Blackmagic URSA Cine - Recording to Blackmagic RAW

Blackmagic RAW files are extremely fast and the codec is optimized for your computer’s
CPU and GPU. This means it has fast smooth playback and eliminates the need for hardware
decoder boards, which is important for laptop use. Software that reads Blackmagic RAW also
gets the advantage of processing via Apple Metal, Nvidia CUDA and OpenCL.
This means that Blackmagic RAW plays back at normal speed like a video file on most
computers, without needing to cache it first or lower the resolution.
It’s also worth mentioning that lens information is recorded in the metadata on a frame by frame
basis. For example, when using compatible lenses, any zoom or focus changes performed over
the length of a clip will be saved, frame by frame, to the metadata in the Blackmagic RAW file.
Recording to Blackmagic RAW
Blackmagic RAW works in two different ways. You have a choice to use either the constant
bitrate codec, or the constant quality codec.
The constant bitrate codec works in a similar way to most codecs. It tries to keep the data rate
at a consistent level and won’t let the data rate go too high. This means even if you are shooting
a complex image that might need a bit more data to store the image, a constant bitrate codec
will just compress the image harder to make sure the images fit within the space allocated.
This can be fine for video codecs, however when shooting RAW you really want to ensure the
quality is predictable. What would happen if the images you were shooting needed more data,
but the codec just compresses harder to make a specified data rate? It’s possible you could
lose quality, but not be sure it’s happening until you return from a shoot.
To solve this problem, Blackmagic RAW also has an alternative codec choice called constant
quality. This codec is technically called a variable bitrate codec, but what it’s really doing is
allowing the size of the file to grow if your images need extra data. There is no upper limit on
the file size if you need to encode an image but maintain quality.
So Blackmagic RAW set to the constant quality setting will just let the file grow as big as
it needs to be to encode your images. It also means the files could be larger or smaller
depending on what you are shooting. I guess if you leave your lens cap on the lens, you won’t
waste space on your media!
It is also worth noting that the quality settings for Blackmagic RAW are not obscure names,
butare more meaningful as they are derived from what’s happening technically. So for example
when you have selected the constant bitrate codec, you will see quality settings such as 3:1, 4:1
and more. These are the ratios of the uncompressed RAW file size vs the file sizes you should
expect when shooting in Blackmagic RAW. 3:1 is better quality as the file is larger, while 18:1
is the smallest file size with the lowest quality. Many users of Blackmagic RAW find that 12:1 or
18:1 has been perfectly ok and they have not seen any quality limitations. However it’s best to
experiment and try various settings for yourself.
When using Blackmagic RAW in constant quality you will see the settings are Q0, Q1, Q3 or Q5.
These are the compression parameters passed to the codec and they are setting how much
compression is applied in a more technical way. This setting is different because the codec
operates differently between constant bitrate vs constant quality. In this constant quality setting,
you really cannot tell what the file size ratio will become as it varies a lot based on what you
areshooting. So in this case the setting is different and the file will become the size needed
tostore your media.
49Blackmagic Media Dock