[FFmpeg-user] Lag when streaming video+audio from RPi Zero W with Logitech C920

[Emanuele]

  I agree that it totally makes sense the two streams aren't in sync.
My main question really was about the huge increase il lag, compared to
the single streams.
This is the complete output:

> ffmpeg version
4.1.6-1~deb10u1+rpt1 Copyright (c) 2000-2020 the FFmpeg developers
>
built with gcc 8 (Raspbian 8.3.0-6+rpi1)
> configuration: --prefix=/usr
--extra-version='1~deb10u1+rpt1' --toolchain=hardened
--incdir=/usr/include/arm-linux-gnueabihf --enable-gpl
--disable-stripping --enable-avresample --disable-filter=resample
--enable-avisynth --enable-gnutls --enable-ladspa --enable-libaom
--enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca
--enable-libcdio --enable-libcodec2 --enable-libflite
--enable-libfontconfig --enable-libfreetype --enable-libfribidi
--enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame
--enable-libmysofa --enable-libopenjpeg --enable-libopenmpt
--enable-libopus --enable-libpulse --enable-librsvg
--enable-librubberband --enable-libshine --enable-libsnappy
--enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora
--enable-libtwolame --enable-libvidstab --enable-libvorbis
--enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265
--enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi
--enable-lv2 --enable-omx --enable-openal --enable-opengl --enable-sdl2
--enable-omx-rpi --enable-mmal --enable-neon --enable-rpi
--enable-libdc1394 --enable-libdrm --enable-libiec61883
--enable-chromaprint --enable-frei0r --enable-libx264 --enable-shared
--libdir=/usr/lib/arm-linux-gnueabihf --cpu=arm1176jzf-s --arch=arm
>
libavutil 56. 22.100 / 56. 22.100
> libavcodec 58. 35.100 / 58. 35.100
>
libavformat 58. 20.100 / 58. 20.100
> libavdevice 58. 5.100 / 58.
5.100
> libavfilter 7. 40.101 / 7. 40.101
> libavresample 4. 0. 0 / 4.
0. 0
> libswscale 5. 3.100 / 5. 3.100
> libswresample 3. 3.100 / 3.
3.100
> libpostproc 55. 3.100 / 55. 3.100
> Input #0, video4linux2,v4l2,
from '/dev/video0':
> Duration: N/A, start: 316950.896790, bitrate:
N/A
> Stream #0:0: Video: h264 (Constrained Baseline), yuvj420p(pc,
progressive), 1920x1080 [SAR 1:1 DAR 16:9], 30 fps, 30 tbr, 1000k tbn,
60 tbc
> Guessed Channel Layout for Input Stream #1.0 : stereo
> Input
#1, alsa, from 'hw:1,0':
> Duration: N/A, start: 1610325291.937835,
bitrate: 1024 kb/s
> Stream #1:0: Audio: pcm_s16le, 32000 Hz, stereo,
s16, 1024 kb/s
> Output #0, rtp, to 'rtp://192.168.0.10:5000':
>
Metadata:
> encoder : Lavf58.20.100
> Stream #0:0: Video: h264
(Constrained Baseline), yuvj420p(pc, progressive), 1920x1080 [SAR 1:1
DAR 16:9], q=2-31, 512 kb/s, 30 fps, 30 tbr, 90k tbn, 30 tbc
> Stream
mapping:
> Stream #0:0 -> #0:0 (copy)
> Stream #1:0 -> #1:0 (pcm_s16le
(native) -> aac (native))
> Press [q] to stop, [?] for help
> [alsa @
0x19cd8a0] Thread message queue blocking; consider raising the
thread_queue_size option (current value: 8)
> Output #1, rtp, to
'rtp://192.168.0.10:5002':
> Metadata:
> encoder : Lavf58.20.100
>
Stream #1:0: Audio: aac (LC), 16000 Hz, mono, fltp, 16 kb/s
>
Metadata:
> encoder : Lavc58.35.100 aac
> [video4linux2,v4l2 @
0x19b20e0] Thread message queue blocking; consider raising the
thread_queue_size option (current value: 8)
> [rtp @ 0x19cf520]
Non-monotonous DTS in output stream 0:0; previous: 0, current: -33025;
changing to 0. This may result in incorrect timestamps in the output
file.
> [rtp @ 0x19cf520] Non-monotonous DTS in output stream 0:0;
previous: 0, current: -27261; changing to 0. This may result in
incorrect timestamps in the output file.
> [rtp @ 0x19cf520]
Non-monotonous DTS in output stream 0:0; previous: 0, current: -21139;
changing to 0. This may result in incorrect timestamps in the output
file.
> [rtp @ 0x19cf520] Non-monotonous DTS in output stream 0:0;
previous: 0, current: -15018; changing to 0. This may result in
incorrect timestamps in the output file.
> [rtp @ 0x19cf520]
Non-monotonous DTS in output stream 0:0; previous: 0, current: -9252;
changing to 0. This may result in incorrect timestamps in the output
file.
> [rtp @ 0x19cf520] Non-monotonous DTS in output stream 0:0;
previous: 0, current: -3132; changing to 0. This may result in incorrect
timestamps in the output file.
> frame= 70 fps= 18 q=-1.0 Lsize= 1352kB
time=00:00:03.90 bitrate=2837.3kbits/s speed= 1x
> video:1339kB
audio:8kB subtitle:0kB other streams:0kB global headers:0kB muxing
overhead: 0.411104%
> [aac @ 0x19cafc0] Qavg: 122.798
 



Con Tiscali Mobile Smart 30 4G hai minuti illimitati, 100 SMS e 30 Giga in 4G a soli 8,99€ al mese. http://tisca.li/smart30