Use WMP12 to stream audio files to DLNA music player via ethernet

I am trying to configure the K-Lite codec pack to stream FLAC files (as well as files native to WMP) from WMP12 to a networked audio player (Marantz NA 7004). Before I install the codec pack streaming works fine, but for native files only. After I install the codec pack I can play all files, including FLAC, mpc etc, on the PC (Win 7 64bit) but streaming doesn't work for any files; the PC cannot contact the Marantz. The PC and the Marantz are on an ethernet network. All cables and switches etc are fine. Is there any way I can solve this problem?

Your receiver does not seem to support FLAC or Musepack.
http://certification.dlna.org/certs/REG63208232.pdf
This means such files need to be transcoded (= on-the-fly conversion) when streaming. I don't think WMP12 does that by default. I found an option that you could try:
WMP12 options > Devices > Advanced > Allow audio files to convert in the background

It is strange that native formats do not work anymore. Did you apply any tweaks with Win7DSFilterTweaker, such as disabling Media Foundation, or any of the MS codecs?

Test if disabling the filters from the pack makes any difference.
Codec Tweak Tool > Codec and Filter Management > DirectShow (x86)
Ones you could (temporarily) disable are: ffdshow, LAV Audio decoder, LAV splitter

Also try this Registry tweak:

Code:

Windows Registry Editor Version 5.00

[HKEY_CLASSES_ROOT\SystemFileAssociations\.mp3]
"PerceivedType"="audio"

Thanks for these quick replies. Some comments:
1. The documentation for the Marantz says that it supports wma, flac, aac, wav and mp3. I know that it does support all of these file types because I have played them through the Marantz from Twonky Server.
2. I have succeeded at streaming native files from WMP12 by following your advice and disabling ffdshow, LAV Audio decoder & LAV splitter in the codec pack.
3. Still no luck at playing flac files though. I have not attempted to disable Media Foundation or any of the MS codecs - I wasn't sure if you were advising for or against doing this. I did check "Allow audio files to convert in the background" in WMP 12 but with this made no difference to WMP12s refusal to stream flac files.
4. My version of regedit is 6.1. I found the .mp3 folder you pointed me to but it seemed not to contain the "PerceivedType" key you named.

So, mixed success but a bit closer to a solution. Any further advice would be greatly appreciated.

The Registry script works with any version of regedit. But you can skip that test, as your other tests have shown the issue is related to the filters.

You are not able to play/stream FLAC because of the disabled splitter.

Can you test streaming of MP3 with the following scenarios:
1) Only LAV Splitter enabled
2) Only ffdshow enabled
3) Only LAV audio enabled

I would really like to find the exact cause of the problems, and try to find some kind of solution or workaround. If we are unable to come up with a good solution, I can recommend you a different DLNA server as an alternative for Media Center.