Comments URL: https://news.ycombinator.com/item?id=42705870

Points: 4

# Comments: 0

Wouldn't this be the OETF? OOTF would include the EOTF, which is typically applied on the display side (as you noted).

I typically only do a full flash for the first build after a sync. Afterwards I just build the pieces I'm changing and use `adb sync` to push them to the device, skipping both the step that packs the image files and the flash. The `sync` target will build just the pieces needed for an `adb sync` if you don't know exactly what you need to build; I typically use it so I don't have to even think about which pieces I'm changing when rebuilding.

So typical flow goes something like:

``` // Rebase is only needed if I have existing local changes > repo sync -j12 && repo rebase

// I don't actually use flashall, we have a tool internally that also handles bootloader upgrades, etc. > m -j && fastboot flashall

// Hack hack hack... then: > m -j sync && syncrestart ```

Where `syncrestart` is an alias for:

``` syncrestart () { adb remount && adb shell stop && sleep 3 && adb sync && adb shell start } ```

Incremental compiles while working on native code are ~10 seconds with this method. Working on framework Java code can be a couple minutes still because of the need to run metalava.

I work on displays within an OS team. Having some basic understanding of colour theory is critical for a significant number of modern display projects, particularly for the high end. For example, enabling colour accurate rendering (games, photos, etc), shipping wide-gamut displays (how do you render existing content on a WCG display?), etc. More specifically to the planckian locus, it generally comes up when deciding which white point to calibrate a given display to at the factory (e.g. iPhone is 6470K, S20 is 7020K in Vivid)[1][2] and if you're doing any sort of chromatic white point adaptation, like Apple's True Tone[1][2].

My background before joining the team was a degree in math, but I really enjoyed doing low level projects in my spare time, so ended up on an OS team. We also have colour scientists who study this full time and have a _significantly_ better understanding of it all than I do :)

[1]: https://www.displaymate.com/iPhone_13Pro_ShootOut_1M.htm#Whi... [2]: https://www.displaymate.com/Galaxy_S20_ShootOut_1U.htm#White... [3]: https://support.apple.com/en-gb/HT208909 [4]: http://yuhaozhu.com/blog/chromatic-adaptation.html

Comments URL: https://news.ycombinator.com/item?id=28038807

Points: 120

# Comments: 104

A couple reasons this isn't as silly as it seems

1) ~All buffers in Android are pipelined, usually with a queue depth of 2 or 3 depending on overall application performance. This means that missing a deadline is recoverable as long as it doesn't happen multiple times in a row. I'd also note that since Netflix probably only cares about synchronization and not latency during video play back they could have a buffer depth of nearly anything they wanted, but I don't think that's a knob Android exposes to applications.

2) The deadline is probably not the end of the current frame but rather than end of the next frame (i.e. ~18ms away) or further. The application can specify this with the presentation time EGL extension[1] that's required to be present on all Android devices.

[1]: https://www.khronos.org/registry/EGL/extensions/ANDROID/EGL_...

It is absolutely settled, and has been tested over and over again. Power is roughly proportional to the amount of light emitted[1], so having dark grey is absolutely a power savings over pure white.

Google slides: https://www.theverge.com/2018/11/8/18076502/google-dark-mode... Display energy modeling: https://onlinelibrary.wiley.com/doi/am-pdf/10.1002/stvr.1635

[1]: This isn't totally true mostly because the display is broken into RGB elements emitting light of differing efficiencies and human perception of the brightness of those elements is not identical.

  And remember… don’t be evil, and if you see something that you think isn’t right – speak up!

> learn how to build Android from sources

https://source.android.com/setup/start has instructions.

> put some binary drivers from official image

https://source.android.com/setup/build/gsi is a set of builds you can flash on any sufficiently modern Android device alongside their binary drivers.

> May be even some guides how to reverse engineer proprietary drivers and rewrite them as open source.

You're on your own for this, but given the kernel and HAL APIs are both open source you could theoretically figure out how to build a viable implementation, but no matter how you go about it, building something like a GPU driver is a substantial task. You could probably build things like the lights HAL without too much difficulty though.

""" SCHED_FIFO and SCHED_RR threads will run until one of the following events occurs:

- The thread goes to sleep or begins waiting for an event

- A higher-priority realtime thread becomes ready to run

If one of these events does not occur, the threads will run indefinitely on that processor, and lower-priority threads will not be given a chance to run. This can result in system service threads failing to run, and operations such as memory swapping and filesystem data flushing not occurring as expected. """

SCHED_DEADLINE, which is newer and not mentioned in the guide, can provide a bit stronger guarantees because it can fail if it thinks the requirements you set aren't actually obtainable based on other system load (including high priority kernel tasks that might need to run, etc).

[1]: https://access.redhat.com/documentation/en-US/Red_Hat_Enterp...

Comments URL: https://news.ycombinator.com/item?id=18943991

Points: 4

# Comments: 1

[1]: https://en.wikipedia.org/wiki/Don%27t_be_evil

When a video is demonetized, only a small subset of advertisers or no advertisers can be shown on that video. If no ads are being shown then neither Google nor the creator are making money (and Google is spending money to host and serve the content), so really this is a lose/lose for both of them.