WHITE PAPER CINEMA EOS EXTENDED RECORDING CAPABILITIES IN THE EOS C700 CAMERA Written by Larry Thorpe Customer Experience Innovation Division, Canon U.S.A., Inc. For more info: cinemaeos.usa.canon.com © 2017 Canon USA, Inc. All rights reserved.
Extended Recording Capabilities in the EOS C700 Camera Content Page Abstract 1 1.0 INTRODUCTION TO EOS C700 CAMERA 1 2.0 OVERVIEW OF THE RECORDING OPTIONS IN THE EOS C700 CAMERA 2 3.
Abstract The original EOS C300 camera was introduced in November 2011. It uses a 4K single image sensor to exclusively originate the 1920 x 1080 HD production format [1]. It records this onboard using an MPEG-2 codec operating 8-bit YCrCb 4:2:2 @ 50 Mbps. The EOS C500 Camera followed in 2012 and supported external 4K RAW recording. The EOS C100 Mark II was introduced in the latter half of 2014 and the EOS C300 Mark II was unveiled at NAB 2015.
2.0 OVERVIEW OF THE RECORDING OPTIONS IN THE C700 The C700 differs from the companion C300 Mark II in five key respects: 1. In addition to the same XF-AVC codec [4] deployed in the C300 Mark II for on-board recording of 4K / UHD / 2K / HD the C700 offers an additional option of the ProRes codec [5]. Both codecs record to two CFast 2.0 memory cards 2. 4K RAW signal output is prepared in a quite different manner to that of the C500 and C300 Mark II.
The EOS C700 has an extended sensitivity range – from ISO 100 up to ISO 102,400. This control is shared between an analog control (controlling the gain of the column amplifier within the CMOS image sensor [ 7 ] ) and a downstream digital control. In the case of the on-board recorded signals both controls are used.
Figure 3 The EOS C700 with the dockable Codex recorder empowers uncompressed RAW recording while also delivering the 4K RAW signal via 3G-SDI output interfaces (the number of these interfaces is dependent upon the frame rate) to an external system or another recording device The combination of the optional Codex CDX-36150 with the EOS C700 camera allows for highspeed 4.5K RAW recording at up to 100fps, 4K RAW at up to 120fps, 4K Apple ProRes at up to 60fps, 2K Apple ProRes at up to 240fps.
4.0 NEW OETF FOR THE 4K / UHD RAW DATA The video processing of the 4K RAW signal in the EOS C700 is quite different to that in the EOS C500 and EOS C300 Mark II. In those three cameras the same video processing was applied to the on-board recorded video as was applied to their RAW signal outputs. As shown in Figure 1 these same video processes are still applied to the signal that is recorded on board the EOS C700.
Figure 5 Illustrating the concept of the special OETF for the 4K Raw data for four exposures Figure 5 shows the concept of the 4K RAW Gamma mapping. For the lowest ISO100 setting the analog signal amplitude applied to the A/D converter is large and accordingly the code levels are particularly favorable to the entire signal. However, the dynamic range is curtailed to just one stop above reference white. As the scene illumination lowers the analog output from the image sensor progressively lowers.
5.0 ON-BOARD RECORDING – IN EITHER XF-AVC OR ProRes As shown in Figure 7 the on-board primary recording uses two CFast memory cards to record any of the chosen 4K / UHD / 2K / HD production formats. At the same time a proxy version for offline editing support is recorded on an SD card at a much lower data rate. Figure 7 6.
7.0 INTRA XF-AVC MODE – 4K / UHD CAPTURE The EOS C700 has extended the XF-AVC recording options beyond those in the EOS C300 Mark II. It can record 4K / UHD YCrCb 4:2:2 up to 50 and 59.94 progressive frames per second at 810 Mbps recording data rate that ensures the highest image capture. The lower frame rates are recorded at 410 Mbps. Variable Bit Rate (VBR) is used and the file wrapper is MXF. TABLE 2 8.
9.0 INTRA XF-AVC MODE – HD / 2K CAPTURE This is the recording mode that supports amazingly high image quality capture. In seeking the very highest performance for 2K / HD, the three full bandwidth RGB 4:4:4 components are recorded at 12-bit or 10-bit at the very high data rates shown in Table 4.
TABLE 5 Intra-frame Recording of RGB 4:4:4 or YCrCb 4:2:2 for 1080-line 2K and HD The Apple ProRes 422 Codecs are contained within the QuickTime "mov" wrapper. 11.0 XF-AVC LONG GOP – HD / 2K BROADCAST TELEVISION This level uses the considerably more compressed implementation of XF-AVC – utilizing the Long Group of Pictures (termed Long GOP) embodiment of AVC/H.264 to achieve this degree of compression. This dramatically lowers the data rate to 50 Mbps.
12.0 XF-AVC PROXY – LOW DATA RATE FOR OFFLINE EDITING To support offline editing of any of the above HD / 2K / UHD / 4K formats, the C700 separately records a low data rate proxy of the format in question. This is an HD or 2K format that is coded as YCrCb 4:2:0 in Long GOP form at 8-bit at frame rates up to 59.94P. While the primary program signal format is being recorded to the CFast memory cards this proxy is recorded in parallel to a separate SD memory card.
Table 8 Slow and Fast Motion Recording for 4K / UHD / 2K / HD in the EOS C700 12
14.0 AUDIO RECORDING Like the EOS C300 Mark II the EOS C700 supports four channels of LPCM 24-bit / 48 kHz audio for all on-board recordings. Linear pulse code modulation (LPCM) is a method for digitally encoding uncompressed sampled analog audio information where the quantization levels are linearly uniform. The output signal is automatically changed to 16bit audio when the camera is working in 4K RAW mode. Figure 8 15.
REFERENCES [1] L.Thorpe, “New Optical and Image Sensor Technologies for High-Resolution Digital Cinematography” SMPTE Motion Imaging Journal, March 2013 [2] Canon White Paper “Image Performance Enhancements in the C300 Mark II Camera”, http://learn.usa.canon.com/resources/articles/2012/cinemaeos_white_papers.shtml [3] Canon White Paper “Ergonomic and Operational Enhancements to C300 Mark II Camera http://learn.usa.canon.com/resources/articles/2012/cinemaeos_white_papers.
