baseparse: bitrate mechanics should not deal with duration update
baseparse: bitrate mechanics should not deal with duration update

... since that is already handled by _update_duration, or should not be done
altogether if the duration is determined by non-estimated means.

Fixes #669502.

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