场和后期工作中。括号中关于 Codex 及其文件格式的额外注释由 Codex 公司的莎拉·普利斯特诺(Sarah Priestnall)提供。本次采访记录首次在《电影与数字时代》58-59 期刊登。

马克、亨宁,ARRI 软件升级包(SUP)9.0版有什么新特性?

 

马克:首先是 ProRes 格式的支持,SUP9.0 升级后可以让 XT 摄影机录制最高 120 帧每秒的 ProRes 4444。之前 ProRes 4444 最高只能达到每秒 60 帧。在 XT 机器上升级 SUP9.0 就能在使用 XR Capture Drives 或 CFast2.0 存储卡时扩展到每秒 120 帧。另一项更新就是所有机器上都能录制 DNxHD 格式了,从原版 ALEXA 到 ALEXA XT 都可以,另外还增添了 DNxHD 444 格式。

 

在我看来大部分客户都选择使用 ProRes 4444 格式和 Log C,我总说要是当初知道这一点的话就不会去研发其他类别的 ProRes 了。现在相当多的片子都用 ProRes 4444 和 Log C 制作,显然已经成为了行业标准。从2013年开始我们注意到 ARRIRAW 格式的使用更加广泛,不过有些人不太喜欢在 ALEXA 机身上挂载额外的录机。ALEXA XT 上市之后那些想尝试 ARRIRAW 的用户就能直接在机内录制了。一些预算不高的剧情片和高端广告片已经开始转向 ARRIRAW,因为 ALEXA XT 摄影机把 ARRIRAW 的录制集成到了机内。

 

SUP 9.0 加入对 CFast2.0 存储卡的支持之后,是不是有更多的人选择 ALEXA 呢?

 

马克:目前刚开始有这个趋势。这种存储卡才刚刚上市,我们不久之前收到了 Codex 设计的第一批 CFast 2.0 存储卡适配器。因为 AMIRA 也使用这种存储卡,我觉得要等到 AMIRA 大量交付使用之后,同时也拥有 ALEXA 的客户才会考虑购买 CFast 2.0 存储卡。就现在来讲 CFast 2.0 的好处在于可以让 ALEXA 录制每秒120帧的 ProRes4444 格式,而之前的 SxS Pro 64GB 存储卡最高只能录制每秒60帧。

 

我们来聊聊 SUP 9.0 升级后 ALEXA XT 的片门全开(Open Gate)全像素成像特性吧

 

马克:片门全开全像素成像只适用于 ARRIRAW 格式下的 ALEXA XT,XT Plus 和 XT Studio 摄影机。对于 ALEXA XT M 的支持我们正在进行开发,届时会随软件升级包10.0版发布。片门全开全像素成像模式使用了 XT 摄影机感光件的全部 3414×2198 有效像素。

 

我们认为大多数人还是会继续使用16:9画幅拍摄传统宽荧幕画面或4:3画幅拍摄变形画面。应该不会有人用片门全开全像素成像功能拍摄一整部片子,不过电影圈什么事情都有可能发生,谁也说不准。我觉得片门全开全像素成像模式会被大量用于特效镜头和远景定场镜头之类。拍摄的时候按需要开启片门全开全像素成像,其他时候则切换回普通模式。

 

在外拍摄的时候,普通模式和片门全开全像素成像模式之间如何进行切换呢?需不需要交给ARRI 相关部门操作?

 

马克:这个取决于摄影机本身。如果是12月1日之前出厂的 ALEXA XT,那么机器必须送到 ARRI 服务部门做特殊调整。然后还要安装软件升级包9.0版。如果是12月1日之后出厂的 ALEXA XT,那么只需要确保机器已经安装 SUP 9.0 就可以了,切换模式直接在机器菜单里调整。选项包括16:9,4:3或是片门全开全像素成像模式。确认之后需要等待30至40秒,然后就可以录制 ARRIRAW 了。有一点非常重要,因为全像素成像模式使用了机器全部的感光区域,成像圈会扩大到33.5毫米左右。所以必须测试镜头能否完全覆盖感光件,尤其是广角镜头。ARRI 自己的 Master Prime 和 Ultra Prime 广角定焦18-21毫米焦段以上完全可用。9.5-18毫米 Ultra Wide Angle Zoom 超广角变焦也没有问题。其他变焦镜头情况就比较复杂了,所以要特别注意。

 

后期制作的时候,怎么辨别片门全开全像素成像模式呢?是在元数据中标明了吗?

