Wednesday, December 31, 2014

HDMI Audio in Mythbuntu

My adventure replacing my old Mythbuntu box with a new one continues. It's been working for a while now, in terms of waking when it should, recording and replaying shows. Yesterday's immediate concern was sound. The PC hooks to my TV via an HDMI cable. While both live TV and recordings viewed through MythTV worked fine (including sound), applications run outside MythTV (such as VLC) had no sound.

As usual, Google was both my friend and my enemy -- it found lots of results for all of my search queries, most of which sent me off chasing wild geese. For some reason, Application > Settings > Settings Manager in Mythbuntu does not provide anything to configure sound, and installing the unity-control-center package did not remedy that. (I wonder if they block it to prevent users from configuring something that conflicts with the MythTV audio settings, which you set when configuring the MythTV front end?) I ran alsamixer and unmuted S/PDIF, but that did not fix things.

I did notice at some point that the configuration for ALSA (the sound system) at the operating system level seemed to default to PulseAudio. I read somewhere that MythTV, which uses ALSA, might kill the PulseAudio service to avoid conflicts with ALSA. That suggested either creating a configuration file for ALSA that avoids PulseAudio or configuring PulseAudio properly. I tried the latter and it worked. The steps were:
  1. Install the pavucontrol package from a repository.
  2. Run pavucontrol in a terminal.
  3. In the Configuration menu, choose the correct output device (in my case, "HDMI").
  4. Exit, cross fingers, reboot and test.
The fix may not be perfect. It works -- both MythTV and the VLC player (run from the desktop) have sound -- but I now get system error messages when I exit MythTV, which I was not getting before. The error messages are not specific (something unnamed apparently crashed), and I haven't poked through the logs. So far, the errors have not coincided with an perceptible loss of functionality, so they're just an annoyance. I can't be positive they are due to the sound fix, but they started immediately after it.

Thursday, December 18, 2014

Remotely Mounting a USB Drive

As I try to retire an old PC running Mythbuntu in favor of a new replacement, I continue to learn things about Linux ... with a gun to my head, as it were.

Without getting into the gory details, I can no longer work directly on the old PC -- I can't get a functioning display. I can, however, connect either by SSH terminal session or remote desktop. Once I get my recordings and database off the old box and onto the new one, I'm going to wipe the operating system, install something like Linux Mint, and then donate the old PC to anyone looking for a slightly noisy space heater.

The problem is moving the 300+ GB of stored recordings. I picked up a 1 TB Western Digital My Passport Ultra USB hard drive to use both for back and for file transfer. The trick was getting the bugger to mount without a direct connection. Using a remote desktop, I could see that Mythbuntu created a drive icon on my desktop, needing only to be mounted. Unfortunately, all that double-clicking the drive to open it, or right-clicking and selecting mount, got me was a message that I was lacking the authority to mount the drive. This is probably a consequence of remote connections having restricted permissions.

The answer proved to be mounting the drive (as root) from the command line -- once I found the key information on how to do so. It's actually quite painless when you know how. What follows was all done in a remote terminal. The first step was to run
sudo mkdir /media/passport 
to create a landing spot for the drive. (Feel free to substitute a different name for "passport".) Next, to get the particulars about the drive, I ran
sudo fdisk -l
(that's an "el", not a "1"), obtaining the following poop (omitting the parts about other drives):

Disk /dev/sdb: 1000.2 GB, 1000170586112 bytes
255 heads, 63 sectors/track, 121597 cylinders, total 1953458176 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x50dfffc7

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1            2048  1953458175   976728064    7  HPFS/NTFS/exFAT

The key takeaways here, from the last line, are that the system sees the device as /dev/sdb1, and that it has an NTFS format (which I already knew from the packaging, which charitably assumes you're buying it for a Windows PC). Following the aforementioned directions, I ran
sudo mount -t ntsf-3g /dev/sdb1 /media/passport
and she was good to go. For FAT drives, refer to the instructions linked above.

Waking Up is Hard to Do

(Apologies to Neil Sedaka for the weak pun in the title.)

