Seek during flac playback not working

Using foobar2000 as the DLNA renderer playing flac files with Serviio server. Trying to do a seek, or jump forward, during playback of a flac file, but it does nothing. Just keeps playing at the current spot. If i play the same track in foobar2000 directly the seek operation works fine. Seek using foobar2000 and Serviio works fine with mp3 files.

Any suggestions?

foo_upnp and BubbleUPnP dev here.

More info in this post.

This issue is not specific to foobar2000, as upmpdcli (a mpd based renderer) also fails to seek in FLAC.
Probably something broken in http Range requests although I could not see anything unusual.

Ok. One more observation. Seek during flac playback works with Windows Media Player as the DLNA renderer. So somehow it appears the issue is a combination of specific renderer and Serviio.

Does that help at all?

After more digging, this is caused by the http response missing the "Accept-Range: bytes" header, making some clients infer that the stream is not seekable while it is:

  Code:

$curl -v http://10.0.0.26:8895/resource/35955/MEDIA_ITEM/FLAC-0/ORIGINAL -o /dev/null
*   Trying 10.0.0.26:8895...
* TCP_NODELAY set
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0* Connected to 10.0.0.26 (10.0.0.26) port 8895 (#0)
> GET /resource/35955/MEDIA_ITEM/FLAC-0/ORIGINAL HTTP/1.1
> Host: 10.0.0.26:8895
> User-Agent: curl/7.68.0
> Accept: */*
>
* Mark bundle as not supporting multiuse
< HTTP/1.1 200 OK
< Content-Length: 38002879
< Content-Type: audio/flac
< Cache-control: no-cache
< Connection: close
< Date: Tue, 18 Feb 2020 12:07:30 GMT
< realTimeInfo.dlna.org: DLNA.ORG_TLAG=*
< Server: Windows_10 UPnP/1.0 DLNADOC/1.50 Serviio/2.0
< transferMode.dlna.org: Streaming

Thanks. Nice work. Sorry for my lack of knowledge, but does that mean the problem is with Serviio or foobar? Is a fix feasible and likely, or should I move on to other SW?

Bump