1 Topic by desidude2000 (edited by desidude2000 2012-01-06 00:23:36)

  • Registered: 2011-12-20
  • Posts: 18

Topic: MythTV Frontend (aka mythfrontend) on Infocast, POC (Proof of Concept)

I managed to get Infocast setup as a myth frontend using Debian chroot method (with direct boot into chroot'ed environment through a debugchumby script under /psp).   Below is a video showing a demo of this:

http://youtu.be/MT0Mdqv4lwg

Since the touchscreen on my Infocast isn't working (as some of you may know from my other thread), I decided to use the iPhone App called MythRemote to remotely control the MythTV frontend on the Infocast.   MythRemote takes advantage of the ability of mythfrontend to be remotely controlled over a TCP/IP port (i.e. no infrared or RF signal is required as long as both the iPhone + MythFrontend are on the same LAN and the frontend allows permission for the app to communicate on a TCP/IP port).

Everything works as excepted from a mythfrontend perceptive.   But there is just a slight tiny bit of problem!  :-)   Video playback stutters, and CPU starvation occurs on the Infocast due to the video being decoded purely in software.    Myth does have the ability to specify an external player for video playback (in lieu of the built in internal player).  If someone knows of a command line player that would utilize Marvell PXA168's hardware capabilities for video playback, that would help greatly.  The player ideally would be simply enough to be executed as:  playerxyz <videofile>  (and not be a .swf / flash based application/player).

I've tried mplayer and I've gotten the same results.   I've been thinking about transcoding the file in real time to FLV using ffmpeg, but not sure if the overhead of transcoding (in real time) would be too much for the CPU too handle while playing back the FLV file which I would hope would get offloaded to some sort of a hardware decoder as the PXA168's datasheet does call for targeting up to 720p video playback! (Source: http://www.marvell.com/selector_guide/d … 168_pb.pdf - Page 2 - Line 6 under Benefits).

Anyway, some work in progress... any suggestions & comments would be welcome to make this project a success to the point where playback of at least 480p video is possible.

  • From: San Francisco
  • Registered: 2011-12-13
  • Posts: 18

Re: MythTV Frontend (aka mythfrontend) on Infocast, POC (Proof of Concept)

nice work!

Quick question though..  Why is it necessary to chroot into debian from the chumby OS?   I don't see anyone here addressing that.

I've been trying to create an sd image to boot directly into Debian on my chumby 1 but I just get the hex string errors at boot.  I can boot with several Angstrom images (OE) but with that distro I can't seem to get what I need cross compiled into it because the bitbake build systems are out of date (trying to compile specific python/pygame midi modules).  So I'd like to just get debian running with its full package repo but the route to getting there seems odd.

  • Registered: 2012-02-26
  • Posts: 40

Re: MythTV Frontend (aka mythfrontend) on Infocast, POC (Proof of Concept)

Hex error at boot could mean a number of things, depending on what it is, but the most likely cause is that you don't have the first (boot blob) partition set up right. Keep in mind that the partition offset is significant — the SOC isn't aware of the partition table.

  • Duane
  • Duane
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  • From: San Diego, CA
  • Registered: 2006-08-24
  • Posts: 8,197

Re: MythTV Frontend (aka mythfrontend) on Infocast, POC (Proof of Concept)

I don't think the PXA-168 has any sort of hardware video decoder - instead, it uses "WMMX2" instructions.  You might be able to get higher performance by tweaking some compiler options to have it generate these instructions.

I seem to recall that Marvell also has some special hand-rolled codecs that use WMMX2 for the inner loops.

Duane's Website

  • From: San Francisco
  • Registered: 2011-12-13
  • Posts: 18

Re: MythTV Frontend (aka mythfrontend) on Infocast, POC (Proof of Concept)

Okay, I've seen people talk about the partition offsets but not much in the way of fine details.  How do I do this?  Any links?

This boot loader looks promising which I plan to test but I'm guessing that its for another ARM processor:

http://www.embeddedarm.com/software/arm … loader.php

The other thing that comes to mind would be to try and reverse engineer the angstrom openembedded image that I have (which is bootable) and try to get debian to boot the same way.

The more I read, the more I think I need a better distro than angstrom with a larger package repo for python/pygame.

Even the python for arm repo listed below is still a subset and missing what I need:

http://www.vanille-media.de/site/index. … arm-linux/

"The build process of Python compiles a core part of it (the parser generator pgen) and tries to execute that later in the build process. This — of course — does not work when cross compiling."

  • Duane
  • Duane
  • Blue Octy
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  • From: San Diego, CA
  • Registered: 2006-08-24
  • Posts: 8,197

Re: MythTV Frontend (aka mythfrontend) on Infocast, POC (Proof of Concept)

I've built python on the chumby itself - it's not too hard.

I needed it to build node, which uses Sconstruct to build v8, which requires python.

Duane's Website

  • From: San Francisco
  • Registered: 2011-12-13
  • Posts: 18

Re: MythTV Frontend (aka mythfrontend) on Infocast, POC (Proof of Concept)

Yes, I have python working.  It's pygame modules for midi that I'm trying to build.

8 Reply by Joan Jett (edited by Joan Jett 2012-07-09 04:16:41)

  • From: Brooklyn, NY (Brian)
  • Registered: 2008-06-21
  • Posts: 176

Re: MythTV Frontend (aka mythfrontend) on Infocast, POC (Proof of Concept)

quispie12@yahoo.com wrote:

nice work!

Quick question though..  Why is it necessary to chroot into debian from the chumby OS?   I don't see anyone here addressing that.

[snip]

So I'd like to just get debian running with its full package repo but the route to getting there seems odd.

Anything going forward on this? I've got the chroot method working, with xfce, but the overhead is crippling.

Additionally, I've not been able to get any openembedded images to work correctly. Even copying the image from the original uSD card to another 2gb card with dd won't boot. Is it a certain block size that needs to be used? I can't imagine how copying the card with dd could change the first partition. Any ideas?

Brian, #1 Joan Jett Fan