roc-recv OPTIONS


Receive real-time audio streams from remote senders and write them to a file or an audio device.


-h, --help Print help and exit
-V, --version Print version and exit
-v, --verbose Increase verbosity level (may be used multiple times)
-o, --output=OUTPUT
 Output file or device
-d, --driver=DRIVER
 Output driver
-s, --source=PORT
 Source port triplet (may be used multiple times)
-r, --repair=PORT
 Repair port triplet (may be used multiple times)
 Session target latency, TIME units
 Session minimum latency, TIME units
 Session maximum latency, TIME units
 Playback target latency, TIME units
 Session no playback timeout, TIME units
 Session broken playback timeout, TIME units
 Session breakage detection window, TIME units
 Maximum packet size, in bytes
 Internal frame size, number of samples
--rate=INT Override output sample rate, Hz
 Disable resampling (default=off)
 Resampler profile (possible values=”low”, “medium”, “high” default=`medium’)
 Resampler sinc table precision
 Number of samples per resampler window
-1, --oneshot Exit when last connected client disconnects (default=off)
--poisoning Enable uninitialized memory poisoning (default=off)
--beeping Enable beeping on packet loss (default=off)


OUTPUT should be file name or device name, for example:

  • - (stdout)
  • file.wav (WAV file)
  • default (default output device)
  • front:CARD=PCH,DEV=0 (ALSA device)
  • alsa_output.pci-0000_00_1f.3.analog-stereo (PulseAudio sink)

Interpretation of the device name depends on the selected driver.

If the output is omitted, some default output is selected. If the driver is omitted or it is a device driver, the default output device is seelcted. If the driver is a file driver, the stdout is selected.


DRIVER defines the type of the output file or device, for example:

  • wav
  • alsa
  • pulseaudio

If the driver is omitted, some default driver is selected. If the user did specify the output and it is a file with a known extension, the appropriate file driver is selected. Otherwise, the first device driver available on the system is selected.


PORT should be in one of the following forms:

  • protocol::portnum ( IP address is used)
  • protocol:ipv4addr:portnum
  • protocol:[ipv6addr]:portnum

For example:

  • rtp+rs8m::10001
  • rtp+rs8m:
  • rtp+rs8m:[::1]:10001

If FEC is enabled on sender, a pair of a source and repair ports should be used for communication between sender and receiver. If FEC is disabled, a single source port should be used instead.

Receiver can listen on multiple source and repair ports of different protocols simultaneously. This allows multiple senders which use different protocols and FEC schemes to connect to a single receiver.

Supported protocols for source ports:

  • rtp (bare RTP, no FEC scheme)
  • rtp+rs8m (RTP + Reed-Solomon m=8 FEC scheme)
  • rtp+ldpc (RTP + LDPC-Starircase FEC scheme)

Supported protocols for repair ports:

  • rs8m (Reed-Solomon m=8 FEC scheme)
  • ldpc (LDPC-Starircase FEC scheme)


TIME should have one of the following forms:
123ns, 123us, 123ms, 123s, 123m, 123h


Listen on two ports on all IPv4 interfaces (but not IPv6):

$ roc-recv -vv -s rtp+rs8m::10001 -r rs8m::10002

Listen on two ports on all IPv6 interfaces (but not IPv4):

$ roc-recv -vv -s rtp+rs8m:[::]:10001 -r rs8m:[::]:10002

Listen on two ports on a particular interface:

$ roc-recv -vv -s rtp+rs8m: -r rs8m:

Listen on two Reed-Solomon ports, two LDPC ports, and one bare RTP port:

$ roc-recv -vv -s rtp+rs8m::10001 -r rs8m::10002 -s rtp+ldpc::10003 -r ldpc::10004 -s rtp::10005

Listen on two ports on all IPv4 interfaces and on two ports on all IPv6 interfaces:

$ roc-recv -vv -s rtp+rs8m::10001 -r rs8m::10002 -s rtp+rs8m:[::]:10001 -r rs8m:[::]:10002

Output to the default ALSA device:

$ roc-recv -vv -s rtp+rs8m::10001 -r rs8m::10002 -d alsa

Output to a specific PulseAudio device:

$ roc-recv -vv -s rtp+rs8m::10001 -r rs8m::10002 -d pulseaudio -o <device>

Output to a file in WAV format:

$ roc-recv -vv -s rtp+rs8m::10001 -r rs8m::10002 -o ./file.wav

Output to stdout in WAV format:

$ roc-recv -vv -s rtp+rs8m::10001 -r rs8m::10002 -d wav -o - > ./file.wav

Force a specific rate on the output device:

$ roc-recv -vv -s rtp+rs8m::10001 -r rs8m::10002 --rate=44100

Select higher session latency and timeouts:

$ roc-recv -vv -s rtp+rs8m::10001 -r rs8m::10002 \
  --sess-latency=5s --min-latency=-1s --max-latency=10s --np-timeout=10s --bp-timeout=10s

Select higher I/O latency:

$ roc-recv -vv -s rtp+rs8m::10001 -r rs8m::10002 --io-latency=200ms

Select resampler profile:

$ roc-recv -vv -s rtp+rs8m::10001 -r rs8m::10002 --resampler-profile=high


roc-send(1), roc-conv(1), sox(1), the Roc web site at


Please report any bugs found via GitHub (


See authors page on the website for a list of maintainers and contributors.