the “maximum” resolution is directly related to maximum pixel clock of 85MHz with audio support. it supports any resolution as long as the pixel clock rate is less that 85MHz when audio is enabled. some examples are:
1280 x 1024 x 60Hz = 78643200 = 78.6MHz
1440 x 900 x 60Hz = 77760000 = 77.7MHz
1920 x 1080 x 30Hz = 62208000 = 62.2MHz
in practice all resolutions “that are supported” are listed with a 50Hz or 60Hz refresh rate. as you can see from the example calculations, you could support a framebuffer of 1920×1080 with low refresh rates, however when the linux kernel does an EDID read, it will select ones with the “standard” refresh rates.
(1920 x 1080 x 60Hz = 124416000 = 124.4MHz)
the beaglebone black can generate up to 125MHz clock for video, however to this leaves no bandwidth for audio to be multiplexed into the hdmi protocol.
so if i wanted full 1920 x 1080 x 60Hz and didn't care about audio,
what would i do? add the appropriate line in uEnv.txt? do i explicitly
need to state that i don't want audio?
rday
in theory - yes you would explicitly specify no audio and the desired resolution
in practicality - no , the code hasn’t reached that level functionality, but will be adapted soon…
Dave
as a side note, as it has been pointed out, even if you wanted to do 1080p, the bbb does not have the processing power to decode 1080p video…
Dave
So we can’t actually modify the resolution the bbb is drawing at yet? It detects the screen at boot and that’s what its stuck at?
You got it! Wasn’t my idea! It has to do with the new and improved DRM driver for Linux. We had this ability under the 3.2 kernel on the BeagleBone. We are working on a couple of things to take care of this but it won’t happen over night.
Gerald
In this thread I saw three messages observing that the BBB will not decode 1080 video. Now we have four of them
It is not like everybory needs decoding 1080 video. Or any video at all.
But If I could get the image of the 3.1Mpix camera cape, and throw (part of) it to a 1920x1080 standard tv / monitor (no audio), this would be wonderful. I see the 1920x1080@24 with no audio as very interesting, and already have BBB and the camera cape.
ivann
Can you elaborate a bit on this?
Are you just reiterating that the BBB has no h264 hw accelerator? Or do you mean that even if you had a raw 1080p stream in “memory”, that there’s not enough bandwidth to push it into the framebuffer?
I suppose they’ve said there is not enough processing power for decoding 1080p video. A quick seach shows that the SG530 in BBB would be limited to decoding 720x480@24.
Considering that, is there any way to force it to boot up at a different resolution, say when building the kernel or something? Because when I was using the Angstrom image that shipped on my BBB, it forced 1280x720, when I put Ubuntu on an uSD card, it booted to 1080p24
I’m not sure what you’re getting at. The SGX530 can support up to a 2048x2048 framebuffer, however, it has no support for video decoding (despite saying it does, heh). Thus, the video decoding would have to be done by the ARM chip itself.
Whatever. My point is that there are users, myself included, who would like to have 1920x1080, without needing any audio or video decoding.
The KMS [video=HDMI-A-1:1024x768@60] seems to be working for the BBB:
video=HDMI-A-1:1024x768@60
ubuntu@arm:~$ cat /proc/cmdline
console=ttyO0,115200n8 video=HDMI-A-1:1024x768@60 root=/dev/mmcblk0p2
ro rootfstype=ext4 rootwait fixrtc ip=
ubuntu@arm:~$ fbset
mode "1024x768"
geometry 1024 768 1024 768 16
timings 0 0 0 0 0 0 0
accel true
rgba 5/11,6/5,5/0,0/0
endmode
video=HDMI-A-1:800x600@60
ubuntu@arm:~$ cat /proc/cmdline
console=ttyO0,115200n8 video=HDMI-A-1:800x600@60 root=/dev/mmcblk0p2
ro rootfstype=ext4 rootwait fixrtc ip=
ubuntu@arm:~$ fbset
mode "800x600"
geometry 800 600 800 600 16
timings 0 0 0 0 0 0 0
accel true
rgba 5/11,6/5,5/0,0/0
endmode
Regards,
In this thread I saw three messages observing that the BBB will not
decode 1080 video. Now we have four of them
here is a fifth 
It is not like everybory needs decoding 1080 video. Or any video at all.
But If I could get the image of the 3.1Mpix camera cape, and throw (part
of) it to a 1920x1080 standard tv / monitor (no audio), this would be
wonderful. I see the 1920x1080@24 with no audio as very interesting, and
already have BBB and the camera cape.
note that the HDMI framer is connected with 16 bits on the BBB, so you get RGB565 only and not 24bit full color, that might impact the display of your camera images
Yes. Perhaps it isn’t fit as a platform for presenting fine art photography of skies and sand dunes, but for capturing well lit images, processing it (opencv or something else), output it with automatic annotations, it is absolutely enough. I have already experimented with beagleXM and the MT9P031, and there we have RGB565 too.
Does that mean I can use a resolution of 1280 *768 * 60Hz with a 720p Video on the BBB
Any updates on this?
I have a simple web-browser application, which I’d like to run in 60Hz rather than the 24. We have no use for audio.
Cheers,
Micael
Plug your numbers into this video timing calculator and you will see that given the AM3358 max pixel clock rate of 126MHz, you cannot do 60Hz.
http://www.fccps.cz/download/adv/frr/video_timings/video_timings.xls
Regards,
John