[Libav-user] Error when open a camera on Android

[craig04reg at 21cn.com]

Hi to all,
I am trying develop an video chat app on android and have ported ffmpeg 2.0.1 to android successfully. The code to open camera is very simple:
AVFormatContext *fmt_ctx = NULL;
AVInputFormat *input_fmt;
input_fmt = av_find_input_format("video4linux2"); 
if (input_fmt == NULL)
return -1；

char f_name[] = "/dev/video0";
if ((ret = avformat_open_input(&fmt_ctx, f_name, input_fmt, NULL)) < 0)        // stuck here
{
LOG_D("can not open camera, ret = %d", ret);
return ret;
}
the strange thing is the ret value is always negative with the following logcat output by av_log:
09-26 15:27:48.901: E/Codec-FFMpeg(17716): ioctl(VIDIOC_G_PARM): Invalid argument
Do i forget anything before calling avformat_open_input()? Thank you!

Regards,
craig
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