DATA



Datatransport

Overview for formulas, storage space and transfer time. Please use as well the Data Calculator in DPP Film Tech App.

Copying data between storage volumes and moving files from one post-production facility to another is a central part of every media production workflow. Raw and compressed media files are in fact copied and stored and shared many times and in different qualities. Raw media is copied from camera magazines to shuttle drives after capture, then from shuttle drives to on-site NAS, from NAS to editing workstations and again to remote facilities for grading, backup and final delivery. Each copy takes time which must be accounted for. Some access must happen in real-time to allow fluent creative work. In such cases it is important to design storage and network bandwidth for sustained througput at the desired rate. 

Storage space and transfer time

Calculating required storage space and transfer times is easy. Both depend on image resolution, color depth, frame rate and the codec's compression ratio. In digital video cameras and professional software you can usually set all or most of these values independently. The resulting amount of data is expressed as a bitrate that defines how many bits per second of video a codec generates. For CBR codecs this is the exact constant value, for VBR codecs this is an average. To simplify handling, many codec vendors provide bitrate tables for common combinations. Be careful to check frame rate and color depth that was used for calculating such numbers to avoid surprises. For measuring the actual speed of your equipment you can use BlackMagic Design SpeedTest or the Davinci Resolve file system speed benchmark tool. 


Formulas

To calculate the approximate bitrate of an uncompressed video you can use the following formula:

bitrate = frame_width x frame_height x color_depth x color_planes x frame_rate


This gives you the bitrate in bit per second (1 Mbit/s = 10^6 bit/s).  Width and height are the image dimensions in pixels, color depth is the number of bits per pixel for a single color component and color planes is the number of colors per pixel (1 for raw Bayer sensor data, 3 for RGB or YCbCr images, 4 for images with an additional alpha channel).
Below are some tables about bitrates, frame and file sizes and transfer times for common video codecs used to compress production-quality content. The numbers reflect a progressive frame rate of 24 fps and a color depth of 12bit per color component with three components excluding alpha channel, except for Red and ArriRaw. Resolutions shown are HD (1920 x 1080), 2k (2048 x 1080), UHD (3840 x 2160), 4k (4096 x 2160).

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