Negotiates src pad caps with downstream elements.
Unmarks GST_PAD_FLAG_NEED_RECONFIGURE in any case. But marks it again
if #GstBaseSrcClass.negotiate() fails.
Do not call this in the #GstBaseSrcClass.fill() vmethod. Call this in
#GstBaseSrcClass.create() or in #GstBaseSrcClass.alloc(), _before_ any
buffer is allocated.
Negotiates src pad caps with downstream elements. Unmarks GST_PAD_FLAG_NEED_RECONFIGURE in any case. But marks it again if #GstBaseSrcClass.negotiate() fails.
Do not call this in the #GstBaseSrcClass.fill() vmethod. Call this in #GstBaseSrcClass.create() or in #GstBaseSrcClass.alloc(), _before_ any buffer is allocated.