Alexey Khit
280 lines
7.3 KiB
Go
280 lines
7.3 KiB
Go
package ps
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import (
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"errors"
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"github.com/AlexxIT/go2rtc/pkg/h264/golomb"
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)
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const firstByte = 0x67
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// Google to "h264 specification pdf"
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// https://www.itu.int/rec/dologin_pub.asp?lang=e&id=T-REC-H.264-201602-S!!PDF-E&type=items
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type SPS struct {
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Profile string
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ProfileIDC uint8
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ProfileIOP uint8
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LevelIDC uint8
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Width uint16
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Height uint16
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}
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func NewSPS(profile string, level uint8, width uint16, height uint16) *SPS {
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s := &SPS{
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Profile: profile, LevelIDC: level, Width: width, Height: height,
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}
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s.ProfileIDC, s.ProfileIOP = DecodeProfile(profile)
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return s
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}
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// https://www.cardinalpeak.com/blog/the-h-264-sequence-parameter-set
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func (s *SPS) Marshal() []byte {
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w := golomb.NewWriter()
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// this is typical SPS for most H264 cameras
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w.WriteByte(firstByte)
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w.WriteByte(s.ProfileIDC)
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w.WriteByte(s.ProfileIOP)
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w.WriteByte(s.LevelIDC)
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w.WriteUEGolomb(0) // seq_parameter_set_id (0)
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w.WriteUEGolomb(0) // log2_max_frame_num_minus4 (depends)
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w.WriteUEGolomb(0) // pic_order_cnt_type (0 or 2)
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w.WriteUEGolomb(0) // log2_max_pic_order_cnt_lsb_minus4 (depends)
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w.WriteUEGolomb(1) // num_ref_frames (1)
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w.WriteBit(0) // gaps_in_frame_num_value_allowed_flag (0)
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w.WriteUEGolomb(uint8(s.Width>>4) - 1) // pic_width_in_mbs_minus_1
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w.WriteUEGolomb(uint8(s.Height>>4) - 1) // pic_height_in_map_units_minus_1
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w.WriteBit(1) // frame_mbs_only_flag (1)
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w.WriteBit(1) // direct_8x8_inference_flag (1)
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w.WriteBit(0) // frame_cropping_flag (0 is OK)
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w.WriteBit(0) // vui_prameters_present_flag (0 is OK)
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w.WriteBit(1) // rbsp_stop_one_bit
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return w.Bytes()
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}
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func (s *SPS) Unmarshal(data []byte) (err error) {
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r := golomb.NewReader(data)
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var b byte
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var u uint
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if b, err = r.ReadByte(); err != nil {
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return
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}
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if b&0x1F != 7 {
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err = errors.New("not SPS data")
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return
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}
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if s.ProfileIDC, err = r.ReadByte(); err != nil {
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return
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}
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if s.ProfileIOP, err = r.ReadByte(); err != nil {
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return
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}
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if s.LevelIDC, err = r.ReadByte(); err != nil {
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return
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}
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s.Profile = EncodeProfile(s.ProfileIDC, s.ProfileIOP)
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u, err = r.ReadUEGolomb() // seq_parameter_set_id
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if s.ProfileIDC == 100 || s.ProfileIDC == 110 || s.ProfileIDC == 122 ||
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s.ProfileIDC == 244 || s.ProfileIDC == 44 || s.ProfileIDC == 83 ||
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s.ProfileIDC == 86 || s.ProfileIDC == 118 || s.ProfileIDC == 128 ||
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s.ProfileIDC == 138 || s.ProfileIDC == 139 || s.ProfileIDC == 134 ||
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s.ProfileIDC == 135 {
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var n byte
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u, err = r.ReadUEGolomb() // chroma_format_idc
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if u == 3 {
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b, err = r.ReadBit() // separate_colour_plane_flag
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n = 12
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} else {
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n = 8
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}
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u, err = r.ReadUEGolomb() // bit_depth_luma_minus8
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u, err = r.ReadUEGolomb() // bit_depth_chroma_minus8
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b, err = r.ReadBit() // qpprime_y_zero_transform_bypass_flag
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b, err = r.ReadBit() // seq_scaling_matrix_present_flag
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if b > 0 {
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for i := byte(0); i < n; i++ {
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b, err = r.ReadBit() // seq_scaling_list_present_flag[i]
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if b > 0 {
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panic("not implemented")
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}
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}
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}
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}
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u, err = r.ReadUEGolomb() // log2_max_frame_num_minus4
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u, err = r.ReadUEGolomb() // pic_order_cnt_type
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switch u {
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case 0:
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u, err = r.ReadUEGolomb() // log2_max_pic_order_cnt_lsb_minus4
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case 1:
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b, err = r.ReadBit() // delta_pic_order_always_zero_flag
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_, err = r.ReadSEGolomb() // offset_for_non_ref_pic
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_, err = r.ReadSEGolomb() // offset_for_top_to_bottom_field
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u, err = r.ReadUEGolomb() // num_ref_frames_in_pic_order_cnt_cycle
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for i := byte(0); i < b; i++ {
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_, err = r.ReadSEGolomb() // offset_for_ref_frame[i]
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}
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}
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u, err = r.ReadUEGolomb() // num_ref_frames
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b, err = r.ReadBit() // gaps_in_frame_num_value_allowed_flag
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u, err = r.ReadUEGolomb() // pic_width_in_mbs_minus_1
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s.Width = uint16(u+1) << 4
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u, err = r.ReadUEGolomb() // pic_height_in_map_units_minus_1
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s.Height = uint16(u+1) << 4
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b, err = r.ReadBit() // frame_mbs_only_flag
