On Thu, Sep 21, 2017 at 5:40 PM, Steve Lhomme <rob...@gmail.com> wrote:
> On Thu, Sep 21, 2017 at 4:58 PM, Vittorio Giovara
> <vittorio.giov...@gmail.com> wrote:
> > On Thu, Sep 21, 2017 at 4:03 PM, Steve Lhomme <rob...@gmail.com> wrote:
> >
> >> From: "Mohammed (Shaan) Huzaifa Danish" <sha...@gmail.com>
> >>
> >> ---
> >> fix previous patch skipping the wrong amount of bits
> >> ---
> >> libavcodec/h264_sei.c | 6 ++++--
> >> libavcodec/h264_sei.h | 1 +
> >> libavcodec/h264_slice.c | 2 ++
> >> libavutil/stereo3d.h | 4 ++++
> >> 4 files changed, 11 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/libavcodec/h264_sei.c b/libavcodec/h264_sei.c
> >> index 03fca9017f..96ac427931 100644
> >> --- a/libavcodec/h264_sei.c
> >> +++ b/libavcodec/h264_sei.c
> >> @@ -315,9 +315,11 @@ static int decode_frame_packing_arrangeme
> nt(H264SEIFramePacking
> >> *h,
> >> h->content_interpretation_type = get_bits(gb, 6);
> >>
> >> // the following skips: spatial_flipping_flag,
> >> frame0_flipped_flag,
> >> - // field_views_flag, current_frame_is_frame0_flag,
> >> + // field_views_flag
> >> + skip_bits(gb, 3);
> >> + h->current_frame_is_frame0_flag = get_bits1(gb);
> >> // frame0_self_contained_flag, frame1_self_contained_flag
> >> - skip_bits(gb, 6);
> >> + skip_bits(gb, 2);
> >>
> >> if (!h->quincunx_subsampling && h->arrangement_type != 5)
> >> skip_bits(gb, 16); // frame[01]_grid_position_[xy]
> >> diff --git a/libavcodec/h264_sei.h b/libavcodec/h264_sei.h
> >> index f6ac6034da..c3a19dd831 100644
> >> --- a/libavcodec/h264_sei.h
> >> +++ b/libavcodec/h264_sei.h
> >> @@ -108,6 +108,7 @@ typedef struct H264SEIFramePacking {
> >> int arrangement_type;
> >> int content_interpretation_type;
> >> int quincunx_subsampling;
> >> + int current_frame_is_frame0_flag;
> >> } H264SEIFramePacking;
> >>
> >> typedef struct H264SEIDisplayOrientation {
> >> diff --git a/libavcodec/h264_slice.c b/libavcodec/h264_slice.c
> >> index 5dd01d836e..f5b78bfe29 100644
> >> --- a/libavcodec/h264_slice.c
> >> +++ b/libavcodec/h264_slice.c
> >> @@ -1112,6 +1112,8 @@ static int h264_export_frame_props(H264Context
> *h)
> >>
> >> if (fp->content_interpretation_type == 2)
> >> stereo->flags = AV_STEREO3D_FLAG_INVERT;
> >> + if (fp->current_frame_is_frame0_flag)
> >> + stereo->flags |= AV_STEREO3D_FLAG_FRAME0;
> >> }
> >>
> >> if (h->sei.display_orientation.present &&
> >> diff --git a/libavutil/stereo3d.h b/libavutil/stereo3d.h
> >> index 0fa9f63a2c..4c8ab5c40a 100644
> >> --- a/libavutil/stereo3d.h
> >> +++ b/libavutil/stereo3d.h
> >> @@ -146,6 +146,10 @@ enum AVStereo3DType {
> >> * Inverted views, Right/Bottom represents the left view.
> >> */
> >> #define AV_STEREO3D_FLAG_INVERT (1 << 0)
> >> +/**
> >> + * This frame is frame0 (left view), otherwise it's the right view.
> >> + */
> >> +#define AV_STEREO3D_FLAG_FRAME0 (1 << 1)
> >>
> >
> > Hey Steve,
> > I would rather not expose a flag for something this specific (as it
> applies
> > to a single type only).
> > The name is also peculiar, and confusing, the left view has always
> priority
> > so that should be the default variant (ie no flag).
>
> If left is the default, how do you signal that it's the right eye ?
>
You can keep track of the decoded frames, if frame_num%2 == 1 it means
you're on a right view.
> Given in all other cases where this SEI is not present you don't know
> if you can assume it's there or not ?
if you want, given that the left view has priority, you could do something
like
if packing_type == 5
if flag0 == 0
flags |= invert
else
flags = 0
> The flag signals that this frame is the left eye and the one coming
> next is the right eye.
>
I'm not sure that's the best approach because this flag would be for a very
specific packing type only, and not generic (like the inverted one).
Do you have a sample available?
--
Vittorio
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