baseparse: make minimum frame size handling more efficient and convenient
baseparse: make minimum frame size handling more efficient and convenient

While some formats allow subclass to determine a specific subsequent
needed frame size, others may to need to scan for markers and can only
request 'additional data' by whatever reasonable available step.

In push mode, trying to minimize additional latency leads to step size
being the next input buffer.  In pull mode, any reasonable step size
(such as already used by buffer caching) can be applied.

jpakkane/gstreamer,magcius/gstreamer,StreamUtils/gstreamer,centricular/gstreamer,justinjoy/gstreamer,jpakkane/gstreamer,collects/gstreamer,krichter722/gstreamer,lubosz/gstreamer,StreamUtils/gstreamer,surround-io/gstreamer,StreamUtils/gstreamer,centricular/gstreamer,mparis/gstreamer,ylatuya/gstreamer,magcius/gstreamer,ahmedammar/platform_external_gst_gstreamer,jpakkane/gstreamer,cfoch/gstreamer,ensonic/gstreamer,ensonic/gstreamer,ensonic/gstreamer,ylatuya/gstreamer,lovebug356/gstreamer,drothlis/gstreamer,cfoch/gstreamer,surround-io/gstreamer,ahmedammar/platform_external_gst_gstreamer,jpakkane/gstreamer,cfoch/gstreamer,cfoch/gstreamer,lubosz/gstreamer,centricular/gstreamer,krieger-od/gstreamer,jpxiong/gstreamer,krichter722/gstreamer,krieger-od/gstreamer,surround-io/gstreamer,shelsonjava/gstreamer,ahmedammar/platform_external_gst_gstreamer,drothlis/gstreamer,Distrotech/gstreamer,Lachann/gstreamer,krieger-od/gstreamer,cablelabs/gstreamer,shelsonjava/gstreamer,Distrotech/gstreamer,jpxiong/gstreamer,collects/gstreamer,cablelabs/gstreamer,collects/gstreamer,Lachann/gstreamer,ahmedammar/platform_external_gst_gstreamer,cablelabs/gstreamer,shelsonjava/gstreamer,surround-io/gstreamer,centricular/gstreamer,magcius/gstreamer,magcius/gstreamer,krichter722/gstreamer,ensonic/gstreamer,krichter722/gstreamer,cablelabs/gstreamer,jpakkane/gstreamer,centricular/gstreamer,krichter722/gstreamer,krieger-od/gstreamer,lubosz/gstreamer,surround-io/gstreamer,StreamUtils/gstreamer,jpxiong/gstreamer,ylatuya/gstreamer,collects/gstreamer,justinjoy/gstreamer,Distrotech/gstreamer,lovebug356/gstreamer,lovebug356/gstreamer,drothlis/gstreamer,justinjoy/gstreamer,collects/gstreamer,lubosz/gstreamer,drothlis/gstreamer,ylatuya/gstreamer,lovebug356/gstreamer,Lachann/gstreamer,ahmedammar/platform_external_gst_gstreamer,krieger-od/gstreamer,cablelabs/gstreamer,ylatuya/gstreamer,StreamUtils/gstreamer,magcius/gstreamer,mparis/gstreamer,Distrotech/gstreamer,lubosz/gstreamer,lovebug356/gstreamer,Distrotech/gstreamer,shelsonjava/gstreamer,jpxiong/gstreamer,mparis/gstreamer,cfoch/gstreamer,justinjoy/gstreamer,Lachann/gstreamer,Lachann/gstreamer,drothlis/gstreamer,shelsonjava/gstreamer,ensonic/gstreamer,jpxiong/gstreamer,mparis/gstreamer,mparis/gstreamer,justinjoy/gstreamer