In the continuing war of man (me) against machine (my new Acer PC, which I'm configuring as a Mythbuntu PVR - see my last post), I've spent a full day trying to get the box to wake on a BIOS real-time clock alarm, so that MythTV can convince it to wake up when a recording is scheduled. The battle took so long because two things needed to be set correctly, and I kept getting stuck on incorrect combinations (this one right, that one wrong; vice versa; both wrong) while spending huge amounts of time searching the web and beating my head against the wall.

I copied a couple of time tested shell scripts from my previous Mythbuntu box, one that sets the BIOS alarm to an arbitrary time (used by MythTV to schedule actual recordings) and another that simply sets up an alarm for five minutes in the future (useful for testing). Before trying them out, I reviewed the official ACPI Wakeup wiki for MythTV. One of the first things it suggests is looking in the kernel log to make sure the BIOS supports ACPI wakeup (although I think pretty much all modern BIOSes do). In the log, I found the good news that the BIOS supports alarms up to one month in advance and this bit of seemingly bad news: "System wakeup disabled by ACPI".

I nonetheless followed the directions on the wiki for tweaking the shutdown script (under "Disable hwclock updates", although the tweak for Ubuntu does not so much disable them as reassert the alarm time after doing them). I ran the wake-in-5 test, and it failed.

Next, I got into the BIOS and checked the power settings. My BIOS has a "Deep Power Off Mode" (enabled by default) and a "Power on by RTC Alarm" feature (disabled by default). According to the BIOS help, the latter works only if you also disable the former. With "Deep Power Off Mode" disabled and "Power on by RTC Alarm" enabled, I was able to schedule a wakeup call for a fixed time either on a give day of every month (e.g., the 15th) or every day of the month. Neither is what I want -- I want to wake up only when there is something to record -- but at least I was able to confirm that the machine could wake on its own.

I'll skip a lot of gory details here, since they pertain to wasted effort. I was doing a lot of reboots during my experiments, and I noticed that one of the system logs was showing about five hours and change between reboots when actually they were minutes apart. Since I'm in the US Eastern time zone (GMT-5), I suspected that some confusion between local time and UTC (a five hour difference) was going on. Eventually I came to look in /etc/default/rcS, where I found the setting "UTC=no", telling the operating system that the BIOS was using local time. That seems to be the default setting, since my desktop PC has it as well. The BIOS on the Acer, however, was using UTC. I changed "no" to "yes", and I think that has fixed the five hour bumps. By itself, however, it did not fix the wakeup problem.

It turns out that having "Power on by RTC Alarm" not only schedules fixed wakeups I don't want, it also blocks the system from setting any other wakeup calls. This is covered in the "Fussy BIOS" section of the ACPI Wakeup document. So I went back into the BIOS, disabled "Power on by RTC Alarm" (but left "Deep Power Off Mode" also disabled), rebooted and ran the five minute wake-up test successfully.

The next step was to program the machine to wake and record a show ... which it did not do. So I went back, followed the directions for Configuring MythTV Automatic Wakeup and Shutdown (following directions -- what a concept!), and it seems to be working now.

Configuring wakeup/shutdown included setting up MythWelcome, which I had planned to do in any case. The directions are very clear and well-written, including explanations of one or two less obvious bits. There is one thing on the page that I find a bit confusing, though. In two different locations, the instructions call for you to exit MythWelcome by starting a terminal (F12 key) and then running a command to kill it. MythWelcome has a pop-up menu (accessed via the 'M' key), and one of the choices on that menu is to exit MythWelcome. It's both easier (much less typing) and a bit more natural/graceful, so I'm not sure why the instructions have you do it the hard way. In any case, I used the menu to exit, and things worked correctly.

Tuesday, December 16, 2014

RStudio Git Support

One of the assignments in the R Programming MOOC (offered by Johns Hopkins University on Coursera) requires the student to set up and utilize a (free) Git version control repository on GitHub. I use Git (on other sites) for other things, so I thought this would be no big deal. I created an account on GitHub, created a repository for my assignment, cloned it to my PC, and set about coding things. As a development IDE, I'm using the excellent (and free) RStudio, which I was happy to discover has built-in support for Git. All went well until I committed some changes and tried to push them up to the GitHub repo, at which point RStudio balked with the following error message(s):
error: unable to read askpass response from 'rpostback-askpass'
fatal: could not read Username for '': No such device or address
I searched high and low in RStudio but could not find any place to enter credentials for the remote repository. No worries, thought I; I'll just add my public encryption key on GitHub, and use the private key on the PC, which works for me when I'm using the NetBeans IDE with BitBucket. Alas, no joy.

