h264: full SPS parsing

[mildsunrise]

Please review #252 first, as it's a dependency for this PR.

Extends H264SeqParameterSet to parse the full descriptor (right now it's not parsing the VUI).

I've basically adapted the code from nal-extractor: https://github.com/medooze/nal-extractor/blob/main/lib/SPS.ts https://github.com/medooze/nal-extractor/blob/main/test/SPS.test.ts

output for:

64001eacb2010020f3cf80b5060606a50000030001000003003c9f162e48

is:

[H264SeqParameterSet
    profile_idc=64
    constraint_set0_flag=0
    constraint_set1_flag=0
    constraint_set2_flag=0
    reserved_zero_5bits=0
    level_idc=1e
    seq_parameter_set_id=0
    log2_max_frame_num_minus4=0
    pic_order_cnt_type=2
    log2_max_pic_order_cnt_lsb_minus4=0
    delta_pic_order_always_zero_flag=0
    offset_for_non_ref_pic=0
    offset_for_top_to_bottom_field=0
    num_ref_frames_in_pic_order_cnt_cycle=0
    num_ref_frames=3
    gaps_in_frame_num_value_allowed_flag=0
    pic_width_in_mbs_minus1=31
    pic_height_in_map_units_minus1=31
    frame_mbs_only_flag=1
    mb_adaptive_frame_field_flag=0
    direct_8x8_inference_flag=1
    frame_crop=[
        left_offset=0
        right_offset=6
        top_offset=0
        bottom_offset=6
    ]
    vui_parameters=[
        aspect_ratio_info=[
            aspect_ratio_idc=1
        ]
        overscan_info=[
            <Not present>
        ]
        video_signal_type=[
            video_format=5
            video_full_range_flag=0
            colour_description=[
                colour_primaries=6
                transfer_characteristics=6
                matrix_coefficients=6
            ]
        ]
        chroma_loc_info=[
            type_top_field=1
            type_bottom_field=1
        ]
        timing_info=[
            num_units_in_tick=1
            time_scale=61
            fixed_frame_rate_flag=1
        ]
        nal_hrd_parameters=[
            <Not present>
        ]
        vcl_hrd_parameters=[
            <Not present>
        ]
        pic_struct_present_flag=1
        bitstream_restriction=[
            motion_vectors_over_pic_boundaries_flag=1
            max_bytes_per_pic_denom=0
            max_bits_per_mb_denom=0
            log2_max_mv_length_horizontal=10
            log2_max_mv_length_vertical=10
            max_num_reorder_frames=0
            max_dec_frame_buffering=3
        ]
    ]
    separate_colour_plane_flag=0
[/H264SeqParameterSet]

For some reason time_scale says 61 rather than 60. I'll investigate later.

[mildsunrise]

(rebased)

[murillo128]

is this ready for review?

[mildsunrise]

it is missing a relatively small change for it to compile without RTTI. sorry, I'll push that change tomorrow. for all other intents and purposes, this can be considered ready to review yes

[murillo128]

I think we should add exceptions to bitstream readers/writters before merging this PR as I think we can simplify the code a lot once the exceptions are included.