Topic: output qt to ntsc composite video

I can output animation to ntsc composite video using this command.

chumby-:/mnt/storage # chumbyflashplayer.x -x 720 -y 480 -i /usr/widgets/alt_opening.swf

Then I want to do the same thing using Qt. I compile analogclock examples and run it in chumby using this environment.


I put the qt library under /mnt/storage/local/lib/.

There is an output on the tv screen, but only occupy half of it. It is also not a picture of a clock, but there are 8 clocks overlapping.

I also did test the framebuffer using framebuffer program in the qt source. The output is similar, only accupy half of it and not three boxes but rather three bars of red, green and blue on top of the screen. Meanwhile, the output on the console is like below.

In short, the output of the qt program is like the output of chumbyflashplayer.x without the -x and -y added.

Does anyone has suggestion?

chumby-:/mnt/storage # ./framebuffer /dev/fb0
The framebuffer device was opened successfully.

Fixed screen info:
        id:          chumbyfwfb
        smem_start:  0x43a00000
        smem_len:    1658880
        type:        0
        type_aux:    0
        visual:      2
        xpanstep:    0
        ypanstep:    1
        ywrapstep:   0
        line_length: 640
        mmio_start:  0x0
        mmio_len:    0
        accel:       0

The framebuffer device was mapped to memory successfully.

Successfully switched to graphics mode.

Variable screen info:
        xres:           720
        yres:           480
        xres_virtual:   720
        yres_virtual:   960
        yoffset:        0
        xoffset:        0
        bits_per_pixel: 16
        grayscale: 0
        red:    offset: 11, length:  5, msb_right:  0
        green:  offset:  5, length:  6, msb_right:  0
        blue:   offset:  0, length:  5, msb_right:  0
        transp: offset:  0, length:  0, msb_right:  0
        nonstd:       0
        activate:     0
        height:       480
        width:        720
        accel_flags:  0x0
        pixclock:     154000
        left_margin:  5
        right_margin: 4
        upper_margin: 3
        lower_margin: 3
        hsync_len:    40
        vsync_len:    2
        sync:         0
        vmode:        0

Frame Buffer Performance test...
        Average:   26700 usecs
        Bandwidth: 59.252 MByte/Sec
        Max. FPS:  37.453 fps

Will draw 3 rectangles on the screen,
they should be colored red, green and blue (in that order).

Re: output qt to ntsc composite video

Sorry to bother you. I found the solution to my problem. All I did was setting the framebuffer using the following command.

chumby-:/mnt/storage # fbset -g 720 480 720 480 16

Re: output qt to ntsc composite video

Thanks for coming back and posting the fix! Now any other Chumby hackers with a similar problem will have the solution at hand!  This tidbit may come in handy for me too (at some point) as I develop my alternative Chumby software.