According to the error messages, the immediate issue seems to be not my password (I don't think the challenge got that far) but my user name. Git has a global value for my user name recorded on my PC, but it's not the same as my user name on GitHub. I was able to set a "local" user name, matching the one I have on GitHub, by opening a terminal in my R project directory and entering the command
git config <my GitHub name, in quotes>
git config <my email address>
That's a bit more arcane than what I would expect a beginner to know, but so be it. I thought that would fix the problem. It did not; the error message remained unchanged. I suspect that the issue is that Git now has two names for me (global and local-to-the-R-project). If I run
git config -l
in the project directory, I see the following:<my global user name><my global email address>

...<my GitHub user name><my GitHub email address, same as the global one>
With two user names to choose from, perhaps RStudio is grabbing the global one? Or perhaps I'm barking up an entirely incorrect tree trying to find the source of the error.

At any rate, I can't seem to push updates from the PC to GitHub using RStudio. Not to worry, though. There are other options. You can do it from the command line (if you are command-line user of Git, which for the most part I'm not). You can also use a separate Git client program, which is what I did. My Git GUI of choice is SmartGit, from which it is no chore to push (or pull) updates.

Sunday, December 14, 2014

Updating Adobe Flash

Within the past week, give or take, Firefox started blocking the Adobe Shockwave plugin from running in web pages, due to a security problem with it. I could (and did, when I trusted the site) override the warning, but in general bypassing security is a bad idea. Even when the site is trusted, you have to consider the possibility that someone managed to sneak a malicious Flash application onto it.

I was initially happy to upgrade the bugger (to version, which I think is the first one Firefox will allow), but the universe conspired to make that ridiculously difficult. I'm running Linux Mint 16 Petra, which is plumbing-compatible with Ubuntu 13.10 Saucy Salamander. Shockwave is packaged for Ubuntu, not for Mint.

The "Plugins" tab of the Firefox Add-ons Manager flagged Shockwave and gave me a link for updating. That link took me to an Adobe page where I selected which Linux release of the latest version I wanted. I was hoping it would then download a .deb package file, but nooo, it gave me an "APT link", to which I needed to associate an application. Fortunately, I had AptURL installed, so I just had to point to it (in /usr/bin/apturl). Unfortunately, it did not work; I got a message about an unknown channel. So I was stymied there.

The Synaptic package manager was no help; it thought (incorrectly) that the version I had was the most recent. I added the Ubuntu Mozilla Security PPA, which has the latest version, as a source, but I still could not update.

I think I finally figured out what was causing all this wasted effort. As best I can tell, Adobe skipped Ubuntu 13.10 when they released The version they released for Ubuntu 12.04 (Precise Pangolin) also apparently works on 13.10 ... but the package manager either can't see it or won't use it, because it's for an earlier version of the operating system than what I have. At least I'm guessing that's the problem. The "unknown channel" error I got trying to update via the Adobe site named "Precise" as the channel, so apparently it was looking for the "Precise" version but the package manager wasn't having any of that.

I did eventually succeed, though, and I'll document it here in case any weary pilgrim stumbles on this page. You can find the AMD64 version of the installer package on the Ubuntu packages site. (If you need a different version, backtrack along the bread crumbs -- and good hunting!) The link on that page will download the installer .deb file. Right-click that file, open it with GDebi, click "Install", give the necessary password, and it will download and install the actual Flash player. Restart Firefox and check on the plugins page to verify that you have the up-to-date version.

This was a rather remarkable time-suck compared to most upgrades on Mint or Ubuntu. :-(

Friday, December 12, 2014

Mythbuntu and USB WiFi

I'm in the (slow, painful) process of configuring a new PC to act as a video recorder. This post contains some notes on how I got it connected to my home WiFi network.

