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_arrangement(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 ?
Given in all other cases where this SEI is not present you don't know
if you can assume it's there or not ?
The flag signals that this frame is the left eye and the one coming
next is the right eye.
> All in all, what problem is this trying to solve?
Differentiate the left and right view for frame sequential 3D files.
> --
> Vittorio
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> libav-devel@libav.org
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