 

亨宁:是的。我们正在更新现有的 SDK 开发包并将这个新格式告知了所有合作厂商。ARRIRAW 转换器可以处理这个格式。很快所有的处理工具将能自动识别这个新格式。后期制作的时候可以选择下变换或是其他选项。我觉得大部分人不会一开始就下变换。做完特效或者画面缩放之后再下变换到高清或是2K成片,也可以上变换到 4K 或是 UHD 2160p。

 

每日素材中片门全开全像素成像格式看起来是什么样的?是不是左右有黑边的特殊画面比例?

 

亨宁:我们推荐做16:9离线编辑,这样一来完整显示的时候画面左右会有黑边,和拍摄时候看到的画面是完全一致的。片门全开全像素成像格式的画面比例是1.55:1。

 

剪辑师在哪一步调整片门全开全像素成像格式的画面位置呢?

 

亨宁:今天我才跟印度那边的一个团队谈过,他们想全程用片门全开全像素成像格式拍片子。我也听说有几个美国的公司也想这么做。在这种情况下,一般是在剪辑素材的时候先下变换到2.39:1或1.85:1的画面,做特效的时候再使用原始画面,不过每部片子都会有不同的需求。

 

马克:我们还认识一个想在喜马拉雅山拍摄的团队。这个外景地挺复杂,他们想用片门全开全像素成像格式拍摄广阔的地貌和天空。我之前说过,电影圈趣事很多,有时候我们都会惊诧于那些人用我们提供的工具做各种登峰造极的事。

 

亨宁:因为 ARRIRAW 超高的画面质量,不到万不得已我不会改动画面分辨率。对于上面提到的自然景观镜头,片门全开全像素成像格式确实非常值得尝试。拍完之后会涉及额外的处理工作,比如需要重新构图和裁切画面。

 

马克:可以自己设定画幅参考线。我们也提供了大部分常见的遮幅预设。但目前还不能自定义遮幅尺寸。使用片门全开全像素成像格式时不能录制音频。最高帧率也不如 4:3 格式。这些不便的地方是要事先理解清楚的。

 

不少人都这么跟我说:“告诉你吧,其实我用不着4K,我只想要稍微多一点像素,用于重新构图、旋转、稳定等等就可以了。”那些人一般都是拍汽车的。我觉得片门全开全像素成像格式特别适合他们,没有4K庞大数据量的负担却依然可以拍摄像素更多的无损无压缩 ARRIRAW 格式。

 

请你解释一下 SUP 9.0 新加入的预录模式吧

 

马克:ProRes 格式下的预录模式将 SxS  Pro、CFast 2.0 或 XR 录制硬盘等存储介质作为循环缓冲区使用。开启预录模式后,摄影机将会持续录制并存储 8-60 秒左右的画面,时长根据帧率和编码会有所不同。按下录制按钮之后,机器会记录下正式录制前的一小段画面。这样就可以拍下还没来得及按录制按钮之前发生的事件。

 

也就是说拍野生动物的时候能录下摄影师被吃掉之前老虎扑过来的画面?

 

马克:我以前跟一位自然摄影师聊过,他大部分时间都在拍猫头鹰。他们会在树枝上呆几个小时然后突然飞走——当然我是指猫头鹰,不是摄影师。如果不当即按下录制按钮的话就拍不到起飞的画面,这样岂不是白忙活了。所以如果能在猫头鹰起飞之前录下10秒钟的画面绝对可以帮大忙。这就是 SUP 9.0 的新特性之一,而且适用于所有 ALEXA 摄影机,包括原版和 XT 系列以及升级 XR 模块后的原版机器。

 

亨宁:是在机内还是在存储卡里缓冲?

