… for Codecs & Media

Tip #1566: What is a “Reference Monitor?”

Larry Jordan – LarryJordan.com

Perfection is impossible. Instead, ask better questions.

Wikipedia defines a reference video monitor as: “Broadcast reference monitors must be used for video compliance at television or television studio facilities, because they do not perform any video enhancements and try to produce as accurate an image as possible.

Alexis van Hurkman wrote an excellent blog on how to pick the right color grading monitor for your projects. While this was written in 2012, it is still worth reading.

My friends, we are making ourselves crazy. To a certain extent, this is necessary. We are professional colorists, and we require excellence in our display technologies. However, in the pursuit of excellence, we have been set to the task of achieving a pinnacle of perfection, while being given imperfect tools.

It seems to me that shopping for a color critical display is similar to being an audiophile—you can make yourself crazy searching for the Nth degree of perfection. Unlike audio technology, displays are subject to a concrete standard; Rec 601, Rec 709, or P3 dictating the gamut, and a gamma setting that depends on your specific application (more on that here), and a specific peak brightness measured in foot-lamberts (more on that here).

Speaking as an end user, display calibration is a frustrating field to follow. The frustration is thus: you’re told to adhere to a standard, and theoretically that’s cut and dried. Here are the numbers, make the display match the numbers. In practice, getting your display to match those numbers is a pretty challenging task, and different probes and software do this differently, and the results have minor deviations from one another, and then everyone gets to quibble about whose delta-E is smaller. (Crudely put, delta-E is the measured difference between what your display is showing, and what is should be showing, during a controlled calibration procedure.)

Smile… I am a huge fan of Alexis’ work. If you are trying to figure out what the important questions are to ask, this is a blog worth reading.

Here’s the link.

… for Codecs & Media

Tip #1300: A Hidden SSD Speed Boost

Larry Jordan – LarryJordan.com

SSDs don’t have seek times or latency. This means MUCH faster storage speeds for multiple apps accessing storage at once.

OK, I admit, I was playing. But I discovered something very intriguing about SSDs. Watch.

As we’ve learned over the last several tips, the speed of spinning hard drives are limited by seek times and latency (Tip #1287)

The speed of a network is limited by how the devices are connected to it (i.e. 100 Mb vs. 1 Gb vs. 10 Gb Ethernet), the number of users and the connected speed of the server.

But, direct-connected SSDs don’t have these limitations. Instead, speeds are controlled based upon the construction and connection protocol of the SSD (PCIe vs. NVMe – and – USB vs. Thunderbolt).

I plan to do this test in more detail in a few weeks, when I get a chance to play with a brand-new, high-performance NVMe SSD.

But, for this quick check, I connected a Samsung T-5 SSD to a 2019 Mac mini running Thunderbolt 3. While the Thunderbolt 3 protocol maxes out around 2500 MB/sec, the T-5 pegged the meter at 479 MB/s write and 526 MB/s read (see the top values in the screen shot).

HOWEVER, when I ran BOTH AJA System Test and Blackmagic Disk Speed Test at the same time, while the speed for each application dropped, the aggregate speed was FASTER than the speed for the isolated test.

NOTE: In my example, the single app read speed was about 525 MB/s. When both apps were running, the aggregate speed was about 660 MB/s!

What this means is that if you have multiple applications reading or writing to SSD storage at the same time – which is typical for many media apps – SSDs provide far less of a slow-down than spinning media because we can access all that storage directly, without waiting for platters to spin and heads to jump into place.

These tests are just preliminary – I’ll have more on this in a few weeks. But I think this is very, VERY interesting!

… for Codecs & Media

Tip #1287: What is “Latency?”

Larry Jordan – LarryJordan.com

Hard drives have latency – SSDs do not.

Latency is directly tied to spinning storage media – the traditional hard drive – and determines how quickly you can access your data. Latency is the average time for the data being accessed to rotate into position under the drive’s magnetic head, after a completed seek.

As PC Tech Guide.com writes:

Disk RPM is a critical component of hard drive performance because it directly impacts the latency and the disk transfer rate. The faster the disk spins, the more data passes under the magnetic heads that read the data; the slower the RPM, the higher the mechanical latencies. Hard drives only spin at one constant speed, and for some time most fast EIDE hard disks spin at 5,400 rpm, while a fast SCSI drive is capable of 7,200 rpm.

Mechanical latencies, measured in milliseconds, include both seek time and rotational latency. Seek Time defines the amount of time it takes a hard drive’s read/write head to find the physical location of a piece of data on the disk. Latency is the average time for the sector being accessed to rotate into position under a head, after a completed seek. It is easily calculated from the spindle speed, being the time for half a rotation.

A drive’s average access time is the interval between the time a request for data is made by the system and the time the data is available from the drive. Access time includes the actual seek time, rotational latency, and command processing overhead time.

EXTRA CREDIT

What makes SSDs so fast is that they don’t spin or have magnetic drive heads. This means that terms like latency and seek time no longer apply. Here’s the full PCTechGuide.com article to learn more.