On Wed, 2014-05-14 at 15:49 +0800, Zhao, Yakui wrote: > On Sun, 2014-05-11 at 23:34 -0600, Gwenole Beauchesne wrote: > > 2014-05-12 7:29 GMT+02:00 Zhao, Yakui <yakui.z...@intel.com>: > > > On Sun, 2014-05-11 at 22:41 -0600, Gwenole Beauchesne wrote: > > >> Hi, > > >> > > >> 2014-05-12 3:34 GMT+02:00 Zhao Yakui <yakui.z...@intel.com>: > > >> > On Fri, 2014-05-09 at 03:06 -0600, Yuan, Feng wrote: > > >> >> Hi, > > >> >> > > >> >> >>> I have a scheme where the decoder ack's received frames - With > > >> >> >>> this > > >> >> >>> information I could resync without an IDR by carefully selecting > > >> >> >>> the > > >> >> >>> reference frame(s). > > >> >> > > > >> >> >> Will you please describe your idea in detail? > > >> >> > > > >> >> >>> long term references would typically be employed as well, but it > > >> >> >>> seems ref-pic-marking was removed may'13? > > >> >> > > > >> >> >> Why do you hope to use the long-term reference? As you know, the > > >> >> >> current encoding is based on hardware-acceleration. When more the > > >> >> >> reference frames can be selected, the driver will be more complex > > >> >> >> and > > >> >> >> then the encoding speed is also affected. > > >> >> > > > >> >> >It's for implementing Cisco's clearpath technology > > >> >> >(http://www.cisco.com/c/dam/en/us/td/docs/telepresence/endpoint/softwa > > >> >> >re/clearpath/clearpath_whitepaper.pdf) > > >> >> >Basically one would periodically mark a P frame as long term > > >> >> >reference, in > > >> >> >case of packet loss one can thus refer to this one instead of > > >> >> >restarting the > > >> >> >stream with an idr. > > >> >> > > > >> >> > > > >> >> >I'm not too concerned about the encoding speed as long as it's above > > >> >> >realtime (60fps 1920x1080) > > >> >> > > >> >> Maybe it's more convenient If libva can have a switch for > > >> >> slice_header made between driver and app. Then some specially > > >> >> cases(ref-reorder, long-term-ref) may let app to manage slice-header. > > >> > > > >> > Thanks for your suggestion. If the slice-header info is also generated > > >> > by the app and then be passed to the driver, it can be easy to do the > > >> > operation of "re-order and long-term-ref" > > >> > > > >> > But this will depend on the policy how the slice header info is > > >> > generated. (by app or the driver). Now this is exported by querying the > > >> > capability of the driver. If we move this into the app, the > > >> > infrastructure will be changed a lot. > > >> > > >> Infrastructure of what? The application? No, it doesn't really change > > >> anything but generating the extra packed slice header. > > > > > > Currently the app will query the capability of encoding and determine > > > which kind of header should be passed by the upper application(For > > > example: PPS/SPS). > > > If the Slice_header info is exposed, the driver will assume that it is > > > the responsibility of generating the slice header info. In such case it > > > is difficult to mix the two working modes without a lot of changes.(One > > > is that the driver generates the slice header info. Another is that the > > > app generates the slice header info). > > > > Then the driver needs to be fixed to not assume anything. The API and > > operation points look clear enough, aren't they? > > Sorry that something is not described very clearly in my previous email > because of one typo error. > > If the Slice_header info is exposed, app should be responsible of > generating the slice header info and then passed it into the driver. > If the slice_header info is not exposed, the driver will be > responsible of generating the slice header info. > > And it is difficult to mix the above two working modes without a lot of > changes.
Another thing is for CBR, the QP might be changed per frame in the driver and app/middleware doesn't not know the final QP. How does app get the right slice_qp_delta to build the right packed slice header ? does app always use a fixed slice_qp_delta ? > > > > > The changes to the codec layer are minimal, and this was done already, > > in multiple instances of codec layers, and with another driver. > > > > >> > Another problem is that it is possible that one frame has multiple > > >> > slices. In such case the user should pass the multiple slice header > > >> > info. > > >> > > >> This is not an an issue. The API mandates that the packed headers are > > >> provided in order. > > > > > > > > > > > >> > > >> Regards, > > >> Gwenole. > > > > > > > > > _______________________________________________ > Libva mailing list > Libva@lists.freedesktop.org > http://lists.freedesktop.org/mailman/listinfo/libva _______________________________________________ Libva mailing list Libva@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/libva