 

马克:是在存储介质里缓冲。因为机内的存储空间不够所以我们设计为在存储介质里缓冲,好处就在于如果选用小尺寸的编码,可以缓冲长达一分钟之久,远远超过很多其他摄影机。

 

SUP 9.0 有哪些其它的新特性呢?

 

马克:我们给无线控制单元 WCU-4 增加了新功能,升级后可以用它查看预录状态,还可以在标准帧率和高速帧率之间切换。马达驱动功能也有更新。另外我们还设计了一个全新的用户按钮,PHASE(相位)按钮,用过胶片机的人肯定记得它,按下 PHASE 按钮就能去掉画面中老式电视机的扫描线。虽然现在片场并不经常出现显像管电视和老式放映机,但毕竟还是有这个需要的。

 

还有另外一点我觉得非常关键:数据保护。我们的原则之一就是数据无价,保证客户录制的画面不出任何问题。ARRI 大部分软件系统都是分层编写的,最核心的那层负责图像录制。其它的附属功能都分布在外层,这样一来如果出什么意外的话,数据记录不会受影响。所以说我们尽其所能保护画面。 ProRes 格式的录制过程是这样的:摄影机创建一个 QuickTime 文件包后进行数据写入,每隔一秒都会关闭文件包,然后打开文件包写入一秒再次关闭。如果由电池问题导致电源中断,文件包却没有关闭的话,那文件包内所有的数据都会丢失。而我们的系统因为文件包是每秒关闭的,可以保证只损失一秒钟的数据。

 

一直以来这个系统都非常实用。不过后来我们发现,素材的元数据有时候会因为断电而出错。素材本身是没有任何问题的,但机器由于无法识别元数据而不能在这张存储卡继续录制。在这次 SUP 9.0 升级中,如果机器检测到卡内有错误的元数据,它会转而分析素材内容并重建元数据。完成之后就可以在那张卡上继续录制了。

 

亨宁:我们给这个功能起了个挺酷的名字:元数据自我修复。

 

(未完待续)

 

 

FDT interview about ALEXA SUP 9.0 (I)

 

In the February issue of his popular industry journal Film and Digital Times, Jon Fauer, ASC, interviews Marc Shipman-Mueller, ARRI Product Manager of Camera Systems, and Henning Rädlein, Head of ARRI Digital Workflow Solutions.They speak about ALEXA’s new Software Update Packet (SUP) 9.0 and how it fits into current production and postproduction procedures. A few additional explanatory notes about Codex technology and files [in brackets] come from Sarah Priestnall of Codex. The interview was first published in Film and Digital Times, issue 58-59.

 

Marc and Henning, what’s new in ARRI Software Update Packet (SUP) 9.0?


Marc: Let’s begin with support for ProRes. With SUP 9.0, we can now record with the XT camera, ProRes 4444 (4×4) up to 120 fps. Previously ProRes 4×4 only went to 60 frames a second. With SUP 9.0 on the XT cameras, it’s up to 120 frames a secondas long as you record to XR Capture Drives or CFast 2.0 cards. Another update is that we now have DNxHD on all cameras, Classic ALEXAs as well as ALEXA XTs, and we’ve added DNxHD 444.

 

I think a large portion of customers record on ProRes 4444 Log C and I always say if we would have known this we probably could have avoided doing some of the other flavors of ProRes.  So much stuff is done 4×4 Log C. That is the standard. What we saw at the beginning of 2013 was an increase in ARRIRAW productions, but people didn’t like the fact that they needed to use an extra recorder on top of the ALEXA. When the ALEXA XT came out a lot of people who wanted to do ARRIRAW got the chance to recordit internally. We’re seeing ARRIRAW on some of the not-so-high budget feature films now, as well as on high-end commercials; because with the ALEXA XT camera, ARRIRAW recording is all included in the camera.

