Rick's b.log - entry 2012/05/16

Beagle xM video

[using my eeePC as a display, playing AKB48's Baby! Baby! Baby! video]

I conducted a few tests of video playback capabilities of the Beagleboard xM using default stuff and s-video output.

First up, we've already done H.263 (XviD/DivX). I've tried it in a variety of resolutions without problems, but didn't have any XviD HD material to hand.

Now for H.264 (so-called MPEG 4). The first test shouldn't be too hard. It is a 360p fan-made video for the song "Fairy Dreaming" which was the theme to "Genocyber", an animé from the days when gore was an artform. Forget logic, science, or basic biology - just go with something because it takes gory and turns it up to eleven...

[Genocyber AMV from YouTube, NSFW!]

Next up was a 480p video for the song "Baby! Baby! Baby!" by AKB48. Initially this stuttered badly for the first 10-15 seconds, and then whenever the mouse was moved. My fault - explanation and resolution below.

[Baby! Baby! Baby! video from YouTube, by AKB48]

Finally, a 720p recorded on my mobile phone. Wouldn't play. Not a hope. I'll need to rustle up some other HD files because I have a suspicion that this might be the fault of the MPlayer. I initially wondered if it was a side-effect of using the s-video port, but besides being a bogus reason, I also noticed that the video FPS (frame rate) is rather incorrect.

How, in order to get the s-video port working, I had to modify the uEnv.txt file. I initially altered mine to be:

defaultdisplay=tv
buddy=unknown
bootargs=console=${console} ${optargs} mpurate=${mpurate} buddy=${buddy} camera=${camera} vram=${vram} omapfb.mode=tv:ntsc omapdss.def_disp=${defaultdisplay} root=${mmcroot} rootfstype=${mmcrootfstype} omapdss.tvcable=composite
uenvcmd= run loaduimage; run mmcboot

The "defaultdisplay" and references to tv/composite are what do the trick.

However after some consideration with regards the original version of the file, I have amended it as follows:

mpurate=1000
defaultdisplay=tv
buddy=unknown
vram=16M
optargs="consoleblank=0"
console="tty0 console=ttyS2,115200n8"
bootargs=console=${console} ${optargs} mpurate=${mpurate} buddy=${buddy} camera=${camera} vram=${vram} omapfb.mode=tv:pal omapdss.def_disp=${defaultdisplay} root=${mmcroot} rootfstype=${mmcrootfstype} omapdss.tvcable=composite
uenvcmd= run loaduimage; run mmcboot

- copy'n'paste note: the line shown in blue is all one line, it is only split on your browser for wordwrapping

The vram setting defaults to zero. Setting this gives memory for the video system, which obviously makes video stuff more fluid. The mpurate setting should be auto-set by U-boot, maybe this is a hangover from a bug in an older version? I copied it from the original uEnv anyway.
The two console settings set up where you can bash command lines - a terminal switchable from the keyboard, plus the serial port. I think this was default anyway.
Finally, the optargs setting consoleblank to zero tells the system that you want to see all the boot-up spewage that Linux creates. There's something reassuring about watching its progress (even if it is full of weird errors).

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poop shit fish, 7th November 2012, 14:54

herp de derp I love genocyber

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