RPi for in-car video player - tasks remaining

Things are going ok with this project.

A reminder of requirements:

1. Play on composite video screens using 4 wire connection (from RPi)
2. Play DVDs from DVDs, using USB DVD player
3. Web interface for controlling the gizmo
4. Play stuff from Airplay or equivalent
5. Provide an in-car wireless hub so it's easy to get into from phones etc.

What remains to be done?

1. Attach DVD drive, check that DVDs play
1. This might require purchasing an MPEG-2 key from RPi - £2.50 :-p
2. Connect composite video screen, see how that works
3. Fiddle with Airplay, but I suspect this is going to hard with Apple's proprietary protocol
4. Do some power supply testing - I'm getting a lightning flash symbol on the upper right of the screen, which is an indication that the power supply is occasionally inadequate!
1. This should include in-car testing from a USB supply thingy

Then package it all up somehow. Marv.

RPi for in-car video player Part Deux

Saved the previous SD card image, switched to LibreElec. Boots straight into Kodi, had to add lcd_rotate=2 to config.txt on the SD card itself (not inside Linux) to get it to be the right way up for the stupid Pi Official LCD Stand, which has the LCD the wrong way up. Bah.

Is this better? It's exactly the same... but let's check out the networking!

It appears to use connman, whatever that is... No sign of /etc/network/interfaces!

Checked connman man entry etc. Interesting. It appears to be possible to remove an interface from connman management, which presumably means one could then do something else with it.

Update: Wow!! There's a wireless AP option on the System/Networks page. Enabled it, can see AP on my iPhone and MBP, but it won't accept the passphrase!! Grrr...

Update: lots of looking for this and that - turned on logging, looked in journalctl, found a suspicious error, which I Googled... no joy. Then I switched on connman logging (touch /storage/.config/debug_connman) and rebooted. Now it works!! Coolio.

RPi for in-car video player

The g-kids have some DVD players in the car, so I thought it might be interesting to try building an RPi-based video streamer that would have some more flexibility in control and outputs.

Requirements:

1. Play on composite video screens using 4 wire connection (from RPi)
2. Play DVDs from DVDs, using USB DVD player
3. Web interface for controlling the gizmo
4. Play stuff from Airplay or equivalent
5. Provide an in-car wireless hub so it's easy to get into from phones etc.

Checked out the Kodi options, and they are:

1. Packaged distro - I'm concerned they won't meet requirement 5, because I won't be able to fiddle with the distro enough
1. LibreElec
2. OpenElec
3. OSMC
2. Raspbian with Kodi installed - maximum flexibility, so let's go with that.

Experimenting with my LCD-equipped RPi stack, including Digi+ ripoff digital interface...

Installed NOOBS on a 8GB SD card, opted for latest Raspbian install

Did 

• sudo apt-get update
• sudo apt-get install kodi - Version 17.4 Krypton apparently
• waited for a bit...
• plugged in USB keyboard
• now trying to get some media installed somehow!
• Tried adding Minimserver uPnP server, but entire system crashed!! Or at least, screen blanked and nothing happened...
• Added USB_Storage from file server, as Pictures, and can now show a folder in a rotating slideshow - hurray!
• Tried adding Server as music storage - crashed again!
• Turns out it's not crashing - the display is blanking when running Kodi over the desktop, so did the following:
• sudo vi /etc/lightdm/lightdm.conf
• [Seat:*] uncommented and edited linexserver-command=X -s 0 dpms
• This appears to have done the trick!

Requirement 3 - Web Interface: Enabled web interface Kodi options, connected to raspberrypi.local/8080 and bingo! UI here... It allows for playing stuff, but not a system-level interface, for that you need to go directly to the server. I'm really struggling with this... it's not intuitive at all! For example, I've added my USB memory stick to the library (I think) in Kodi, but I can't see my movies in the WebUI.

OK, added my Server/Music folder as a library and I can see it on the WebUI now. Hurray. Still can't see the content of the USB stick - it claims "no content" when it tries to index it! Strange.

Requirement X - Play stuff: Currently still trying to add some media files - trying a USB stick which I'll mount. Takes a long time to copy many GB! Works fine - added two movies, currently playing one - see above for indexing/access.