 

With SUP 9.0 supporting the CFast 2.0 card, are you seeing more people using them on ALEXAs?


Marc: That’s starting very slowly. The cards are just coming to the market. I think we’ve just received our first adapters from Codex for the CFast 2.0 cards. They are the same cards that the AMIRA uses. I actually think very little is going to happen on that front with ALEXA until the AMIRA hits and then some people with both cameras are going to choose to buy CFast cards. Right now the advantage of CFast cards on ALEXA is recording ProRes 4×4 at 120 fps, whereas on the SxS Pro64 GB card you can only record up to 60 fps.

 

Let’s talk about the ALEXA XT Open Gate in SUP 9.0.


Marc: Open Gate works only for ALEXA XT, XT Plus and XT Studio cameras in ARRIRAW. ALEXA XT M support is planned for Software Update Packet 10, which, by the way, we’re working on right now. Open Gate on the XT cameras uses the sensor’s entire active image area of 3414 x 2198 photosites.

 

We think that most people will continue to shoot most of their footage in 16:9 for spherical or 4:3 for anamorphic shows. I don’t think people are going to shoot a whole show on Open Gate, even though it’s an interesting industry and anything is possible. I think Open Gate will be used for visual effects, wide angle establishing shots, things like that. They may record those scenes in Open Gate, and then switch back to whatever their regular format is for the rest of the show.

 

How do you switch from regular to Open Gate if you are a camera crew in the field? Do you have to send it back to ARRI?


Marc: It depends what kind of camera you have. If you have an ALEXA XT made before December 1st, 2013, the camera actually has to go into ARRI service for a special adjustment.You have to have Software Update Packet 9.0 installed. If you have an ALEXA XT that was built after December 1, you just have to make sure it has SUP 9.0 and then there’s just one switch in the menu. You select from sensor mode 16:9, 4:3, or Open Gate. It takes about 30 to 40 seconds and then you are in Open Gate and you can record ARRIRAW. One thing is important to note. Since we are using the whole sensor, you now have an image circle of about 33.5 mm. So youmust be sure to test, especially with wide angle lenses, to make sure that they cover the entire image area. We found with our wide angle Master Primes and Ultra Primes the boundary is somewhere around 18 to 21 mm. Our 9.5-18 mm Ultra Wide Angle Zoom covers fully. With other zoom lenses, it’s all over the place, so be careful.

 

In postproduction, how do you know that it’s Open Gate? Is it in metadata?


Henning: Yes, it’s in metadata. We are currently updating all the SDKs out there and informing all our partner companies about this new format. The ARRIRAW converter is available and able to process it. Very soon all the tools will beable to understand automatically that this is another format. They can downscale, or we’ll offer options in another menu. I think most people will process without downscaling. They’ll do their effects work or pan-scan, and then downscale to the HD or 2K deliverable format or upscale to 4K or UHD-1.

 

What does Open Gate look like in dailies? Do you see it in a new aspect ratio with black on the sides?


Henning: You will get a pillarbox image if you do 16:9 offline editing which is probably the preferred way. So you will have right and left black bars if you want to see the full height of the image. The important thing is that you see all that has been shot. The aspect ratio of Open Gate is 1.55:1.

 

At what stage does an editor do the repositioning of an Open Gate image?

 

Henning: I talked earlier today with somebody in India who said they want to shoot the whole film in Open Gate. I also hear that several studios in the US are planning to do so. In this case, they will probably downsize to the final ‘Scope or 1.85 ratio for editing in dailies and pull the original Open Gate todiscuss VFX work. It’s a different situation for each production.

 

Marc: We have another guy who wants to shoot in the Himalayas right now – not a very easy location – they’re thinking Open Gate, wide landscape, big sky. As I said, it’s an interesting industry and sometimes we are surprised how far filmmakers go with the tools we provide.

