Write webcam video with avconv
===

Have problem to write video avi with avconv

I try using 

    avconv -v debug -f video4linux2 -i /dev/video1 frontal.avi

but video not correct. I see this line `[video4linux2 @ 0x8100b00] The v4l2 frame is 8160 bytes, but 614400 bytes are expected` and I don't identify options to correct this.

Output of debug

	avconv version 0.8.3-4:0.8.3-0ubuntu0.12.04.1, Copyright (c) 2000-2012 the Libav developers
	  built on Jun 12 2012 16:37:58 with gcc 4.6.3
	  configuration: --extra-version='4:0.8.3-0ubuntu0.12.04.1' --arch=i386 --prefix=/usr --libdir=/usr/lib/i386-linux-gnu --enable-vdpau --enable-bzlib --enable-libgsm --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-pthreads --enable-zlib --enable-libvpx --enable-runtime-cpudetect --enable-libfreetype --enable-vaapi --enable-gpl --enable-postproc --enable-swscale --enable-x11grab --enable-libdc1394 --shlibdir=/usr/lib/i386-linux-gnu/i686/cmov --cpu=i686 --enable-shared --disable-static
	  libavutil    51. 22. 1 / 51. 22. 1
	  libavcodec   53. 35. 0 / 53. 35. 0
	  libavformat  53. 21. 0 / 53. 21. 0
	  libavdevice  53.  2. 0 / 53.  2. 0
	  libavfilter   2. 15. 0 /  2. 15. 0
	  libswscale    2.  1. 0 /  2.  1. 0
	  libpostproc  52.  0. 0 / 52.  0. 0
	[video4linux2 @ 0x8100b00] [3]Capabilities: 4000001
	[video4linux2 @ 0x8100b00] Querying the device for the current frame size
	[video4linux2 @ 0x8100b00] Setting frame size to 640x480
	[video4linux2 @ 0x8100b00] The V4L2 driver set input_id: 0, input: Camera 1
	[video4linux2 @ 0x8100b00] The v4l2 frame is 8160 bytes, but 614400 bytes are expected
	[rawvideo @ 0x8102920] err{or,}_recognition separate: 1; 1
	[rawvideo @ 0x8102920] err{or,}_recognition combined: 1; 1
	[video4linux2 @ 0x8100b00] Estimating duration from bitrate, this may be inaccurate
	Input #0, video4linux2, from '/dev/video1':
	  Duration: N/A, bitrate: 147456 kb/s
		Stream #0.0, 0, 1/1000000: Video: rawvideo, yuyv422, 640x480, 1/30, 147456 k
	File 'frontal.avi' already exists. Overwrite ? [y/N] y
	Incompatible pixel format 'yuyv422' for codec 'mpeg4', auto-selecting format 'yu
	[buffer @ 0x81020c0] w:640 h:480 pixfmt:yuyv422
	[avsink @ 0x81022a0] auto-inserting filter 'auto-inserted scaler 0' between the
	[scale @ 0x81026e0] w:640 h:480 fmt:yuyv422 -> w:640 h:480 fmt:yuv420p flags:0x4
	[mpeg4 @ 0x81019a0] err{or,}_recognition separate: 1; 1
	[mpeg4 @ 0x81019a0] err{or,}_recognition combined: 1; 1
	[mpeg4 @ 0x81019a0] detected 1 logical cores
	[mpeg4 @ 0x81019a0] Unsupported bit depth: 0
	[rawvideo @ 0x8102920] err{or,}_recognition separate: 1; 1
	[rawvideo @ 0x8102920] err{or,}_recognition combined: 1; 1
	Output #0, avi, to 'frontal.avi':
	  Metadata:
		ISFT            : Lavf53.21.0
		Stream #0.0, 0, 1/30: Video: mpeg4, yuv420p, 640x480, 1/30, q=2-31, 200 kb/s