opengl颜色转换/或SDI信号转换？
我用 RGBA 颜色在 opengl 中绘制这些文本（括号内的颜色）： 红色-alpha50 (255,0,0,50) 红色-alpha128 (255,0,0,128) 红色-alpha255 (255,0,0,255) 绿色-alpha50 (0,255,0,50) 绿色-alpha128 (0,255,0,128) 绿色-alpha255 (0,255,0,255) BLUE-alpha50 (0,0,255,50) BLUE-alpha128 (0,0,255,128) BLUE-alpha255 (0,0,255,255)
I memcpy 在使用 bmdFormat8BitBGRA 格式创建的帧的缓冲区 (getByte) 中 尺寸为 1280 像素 x 720 像素， 然后将其发送到视频采集卡的 SDI 输出。
以下是我们在电视机上看到的屏幕截图的链接： 通道 A（应该是填充：所以我们期望 RGB 值） Heberger 图片 http://img11.hostingpics.net/thumbs/mini_444718SDIChA.jpg< /a>
通道 B（应该是关键：所以我们期望灰度值）
Heberger 图片 http://img11.hostingpics.net/thumbs/mini_449411SDIChB.jpg
我不确定应该尝试哪种颜色转换。
=>有人可以给我提示或工作轨迹，为什么应该是黑色的背景是“半”绿色（我认为它是绿色，50% alpha：0,255,0,128 或 YUV 中的其他）？
=>这是一个无符号字节与字节的问题：为什么我用 (255,0,0,128) 获得黑色，用 (255,0,0,255) 获得红色：为什么 alpha 达到 128 和 255 之间的红色范围？ （但绿色在 (0,255,0,255) 处变得更白，蓝色在 (0,0,255,128) 处有点绿）。
=>是SDI转HDMI的问题还是HDCP的问题？
感谢大家的帮助， 我有点眼花缭乱，对颜色转换还很陌生， 任何帮助都会非常大， 干杯，
I draw in opengl with RGBA colors these texts (with the color between parenthesis) :
RED-alpha50 (255,0,0,50) RED-alpha128 (255,0,0,128) RED-alpha255 (255,0,0,255)
GREEN-alpha50 (0,255,0,50) GREEN-alpha128 (0,255,0,128) GREEN-alpha255 (0,255,0,255)
BLUE-alpha50 (0,0,255,50) BLUE-alpha128 (0,0,255,128) BLUE-alpha255 (0,0,255,255)I memcpy in the buffer (getByte) of a frame created with the format bmdFormat8BitBGRA
at the size of 1280 pixels by 720 pixels,
and then send it to the SDI output of a video capture card.Here are links to screenshot of what we see on the TV set :
Channel A (should be the fill : so we expect RGB values)
Heberger image http://img11.hostingpics.net/thumbs/mini_444718SDIChA.jpg
Channel B (should be the key : so we expect grey-scale values)
Heberger image http://img11.hostingpics.net/thumbs/mini_449411SDIChB.jpg
I am not sure which color conversion I should try.
=> Can someone give me hint or working tracks for why the background which should be black is a "half" green (I reckon it to be green with 50% alpha : 0,255,0,128 or else in YUV) ?
=> Is it a question of unsigned byte vs byte : why do I obtain black with (255,0,0,128) and red with (255,0,0,255) : why is the red range reached with alpha between 128 and 255 ?
(but green gets whiter at (0,255,0,255) and blue is a little greenish at (0,0,255,128)).
=> is it a question of converting SDI to HDMI or a HDCP issue ?
Thanks to all for any help,
I am a bit dazzled, and quite new to color conversion,
any help will be so great,
cheers,
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好的：发现：这是一个硬件问题：我们使用的 SDI 到 HDMI 转换器仅接受 4:2:2 采样信号。我们提供 4:4:4 信号。因此，对于 4:2:2 信号，不再有绿色背景：我们确实有 alpha 通道的灰度值和另一个通道上的填充
Ok : found : it was a hardware problem : the SDI to HDMI converter we were using only accepts 4:2:2 sampled signal. And we were supplying a 4:4:4 signal. So with the 4:2:2 signal no more green background : we do have grey-scaled values for alpha channel and the fill on the other channel