Requirement 2 - Play DVDs: Configuration menu provides for DVD playing, so all I need is an appropriate USB-connected DVD/Blueray drive! Ordered one off eBay for £8, should arrive Friday.

Requirement 1 - Connect using composite video 4 wires: I don't have a cable, but I do have an elderly in-car DVD player inherited off the guys with composite video in. I'll get a cable and try it out - the only problem is likely to be getting the connections right, so I might need 3.5 jack to 4 RCA and v.v. to enable easy switching around. Bought 3.5mm -> RCA Female, RCA Male -> 3.5mm on eBay, so can easily connect anything to anything.

Requirement 4 - Airplay: Just tried that out from MacBook Pro running iTunes and Mad Men DVD rip from HD. Oops. MBP said it was trying to play on Kodi, but Kodi froze, then stiffed - it's now restarted (?) and looking for me to tell it what to do. But the WebUI did declare it was playing airplay.m4v, which is pretty interesting.

Requirement 5 - Wifi hub: Using this helpful note,  I did

• sudo apt-get install hostapd udhcpd

And then did a couple of other things, but noticed that the /etc/networks/interfaces file was nothing like the example, and after some delving in the /etc/dhcpcd.conf file, decided I needed a better documented approach that matched my RPi config!! Bugger.

This looks like a better approach... I note that this also assumes there are useful lines in the interfaces config file, unlike mine! Hey ho...

• The usual
• sudo apt-get update
• sudo apt-get dist-upgrade
• As previously with some extras
• sudo apt-get install dnsmasq hostapd
• Stop the new services...
• sudo systemctl stop dnsmasq
• sudo systemctl stop hostapd
• Disable current wlan0 handling
• sudo nano /etc/dhcpcd.conf
• Add deny interfaces wlan0 somewhere...
• Saved as /etc/dhcpcd.conf.new
• Time to try editing the interfaces file!
• Nope, that really isn't working. The dhcpcd demon quits declaring that it's not going to get involved because someone has configured a static IP address in interfaces - guilty as charged! Another post explains exactly why - apparently the latest Raspbian version (Stretch) has radically changed how the networking is organised, and none of the old stuff works. I can concur.

So - what to do? Frankly, Linux networking is a nightmare. It is almost impossible to untangle, and not explained anywhere sensible, with so many levels of indirection and files it's really not obvious what does what. Hmm... I wonder if one of the Kodi-specific builds is simpler? They are only Linux after all.

RPi 7" Touch Screen - it's alive!

I've been living with the rather lashed up setup of the RPi and IQAudio DAC, albeit in a nice shiny black box, in conjunction with the Linkwitz LXMinis and accompanying miniDSP 2x4 for maybe six months now. The main drawbacks, if there are any, are

• Wife finds it impossible to use, because she hasn't really got a handle on using a browser or the Kazoo app to select music to play, and really she'd like to have the facility for putting on a CD, as we once could :-o
• Turning off the music at source without having the phone or laptop to hand whilst walking through the stereo listening room is a pain - yeah, bit of a 1st world problem, but Lumin, Kazoo etc are relatively slow to get their act together
• Whilst connecting the CD player (which has an analogue output only, and 5 pin DIN at that, bloody Naim with their silly ideas about hifi) is possible, it currently involves unplugging the RPi from the miniDSP and plugging the CD player into it instead. Boring.

It would be nice (as well as interesting :-) ) to have a handy interface with the renderer. So why not a nice RPi Official © RPi Inc 7" Touch Screen Display? Coming right up, sir...

Bought from thepihut.com, along with a nifty black plexiglass stand, for about £65 (ouch, but hey...), arrived in a couple of days. 

The screen is chunky, heavy, black bezel. It has a PCB with the serial-parallel electronics bolted on the back. You have to attach the RPi to it with the usual threaded standoffs, and then there's the option of powering it all by

1. Connecting USB supply to the screen, and linking power to the RPi with a short USB-USB Micro cable
2. Connecting USB supply to the RPi, and using the supplied patch-type cables to connect RPi GPIO 5.5v/Gnd to screen 5.5v/Gnd inputs

Looks like using a hat DAC prevents option 2, because the DAC uses the GPIO pins...

