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Bug 1147744: Part2. Properly calculate cropping value. r=k17e

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If chroma_format_idc isn't defined, chroma_format_idc shall be inferred to be
equal to 1 (4:2:0 chroma format).
Also, ignore nonsensical cropping values as per spec.
This commit is contained in:
Jean-Yves Avenard 2015-04-08 14:26:38 +10:00
parent cb95c32927
commit dfb7ffd7e5
2 changed files with 49 additions and 15 deletions
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36
media/libstagefright/binding/H264.cpp
View File

@ -9,6 +9,7 @@
#include "mp4_demuxer/ByteWriter.h"
#include "mp4_demuxer/H264.h"
#include <media/stagefright/foundation/ABitReader.h>
#include <limits>
using namespace mozilla;
@ -74,6 +75,7 @@ SPSData::SPSData()
{
PodZero(this);
// Default values when they aren't defined as per ITU-T H.264 (2014/02).
chroma_format_idc = 1;
video_format = 5;
colour_primaries = 2;
transfer_characteristics = 2;
@ -182,6 +184,11 @@ H264::DecodeSPS(const ByteBuffer* aSPS, SPSData& aDest)
}
}
}
} else if (aDest.profile_idc == 183) {
aDest.chroma_format_idc = 0;
} else {
// default value if chroma_format_idc isn't set.
aDest.chroma_format_idc = 1;
}
aDest.log2_max_frame_num = br.ReadUE() + 4;
aDest.pic_order_cnt_type = br.ReadUE();
@ -222,8 +229,6 @@ H264::DecodeSPS(const ByteBuffer* aSPS, SPSData& aDest)
// Calculate common values.
// FFmpeg and VLC ignore the left and top cropping. Do the same here.
uint8_t ChromaArrayType =
aDest.separate_colour_plane_flag ? 0 : aDest.chroma_format_idc;
// Calculate width.
@ -232,16 +237,33 @@ H264::DecodeSPS(const ByteBuffer* aSPS, SPSData& aDest)
if (ChromaArrayType != 0) {
CropUnitX = SubWidthC;
}
uint32_t cropX = CropUnitX * aDest.frame_crop_right_offset;
aDest.pic_width = aDest.pic_width_in_mbs * 16 - cropX;
// Calculate Height
uint32_t CropUnitY = 2 - aDest.frame_mbs_only_flag;
uint32_t SubHeightC = aDest.chroma_format_idc <= 1 ? 2 : 1;
if (ChromaArrayType != 0)
if (ChromaArrayType != 0) {
CropUnitY *= SubHeightC;
uint32_t cropY = CropUnitY * aDest.frame_crop_bottom_offset;
aDest.pic_height = aDest.pic_height_in_map_units * 16 - cropY;
}
uint32_t width = aDest.pic_width_in_mbs * 16;
uint32_t height = aDest.pic_height_in_map_units * 16;
if (aDest.frame_crop_left_offset <= std::numeric_limits<int32_t>::max() / 4 / CropUnitX &&
aDest.frame_crop_right_offset <= std::numeric_limits<int32_t>::max() / 4 / CropUnitX &&
aDest.frame_crop_top_offset <= std::numeric_limits<int32_t>::max() / 4 / CropUnitY &&
aDest.frame_crop_bottom_offset <= std::numeric_limits<int32_t>::max() / 4 / CropUnitY &&
(aDest.frame_crop_left_offset + aDest.frame_crop_right_offset) * CropUnitX < width &&
(aDest.frame_crop_top_offset + aDest.frame_crop_bottom_offset) * CropUnitY < height) {
aDest.crop_left = aDest.frame_crop_left_offset * CropUnitX;
aDest.crop_right = aDest.frame_crop_right_offset * CropUnitX;
aDest.crop_top = aDest.frame_crop_top_offset * CropUnitY;
aDest.crop_bottom = aDest.frame_crop_bottom_offset * CropUnitY;
} else {
// Nonsensical value, ignore them.
aDest.crop_left = aDest.crop_right = aDest.crop_top = aDest.crop_bottom = 0;
}
aDest.pic_width = width - aDest.crop_left - aDest.crop_right;
aDest.pic_height = height - aDest.crop_top - aDest.crop_bottom;
aDest.interlaced = !aDest.frame_mbs_only_flag;

28
media/libstagefright/binding/include/mp4_demuxer/H264.h
View File

@ -40,6 +40,11 @@ struct SPSData
float sample_ratio;
uint32_t crop_left;
uint32_t crop_right;
uint32_t crop_top;
uint32_t crop_bottom;
/*
H264 decoding parameters according to ITU-T H.264 (T-REC-H.264-201402-I/en)
http://www.itu.int/rec/T-REC-H.264-201402-I/en
@ -68,18 +73,25 @@ struct SPSData
uint8_t seq_parameter_set_id;
/*
When the value of chroma_format_idc is equal to 1, the nominal vertical
and horizontal relative locations of luma and chroma samples in frames are
shown in Figure 6-1. Alternative chroma sample relative locations may be
indicated in video usability information (see Annex E).
chroma_format_idc specifies the chroma sampling relative to the luma
sampling as specified in clause 6.2. The value of chroma_format_idc shall be
in the range of 0 to 3, inclusive. When chroma_format_idc is not present,
it shall be inferred to be equal to 1 (4:2:0 chroma format).
When profile_idc is equal to 183, chroma_format_idc shall be equal to 0
(4:0:0 chroma format).
*/
uint8_t chroma_format_idc;
/*
If separate_colour_plane_flag is equal to 0, each of the two chroma arrays
has the same height and width as the luma array. Otherwise
(separate_colour_plane_flag is equal to 1), the three colour planes are
separately processed as monochrome sampled pictures.
separate_colour_plane_flag equal to 1 specifies that the three colour
components of the 4:4:4 chroma format are coded separately.
separate_colour_plane_flag equal to 0 specifies that the colour components
are not coded separately. When separate_colour_plane_flag is not present,
it shall be inferred to be equal to 0. When separate_colour_plane_flag is
equal to 1, the primary coded picture consists of three separate components,
each of which consists of coded samples of one colour plane (Y, Cb or Cr)
that each use the monochrome coding syntax. In this case, each colour plane
is associated with a specific colour_plane_id value.
*/
bool separate_colour_plane_flag;