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if b == 0 {
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_, err = r.ReadBit()
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}
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b, err = r.ReadBit() // direct_8x8_inference_flag
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b, err = r.ReadBit() // frame_cropping_flag
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if b > 0 {
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u, err = r.ReadUEGolomb() // frame_crop_left_offset
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s.Width -= uint16(u) << 1
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u, err = r.ReadUEGolomb() // frame_crop_right_offset
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s.Width -= uint16(u) << 1
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u, err = r.ReadUEGolomb() // frame_crop_top_offset
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s.Height -= uint16(u) << 1
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u, err = r.ReadUEGolomb() // frame_crop_bottom_offset
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s.Height -= uint16(u) << 1
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}
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b, err = r.ReadBit() // vui_prameters_present_flag
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if b > 0 {
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b, err = r.ReadBit() // vui_prameters_present_flag
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if b > 0 {
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u, err = r.ReadBits(8) // aspect_ratio_idc
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if b == 255 {
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u, err = r.ReadBits(16) // sar_width
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u, err = r.ReadBits(16) // sar_height
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}
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}
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b, err = r.ReadBit() // overscan_info_present_flag
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if b > 0 {
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b, err = r.ReadBit() // overscan_appropriate_flag
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}
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b, err = r.ReadBit() // video_signal_type_present_flag
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if b > 0 {
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u, err = r.ReadBits(3) // video_format
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b, err = r.ReadBit() // video_full_range_flag
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b, err = r.ReadBit() // colour_description_present_flag
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if b > 0 {
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u, err = r.ReadBits(8) // colour_primaries
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u, err = r.ReadBits(8) // transfer_characteristics
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u, err = r.ReadBits(8) // matrix_coefficients
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}
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}
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b, err = r.ReadBit() // chroma_loc_info_present_flag
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if b > 0 {
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u, err = r.ReadUEGolomb() // chroma_sample_loc_type_top_field
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u, err = r.ReadUEGolomb() // chroma_sample_loc_type_bottom_field
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}
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b, err = r.ReadBit() // timing_info_present_flag
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if b > 0 {
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u, err = r.ReadBits(32) // num_units_in_tick
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u, err = r.ReadBits(32) // time_scale
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b, err = r.ReadBit() // fixed_frame_rate_flag
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}
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b, err = r.ReadBit() // nal_hrd_parameters_present_flag
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if b > 0 {
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//panic("not implemented")
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return nil
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}
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b, err = r.ReadBit() // vcl_hrd_parameters_present_flag
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if b > 0 {
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//panic("not implemented")
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return nil
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}
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// if (nal_hrd_parameters_present_flag || vcl_hrd_parameters_present_flag)
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// b, err = r.ReadBit() // low_delay_hrd_flag
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b, err = r.ReadBit() // pic_struct_present_flag
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b, err = r.ReadBit() // bitstream_restriction_flag
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if b > 0 {
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b, err = r.ReadBit() // motion_vectors_over_pic_boundaries_flag
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u, err = r.ReadUEGolomb() // max_bytes_per_pic_denom
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u, err = r.ReadUEGolomb() // max_bits_per_mb_denom
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u, err = r.ReadUEGolomb() // log2_max_mv_length_horizontal
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u, err = r.ReadUEGolomb() // log2_max_mv_length_vertical
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u, err = r.ReadUEGolomb() // max_num_reorder_frames
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u, err = r.ReadUEGolomb() // max_dec_frame_buffering
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}
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}
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b, err = r.ReadBit() // rbsp_stop_one_bit
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return
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}
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func EncodeProfile(idc, iop byte) string {
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// https://datatracker.ietf.org/doc/html/rfc6184#page-41
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switch {
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// 4240xx 42C0xx 42E0xx
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case idc == 0x42 && iop&0b01001111 == 0b01000000:
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return "CB"
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case idc == 0x4D && iop&0b10001111 == 0b10000000:
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return "CB"
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case idc == 0x58 && iop&0b11001111 == 0b11000000:
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return "CB"
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// 4200xx
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case idc == 0x42 && iop&0b01001111 == 0:
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return "B"
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case idc == 0x58 && iop&0b11001111 == 0b10000000:
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return "B"
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// 4d40xx
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case idc == 0x4D && iop&0b10101111 == 0:
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return "M"
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case idc == 0x58 && iop&0b11001111 == 0:
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return "E"
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case idc == 0x64 && iop == 0:
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return "H"
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case idc == 0x6E && iop == 0:
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return "H10"
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}
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return ""
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}
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func DecodeProfile(profile string) (idc, iop byte) {
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switch profile {
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case "CB":
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return 0x42, 0b01000000
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case "B":
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return 0x42, 0 // 66
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case "M":
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return 0x4D, 0 // 77
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case "E":
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return 0x58, 0 // 88
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case "H":
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return 0x64, 0
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}
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return 0, 0
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}
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