FFMPEG webcam stream to Youtube drops frames

Question

I need to do a live videostream on Youtube using a Logitech HD Pro Webcam C920. My OS is Fedora 20, and the command I am trying to use is:

ffmpeg -f v4l2 -i /dev/video0 -flags +global_header -ac 1 -ar 44100 -ab 16k -s 640x360 -vcodec h264 -pix_fmt yuv420p -g 25 -vb 32k -profile:v baseline -r 30 -f flv "rtmp://a.rtmp.youtube.com/live2/NAME_OF_STREAM_REMOVED"

As soon I start the streaming, I obtain a lot of drops, and Youtube says it is not receiving any data. To see if the system was okay, I tried to stream a video file, and it worked, so I don't know what problem I am experiencing.

ffmpeg output:

$ ffmpeg -f v4l2 -i /dev/video0 -flags +global_header -ac 1 -ar 44100 -ab 16k -s 640x360 -vcodec h264 -pix_fmt yuv420p -g 25 -vb 32k -profile:v baseline -r 30 -f flv "rtmp://a.rtmp.youtube.comremoved-privacy-reasons"
ffmpeg version 2.1.4 Copyright (c) 2000-2014 the FFmpeg developers
  built on Feb 25 2014 08:24:47 with gcc 4.8.2 (GCC) 20131212 (Red Hat 4.8.2-7)
  configuration: --prefix=/usr --bindir=/usr/bin --datadir=/usr/share/ffmpeg --incdir=/usr/include/ffmpeg --libdir=/usr/lib64 --mandir=/usr/share/man --arch=x86_64 --optflags='-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic' --enable-bzlib --disable-crystalhd --enable-frei0r --enable-gnutls --enable-libass --enable-libcdio --enable-libcelt --enable-libdc1394 --disable-indev=jack --enable-libfreetype --enable-libgsm --enable-libmp3lame --enable-openal --enable-libopencv --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libvorbis --enable-libv4l2 --enable-libvpx --enable-libx264 --enable-libxvid --enable-x11grab --enable-avfilter --enable-avresample --enable-postproc --enable-pthreads --disable-static --enable-shared --enable-gpl --disable-debug --disable-stripping --shlibdir=/usr/lib64 --enable-runtime-cpudetect
  libavutil      52. 48.101 / 52. 48.101
  libavcodec     55. 39.101 / 55. 39.101
  libavformat    55. 19.104 / 55. 19.104
  libavdevice    55.  5.100 / 55.  5.100
  libavfilter     3. 90.100 /  3. 90.100
  libavresample   1.  1.  0 /  1.  1.  0
  libswscale      2.  5.101 /  2.  5.101
  libswresample   0. 17.104 /  0. 17.104
  libpostproc    52.  3.100 / 52.  3.100
Input #0, video4linux2,v4l2, from '/dev/video0':
  Duration: N/A, start: 1144393.765046, bitrate: 147456 kb/s
    Stream #0:0: Video: rawvideo (YUY2 / 0x32595559), yuyv422, 640x480, 147456 kb/s, 30 fps, 30 tbr, 1000k tbn, 1000k tbc
Codec AVOption ab (set bitrate (in bits/s)) specified for output file #0 (rtmp://a.rtmp.youtube.comremoved-privacy-reasons) has not been used for any stream. The most likely reason is either wrong type (e.g. a video option with no video streams) or that it is a private option of some encoder which was not actually used for any stream.
[libx264 @ 0x1d276c0] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX XOP FMA4 FMA3 LZCNT BMI1
[libx264 @ 0x1d276c0] profile Constrained Baseline, level 3.0
[libx264 @ 0x1d276c0] 264 - core 138 r2363 c628e3b - H.264/MPEG-4 AVC codec - Copyleft 2003-2013 - http://www.videolan.org/x264.html - options: cabac=0 ref=3 deblock=1:0:0 analyse=0x1:0x111 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=0 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=12 lookahead_threads=2 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=0 weightp=0 keyint=25 keyint_min=2 scenecut=40 intra_refresh=0 rc_lookahead=25 rc=abr mbtree=1 bitrate=32 ratetol=1.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
Output #0, flv, to 'rtmp://a.rtmp.youtube.comremoved-privacy-reasons':
  Metadata:
    encoder         : Lavf55.19.104
    Stream #0:0: Video: h264 (libx264) ([7][0][0][0] / 0x0007), yuv420p, 640x360, q=-1--1, 32 kb/s, 1k tbn, 30 tbc
Stream mapping:
  Stream #0:0 -> #0:0 (rawvideo -> libx264)
Press [q] to stop, [?] for help
[video4linux2,v4l2 @ 0x1d420c0] The v4l2 frame is 748 bytes, but 614400 bytes are expectedop=454    
/dev/video0: Invalid data found when processing input
[flv @ 0x1d27120] Failed to update header with correct duration.
[flv @ 0x1d27120] Failed to update header with correct filesize.
frame= 3642 fps= 27 q=-1.0 Lsize=     617kB time=00:02:17.73 bitrate=  36.7kbits/s dup=0 drop=454    
video:545kB audio:0kB subtitle:0 global headers:0kB muxing overhead 13.088289%
[libx264 @ 0x1d276c0] frame I:146   Avg QP:37.27  size:  2457
[libx264 @ 0x1d276c0] frame P:3496  Avg QP:39.47  size:    57
[libx264 @ 0x1d276c0] mb I  I16..4: 84.6%  0.0% 15.4%
[libx264 @ 0x1d276c0] mb P  I16..4:  1.2%  0.0%  0.0%  P16..4:  1.4%  0.0%  0.0%  0.0%  0.0%    skip:97.3%
[libx264 @ 0x1d276c0] final ratefactor: 39.11
[libx264 @ 0x1d276c0] coded y,uvDC,uvAC intra: 9.5% 18.8% 3.1% inter: 0.0% 0.1% 0.0%
[libx264 @ 0x1d276c0] i16 v,h,dc,p: 49% 34% 14%  4%
[libx264 @ 0x1d276c0] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 36% 17% 21%  6%  4%  4%  4%  4%  3%
[libx264 @ 0x1d276c0] i8c dc,h,v,p: 94%  4%  3%  0%
[libx264 @ 0x1d276c0] ref P L0: 39.1% 49.9% 11.0%
[libx264 @ 0x1d276c0] kb/s:32.40
[video4linux2,v4l2 @ 0x1d420c0] Some buffers are still owned by the caller on close.

Answer 1

The problem was that I set options for an audio stream, but don't actually have one anywhere This is the command that works

ffmpeg -f v4l2 -i /dev/video0 -f alsa -ac 1 -i hw:1 -flags +global_header -ar 44100 -ab 16k -s 640x360 -vcodec h264 -pix_fmt yuv420p -g 25 -vb 32k -profile:v baseline -r 30 -f flv "rtmp://a.rtmp.youtube.com/live2/REMOVED"