First, a note to self/strong suggestion to others: before screwing with anything that is likely to cause reboots, go into Applications > System > Mythbuntu Control Center > Startup behaviors and uncheck the box that starts the MythTV front end automatically at boot. Turn that back on only after all configuration agony is behind you. This is particularly important with the keyring nag (below), in which the front end started (and wiped out my access to the nag) before I could type the password, and then promptly froze the system.

The machine came with a flavor of Windows, but I immediately downloaded the latest version of Mythbuntu, burned the ISO file onto a DVD (using Brasero), and installed it on the PC, wiping away any vestige of Windows. I then rebooted and tried to configure Mythbuntu (but I'm pretty sure I will need to redo that later).

The PC comes with onboard Ethernet (one jack) but no WiFi. I will spare you the gory details (and myself the painful memories) of three failed attempts to add a USB WiFi adapter. Let's just say there were compatibility issues.

I finally ordered an Edimax EW-7811Un adapter. The Edimax is incredibly small, even more incredibly cheap (about a quarter the cost of some of the adapters I tried), and is advertised to be compatible with most Linux systems. With the power off, I plugged it into a USB slot and booted the new PC.

Oops. No network connection. Running lsusb in a terminal showed the Edimax device, but Settings > Network Connections showed two Ethernet connections and no WiFi connections. I don't think either of the "Ethernet" connections was the Edimax, but if it was, that was unhelpful, because my home LAN is secured (meaning the PC needs a password to get on it).

So I unplugged the Edimax. The Settings > Network Connections application still showed two Ethernet connections. I deleted both, not needing the onboard one and thinking the other was spurious. Big mistake. My external TV tuner is a Hauppauge WinTV-DCR, which MythTV mistakes for an HDHomeRun Prime (close enough). The first connection (which I eventually restored), eth0, was indeed the onboard Ethernet adapter. The second connection, eth1, was actually the Hauppauge tuner (even though it is coming in via a USB cable and not into an Ethernet jack). I wasted a lot of time unsuccessfully trying to install a channel lineup before it finally dawned on me that MythTV could not talk to the tuner because I had disconnected it. Fortunately, restoring the connection fixed that.

With the PC rebooted (and Settings > Network Connections showing no connections at all), I plugged in the Edimax. This time, the system immediately gave me a notification that a secured WiFi network was available. Back in Settings > Network Connections, I added a new connection, set it to WiFi, filled in my home LAN's SSID, set the security to "WPA & WPA2 Personal" and filled in the network password. Just like that, I had working WiFi.

To finish (hah! I should be so lucky) the job, I further edited the connection and made the IP address (obtained by running ifconfig in a terminal, and confirmed by looking at the status screen for my network modem) static, with mask and gateway I got those values by connecting my (Linux Mint) laptop to the WiFi network and running route -n in a terminal.

Next problem: on every reboot or log-in, I was nagged to type in a password to unlock the default keyring. (The correct password is my login password.) This was more than just annoying; it was fatal, as the front end would start without waiting for the password and then frequently freeze the system. Failure to unlock the keyring also seemed to keep the machine from gaining access to the WiFi network (at least I think that was the culprit). The solution I found was as follows:
  1. Unlock the bleeping keyring so that I could connect to WiFi.
  2. Install the "Passwords and Keys" application using the Ubuntu Software Center. (Seems to me this should be installed by default, even if the installation is purely a networked backend server.)
  3. Go to Applications > Settings > Passwords and Keys, and right-click the Default keyring entry.
  4. Select "Change password" and enter the current (login) password as the "old" password.
  5. Leave the new password blank (horrors! -- a major security hole!) and finish.
After a restart, the bloody keyring nag was gone and the machine connected to my WiFi LAN.

After all this, I found that I could ping outside servers by IP address but not by name. My LAN uses a (now obsolete?) 2Wire wireless DSL modem. Turns out I had to go back to Settings > Network Connections, edit the WiFi connection, and enter the gateway address (, same as before) in the field for DNS servers. With that, I finally had a useable WiFi connection (which has survived a few reboots).

Sadly, there is still a lot of configuring to do.