Before the Shadow Play

Tag: os x

  • High Sierra Wifi Poor Performance Fix for 2010 MacBook Pro

    I’ve been working remotely at an AirBNB this week and was having a really frustrating time of it. The 2010-vintage MacBook Pro I have would connect to the Wifi, go for awhile — sometimes a half-hour, sometimes not more than a minute, — and then drop the connection. Shutting off wireless and reinstating it would restart the connection, but it would be unstable and drop again. The length of time it would stay connected was completely unpredictable, and whether or not it would reconnect, and how long it would take was also completely random.

    I was getting speed test results of 0.15 MB/s up and 0.18 down. This was unusable, and I fell back on my hotspot for any sustained connection. Weirdly, I could connect fine with the Amazon Dot I’d brought along – flawlessly, in fact. What was going on?

    Late Friday evening, after a particularly frustrating session attempting to get Netflix to work (I really wanted to see Disenchantment — great show, by the way!), I started doing some research and came across an article that recommended reducing the MTU for the wireless device to 1453 (from the default somewhere in the 1500’s). Really? Okay…

    Magic. It has now been solid for several hours, including streaming video. If you’re having any trouble at all, I’d recommend at least trying it. The article shows you how to set up a separate “location” with the different MTU, so it’s simple to switch it on or off as you choose.

    Update: 12 hours later, I’m getting terrible performance again. A little more searching turned up a tutorial on readjusting the MTU to optimum with ping. Reset your MTU size to default, then starting at your 1500, try the following commad (replacing mtusize with the actual number!):

    ping -D -s mtusize -c 2 google.com

    If you get “message too long” in the ping output, drop the MTU size a bit a try again. If you have no idea what MTU size is good, start at 1500, which will be too big, and go down by 100s until you start seeing “xxxx bytes from google.com:…” messages, which let you know your ping is getting through. You can then go up by tens until you get “message too long” again, then back down by 1’s until you find the maximum MTU size that doesn’t get “message too long”.

    I had to reduce my MTU size further to 1425, and I’m near 10 megabits/second again.

  • Necessary steps to get the GitLab Rails template app running on OS X

    The GitLab template is a great way to get started on a new Rails app – it sets up most of what you need simply by checking out the code, but there are a few things you need to do if you’re starting fresh on a
    new Mac.

    The template app assumes you’ll be using Postgres for your database. I recommend sticking with this; if you grow your app past the proof-of-concept step, you’re going to want it configured for a robust and responsive  database. I love SQlite, but it’s not that much harder to go ahead and get Postgres running, so let’s do that instead of downgrading the template.

    If you have Homebrew installed, skip down to the brew install postgres section. If you don’t, run the following command:

    /usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"

    Wait for a while for that to finish, and Homebrew will be installed. Once that’s done you can move on to installing and configuring Postgres:

    brew update
brew install postgres
initdb /usr/local/var/postgres -E utf8

    Now you need to configure your databases. The initdb above sets up your user ID as a root user to start, so you can now add the application’s user and databases. (Substitute an appropriate username for yourappdev).

    psql postgres
create role yourappdev with login password '...some password here...';
alter user yourappdev createdb;

    Now exit psql (^D will do) and log back in again as the yourappdev user to create the development and test databases for your Rails app. If you set a password, psql will prompt you for it. (If you forgot it, your root-level user created when you installed Postgres can still log in without a password at the moment.)

    psql postgres -U yourappdev
create database yourapp_development;
create database yourapp_test;

    Securing the production database

    You now need to create the database that you’ll run in production. Remember this is the one with the important user data in it that you don’t want to lose, so we want to create a whole separate username that will be the creator of the database and give it a good strong password that you record in your password manager. (If you don’t have a password manager, get one! It’s way safer than writing it down on a sticky and putting it in an envelope.)

    psql postgres
create role yourapp with login password 'a very strong password please';
alter user yourapp createdb;
^D
psql postgres -U yourapp
create database yourapp

    You’re now ready to work on your Rails app. When you want to run the production version, you’ll need to set the DATABASE_URL environment variable like this:

    DATABASE_URL=”postgres://yourapp:strongpassword@localhost/yourapp”

    Further deployment issues are beyond the scope of this post.

  • xmonad on OS X Mavericks

    I installed XQuartz today, and while looking around for a low-distraction window manager, I came across xmonad. It looked interesting, and I started following the installation instructions and found they were out of date. Here’s an updated set of instructions for installing xmonad.

