Re: [PATCH v3] media: venus: add support for key frame

[mgottam]

Hi Stan,

On 2018-11-29 16:01, Stanimir Varbanov wrote:
> Hi Tomasz,
>
> On 11/3/18 5:01 AM, Tomasz Figa wrote:
> > Hi Malathi,
> >
> > On Fri, Nov 2, 2018 at 9:58 PM Malathi Gottam <mgottam@xxxxxxxxxxxxxx> 
> > wrote:
> > > When client requests for a keyframe, set the property
> > > to hardware to generate the sync frame.
> > >
> > > Signed-off-by: Malathi Gottam <mgottam@xxxxxxxxxxxxxx>
> > > ---
> > >  drivers/media/platform/qcom/venus/venc_ctrls.c | 20 
> > > +++++++++++++++++++-
> > >  1 file changed, 19 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/media/platform/qcom/venus/venc_ctrls.c 
> > > b/drivers/media/platform/qcom/venus/venc_ctrls.c
> > > index 45910172..59fe7fc 100644
> > > --- a/drivers/media/platform/qcom/venus/venc_ctrls.c
> > > +++ b/drivers/media/platform/qcom/venus/venc_ctrls.c
> > > @@ -79,8 +79,10 @@ static int venc_op_s_ctrl(struct v4l2_ctrl *ctrl)
> > >  {
> > >         struct venus_inst *inst = ctrl_to_inst(ctrl);
> > >         struct venc_controls *ctr = &inst->controls.enc;
> > > +       struct hfi_enable en = { .enable = 1 };
> > >         u32 bframes;
> > >         int ret;
> > > +       u32 ptype;
> > >
> > >         switch (ctrl->id) {
> > >         case V4L2_CID_MPEG_VIDEO_BITRATE_MODE:
> > > @@ -173,6 +175,19 @@ static int venc_op_s_ctrl(struct v4l2_ctrl 
> > > *ctrl)
> > >
> > >                 ctr->num_b_frames = bframes;
> > >                 break;
> > > +       case V4L2_CID_MPEG_VIDEO_FORCE_KEY_FRAME:
> > > +               mutex_lock(&inst->lock);
> > > +               if (inst->streamon_out && inst->streamon_cap) {
> >
> > We had a discussion on this in v2. I don't remember seeing any 
> > conclusion.
> >
> > Obviously the hardware should generate a keyframe naturally when the
> > CAPTURE streaming starts, which is where the encoding starts, but the
> > state of the OUTPUT queue should not affect this.
> >
> > The application is free to stop and start streaming on the OUTPUT
> > queue as it goes and it shouldn't imply any side effects in the
> > encoded bitstream (e.g. a keyframe inserted). So:
> > - a sequence of STREAMOFF(OUTPUT),
> > S_CTRL(V4L2_CID_MPEG_VIDEO_FORCE_KEY_FRAME), STREAMON(OUTPUT) should
> > explicitly generate a keyframe,
>
> I agree with you, but presently we don't follow strictly the stateful
> encoder spec. In this spirit I think proposed patch is applicable to 
> the
> current state of the encoder driver, and your comment should be
> addressed in the follow-up patches where we have to re-factor a bit
> start/stop_streaming according to the encoder documentation.
>
> But until then we have to get that patch.

So I can see that this patch is good implementation of forcing sync 
frame
under current encoder state.

Can you please ack the same.

Thanks,
Malathi.

> > - a sequence of STREAMOFF(OUTPUT), STREAMON(OUTPUT) should _not_
> > explicitly generate a keyframe (the hardware may generate one, if the
> > periodic keyframe counter is active or a scene detection algorithm
> > decides so).
> >
> > Please refer to the specification (v2 is the latest for the time being
> > -> https://lore.kernel.org/patchwork/patch/1002476/) for further
> > details and feel free to leave any comment for it.
> >
> > Best regards,
> > Tomasz