Problems with AAC+ streams while connected to 5GHz networks

I have a really strange problem with dropouts while listening to AAC+ streams…

The AAC stream from Radio Swiss Classic will play all day if the wifi adapter happens to connect over 2.4GHz 802.11g (at about 70Mb/s). But if I connect at high speed over 5GHz at a 433Mb/s bitrate, AAC+ streams drop—sometimes in seconds, sometimes in minutes. Sometimes it hangs for ten or twenty seconds and comes back, other times it never comes back.

I am using and Edimax AC600 wifi adapter using a driver I installed on top of Volumio. I tried upgrading to a faster SD card—didn’t help. I use the faster 5GHz network to play back DSD64 files without popping. Other than this issue, it works well.

I’m pretty sure the culprit is mpd. I looked in the mpd log file—nothing strange seems to be going on.

Any ideas?


mpd has no idea of which network you are using, that is surely not the cause of the problem.
Maybe the 5 GHz network takes too much CPU power or current and the card resets when there is higher load.
Try moving big files to/from Volumio using the 5 GHz and see if the transfer rate is actually what you think it is, and if there are pauses.

The strange thing is the dropouts are specific to AAC+ streams while connected to high-bandwidth wifi.

I can play MP3 streams while attached to a 5GHz network all day with no dropouts. I can also play high-res DSD64 or 24-bit/176kHz files from my Time Capsule NAS with no dropouts or clicks (this was the reason I got the 802.11ac adapter — those files won’t play back at 802.11g speeds). These high-res files must use way more bandwidth/CPU/power than a 128kbps AAC+ stream…

My guess is the problem is in the AAC decoder. I tried using gdb to get a backtrace of where the dropout is happening, but it seems the mpd file wasn’t compiled with debugging information. (I’m not even entirely sure what module actually does aac decoding).

FWIW, I’m using a HifiBerry Digi+ card for SPDIF output.


Why don’t you do the test I mentioned? check the ACTUAL bandwidth of the 5 GHz network by transferring files specifically to AND from Volumio (use an external USB disk, if needed, or save/read them to/from the SD card).

Of course MP3 play well, they have lower bitrate most of the time.

And again I doubt the AAC decoder has any clue about how the files get there.
If you still think that is the cause, after the test I mentioned, maybe it’s worth investigating further.
But I mean, no one else had that issue… I doubt it’s the AAC decoder.

This basically is impossible 802.11g has a theoretical 54Mbit/s max speed.

Besides that, 2,4ghz has more range then the 5ghz signal. 2,4ghz is a bit less power hungry. So as lag-na posted the cpu and usb load is higher.

After the proposed test, You could try increasing the buffer size and buffer before play values and see if that helps.

And search for more information about the playback with your dac. I’ve seen posts about popping using some dacs and recievers.