    1. Install XQuartz.
    2. Install homebrew if you don’t already have it.
    3. brew update
    4. brew install ghc cabal-install wget
    5. cabal update
    6. export LIBRARY_PATH=/usr/local/lib:/usr/X11/lib
    7. cabal install xmonad
    8. Launch XQuartz and go to Preferences (command-,). Set the following:
      •  Output
        • Enable “Full-screen mode”
      •  Input
        • Enable “Emulate three button mouse”
        • Disable “Follow system keyboard layout”
        • Disable “Enable key equivalents under X11”
        • Enable “Option keys sent Alt_L and Alt_R”
      •  Pasteboard
        • Enable all of the options

    monad has been installed in $HOME/.cabal/bin/xmonad. You now need to create an .xinitrc that will make XQuartz run monad. Edit ~/.xinitrc and add these lines:

    [[ -f ~/.Xresources ]] && xrdb -load ~/.Xresources
xterm &
$HOME/.cabal/bin/xmonad

    You can now launch XQuartz; nothing seems to happen, but press command-option-A and the xmonad  “desktop” (one huge xterm) will appear, covering the whole screen. Great! It’s using the default teeny and nasty xterm font, though. Let’s pretty it up a bit by making it use Monaco instead. Edit ~/.xresources and add these lines:

    xterm*background: Black
xterm*foreground: White
xterm*termName: xterm-color
xterm*faceName: Monaco

    Quit XQuartz with command-Q, and then relaunch, then hit command-option-A again to see the XQuartz desktop. The terminal should now be displaying in Monaco.

    At this point, you should take a look at the guided tour and get familiar with xmonad. If you’re looking for a distraction-free working environment, this might be good for you. I’m going to give it a try and see how it works out.

  • Bluetooth, LineIn, Soundflower: talking over Skype and playing music

    Someone who wants to teach dance classes online asked me if there was a reasonable way (i.e.., without spending a lot of money) to set up a Skype link that can be used for both music and a wireless microphone setup.

    The plan is to put something together that allows her to

    • Get far enough away from the camera that she can be seen head to toe (being able to see the footwork is important) and with a wide enough angle that she doesn’t have to dance unnaturally in one spot.
    • Send iTunes output and her voice over the line at the same time to one or more people,  in sync to the music.
    • Have some kind of a wireless mic to be able to communicate to her students without shouting.
    • Be able to hear her students talk back without their hearing their own voices delayed, or her hearing her own voice, delayed.

    This turns out to be more complicated than it might seem. The iSight camera doesn’t work very well for this; its field of view is quite narrow, and it’s very difficult to adjust it so that it pointed properly on top of that. This was relatively easy to solve: a Logitech HD Pro 920 works fine for both the wide-angle and head-to-toe issues; it can be mounted on a tripod (it has the necessary threading to mount on a standard photo tripod), and after an upgrade to a more powerful laptop – her 2008 MacBook Air was just not cutting it! – the video issue was solved.

    The audio issue was thornier. Originally, I hit up Sweetwater Sound for a real wireless mic setup; after realizing this was going to be well north of $300 once I got the mic, the base station, and the computer interface to actually hook it up with, and that this was going to be a lot of different hardware issues to deal with as well, I decided I’d better scout around for a better option.

    I was stuck until the instructor suggested a Bluetooth headset instead. It’s a reasonable, good-enough audio input channel at 8KHz – she wants to talk across it, not record studio-quality audio, so a little bit tinny is OK – and it’s definitely wireless. After a bit of investigation, I settled on the Jawbone ERA as the most-likely-workable option. The ERA is light, small, fits tightly (important for a dancer) and is the current best headset suggestion from Wirecutter, who I have learned to trust on stuff like this. It’s easy to connect a Bluetooth headset to OS X (getting it to talk properly to the software’s a different issue, see below). This takes a lot of hardware complication out of the way. Skype supports Bluetooth, so I thought I’d solved the problem.

    Unfortunately, an audio test with the music and voice both going through the Bluetooth mic showed me I’d have to get more creative; the music was either inaudible or distorted (that 8KHz bandwidth made it sound hideous, when you could hear it at all). It needed to be audible and undistorted if it was going to be possible for a student on the far end to use it to dance along with.

    A lot of Googling finally led me to thisevilempire’s blog entry on how to play system audio in Skype calls on OS X. This got me part of the way: I had, according to tests with the Skype Audio Tester “number”, gotten the audio to play nicely across the link, but I was getting a half-second delay of my voice back on the same channel, which made it hard to talk continuously. Not good enough for an instructor.

