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pps.go
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pps.go
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package ps
import (
"errors"
"github.com/AlexxIT/go2rtc/pkg/h264/golomb"
)
const PPSHeader = 0x68
// https://www.itu.int/rec/T-REC-H.264
// 7.3.2.2 Picture parameter set RBSP syntax
type PPS struct{}
func (p *PPS) Marshal() []byte {
w := golomb.NewWriter()
// this is typical PPS for most H264 cameras
w.WriteByte(PPSHeader)
w.WriteUEGolomb(0) // pic_parameter_set_id
w.WriteUEGolomb(0) // seq_parameter_set_id
w.WriteBit(1) // entropy_coding_mode_flag
w.WriteBit(0) // bottom_field_pic_order_in_frame_present_flag
w.WriteUEGolomb(0) // num_slice_groups_minus1
w.WriteUEGolomb(0) // num_ref_idx_l0_default_active_minus1
w.WriteUEGolomb(0) // num_ref_idx_l1_default_active_minus1
w.WriteBit(0) // weighted_pred_flag
w.WriteBits(0, 2) // weighted_bipred_idc
w.WriteSEGolomb(0) // pic_init_qp_minus26
w.WriteSEGolomb(0) // pic_init_qs_minus26
w.WriteSEGolomb(0) // chroma_qp_index_offset
w.WriteBit(1) // deblocking_filter_control_present_flag
w.WriteBit(0) // constrained_intra_pred_flag
w.WriteBit(0) // redundant_pic_cnt_present_flag
w.WriteBit(1) // rbsp_trailing_bits()
return w.Bytes()
}
func (p *PPS) Unmarshal(data []byte) (err error) {
r := golomb.NewReader(data)
var b byte
var u uint
if b, err = r.ReadByte(); err != nil {
return
}
if b&0x1F != 8 {
err = errors.New("not PPS data")
return
}
// pic_parameter_set_id
if u, err = r.ReadUEGolomb(); err != nil {
return
}
// seq_parameter_set_id
if u, err = r.ReadUEGolomb(); err != nil {
return
}
// entropy_coding_mode_flag
if b, err = r.ReadBit(); err != nil {
return
}
// bottom_field_pic_order_in_frame_present_flag
if b, err = r.ReadBit(); err != nil {
return
}
// num_slice_groups_minus1
if u, err = r.ReadUEGolomb(); err != nil {
return
}
if u > 0 {
//panic("not implemented")
return nil
}
// num_ref_idx_l0_default_active_minus1
if _, err = r.ReadUEGolomb(); err != nil {
return
}
// num_ref_idx_l1_default_active_minus1
if _, err = r.ReadUEGolomb(); err != nil {
return
}
// weighted_pred_flag
if _, err = r.ReadBit(); err != nil {
return
}
// weighted_bipred_idc
if _, err = r.ReadBits(2); err != nil {
return
}
// pic_init_qp_minus26
if _, err = r.ReadSEGolomb(); err != nil {
return
}
// pic_init_qs_minus26
if _, err = r.ReadSEGolomb(); err != nil {
return
}
// chroma_qp_index_offset
if _, err = r.ReadSEGolomb(); err != nil {
return
}
// deblocking_filter_control_present_flag
if _, err = r.ReadBit(); err != nil {
return
}
// constrained_intra_pred_flag
if _, err = r.ReadBit(); err != nil {
return
}
// redundant_pic_cnt_present_flag
if _, err = r.ReadBit(); err != nil {
return
}
if !r.End() {
//panic("not implemented")
}
return
}