[FFmpeg-trac] #1570(avdevice:open): libv4l2: error dequeuing buf: Resource temporarily unavailable

[FFmpeg]

#1570: libv4l2: error dequeuing buf: Resource temporarily unavailable
-------------------------------------+-------------------------------------
             Reporter:  llarevo      |                    Owner:
                 Type:  defect       |                   Status:  open
             Priority:  normal       |                Component:  avdevice
              Version:  unspecified  |               Resolution:
             Keywords:               |               Blocked By:
  video4linux, video4linux2,         |  Reproduced by developer:  0
  v4l2.c, regression, capture,       |
  analog, tv                         |
             Blocking:               |
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------

Comment (by ubitux):

 Replying to [comment:7 llarevo]:
 > The output of the unpatched 0.11.1 with -debug 1 is
 > {{{
 > /usr/local/bin/ffmpeg -debug 1 -t 300 -f video4linux2 -s vga -r 25 -b
 2000k -i /dev/video0 out-vga-2M-5min.mpg
 > ffmpeg version 0.11.1 Copyright (c) 2000-2012 the FFmpeg developers
 >   built on Jul 29 2012 15:53:10 with gcc 4.7.0 20120507 (Red Hat
 4.7.0-5)
 >   configuration: --prefix=/usr/local --libdir=/usr/local/lib64
 --shlibdir=/usr/local/lib64 --enable-nonfree --enable-gpl --enable-libfaac
 --enable-libgsm --enable-libmp3lame --enable-libtheora --enable-libxvid
 --disable-asm --disable-crystalhd
 >   libavutil      51. 54.100 / 51. 54.100
 >   libavcodec     54. 23.100 / 54. 23.100
 >   libavformat    54.  6.100 / 54.  6.100
 >   libavdevice    54.  0.100 / 54.  0.100
 >   libavfilter     2. 77.100 /  2. 77.100
 >   libswscale      2.  1.100 /  2.  1.100
 >   libswresample   0. 15.100 /  0. 15.100
 >   libpostproc    52.  0.100 / 52.  0.100
 > Please use -b:a or -b:v, -b is ambiguous
 > [video4linux2,v4l2 @ 0x2ecd1e0] [3]Capabilities: 5010015
 > [video4linux2,v4l2 @ 0x2ecd1e0] The V4L2 driver using the interlaced
 modeThe V4L2 driver set input_id: 0, input: Television
 > [video4linux2,v4l2 @ 0x2ecd1e0] Setting time per frame to 1/25
 > [video4linux2,v4l2 @ 0x2ecd1e0] ioctl set time per frame(1/25) failed
 > /dev/video0: Input/output error
 > }}}

 That makes me wonder if one of your parameter isn't wrong: you specify -r
 25 which might be not supported by your card. Can you make some tests with
 something simple such as:

 {{{
 ./ffplay -f v4l2 -i /dev/video0
 }}}

 to see if it doesn't show anything? (for old version you might need to
 change v4l2 into video4linux2)

-- 
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/1570#comment:8>
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