| Message ID | 20190610085250.3255-4-boris.brezillon@collabora.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | media: uapi: h264: First batch of adjusments | expand |
Hi, On Mon, 2019-06-10 at 10:52 +0200, Boris Brezillon wrote: > Those lists can be extracted from the dpb, let's simplify userspace > life and build that list kernel-side (generic helpers will be provided > for drivers that need this list). I don't really have any clear idea about that, but there was a discussion about DPB vs reference picture lists some weeks ago. Is there some mail thread with a rationale about it, some IRC logs I could look at or could the people involved in the discussion provide some additional background at this point? IIRC we also talked about removing the DPB or at least renaming it, but I don't have a clear idea of the outcome as well. Cheers, Paul > Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com> > --- > Changes in v2: > * None > --- > Documentation/media/uapi/v4l/ext-ctrls-codec.rst | 9 --------- > 1 file changed, 9 deletions(-) > > diff --git a/Documentation/media/uapi/v4l/ext-ctrls-codec.rst b/Documentation/media/uapi/v4l/ext-ctrls-codec.rst > index e3b9ab73a588..8be0ca5c96ab 100644 > --- a/Documentation/media/uapi/v4l/ext-ctrls-codec.rst > +++ b/Documentation/media/uapi/v4l/ext-ctrls-codec.rst > @@ -1949,15 +1949,6 @@ enum v4l2_mpeg_video_h264_hierarchical_coding_type - > * - __u16 > - ``nal_ref_idc`` > - NAL reference ID value coming from the NAL Unit header > - * - __u8 > - - ``ref_pic_list_p0[32]`` > - - Backward reference list used by P-frames in the original bitstream order > - * - __u8 > - - ``ref_pic_list_b0[32]`` > - - Backward reference list used by B-frames in the original bitstream order > - * - __u8 > - - ``ref_pic_list_b1[32]`` > - - Forward reference list used by B-frames in the original bitstream order > * - __s32 > - ``top_field_order_cnt`` > - Picture Order Count for the coded top field
On Wed, 26 Jun 2019 13:33:41 +0200 Paul Kocialkowski <paul.kocialkowski@bootlin.com> wrote: > Hi, > > On Mon, 2019-06-10 at 10:52 +0200, Boris Brezillon wrote: > > Those lists can be extracted from the dpb, let's simplify userspace > > life and build that list kernel-side (generic helpers will be provided > > for drivers that need this list). > > I don't really have any clear idea about that, but there was a > discussion about DPB vs reference picture lists some weeks ago. What we call DPB right now is actually a list of reference pictures (each entry being flagged long or short term). When reading the spec, you said DPB was referring to something that's more implementation specific, and I think that's what motivated your initial suggestion to rename this field into something more appropriate (ref_pics?). TBH, I'm just guessing here, since you were the one initially proposing this change, and I must say that having to explain what you had in mind at that time is a bit weird :P. > > Is there some mail thread with a rationale about it, some IRC logs I > could look at or could the people involved in the discussion provide > some additional background at this point? Well, you were part of the discussion, and I think most of it happened in the "Proposed updates and guidelines for MPEG-2, H.264 and H.265 stateless support" thread you started. > > IIRC we also talked about removing the DPB or at least renaming it, but > I don't have a clear idea of the outcome as well. The list of long/short refs has to be passed, and that's actually what we currently call "DPB", so we're just talking about a rename here, nothing more. The ordered P/B0/B1 reflists can easily be built from the un-ordered list of ref pics, so I'm just proposing to get rid of these fields and have a generic implementation kernel-side so that drivers that need it don't have to re-implement it.
diff --git a/Documentation/media/uapi/v4l/ext-ctrls-codec.rst b/Documentation/media/uapi/v4l/ext-ctrls-codec.rst index e3b9ab73a588..8be0ca5c96ab 100644 --- a/Documentation/media/uapi/v4l/ext-ctrls-codec.rst +++ b/Documentation/media/uapi/v4l/ext-ctrls-codec.rst @@ -1949,15 +1949,6 @@ enum v4l2_mpeg_video_h264_hierarchical_coding_type - * - __u16 - ``nal_ref_idc`` - NAL reference ID value coming from the NAL Unit header - * - __u8 - - ``ref_pic_list_p0[32]`` - - Backward reference list used by P-frames in the original bitstream order - * - __u8 - - ``ref_pic_list_b0[32]`` - - Backward reference list used by B-frames in the original bitstream order - * - __u8 - - ``ref_pic_list_b1[32]`` - - Forward reference list used by B-frames in the original bitstream order * - __s32 - ``top_field_order_cnt`` - Picture Order Count for the coded top field
Those lists can be extracted from the dpb, let's simplify userspace life and build that list kernel-side (generic helpers will be provided for drivers that need this list). Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com> --- Changes in v2: * None --- Documentation/media/uapi/v4l/ext-ctrls-codec.rst | 9 --------- 1 file changed, 9 deletions(-)