ff_alloc_input_device_context  234 libavdevice/avdevice.c     if ((ret = ff_alloc_input_device_context(&s, device, device_name)) < 0)
ff_alloc_input_device_context   24 libavdevice/internal.h int ff_alloc_input_device_context(struct AVFormatContext **avctx, struct AVInputFormat *iformat,