Screen standing with stand :-) - cool!

The screen and stand are easily assembled, once you take the attached PCB off the screen! The stand is multi-layer plexiglass, and one layer is a bit tricky to get the right way round, but there's only two ways to put it so...

I struggled a bit with the flat ribbon cable to connect the RPi display connector to the screen connector, but I find that with all these flat cable connectors - it's hard to see which side of the connecter the cable goes in!

Rear of screen and stand - note re-attached PCB

I removed the SPDIF interface board from my sample RPi3 and attached it, using the GPIO pin power connections. A quick power up - screen on, RPi on, BUT... the screen was just showing varicoloured vertical lines. Yuck. Power off, retry connection to RPi, power up, and hooray! This time the screen worked, and ended up showing a terminal prompt. Lovely...

Rear view showing attached/connected RPi

I then used a browser on my laptop to point to the Rune instance on the RPi (which was running a previously set up image...) and configured "Start a browser on HDMI/TFT" in the Settings. Restart... and...

Screen showing Rune browser interface!

Result!!

A quick test of the touch capabilities - all the screen touch points and selections work fine, as defined by the browser page. The lower ones are a tiny bit tricky to hit, but it's easy to adjust one's touch point :-). Fantastic, and ridiculously easy. Maybe I should have tried something harder, like integrating a cheap display...

Is Bluetooth useful?

I have "acquired" (translation: I have borrowed from Code Club) a couple of BBC micro:bits. These have a Bluetooth stack on them, which can be used to connect to other devices. The uBits are pretty capable microcontrollers, with lots of low power features, and if they were connected to sensors etc. they could easily transmit information to more powerful devices, like... a Raspberry Pi! Quite what I'll do with this yet I don't know, but in the best open-ended fashion, let's see if I can get anything working before we worry about an interesting application. Code Club Kids might like this...

First thing is to identify a suitable RPi. I'll be using the server, all the others are configured with the Rune image.

Next, check on the installation of BlueZ, the Linux Bluetooth stack. Need to update the distro and firmware - apt-get update, apt-get upgrade, apt-get dist-upgrade. Hurrah!

Testing... Running bluetoothctl, but it can't see any Bluetooth controllers. More research - try installing pi-bluetooth, already installed. BlueZ also already installed, but bluem not... apt running hard on this one! Still no controllers visible. Reboot....

Bingo. Controller available!

pi@server:~ $ sudo bluetoothctl

[NEW] Controller B8:27:EB:BF:C4:1D server [default]

[NEW] Device 48:74:6E:CD:96:2A John's iPhone

As can be seen, my phone is visible. Hurrah. Can't connect though. However, I'm interested as much in connecting the uBit, let's find out about that.

Super useful blog here - Martin W is a Bluetooth aficionado and has lots of info and help on Bt generally and RPi/uBit specifically.

Bluetooth Roles: (credited to Martin Woolley, at the above blog)

Bluetooth devices will play one of 4 possible Bluetooth roles as defined by that masterpiece, the Bluetooth core specification. The four roles are called

1. Peripheral
2. Central
3. Broadcaster
4. Observer

These terms are part of "GAP", the Generic Access Profile, which is a part of the Bluetooth architecture.

A Peripheral (like a uBit, smartphones with specific software) advertises, inviting and (perhaps) accepting connections from Central devices. 'Advertising' means transmitting small amounts of data, quite frequently, which other Bluetooth devices can receive and act upon if they think the advertising device is of interest.

A Central (smartphones) device scans, looking for advertising packets and based on their content, may decide to connect to a device it thinks is suitable.

A Broadcaster (Bluetooth beacon) is like a peripheral in that it advertises but it does not accept connections. It's sole purpose is to advertise.

An Observer (e.g. a beacon app on a smartphone, alerting one to special offers etc.) scans and processes advertising packets but never tries to connect to another device.

More Ripping Yarns

Background

In this post, I wrote about ripping CDs and the apparently large number of errors you get when you actually bother to check for them. I actually asked the question "Why don't programs provided on CD fail because they have so many bit errors that the code is defective?".  I discussed this with some ex-work colleagues over lunch yesterday, and we reckoned something else must be going on... A bit of research reveals that that is in fact the case!

