The implementation of OSD on rk1126 platform supports color translucency and multi-channel support for Chinese

Let's take a look at the renderings first Red is the main stream channel , White is the sub code stream channel , Support Chinese display Later, we need to realize multi line display Different positions display And left alignment Right alignment problem  

 

 

Generally speaking   IPC Both need to be implemented OSD The function of That is, time stamps need to be superimposed on the video The current main code stream, sub code stream and other information have been identified

  Before in Hisilicon 3518EV300 Platform implemented The following figure shows Hisilicon 3518EV300 The actual effect on the camera  

In fact, the principle is not complicated , Is to put osd The content is converted to bitmap and then superimposed on yuv On the data

osd The process of converting bitmap Mostly through freetype To achieve , The previous Hisilicon is also  

But after the code of Hisilicon was transplanted directly The display is not normal as follows ：

Two lines are displayed directly Then the font color is also wrong Not pure white

 

After a period of continuous exploration , At last I found the reason .

The reason is that the Hisilicon platform OSD There are many supported pixel formats, and then ARGB565 （ There is no Hisilicon code on this computer ） I don't remember the specific name, probably In short, one pixel is occupied 2 Bytes  

and RK1126 Platform OSD The supported formats are as follows

Only one is supported PIXEL_FORMAT_ARGB_8888 That is, one pixel occupies 4 Bytes In all relevant places, it is changed to 4 You can operate in the way of bytes   The following two places All need to be modified Otherwise, the display will be abnormal