 

Henning: When I see the superb quality of ARRIRAW I would stay with that pixel count for most of the production. You can go with the Open Gate format for those shots that really make sense. This is definitely a handmade visual effects scenario. Ofcourse, you have to reposition and alter the frame lines.

 

Marc: There are user rectangles you can set. We have frame lines for most of the common formats that are built in. The one thing you can’t do is set user frame lines. Those are custom lines you can make. Open Gate doesn’t do audio. It’s not quite as fast as 4:3 in terms of maximum frame rate. So there are some disadvantages you inherit when you do this.

 

I’ve talked to a number of people who said,“You know what, I don’t necessarily want 4K. I’d just like a little more, a few more pixels for repositioning, rotating, stabilizing, that kind of stuff.” Those people are mostly car shooters. I think to them that would be agreat option because you don’t incur the data weight penalty you have with 4K. You can still shoot uncompressed, unencrypted ARRIRAW and have a few more pixels around the edges.

 

Explain the new pre-recording feature of SUP 9.0.


Marc: Pre-recording for ProRes essentially uses the storage space on the media: SxS Pro, CFast 2.0or XR Capture Drives as a ring buffer. When you go to prerecording mode the camera will continuously record the footage and store between 8 and 60 seconds, depending on your frame rate and codec. When you push the record button it’ll actually keep a certain number of seconds before you started recording. So you can capture an event that happened before you push the record button.

 

Before you get eaten by the tiger that’s about to charge at you when you’re doing wildlife photography.

 

Marc: You know, I was talking to a nature cinematographer who spends most of his time filming owls. They will sit for hours on a branch and then all of a sudden take off – the owls, not the cinematographers. If you don’t push the button at just the right time you miss it and the whole day is wasted. So if you give him the option to be able to capture the 10 seconds before the owl takes off, his day would be saved. That’s a new feature of SUP 9.0 and that works for all the ALEXAs: Classic as well as XT cameras, and Classic cameras upgraded with the XR module.

 

Henning: Is it actually buffering in the camera or on the card?

 

Marc: It’s buffering on the recording media. We didn’t have enough storage in the camera so we’re buffering out to the recording media, which has an advantage. If you use a slim codec you can buffer up to a minute—much more than most other cameras.

 

What else is new on SUP 9.0?


Marc: We have extra features for the Wireless Control Unit, WCU-4, so you can see what the pre-recording status is. You can switch from regular to high speed. There are some new motor functions. And we have just introduced a new user button, the PHASE button, which I’m sure you remember from the film cameras, where you push the PHASE button to remove the television scan line from the picture. Not a lot of people are shooting with CRTs or real projectors, but there still are some.

 

There’s one more thing that I think is important: protecting data. One of our philosophies is that the image is holy. We always need to make sure that you can record a good image. In fact, most of our software is in layers and the holy layer is concerned with recording the image. Accessories and other thingsare in an outer layer, so if anything goes wrong you’re still going to be able to record an image. We protect your images. So if you examine the progression of our ProRes recording, here is what happens: the camera opens the QuickTime wrapper, starts recording footage into it, and every second it closes the wrapper. Then it opens it again, ads another second of footage, and closes it again. So if your battery goes down—you experience a power loss. If the wrapper were still open while the power was lost, everything recorded into the open wrapper would be lost. But with our system, you just lose the last second because the previous wrapper was closed.

 

Now this works really well and we’ve had that all along. But then we found that the metadata sometimes got scrambled when we had a power loss. Your footage was still OK, but the camera wouldn’t allow you to record onto the card anymore because it couldn’t make sense of the metadata. With SUP 9.0, if the camera finds a card with scrambled metadata it’ll look at the actual footage, analyze the footage, look at the metadata and then rewrite the metadata based on the footage so you can still continue to record on that card.

 

Henning: We have a good name for that: Self-Healing Metadata.

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