The underlying storage mechanism is the same for CD-DA and CD-ROM (and its derivatives), but essentially, the "file system" is different.

Firstly, all CDs use the same encoding scheme - 

The Red Book specifies the physical parameters and properties of the CD, the optical "stylus" parameters, deviations and error rate, modulation system (eight-to-fourteen modulation, EFM) and error correction facility (cross-interleaved Reed–Solomon coding, CIRC), and the eight subcode channels. These parameters are common to all compact discs and used by all logical formats, such as CD-ROM. (wikipedia). 

The CIRC encoding system basically wraps lots of extra bits around the data as part of the encoding. It also scatters the logical audio frames around a number of physical frames, so that disk faults can be more easily recovered from, since they will generally degrade recoverably a number of logical frames and not obliterate the one with the error.

However, CD-ROM, as opposed to CD Digital Audio, adds in more error checksums and another layer of error correction... because it is assumed that computer data cannot be interpolated like audio data, but must be bit-perfect!!

The structures used to group data on a CD-ROM (the Yellow Book) are also derived from the Red Book. Like audio CDs (CD-DA), a CD-ROM sector contains 2,352 bytes of user data... To structure, address and protect this data, the CD-ROM standard further defines two sector modes, Mode 1 and Mode 2, which describe two different layouts for the data inside a sector.

Both Mode 1 and 2 sectors use the first 16 bytes for header information, but differ in the remaining 2,336 bytes due to the use of error correction bytes. Unlike an audio CD, a CD-ROM cannot rely on error concealment by interpolation; a higher reliability of the retrieved data is required. 

• Mode 1, used mostly for digital data, adds a 32-bit cyclic redundancy check (CRC) code for error detection, and a third layer of Reed–Solomon error correction leaving 2,048 bytes per sector available for data. 
• Mode 2, which is more appropriate for image or video data (where perfect reliability may be a little bit less important), contains no additional error detection or correction bytes, having therefore 2,336 available data bytes per sector. 

Note that both modes, like audio CDs, still benefit from the lower layers of error correction at the frame level.

Format	← 2,352 byte sector structure →
CD digital audio:	2,352 (Digital audio)
CD-ROM Mode 1:	12 (Sync pattern)	3 (Address)	1 (Mode, 0x01)	2,048 (Data)	4 (Error detection)	8 (Reserved, zero)	276 (Error correction)
CD-ROM Mode 2:	12 (Sync pattern)	3 (Address)	1 (Mode, 0x02)	2,336 (Data)

So I guess CD-DA is more liable to uncorrected errors, because nobody gives a toss about audio errors... 

Ripping programs can

• Read a sector multiple times and check they get the same result
• Use the "C2" feature implemented in many drives that allows the drive to report potential errors as guidance to the reading program

but of course, nothing can actually fix the errors if they can't be recovered, even if detected. Boo. Oh well. Off to eBay to source another CD-ROM drive...

New Ripping Software - Perfect Sound, Forever!! 

I've spent a lot of time trying to use XLD to rip my copies of Wagner's Ring to disk, and it's been very hard work. I don't know why these are so hard, but there are lots of errors, an they almost never match the AccurateRip database. So I thought I'd try dbpowerasp, the ripper produced by Spoon/Illuminate, the people who own the AccurateRip database. 

The software seems to work well in itself, it needs some adjusting in terms of tagging and filenames, but it it is taking an extraordinarily long time to rip the firstdisk. I started ripping last night, it read the first track, then announced it would retry 2000+ errors sectors. Great. I left it running when I went to bed... and when I came down this morning it was onto the 3rd track! It's 15.19, and it's still ripping the 4th, with 2676 frames to retry! The first track took 6.30 hours to rip, with its 2000 duff sectors. What is going on?! Are all my CDs going to be this hard? I reckon I should forget ripping CDs, and just play stuff off Tidal, because I can and life's too short!

