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/*
* Copyright (C) 2010 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "include/avc_utils.h"
#include <media/stagefright/foundation/ABitReader.h>
#include <media/stagefright/foundation/ADebug.h>
namespace android {
unsigned parseUE(ABitReader *br) {
unsigned numZeroes = 0;
while (br->getBits(1) == 0) {
++numZeroes;
}
unsigned x = br->getBits(numZeroes);
return x + (1u << numZeroes) - 1;
}
// Determine video dimensions from the sequence parameterset.
void FindAVCDimensions(
const sp<ABuffer> &seqParamSet, int32_t *width, int32_t *height) {
ABitReader br(seqParamSet->data() + 1, seqParamSet->size() - 1);
unsigned profile_idc = br.getBits(8);
br.skipBits(16);
parseUE(&br); // seq_parameter_set_id
unsigned chroma_format_idc = 1; // 4:2:0 chroma format
if (profile_idc == 100 || profile_idc == 110
|| profile_idc == 122 || profile_idc == 244
|| profile_idc == 44 || profile_idc == 83 || profile_idc == 86) {
chroma_format_idc = parseUE(&br);
if (chroma_format_idc == 3) {
br.skipBits(1); // residual_colour_transform_flag
}
parseUE(&br); // bit_depth_luma_minus8
parseUE(&br); // bit_depth_chroma_minus8
br.skipBits(1); // qpprime_y_zero_transform_bypass_flag
CHECK_EQ(br.getBits(1), 0u); // seq_scaling_matrix_present_flag
}
parseUE(&br); // log2_max_frame_num_minus4
unsigned pic_order_cnt_type = parseUE(&br);
if (pic_order_cnt_type == 0) {
parseUE(&br); // log2_max_pic_order_cnt_lsb_minus4
} else if (pic_order_cnt_type == 1) {
// offset_for_non_ref_pic, offset_for_top_to_bottom_field and
// offset_for_ref_frame are technically se(v), but since we are
// just skipping over them the midpoint does not matter.
br.getBits(1); // delta_pic_order_always_zero_flag
parseUE(&br); // offset_for_non_ref_pic
parseUE(&br); // offset_for_top_to_bottom_field
unsigned num_ref_frames_in_pic_order_cnt_cycle = parseUE(&br);
for (unsigned i = 0; i < num_ref_frames_in_pic_order_cnt_cycle; ++i) {
parseUE(&br); // offset_for_ref_frame
}
}
parseUE(&br); // num_ref_frames
br.getBits(1); // gaps_in_frame_num_value_allowed_flag
unsigned pic_width_in_mbs_minus1 = parseUE(&br);
unsigned pic_height_in_map_units_minus1 = parseUE(&br);
unsigned frame_mbs_only_flag = br.getBits(1);
*width = pic_width_in_mbs_minus1 * 16 + 16;
*height = (2 - frame_mbs_only_flag)
* (pic_height_in_map_units_minus1 * 16 + 16);
if (!frame_mbs_only_flag) {
br.getBits(1); // mb_adaptive_frame_field_flag
}
br.getBits(1); // direct_8x8_inference_flag
if (br.getBits(1)) { // frame_cropping_flag
unsigned frame_crop_left_offset = parseUE(&br);
unsigned frame_crop_right_offset = parseUE(&br);
unsigned frame_crop_top_offset = parseUE(&br);
unsigned frame_crop_bottom_offset = parseUE(&br);
unsigned cropUnitX, cropUnitY;
if (chroma_format_idc == 0 /* monochrome */) {
cropUnitX = 1;
cropUnitY = 2 - frame_mbs_only_flag;
} else {
unsigned subWidthC = (chroma_format_idc == 3) ? 1 : 2;
unsigned subHeightC = (chroma_format_idc == 1) ? 2 : 1;
cropUnitX = subWidthC;
cropUnitY = subHeightC * (2 - frame_mbs_only_flag);
}
LOGV("frame_crop = (%u, %u, %u, %u), cropUnitX = %u, cropUnitY = %u",
frame_crop_left_offset, frame_crop_right_offset,
frame_crop_top_offset, frame_crop_bottom_offset,
cropUnitX, cropUnitY);
*width -=
(frame_crop_left_offset + frame_crop_right_offset) * cropUnitX;
*height -=
(frame_crop_top_offset + frame_crop_bottom_offset) * cropUnitY;
}
}
} // namespace android
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