Let's brainstorm..Setting up MinimServer to feed a USB DAC

[classical11]

Hi Pete,

Thanks very much for your MediaPlayer OpenHome renderer!

Following your detailed instructions it was very easy to set it up on a Raspberry Pi (Model B with 512MB RAM running at 700MHz) under Raspbian hard float. So far I'm using the standard 3.5mm output and testing it with headphones but I've ordered the USB DAC you recommended (Stoner Acoustics UD110 v2). The quality is failry good already, I can only imagine what it would be like with the DAC in place!

I am using it in conjunction with MinimServer (of course!) and BubbleUPnP as the control point. I started testing it with a Wifi dongle installed on the Pi but I had connection problems and switched to wired Ethernet. The issues I came across (see below) have all been tested using wired Ethernet unless stated otherwise.

It has been pretty stable for the last few days of testing. I am particularly impressed with how well gapless works (in fact it even seems to work for mp3s; I am a but confused as I thought the mp3 format could not do gapless?!). I also like the fact that you chose to implement the OpenHome extensions and not just stadard UPnP, making it possible to turn off the control point without stopping playback or losing the playlist as well as being able to control the renderer with multiple CPs at the same time.

I've been testing with 16 bit 44.1 KHz flac and mp3s encoded at various bitrates. Unfortunately I don't have any high definition files to test with. The CPU usage of java (only used to run MediaPlayer) is around 1-2% and mpd uses 2-4% for flacs and 8-9% for mp3s, hardly taxing the low-powered Raspberry device.

Summary of hardware/software used:
- Raspberry Pi (Model B with 512MB RAM running at 700MHz), connected via wired Ethernet
- Tablet: Samsung Note 10.1 with Android 4.1.2
- Phone: Samsung Galaxy 1 with Android 2.3.6
- MediaPlayer v. 0.0.0.6 (got the version from the logs) (running on Raspberry Pi)
- MinimServer v. 0.72 (running on Linux PC)
- BubbleUPnP v. 1.7.6.1 (running on tablet and phone)

The issues I came across are almost all to do with playlists (i.e. the ad hoc playlist created when you want to play something, not the playlists stored on the server). They could be due to the interaction between your MediaPlayer and BubbleUPnP CP rather than due to problems in the MediaPlayer itself.

1. Adding albums to the playlist seems a bit slow. Here are some results (using BubbleUPnP running on a Galaxy Note 10.1):
- album with 6 tracks - 6 seconds
- 12 tracks - 10s
- 21 tracks - 15s
- 32 tracks - 19s
- 55 tracks - 31s
- 153 tracks - 1min 26s
- 247 tracks - 2min 28s

I re-tested the above with a different renderer and I got these results:
- 6 tracks - 6s
- 12 tracks - 7s
- 21 tracks - 7s
- 32 tracks - 8s
- 55 tracks - 12s
- 153 tracks - 28s
- 247 tracks - 43s


2. When adding large multi-disk albums (over 50 tracks or so), BubbleUPnP does not populate the playlist nor the Now Playing screen. The music starts playing and I can even jump to the next track but I don't see any metadata, progress bar or album art. I don't see this behaviour with Bubble's built in renderer, even when I add the album through a stand-alone BubbleUPnP control point on my phone.

3. If I have a playlist created already, I am unable to append any new tracks to it ("Enqueue" in BubbleUPnP). I get a busy cursor for a few seconds but nothing gets added to the playlist. Looking at the MediaPlayer logs, it appears that it receives the information for the new tracks but it's not reflected on the control point.

4. When I was initially testing over Wifi, it appeared that sometimes the Wifi connection dropped when adding large albums to the playlist (as in 2. above). It didn't happen every time but I have seen it about 3 times. The system log would then show something like this:
Dec 16 00:44:42 pi1 kernel: [ 6753.015649] rtw_cmd_thread: DriverStopped(0) SurpriseRemoved(1) break at line 482
If I unplugged the Wifi dongle and then plugged it back in again, it would reconnect without problems so the system as a whole was not affected by this.

It sems strange that it would be related to adding tracks to the playlist, perhaps it's just a coincidence? I did have connection problems with the Wifi dongle during playback too but not as often. (I also did an overnight test copying over 180GB of data over Wifi without any disconnection problems but obviously the driver is not terribly stable.)

5. When seeking through flac files (16 bit, 44.1 KHz), and the end of the track is reached, playback does not advance to the next track. This happens for me about 50% of the time with flac files only (it works fine for mp3s). Just to clarify, by seeking I mean jumping somewhere towards the end of the file and then I let it play normally until the end. Playback stops at the end of the track. Again, this does not happen with Bubble's built in renderer.

6. Using Kinsky v. 4.3.17 running on OS X Mavericks, I can see the renderer but I cannot add tracks to it or control playback. Also, changes to the playlist performed through BubbleUPnP do not get reflected here.

7. Using AssetControl v. 1.0.0.5 on Windows XP I cannot even see the renderer.


Please let me know if you need logs or any help testing any of the above.

Anyway, thanks again for MediaPlayer. It doesn't get much better than this: an open-source, software-based renderer, running on a cheap, silent computer but producing very high quality results through a cheap DAC. This is filling the last remaining piece of the puzzle (the other 2 great pieces being MinimServer and Bubble control point).

Cheers,
Ciprian