    More searching found a post on Lockergnome spelling out how to transmit clean audio, overlay voice,  and hear the returned call without an echo. Here’s how:

    1. Install Soundflower and LineIn, both free.
    2. Make sure the Bluetooth headset is on.
    3. Open the Sound preference pane in System Preferences.
    4. Set the
      1. Jawbone ERA as the input device
      2. Soundflower (64ch) as the output.
    5. Duplicate LineIn in the Applications folder, and rename both copies: one to “LineIn Bluetooth” and the other to “Bluetooth System”. The names aren’t important; this just so you can tell them apart.
    6. Launch both copies of LineIn. You’ll need to drag one window aside to reveal them both; they initially launch in exactly the same spot.
    7. Choose the “LineIn Bluetooth” instance in the Dock, and set
      1. Input to “ERA by Jawbone”
      2. Output to Soundflower (2ch).
      3. Click the “Pass thru” button.
    8. Select the other instance, “LineIn System”, and set
      1. Input to Soundflower (16ch)
      2. Output to Soundflower (2ch).
      3. Click the “Pass thru” button.
    9. Run Soundflowerbed (installed in the Applications folder by the Soundflower install). In the menu bar, click on the little flower icon, and
      1. Select “None” under Soundflower (2ch)
      2. Select “Built-in Output” under Soundflower (16ch).
    10. Run Skype, and open its preferences.
      1. Select “Soundflower 2ch” in its Microphone pulldown, and leave everything else alone.
      2. If you have an alternate camera attached, switch the Camera pulldown to the appropriate camera.

    You should now be able to make a Skype call, and play music from iTunes, DVD Player, or Youtube over the wire at full fidelity, and talk at the same time. You should hear the far end’s voice on your  speakers, along with the music you’re sending across (undelayed).

    Try to keep the headset away from the speakers to minimize the chances of feedback.

    It’s not all that  difficult; it’s just the tricky bits of being able to reroute the audio internally via the two LineIn instances and Soundflower. Getting those tricky bits right is the difficult part.

    I’ve tested this with the Skype test call and it seems to have worked; the big test will be the full-up video camera plus the streaming audio. We’ll give that a shot soon and I’ll follow up on whether the Bluetooth mic is good enough, or if a better mic is needed.

    Update: Undoing the process!

    It’s necessary to restore the normal audio routing after the call; you can do this with System Preferences.

    1. Open System Preferences and select Sound.
    2. Set Input to Internal Microphone. If you’re wearing the ERA, it will make a little descending bleep to let you know it’s been disconnected.
    3. Set Output to Internal Speakers.
    4. Quit both copies of LineIn.
    5. Check the Soundflowerbed menu; it should have both Soundflower 2ch and SoundFlower 64ch pointing to None. Quit Soundflowerbed.
    6. Turn off the Bluetooth headset; put it on its charger for a while.
    7. Quit Skype.

    You should be all set.

  • youtube-dl: it just works

    I was having trouble watching the Théâtre du Châtelet performance of Einstein on the beach at home; my connection was stuttering and buffering, which makes listening to highly-pulsed minimalist music extremely unrewarding. Nothing like a hitch in the middle of the stream to throw you out of the zone that Glass is trying to establish. (This is a brilliant staging of this opera and you should go watch it Right Now.)

    So I started casting around for a way to download the video and watch it at my convenience. (Public note: I would never redistribute the recording; this is solely to allow me to timeshift the recording such that I can watch it continuously.) I looked at the page and thought, “yeah, I could work this out, but isn’t there a better way?” I searched for a downloader for the site in question, and found it mentioned in a comment in the GitHub pages for youtube-dl.

    I wasn’t 100% certain that this would work, but a quick perusal seemed to indicate that it was a nicely sophisticated Python script that ought to be able to do the job. I checked it out and tried a run; it needed a few things installed, most importantly ffmpeg. At this point I started getting a little excited, as I knew ffmpeg should technically be quite nicely able to do any re-enoding etc. that the stream might need.