Network Problems

Debugging the dodgy network... On the current running system (cheated on the systemd entry :-) ):

[root@Frontroom ~]# journalctl --output=short-iso | grep "eth0: carrier lost"

2017-02-22T18:35:43+0000 Frontroom systemd[1]: Time has been changed 

2017-02-24T04:35:42+0000 Frontroom dhcpcd[677]: eth0: carrier lost

2017-02-25T20:28:51+0000 Frontroom dhcpcd[677]: eth0: carrier lost

giving about 143,589 and 122,399 seconds between events. The lease is for 86400 seconds.

Annoyingly the Rune image clock starts on 22 Feb 2016, which is annoyingly close to the current date (25 Feb!). The --output=short-iso is required to display the year on the clock...

More data required... so I need to make the journal files non-volatile...

By default, the journal stores log data in /run/log/journal/. Since /run/ is volatile, log data is lost at reboot. To make the data persistent, it is sufficient to create /var/log/journal/ wheresystemd-journald will then store the data:

mkdir -p /var/log/journal
systemd-tmpfiles --create --prefix /var/log/journal

Tried that. Let's see if there are any more entries and if they survive a reboot!
I note that no entries have appeared in that directory yet... I wonder if I have to do something more?

Update: I edited /etc/systemd/journald.conf to change the Storage=volatile to Storage=persistent, then did systemctl restart systemd-journald.service to restart the logging with non-volatile storage. Hurrah - works!

Update:
The router log has the following entries around the time of the last outage (relevant bold):

[DHCP IP: (192.168.1.16)] to MAC address 00:BB:3A:33:62:DA, Saturday, Feb 25,2017 20:35:46
[DHCP IP: (192.168.1.3)] to MAC address B8:27:EB:25:C4:1A, Saturday, Feb 25,2017 20:28:53
[UPnP set event: Public_UPNP_C3] from source 192.168.1.11, Saturday, Feb 25,2017 20:25:28
[UPnP set event: Public_UPNP_C3] from source 192.168.1.11, Saturday, Feb 25,2017 20:10:27
[Time synchronized with NTP server] Saturday, Feb 25,2017 20:09:33
[Internet connected] IP address: 192.168.0.3, Saturday, Feb 25,2017 20:08:45
[UPnP set event: Public_UPNP_C3] from source 192.168.1.11, Saturday, Feb 25,2017 19:55:28
[UPnP set event: Public_UPNP_C3] from source 192.168.1.11, Saturday, Feb 25,2017 19:40:27
[Time synchronized with NTP server] Saturday, Feb 25,2017 19:38:43

That doesn't tell me a lot, but at least they agree! And there is no apparent fault with the router. I do note that my phone gets a lot of IP address assignments, at sub-10 minute intervals, which I notice. Maybe the signal is bad for that?

As an experiment, I might try plugging in the network extender I have and using that to provide a wired interface, to see if that makes a difference. The office RPi is using one of those and has no wired problem, although the wireless connection does fail a lot, despite using the wireless extender in the same room!!!

Update 2017-02-28:

Well, the link has been up now for 64 hours, without failing, using the Powerline network extender and a new, short Cat5 cable. This is positive. Maybe it's like my N years spent complaining about the laser printer's inadequacy and the uselessness of the drivers, when it was the cable all along...

Rune vs. Roon?

Up until now I've used Rune as the audio player on my Raspberry Pis. It's a cut-down ArchLinux using mpd as the player and a PHP-based web interface and control server to manage and configure the mpd and o/s.

It works ok most of the time. However, and maybe this is not a problem specific to Rune, it is fairly flakey in respect of network connectedness. Yeah, on startup it usually connects and exposes itself as host.local, connects to the server for ripped data, is ready to receive DLNA/uPnP streams and reports to interested parties like Linn Kazoo and Lumin on iOS.

It's hard to work out what's going on, because the problem is network connectivity, so beaming in on SSH is not possible, and a restart appears to kill the log files - I need to research this a bit more. The log shows outage of the wired connection, which is weird... These entries show it's down for around 1 second! What's going on?

Feb 25 20:28:51 Frontroom kernel: smsc95xx 1-1.1:1.0 eth0: link down

Feb 25 20:28:51 Frontroom dhcpcd[677]: eth0: carrier lost

Feb 25 20:28:51 Frontroom dhcpcd[677]: eth0: deleting route to 192.168.1.0/24

Feb 25 20:28:51 Frontroom dhcpcd[677]: eth0: deleting default route via 192.168.1.1

Feb 25 20:28:51 Frontroom avahi-daemon[275]: Withdrawing address record for 192.168.1.3 on eth0.

