Le dimanche 12 juillet 2020 à 19:59 -0300, Ezequiel Garcia a écrit : > On Sat, 2020-07-11 at 10:21 +0000, Jonas Karlman wrote: > > On 2020-07-10 23:49, Nicolas Dufresne wrote: > > > Le vendredi 10 juillet 2020 à 09:25 -0300, Ezequiel Garcia a écrit : > > > > +Nicolas > > > > > > > > On Fri, 2020-07-10 at 14:05 +0200, Boris Brezillon wrote: > > > > > On Fri, 10 Jul 2020 08:50:28 -0300 > > > > > Ezequiel Garcia wrote: > > > > > > > > > > > On Fri, 2020-07-10 at 10:13 +0200, Boris Brezillon wrote: > > > > > > > On Fri, 10 Jul 2020 01:21:07 -0300 > > > > > > > Ezequiel Garcia wrote: > > > > > > > > > > > > > > > Hello Jonas, > > > > > > > > > > > > > > > > In the context of the uAPI cleanup, > > > > > > > > I'm revisiting this patch. > > > > > > > > > > > > > > > > On Sun, 2019-09-01 at 12:45 +0000, Jonas Karlman wrote: > > > > > > > > > Add DPB entry flags to help indicate when a reference frame is a > > > > > > > > > field picture > > > > > > > > > and how the DPB entry is referenced, top or bottom field or full > > > > > > > > > frame. > > > > > > > > > > > > > > > > > > Signed-off-by: Jonas Karlman > > > > > > > > > --- > > > > > > > > > Documentation/media/uapi/v4l/ext-ctrls-codec.rst | 12 ++++++++++++ > > > > > > > > > include/media/h264-ctrls.h | 4 ++++ > > > > > > > > > 2 files changed, 16 insertions(+) > > > > > > > > > > > > > > > > > > diff --git a/Documentation/media/uapi/v4l/ext-ctrls-codec.rst > > > > > > > > > b/Documentation/media/uapi/v4l/ext-ctrls-codec.rst > > > > > > > > > index bc5dd8e76567..eb6c32668ad7 100644 > > > > > > > > > --- a/Documentation/media/uapi/v4l/ext-ctrls-codec.rst > > > > > > > > > +++ b/Documentation/media/uapi/v4l/ext-ctrls-codec.rst > > > > > > > > > @@ -2022,6 +2022,18 @@ enum > > > > > > > > > v4l2_mpeg_video_h264_hierarchical_coding_type - > > > > > > > > > * - ``V4L2_H264_DPB_ENTRY_FLAG_LONG_TERM`` > > > > > > > > > - 0x00000004 > > > > > > > > > - The DPB entry is a long term reference frame > > > > > > > > > + * - ``V4L2_H264_DPB_ENTRY_FLAG_FIELD_PICTURE`` > > > > > > > > > + - 0x00000008 > > > > > > > > > + - The DPB entry is a field picture > > > > > > > > > + * - ``V4L2_H264_DPB_ENTRY_FLAG_REF_TOP`` > > > > > > > > > + - 0x00000010 > > > > > > > > > + - The DPB entry is a top field reference > > > > > > > > > + * - ``V4L2_H264_DPB_ENTRY_FLAG_REF_BOTTOM`` > > > > > > > > > + - 0x00000020 > > > > > > > > > + - The DPB entry is a bottom field reference > > > > > > > > > + * - ``V4L2_H264_DPB_ENTRY_FLAG_REF_FRAME`` > > > > > > > > > + - 0x00000030 > > > > > > > > > + - The DPB entry is a reference frame > > > > > > > > > > > > > > > > > > ``V4L2_CID_MPEG_VIDEO_H264_DECODE_MODE (enum)`` > > > > > > > > > Specifies the decoding mode to use. Currently exposes slice- > > > > > > > > > based and > > > > > > > > > diff --git a/include/media/h264-ctrls.h b/include/media/h264-ctrls.h > > > > > > > > > index e877bf1d537c..76020ebd1e6c 100644 > > > > > > > > > --- a/include/media/h264-ctrls.h > > > > > > > > > +++ b/include/media/h264-ctrls.h > > > > > > > > > @@ -185,6 +185,10 @@ struct v4l2_ctrl_h264_slice_params { > > > > > > > > > #define V4L2_H264_DPB_ENTRY_FLAG_VALID 0x01 > > > > > > > > > #define V4L2_H264_DPB_ENTRY_FLAG_ACTIVE 0x02 > > > > > > > > > #define V4L2_H264_DPB_ENTRY_FLAG_LONG_TERM 0x04 > > > > > > > > > +#define V4L2_H264_DPB_ENTRY_FLAG_FIELD_PICTURE 0x08 > > > > > > > > > +#define V4L2_H264_DPB_ENTRY_FLAG_REF_TOP 0x10 > > > > > > > > > +#define V4L2_H264_DPB_ENTRY_FLAG_REF_BOTTOM 0x20 > > > > > > > > > +#define V4L2_H264_DPB_ENTRY_FLAG_REF_FRAME 0x30 > > > > > > > > > > > > > > > > > > > > > > > > > I've been going thru the H264 spec and I'm unsure, > > > > > > > > are all these flags semantically needed? > > > > > > > > > > > > > > > > For instance, if one of REF_BOTTOM or REF_TOP (or both) > > > > > > > > are set, doesn't that indicate it's a field picture? > > > > > > > > > > > > > > > > Or conversely, if neither REF_BOTTOM or REF_TOP are set, > > > > > > > > then it's a frame picture? > > > > > > > > > > > > > > I think that's what I was trying to do here [1] > > > > > > > > > > > > > > [1]https://patchwork.kernel.org/patch/11392095/ > > > > > > > > > > > > Right. Aren't we missing a DPB_ENTRY_FLAG_TOP_FIELD? > > > > > > > > > > > > If I understand correctly, the DPB can contain: > > > > > > > > > > > > * frames (FLAG_FIELD not set) > > > > > > * a field pair, with a single field (FLAG_FIELD and either TOP or BOTTOM). > > > > > > * a field pair, with boths fields (FLAG_FIELD and both TOP or BOTTOM). > > > > > > > > > > Well, my understand is that, if the buffer contains both a TOP and > > > > > BOTTOM field, it actually becomes a full frame, so you actually have > > > > > those cases: > > > > > > > > > > * FLAG_FIELD not set: this a frame (note that a TOP/BOTTOM field > > > > > decoded buffer can become of frame if it's complemented with the > > > > > missing field later during the decoding) > > > > > * FLAG_FIELD set + BOTTOM_FIELD not set: this is a TOP field > > > > > * FLAG_FIELD set + BOTTOM_FIELD set: this is a BOTTOM field > > > > > * FLAG_FIELD not set + BOTTOM_FIELD set: invalid combination > > > > > > Let's admit, while this work, it's odd. Can we just move to that instewad ? > > > > > > FLAG_TOP_FIELD > > > FLAG_BOTTOM_FIELD > > > FLAG_FRAME = (FLAG_TOP_FIELD | FLAG_BOTTOM_FIELD) > > > > > > So it can be used as a flag, but also is a proper enum and there is no longer an > > > invalid combination. > > > > > > > > but I might be wrong. > > > > There seems to be some misunderstanding here, the top/bottom flagging should > > not be used to describe if the picture is a field, field pair or frame, it > > should be used to flag if a frame or the top and/or bottom field (in case of > > a field pair) is "used for short-term reference". > > > > I'm not sure why "used for short-term reference" instead > of "used for reference". > > > FLAG_TOP_REF > > FLAG_BOTTOM_REF > > FLAG_FRAME_REF = (FLAG_TOP_REF | FLAG_BOTTOM_REF) > > > > Would be a more appropriate naming. > > > > The FIELD_PIC flag would then be used to describe if the picture is a > > reference frame or a complementary reference field pair. > > > > As described in hantro h264 driver [1] the MV buffer is split in two > > for field encoded frames, and I guess the rkvdec block does something > > similar and therefore the HW blocks probably needs to know if the reference > > picture is a reference frame or a complementary reference field pair. > > It should be possible to keep such state in driver but since such information > > was easily available in ffmpeg and the driver being "stateless" using a flag > > seamed like a good choice at the time. > > > > Please note that I have not done any test without the "field pic" flagging > > but both mpp and the imx/hantro reference code are configuring this bit. > > > > [1] https://git.linuxtv.org/media_tree.git/tree/drivers/staging/media/hantro/hantro_g1_h264_dec.c#n265 > > > > How about this: > > #define V4L2_H264_DPB_ENTRY_FLAG_VALID 0x01 > #define V4L2_H264_DPB_ENTRY_FLAG_ACTIVE 0x02 > #define V4L2_H264_DPB_ENTRY_FLAG_LONG_TERM 0x04 > #define V4L2_H264_DPB_ENTRY_FLAG_FIELD 0x08 > > enum v4l2_h264_dpb_reference { > V4L2_H264_DPB_TOP_REF = 0x1, > V4L2_H264_DPB_BOTTOM_REF = 0x2, > V4L2_H264_DPB_FRAME_REF = 0x3, > }; > > With the following semantics (which should be > specified in the documentation): > > * VALID: non-empty DPB entry. > * ACTIVE: picture is marked as "used for reference" (short-term or long-term). > * LONG_TERM: picture is marked as "used for long-term". > * FIELD: picture is a single field, or a complementary field pair. > > The v4l2_h264_dpb_reference enum would flag which > of the fields as used for reference. > > This enum seems less ambiguous and easier to use for both > drivers and applications. > > I am not exactly sure why a driver would ever need to > configure an "unused for reference" decoded picture > (i.e. VALID=1, ACTIVE=0), but I guess it's just clearer > to include this in the interface. Indeed, that might have leaked from what we do in userspace, were we need to track this. I haven't seen anything that would do concealment or anything anyway. I don't have definitive opinion on the above, but I think it's getting in the right direction. > > Thanks, > Ezequiel > > > Regards, > > Jonas > > > > > > Yes, perhaps that's correct. I was trying to think strictly > > > > in terms of the H264 semantics, to define a clean interface. > > > > > > > > From the mpp code, looks like the above is enough for rkvdec > > > > (although I haven't done any tests). > > > > > > > > Ezequiel > > > > > > > > > > > > > >