Playing RTL-SDR radio through VLC

[peppy.player]

I didn't find a better place for this question.
I'd like to play FM radio streams from RTL-SDR USB dongle. Here is the whole shell command for that using 'aplay' as the audio player:

rtl_fm -M fm -l 0 -A std -p 0 -s 171k -g 20 -F 9 -f 97.3M | redsea -e | aplay -r 171000 -f S16_LE

'redsea' is for getting RDS messages (artist name, song name etc) from FM signal.
Is is possible to use 'cvlc' instead of 'aplay' ? I couldn't find a way to define sample rate and signal format as command line arguments for 'cvlc'.
If I put 'cvlc' without any arguments it doesn't work.

Thanks in advance!

[Rémi Denis-Courmont]

If it's a proper ALSA device, it should show under Audio capture in the playlist. Otherwise, you need to open it manually with alsa:// or pulse:// followed by the device name.

[peppy.player]

I can probably define Alsa and device using these command line arguments:
--aout=alsa --alsa-audio-device=hw

The question is more about sample rate and format of the input stream. Can 'cvlc' auto-detect that or should I specify it in a similar way as I'm doing that for 'aplay'? If the latter how can I do that?
Thanks!

[peppy.player]

There is the option "-" for reading from 'stdin': https://wiki.videolan.org/Uncommon_uses/
So I tried:
rtl_fm -M fm -l 0 -A std -p 0 -s 171k -g 20 -F 9 -f 97.3M | redsea -e | cvlc -
and got the following messages:
VLC media player 2.2.6 Umbrella (revision 2.2.6-0-g1aae78981c)
Found 1 device(s):
0: Realtek, RTL2838UHIDIR, SN: 00000001

Using device 0: Generic RTL2832U OEM
[001b90c8] pulse audio output error: PulseAudio server connection failure: Connection refused
[001d3568] core interface error: no suitable interface module
[0011f918] core libvlc error: interface "globalhotkeys,none" initialization failed
[001d3568] dbus interface error: Failed to connect to the D-Bus session daemon: Unable to autolaunch a dbus-daemon without a $DISPLAY for X11
[001d3568] core interface error: no suitable interface module
[0011f918] core libvlc error: interface "dbus,none" initialization failed
[001d3568] dummy interface: using the dummy interface module...
Found Rafael Micro R820T tuner
Tuner gain set to 19.70 dB.
Tuned to 97642000 Hz.
Oversampling input by: 8x.
Oversampling output by: 1x.
Buffer size: 5.99ms
Exact sample rate is: 1368000.013046 Hz
Sampling at 1368000 S/s.
Output at 171000 Hz.
[mp3 @ 0x73836cf0] Header missing
[mp3 @ 0x73836cf0] Header missing
[mp3 @ 0x73836cf0] Header missing
...

So it looks like vlc cannot detect the input stream format.The same question still remains - how can I define the sample rate of the input stream?
Thanks!

[peppy.player]

If I create named pipe/fifo:
mkfifo fff
And then run:
rtl_fm -M fm -l 0 -A std -p 0 -s 171k -g 20 -F 9 -f 97.3M | redsea -e > fff
and run vlc in separate terminal:
cvlc fff
I had the same result:
[mp3 @ 0x73d39180] Header missing

mplayer also fails:
mplayer fff
MPlayer 1.3.0 (Debian), built with gcc-6.2.1 (C) 2000-2016 MPlayer Team

Playing fff.
libavformat version 57.56.101 (external)
Mismatching header version 57.56.100
Cannot seek backward in linear streams!
Seek failed
Cannot seek backward in linear streams!
Seek failed
...

[Rémi Denis-Courmont]

VLC negotiates the sample format and sample rate automatically with the ALSA device driver, of course.

[peppy.player]

Does it mean that vlc cannot detect input stream format? As I mentioned 'aplay' works fine if I define the sample rate and format:
aplay -r 171000 -f S16_LE

I use vlc as the main audio player in my own app. It would be a pity to switch to 'aplay' just for handling RTL-SDR radio streams. But so far I didn't find any way to make vlc working

[peppy.player]

Just in case anybody else will need a solution here are the command line parameters which define the sample rate and format of the input stream:

rtl_fm -M fm -l 0 -A std -p 0 -s 171k -g 20 -F 9 -f 97.3M | redsea -e | cvlc --demux=rawaud --rawaud-channels=1 --rawaud-samplerate=171000 --rawaud-fourcc=s16l -

The dash in the end can be replaced either by stream:///dev/stdin or fd://0

The solution was suggested at the diyAudio forum: https://www.diyaudio.com/forums/pc-based/341527-playing-rtl-sdr-radio-vlc.html#post5886696