孤雨独火 发表于 2020-6-24 03:21
hdr模式下这个数字没错，不然按照我当前环境100nit整个片子偏灰，跟sdr屏幕直接看hdr影片一样。
100nit HDR这个数值太低了，请单独给HDR一个校准版本，HDR亮度请不要低于200nit，具体数值你可以参考如今的HDR影片绝大部分场景下的亮度值去设。
chungexcy 发表于 2020-6-23 16:37
mpv/madvr的自适应tone mapping基本是给那些HDR转SDR用的，不适合于显示设备自带HDR。当然设备HDR性能有 ...
本质都是一样的，没有什么不适合。当然这个需要有校色仪，但是现在绝大部分 HDR 屏幕都依赖 local dimming，峰值亮度也都会受显示面积影响，这些机制用户也都完全无法控制，导致校色仪基本是不可能测得准了，所以这个意义上说也大概确实不太适合吧。但是屏幕厂家提供的处理就会更好吗？我其实也非常怀疑。
比较理想的情况应该是像 @haasn 说的这样：
"If I was to buy a HDR display, I would make sure it has a linear response and high static contrast ratio (no dynamic contrast or local dimming techniques), and I would adjust the hardware brightness controls to max out at some fixed peak brightness e.g. 400 cd/m² (typical OLED peak), with a 10-bit or higher display connection. Then, I would use my GPU's CLUTs to switch between “SDR mode” (where 1.0 maps to 100 cd/m²) and “HDR mode” (where 1.0 maps to 400 cd/m²), so I can switch between the modes in software (e.g. when mpv is fullscreen). The use of a 10-bit display connection instead of an 8-bit connection will be enough to overcome the loss of 2 bits due to the 4x increase in peak brightness."
https://github.com/mpv-player/mpv/issues/5521#issuecomment-365157536
hsmms 发表于 2020-6-23 22:42
MPV跟madvr对于动态映射处理并不相同，不知道MPV是如何处理这方面的？
我反而是没怎么研究过 madVR 是如何处理的，两三年前大概试过，不太清楚现在的情况。
mpv 的话应该就是这么三个东西：
--hdr-compute-peak=<auto|yes|no>
Compute the HDR peak and frame average brightness per-frame instead of relying on tagged metadata. These values are averaged over local regions as well as over several frames to prevent the value from jittering around too much. This option basically gives you dynamic, per-scene tone mapping. Requires compute shaders, which is a fairly recent OpenGL feature, and will probably also perform horribly on some drivers, so enable at your own risk. The special value auto (default) will enable HDR peak computation automatically if compute shaders and SSBOs are supported.
--hdr-peak-decay-rate=<1.0..1000.0>
The decay rate used for the HDR peak detection algorithm (default: 100.0). This is only relevant when --hdr-compute-peak is enabled. Higher values make the peak decay more slowly, leading to more stable values at the cost of more "eye adaptation"-like effects (although this is mitigated somewhat by --hdr-scene-threshold). A value of 1.0 (the lowest possible) disables all averaging, meaning each frame's value is used directly as measured, but doing this is not recommended for "noisy" sources since it may lead to excessive flicker. (In signal theory terms, this controls the time constant "tau" of an IIR low pass filter)
--hdr-scene-threshold-low=<0.0..100.0>, --hdr-scene-threshold-high=<0.0..100.0>
The lower and upper thresholds (in dB) for a brightness difference to be considered a scene change (default: 5.5 low, 10.0 high). This is only relevant when --hdr-compute-peak is enabled. Normally, small fluctuations in the frame brightness are compensated for by the peak averaging mechanism, but for large jumps in the brightness this can result in the frame remaining too bright or too dark for up to several seconds, depending on the value of --hdr-peak-decay-rate. To counteract this, when the brightness between the running average and the current frame exceeds the low threshold, mpv will make the averaging filter more aggressive, up to the limit of the high threshold (at which point the filter becomes instant).
boday 发表于 2020-6-24 06:09
我反而是没怎么研究过 madVR 是如何处理的，两三年前大概试过，不太清楚现在的情况。
mpv 的话应该就是 ...
你前面说的madvr动态化处理是针对的是哪个版本？
boday 发表于 2020-6-24 06:09
我反而是没怎么研究过 madVR 是如何处理的，两三年前大概试过，不太清楚现在的情况。
mpv 的话应该就是 ...
所以就是不知道是根据测量的数据整体优化还是根据测量的数据对每一帧或者每一个场景单独的映射优化
hsmms 发表于 2020-6-24 03:40
100nit HDR这个数值太低了，请单独给HDR一个校准版本，HDR亮度请不要低于200nit，具体数值你可以参考如今 ...
激发hdr模式下这个影片低于600nit颜色都是明显错误的。hdr转sdr的话至少对这个影片200尼特以下都不行，对比如下：
标准sdr对照
hdr2sdr 250 500 1000
boday 发表于 2020-6-24 05:56
本质都是一样的，没有什么不适合。当然这个需要有校色仪，但是现在绝大部分 HDR 屏幕都依赖 local dimming ...
然而以当前lcd的特性不依赖分区控光根本没法做到极高的静态对比度
孤雨独火 发表于 2020-6-24 12:10
激发hdr模式下这个影片低于600nit颜色都是明显错误的。hdr转sdr的话至少对这个影片200尼特以下都不行，对 ...
用的什么播放设备？
孤雨独火 发表于 2020-6-24 12:35
然而以当前lcd的特性不依赖分区控光根本没法做到极高的静态对比度
分区背光数量太少我觉得还不如不开
孤雨独火 发表于 2020-6-24 12:10
激发hdr模式下这个影片低于600nit颜色都是明显错误的。hdr转sdr的话至少对这个影片200尼特以下都不行，对 ...
而且我不建议简单拿sdr版本跟转换sdr进行对比。转换sdr应该是尽可能保留hdr数据而不是丢失数据去迎合sdr版本。所以请建立个p3色域的转换sdr版本