Issues when streaming to Gmediarender DLNA renderer

[gsp]

First, congratulations to the developers for such a great app! I have recently purchased Neutron and I am nicely impressed.

However, I noticed a few issues when using Neutron on an Android device streaming music to a Raspberry pi running Gmediarender DLNA renderer. I describe the issues in the following along with what I understood so far about Neutron. Kindly correct me if I am wrong. An important note, most of the observations reported below about using Neutron or other apps come from the Gmediarender logfile on the DLNA renderer.

1) Apparently the file format of currently playing music files has to be set in "Output to" settings (choice among LPCM, FLAC, MP£, etc..). That is, the format is not recognized automatically based on the file type. As a consequence, the DLNA renderer (gstreamer) uses in some cases a resampled music stream even if it is capable to play "natively" all the music formats of my library. For comparison, this is not the case when using another Android app, DS AUDIO from Synology, which nicely recognizes the music format and informs the DLNA renderer accordingly. Thus, gstreamer always uses the appropriate codec.

2) Apart the file format, when using Neutron it seems that the track metedata are not transmitted to the DLNA renderer. This is in contrast to DS AUDIO or BubbleUpnUP, for example, which nicely send out all track info (as shown in Gmediarenderer logfile). I guess this info could be important if the DLNA renderer is used also to show current track info on a connected screen (something I would like to achieve).

3) When music is paused, Neutron sends a "STOP" message to the DLNA renderer (TransportState: STOPPED) instead of "PAUSED_PLAYBACK" (as BubbleUpnp does). This has some unwanted consequences. Music can be resumed only with a noticeable delay or the renderer becomes irremediably disconnected from the streamer (very annoying).

4) Perhaps, the most problematic issue is related with FLAC files after setting FLAC format in the "Output to" settings. In this case (apparently not with LPCM format), the renderer gets disconnected when music is stopped and cannot be resumed. The workaround is setting LPCM and then again FLAC in the settings. Usually, after a few times, I can finally succeed. If I keep LPCM format, music is resampled to 44Hz/16bit.

I believe Neutron could be, at least for me, a much better alternative to various DLNA servers and MPD clients/server for its capability to nicely support all music formats, cuesheet files and cover arts in my library (not the case with other software) and I hope the above issues could be soon fixed. Thank you in advance for your help.


My system:
- Music stored on a Synology NAS (ape, flac, mp3, etc...) and organized with Guayadeque (Linux)
- Samsung S9+ with Neutron app as a DLNA control point (music imported from LAN)
- Raspberry Pi running Gmediarenderer (gstreamer1.0) as a DLNA renderer and playing music through an external USB DAC using ALSA to transfer digital music without software alterations

[blaubär]

1) Apparently the file format of currently playing music files has to be set in "Output to" settings (choice among LPCM, FLAC, MP£, etc..). That is, the format is not recognized automatically based on the file type.
[...]
- Samsung S9+ with Neutron app as a DLNA control point (music imported from LAN)

The question would be whether Neutron is designed to act as a controller and only a controller, without being a renderer. Afaik Neutron renders the music ( it decodes it, performs dsp ) and then streams the rendered music to the output, which can be different from the local DAC. An automatic file format setting for this output might be possible, but wouldn't and couldn't ( want to ) avoid a second rendering at the chosen output device/service. If Neutron would want to avoid ( the first ) rendering altogether then it would have to send its input file/stream as it is to the output. Then you couldn't use its DSP ( equalizer etc ), you wouldn't be able to see the progression in the track etc. Or so I think. But I'm no expert in this. I suggest you write to neutronmp@gmail.com to clarify this. If you find something out please tell us !

[blaubär]

also see Wikipedia : List of UPnP AV media servers and clients

Neutron Music Player, a cross platform UPnP/DLNA client which is able to read music files from UPnP/DLNA Media Server or send processed audio to UPnP/DLNA Media Renderer as an endless stream.

So it would seem that Neutron isn't supposed to act only as a dlna controller.

[blaubär]

On the other hand Neutron tells us

Neutron can source music files from device or network sources such as SMB/CIFS, UPnP/DLNA, FTP, WebDAV and send audio either to headphones, or directly to USB DAC or to UPnP/DLNA or Chromecast renderer without a format limitation!

So this might work.

[blaubär]

4) Perhaps, the most problematic issue is related with FLAC files after setting FLAC format in the "Output to" settings. In this case (apparently not with LPCM format), the renderer gets disconnected when music is stopped and cannot be resumed. The workaround is setting LPCM and then again FLAC in the settings. Usually, after a few times, I can finally succeed. If I keep LPCM format, music is resampled to 44Hz/16bit.

I suggest you keep using LPCM, as you only so can avoid a second encoding/decoding. As to the frequency : if you activate Settings > Audio Hardware > Follow Source Frequency I'd expect Neutron to keep the sampling rate of the source as output frequency. Does this work ?

[gsp]

Thank you for your suggestions, blaubär.
Let me say that I am very fine with Neutron philosophy. I am a newbie in the DSP/EQ field but I'd like to experiment a bit in the near future thanks to Neutron. In fact, EQ works well when streaming to a DLNA renderer. Also track progression works well, to address one of your concerns.

I believe (not sure though) that most of the issues I talked about could be simply fixed by changing the info transmitted by Neutron over DLNA streaming. The track metadata, the track file format (to be handled by gstreamer) and the "pause" signal ("PAUSED_PLAYBACK" instead of "STOPPED") I suspect can be fixed within the data message to the DLNA renderer.

As I said the most annoying issue is represented by unstable streaming when the FLAC option in "Output to" is selected. If I select LPCM as you suggested, a FLAC file encoded at 96kHz/24bit is downgraded to 44.1kHz/16bit and activation of "Settings > Audio Hardware > Follow Source Frequency" does not seem to work. I believe the latter may work for local playing when using the same Hardware running Neutron (phone).

Hopefully, developers could give a look into this soon.

[gsp]

For those of you interested, I could fix one of the issues (the most annoying one) described initially, which was related to the unstable streaming of FLAC files (FLAC option in "Output to") to Gmediarenderer. I set Buffer size to 0 in the configuration file of gmediarenderer in /etc/init.d/. Apparently, gstreamer does not like the use of any buffering in combination with FLAC files, at least with NEUTRON. This seems not an issue with other apps, such as DS AUDIO from Synology, which makes me believe it is also an issue related with Neutron way of communicating with DLNA Gmediarenderer. In any case, I can now enjoy my Neutron + DLNA renderer setup.