I am using a Creative Webcam NX Ultra(Model No-PD1120) . I tried using the following command to capture the webcam video to an avi file.
ffmpeg -f video4linux2 -s 640x480 -i /dev/video0 -y sample.avi

I am getting the following error message:
ffmpeg version N-50294-gbb7bc34 Copyright (c) 2000-2013 the FFmpeg developers
built on Feb 25 2013 12:06:20 with gcc 4.6.1 (Ubuntu/Linaro 4.6.1-9ubuntu3)
configuration:
libavutil 52. 17.103 / 52. 17.103
libavcodec 54. 92.100 / 54. 92.100
libavformat 54. 63.100 / 54. 63.100
libavdevice 54. 3.103 / 54. 3.103
libavfilter 3. 41.100 / 3. 41.100
libswscale 2. 2.100 / 2. 2.100
libswresample 0. 17.102 / 0. 17.102
[video4linux2,v4l2 @ 0x2d300e0] Cannot find a proper format for codec 'none' (id 0), pixel format 'none' (id -1)
Assertion *codec_id != AV_CODEC_ID_NONE failed at libavdevice/v4l2.c:824
Aborted


Can anyone help me with this please, my situation is very critical. I expect some help very soon. Thank you in advance.