Feb 25 20:28:51 Frontroom avahi-daemon[275]: Leaving mDNS multicast group on interface eth0.IPv4 with address 192.168.1.3.

Feb 25 20:28:51 Frontroom avahi-daemon[275]: Interface eth0.IPv4 no longer relevant for mDNS.

Feb 25 20:28:52 Frontroom ifplugd[280]: Link beat lost.

Feb 25 20:28:52 Frontroom dhcpcd[677]: eth0: carrier acquired

Feb 25 20:28:52 Frontroom kernel: smsc95xx 1-1.1:1.0 eth0: link up, 100Mbps, full-duplex, lpa 0x45E1

Feb 25 20:28:52 Frontroom dhcpcd[677]: eth0: IAID eb:25:c4:1a

Feb 25 20:28:53 Frontroom dhcpcd[677]: eth0: rebinding lease of 192.168.1.3

Feb 25 20:28:53 Frontroom dhcpcd[677]: eth0: probing address 192.168.1.3/24

Feb 25 20:28:53 Frontroom ifplugd[280]: Link beat detected.

Feb 25 20:28:54 Frontroom ntpd[348]: Deleting interface #5 eth0, 192.168.1.3#123, interface stats: received=73, sent=75, dropped

Feb 25 20:28:54 Frontroom ntpd[348]: 178.79.160.57 local addr 192.168.1.3 -> <null>

Feb 25 20:28:57 Frontroom dhcpcd[677]: eth0: leased 192.168.1.3 for 86400 seconds

Feb 25 20:28:57 Frontroom avahi-daemon[275]: Joining mDNS multicast group on interface eth0.IPv4 with address 192.168.1.3.

Feb 25 20:28:57 Frontroom avahi-daemon[275]: New relevant interface eth0.IPv4 for mDNS.

Feb 25 20:28:57 Frontroom avahi-daemon[275]: Registering new address record for 192.168.1.3 on eth0.IPv4.

Feb 25 20:28:57 Frontroom dhcpcd[677]: eth0: adding route to 192.168.1.0/24

Feb 25 20:28:57 Frontroom dhcpcd[677]: eth0: adding default route via 192.168.1.1

Feb 25 20:28:57 Frontroom dhcpcd[677]: eth0: removing route to 192.168.1.0/24

Feb 25 20:28:59 Frontroom ntpd[348]: Listen normally on 6 eth0 192.168.1.3:123

Feb 25 20:28:59 Frontroom ntpd[348]: 178.79.160.57 local addr 192.168.1.12 -> 192.168.1.3

Feb 25 20:28:59 Frontroom ntpd[348]: new interface(s) found: waking up resolver

Anyway, I've been investigating Roon, which I first encountered at Keith's house when I heard the Kii Audio Threes. He's running a MacMini as the Roon Core, the Rune Control on an iPad and using the Mac Mini as a Roon Output. it all seems very well thought through, and pretty robust. The one drawback is that it costs money, continuing money, at $120/year or $500 lifetime! It does have a fantastic interface, some amazing metadata capabilities and it also interfaces utterly seamlessly with Tidal. I'd have to provide a sensibly powerful box for the Core, I suspect an RPi isn't going to cut it, in fact, the Roon doco explicitly says it won't. 

But all this is moot if my hub is letting me down - how do I debug the network interface??

A Video Sidetrack

I have a spare USB cam, a new RPi 3 B and a boiler in the loft that I want to monitor the front panel of without constantly going upstairs, climbing the ladder and hoiking myself into the roof. Clearly a webcam is the answer!

I tried using ssh & X to connect remotely and view the camera in real-time, but it seems to have problems of one sort or another. The whole thing works fine when using the HDMI output, but not so well over X. I tried using cheese, but that doesn't work over X (bug!) and VLC - that struggles too, it can't find any useful OpenGL renderers for X. So I'm about to try UV4L from http://www.linux-projects.org/uv4l/installation/, which appears to offer live streaming options. Hurray!