    A quick brew install later, I had ffmpeg, and I asked for the download (this is where we’d gotten to while I’ve been writing this post):

    $ youtube_dl/__main__.py http://culturebox.francetvinfo.fr/einstein-on-the-beach-au-theatre-du-chatelet-146813
 [culturebox.francetvinfo.fr] einstein-on-the-beach-au-theatre-du-chatelet-146813: Downloading webpage
 [culturebox.francetvinfo.fr] EV_6785: Downloading XML config
 [download] Destination: Einstein on the beach au Théâtre du Châtelet-EV_6785.mp4
 ffmpeg version 1.2.1 Copyright (c) 2000-2013 the FFmpeg developers
 built on Jan 12 2014 20:50:55 with Apple LLVM version 5.0 (clang-500.2.79) (based on LLVM 3.3svn)
 configuration: --prefix=/usr/local/Cellar/ffmpeg/1.2.1 --enable-shared --enable-pthreads --enable-gpl --enable-version3 --enable-nonfree --enable-hardcoded-tables --enable-avresample --enable-vda --cc=cc --host-cflags= --host-ldflags= --enable-libx264 --enable-libfaac --enable-libmp3lame --enable-libxvid
 libavutil 52. 18.100 / 52. 18.100
 libavcodec 54. 92.100 / 54. 92.100
 libavformat 54. 63.104 / 54. 63.104
 libavdevice 54. 3.103 / 54. 3.103
 libavfilter 3. 42.103 / 3. 42.103
 libswscale 2. 2.100 / 2. 2.100
 libswresample 0. 17.102 / 0. 17.102
 libpostproc 52. 2.100 / 52. 2.100
 [h264 @ 0x7ffb5181ac00] non-existing SPS 0 referenced in buffering period
 [h264 @ 0x7ffb5181ac00] non-existing SPS 15 referenced in buffering period
 [h264 @ 0x7ffb5181ac00] non-existing SPS 0 referenced in buffering period
 [h264 @ 0x7ffb5181ac00] non-existing SPS 15 referenced in buffering period
 [mpegts @ 0x7ffb52deb000] max_analyze_duration 5000000 reached at 5013333 microseconds
 [mpegts @ 0x7ffb52deb000] Could not find codec parameters for stream 2 (Unknown: none ([21][0][0][0] / 0x0015)): unknown codec
 Consider increasing the value for the 'analyzeduration' and 'probesize' options
 [mpegts @ 0x7ffb52deb000] Estimating duration from bitrate, this may be inaccurate
 [h264 @ 0x7ffb51f9aa00] non-existing SPS 0 referenced in buffering period
 [h264 @ 0x7ffb51f9aa00] non-existing SPS 15 referenced in buffering period
 [hls,applehttp @ 0x7ffb51815c00] max_analyze_duration 5000000 reached at 5013333 microseconds
 [hls,applehttp @ 0x7ffb51815c00] Could not find codec parameters for stream 2 (Unknown: none ([21][0][0][0] / 0x0015)): unknown codec
 Consider increasing the value for the 'analyzeduration' and 'probesize' options
 Input #0, hls,applehttp, from 'http://ftvodhdsecz-f.akamaihd.net/i/streaming-adaptatif/evt/pf-culture/2014/01/6785-1389114600-1-,320x176-304,512x288-576,704x400-832,1280x720-2176,k.mp4.csmil/index_2_av.m3u8':
 Duration: 04:36:34.00, start: 0.100667, bitrate: 0 kb/s
 Program 0
 Metadata:
 variant_bitrate : 0
 Stream #0:0: Video: h264 (Main) ([27][0][0][0] / 0x001B), yuv420p, 704x396, 12.50 fps, 25 tbr, 90k tbn, 50 tbc
 Stream #0:1: Audio: aac ([15][0][0][0] / 0x000F), 48000 Hz, stereo, fltp, 102 kb/s
 Stream #0:2: Unknown: none ([21][0][0][0] / 0x0015)
 Output #0, mp4, to 'Einstein on the beach au Théâtre du Châtelet-EV_6785.mp4.part':
 Metadata:
 encoder : Lavf54.63.104
 Stream #0:0: Video: h264 ([33][0][0][0] / 0x0021), yuv420p, 704x396, q=2-31, 12.50 fps, 90k tbn, 90k tbc
 Stream #0:1: Audio: aac ([64][0][0][0] / 0x0040), 48000 Hz, stereo, 102 kb/s
 Stream mapping:
 Stream #0:0 -> #0:0 (copy)
 Stream #0:1 -> #0:1 (copy)
 Press [q] to stop, [?] for help
 frame=254997 fps=352 q=-1.0 size= 1072839kB time=02:49:59.87 bitrate= 861.6kbits/s

    Son of a gun. It works.

    I’m waiting for the download to complete to be sure I got the whole video, but I am pretty certain this is going to work. Way better than playing screen-capture games. We’ll see how it looks when we’re all done, but I’m quite pleased to have it at all. The download appears to be happening at about 10x realtime, so I should have it all in about 24 minutes, give or take (it’s a four-hour, or 240 minute, presentation).

    Update: Sadly, does not work for PBS videos, but you can actually buy those; I can live with that.