Allwinner V853 LVGL video playback interface implementation method

aleksib

Allwinner V853 LVGL video playback interface implementation method [Copy link]

 

### 1. Theme LVGL video playback interface implementation method### 2. Problem background Use LVGL to develop and need to display video or camera data in the UI, but don't know how to implement it, either only display UI or only display video. ### 3. Specific performance can be seen by looking at what elements are there when the video is playing.  There are interactive controls such as play buttons, progress bars, settings, etc., which are all located in the UI layer. Below the UI is a frame of video data after decoding, and the video data is located in the video layer. ### 4. Problem analysis Generally, the UI layer is located above the video layer. If the UI layer does not set transparency, there will be a background color that covers the video layer, resulting in only the background color and some control buttons being visible. 0] 1280x 800 err:0 skip:67 irq:2300 vsync:0 vsync_skip:0 BUF enable 0x00:0 1280x800 err:0 skip:67 irq:2300 vsync:0 vsync_skip:0 BUF enable 0x00:0 1280x800 err:0 skip:67 irq:2300 vsync:0 vsync_skip:0 BUF enable 0x00:0 1280x800 err:0 skip:67 irq:2300 vsync:0 vsync_skip:0 BUF enable 0x00:0 1280x800 err:0 skip:67 irq:2300 vsync:0 vsync_skip:0 BUF enable ch[0] lyr[0] z[0] prem[N] a[pixel 0] fmt[ 77] fb[1280, 736; 640, 368; 640, 368] crop[ 0, 0,1280, 720] frame[ 0, 0,1280, 800] addr[fb200000,fb2e6000, fb359000] flags[0x 0] trd[0,0] depth[ 0] BUF enable ch[1] lyr[0] z[16] prem[N] a[pixel 255] fmt[ 0] fb[1280, 800;1280, 800;1280, 800] crop[ 0, 0,1280, 800] frame[ 0, 0,1280, 800] addr[ff800000, 0, 0] flags[0x 0] trd[0,0] ``` During kernel initialization, the display driver registers /dev/fb0 and applies for the UI layer. You can see ch[1] lyr[0]. Generally, the UI has only one address addr[ff800000, 0, 0], which is also the top layer z[16]. The blending mode a[pixel 255] indicates that the transparency of the UI layer is controlled by the application. When playing a video (using the TPlayer interface), the video layer is applied for through the middleware. You can see ch[0] lyr[0], and the three addresses of yuv are constantly changing addr[fb200000,fb2e6000,fb359000]. Usually, the video is placed at the bottom layer z[0]. When the application is not transparent, because the zorder of the UI layer is larger than the video layer, only the UI can be seen, but not the video, so the application needs to be "hollowed out". ### 6. Solution The screen in the code below generally refers to /dev/fb0, and the LVGL version is 8.3.2. Before using the following code, you need to set parameters in lv_conf.h: ```cpp #define LV_COLOR_SCREEN_TRANSP 1 ``` ```cpp /* Initialize screen style*/ static lv_style_t style_scr_act; if (style_scr_act.prop_cnt == 0) { lv_style_init(&style_scr_act); /* It is not transparent by default, and can be switched as needed later*/ lv_style_set_bg_opa(&style_scr_act, LV_OPA_COVER); /* Be sure to apply the style, otherwise it will have no effect*/ lv_obj_add_style(lv_scr_act(), &style_scr_act, 0); } /* Here, different styles are switched according to the button state. One is that the UI can transparently see the video underneath, and the other is that the UI covers the video and the video cannot be seen*/ if (lv_obj_has_state(btn, LV_STATE_CHECKED)) { /* Switch to UI transparency here*/ lv_label_set_text(label, "Stop"); /* Set the screen to be transparent here*/ lv_disp_get_default()->driver->screen_transp = 1; /* Set the screen background to be transparent here*/ lv_disp_set_bg_opa(lv_disp_get_default(), LV_OPA_TRANSP); /* Clear the screen here. If not, it may not take effect*/ lv_memset_00(lv_disp_get_default()->driver->draw_buf->buf_act, lv_disp_get_default()->driver->draw_buf->size * sizeof(lv_color32_t)); /* The screen style is switched to transparent here*/ lv_style_set_bg_opa(&style_scr_act, LV_OPA_TRANSP); /* Notify style changes, need to be updated*/ lv_obj_report_style_change(&style_scr_act); } else { /* Switch to UI opaque here, that is, cover the video*/ lv_label_set_text(label, "Play"); /* Set the screen to be opaque here*/ lv_disp_get_default()->driver->screen_transp = 0; /* Set the screen background to be opaque here*/ lv_disp_set_bg_opa(lv_disp_get_default(), LV_OPA_COVER); /* The screen style is switched to opaque here*/ lv_style_set_bg_opa(&style_scr_act,LV_OPA_COVER); /* Notify style changes, need to be updated*/ lv_obj_report_style_change(&style_scr_act); } ```

火辣西米秀

Does it have to be LVGL version 8.3.2?

wangerxian

Are there any effect pictures? I haven't thought about using LVGL for the video playback interface yet.

吾妻思萌

The player looks good.