[FFmpeg-user] Choppy ffmpeg audio RTP streaming over wifi
awidgery at gmail.com
Mon Dec 14 18:21:49 CET 2015
I have a Raspberry Pi, with a USB mic and a WiFi dongle dongle connected.
I'm trying to stream audio only from the Pi, with the intention of
receiving the stream over wifi to a custom iOS mobile app using
The code executed on the Pi is:
ffmpeg -f alsa -i plughw:1,0 -acodec libmp3lame -ab 128k -ac 1 -ar
44100 -f rtp rtp://184.108.40.206:1234
ffmpeg version N-77183-g9553689 Copyright (c) 2000-2015 the FFmpeg developers
built with gcc 4.9.2 (Raspbian 4.9.2-10)
configuration: --enable-libfreetype --enable-gpl --enable-nonfree
--enable-libass --enable-libmp3lame --bindir=/usr/local/bin
libavutil 55. 10.100 / 55. 10.100
libavcodec 57. 17.100 / 57. 17.100
libavformat 57. 19.100 / 57. 19.100
libavdevice 57. 0.100 / 57. 0.100
libavfilter 6. 20.100 / 6. 20.100
libswscale 4. 0.100 / 4. 0.100
libswresample 2. 0.101 / 2. 0.101
libpostproc 54. 0.100 / 54. 0.100
Guessed Channel Layout for Input Stream #0.0 : stereo
Input #0, alsa, from 'plughw:1,0':
Duration: N/A, start: 1450113372.115946, bitrate: 1536 kb/s
Stream #0:0: Audio: pcm_s16le, 48000 Hz, 2 channels, s16, 1536 kb/s
Output #0, rtp, to 'rtp://220.127.116.11:1234':
encoder : Lavf57.19.100
Stream #0:0: Audio: mp3 (libmp3lame), 44100 Hz, mono, s16p, 128 kb/s
encoder : Lavc57.17.100 libmp3lame
Stream #0:0 -> #0:0 (pcm_s16le (native) -> mp3 (libmp3lame))
o=- 0 0 IN IP4 127.0.0.1
c=IN IP4 18.104.22.168
m=audio 1234 RTP/AVP 14
Press [q] to stop, [?] for help
size= 4653kB time=00:04:53.96 bitrate= 129.7kbits/s
On the Pi end I have a device playing (Christmas!) music constantly
into the USB mic for testing purposes. The Pi is only connected by
WiFi - not ethernet.
For testing receiving the stream, I'm using VLC (on a Macbook/iPhone).
When the Mac is connected through Ethernet, the stream works fine, as
you can see here:
However, when the Mac is connected via WiFi, the stream is choppy, as
you can see here:
You can also see a ping trace from the Mac to the Pi, and the VLC
stats. As you can see there doesn't seem to be a correlation between
either of these and the choppiness.
I've tried the VLC iOS app and the choppiness is the same as the Mac on WiFi.
How can I decrease/remove this chop, even if doing so increases latency a bit?
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