OBU WIP

avif.odin

@@ -7,7 +7,7 @@ import "core:encoding/endian"
 import "core:io"
 import "core:strings"
 
-Error :: image.Error
+//Error :: image.Error
 //Image   :: image.Image
 Options :: image.Options
 
@@ -130,14 +130,14 @@ read_box :: proc(img: ^Image, reader: ^Reader) -> (err: io.Error) {
     }
 
     // if the Box has a size 0 then it's the last Box, parse it and return EOF
-    if reader.size == 0 {
+    if reader.box.size == 0 {
         err = .EOF
     }
 
-    fmt.println("box size:", reader.size)
+    fmt.println("box size:", reader.box.size)
-    fmt.println("type:", reader.type)
+    fmt.println("type:", reader.box.type)
 
-    #partial switch reader.type {
+    #partial switch reader.box.type {
         case .FTYP:
             read_ftyp(img, reader)
         case .META:
@@ -164,6 +164,8 @@ read_box :: proc(img: ^Image, reader: ^Reader) -> (err: io.Error) {
             read_colr(reader)
         case .IPMA:
             read_ipma(reader)
+        case .MDAT:
+            read_mdat(reader)
         case:
             // Skip unknown boxes
             skip_box(reader)
@@ -172,6 +174,15 @@ read_box :: proc(img: ^Image, reader: ^Reader) -> (err: io.Error) {
     return err
 }
 
+@(private)
+read_mdat :: proc(reader: ^Reader) {
+    // TODO:
+    read_obu(reader)
+    read_obu(reader)
+    read_obu(reader)
+    read_obu(reader)
+}
+
 @(private)
 read_ipma :: proc(reader: ^Reader) {
     vaf, _ := read_bitfield(reader, VersionAndFlags)

box.odin

@@ -3,12 +3,14 @@ package avif
 import "core:encoding/endian"
 import "core:fmt"
 import "core:io"
+import "core:math"
+import "core:image"
 import "core:strings"
 import "core:unicode/utf8"
 
 BOX_HEADER_SIZE :: 8 // 4 for box size, 4 for box type
 
-_BoxError :: enum {
+BoxError :: enum {
     ReadExceedsBox,
 }
 
@@ -33,125 +35,151 @@ BoxType :: enum u32 {
     CLLI = 'c' << 24 | 'l' << 16 | 'l' << 8 | 'i', // Content Light Level Info
 }
 
-BoxError :: union {
+Error :: union {
     io.Error,
-    _BoxError,
+    BoxError,
+    OBUError,
+    image.General_Image_Error,
 }
 
 Box :: struct {
     size: u32,
     type: BoxType,
+    pos: i64,
 }
 
 Reader :: struct {
-    using current_box: Box,
+    box: Box,
     s:                 []byte, // read-only buffer
     i:                 i64, // current reading index
-    box_pos:           i64, // Byte index for the Box
+    bits_read_in_byte: u8,
 }
 
 reader_init :: proc(r: ^Reader, s: []byte) {
     r.s = s
     r.i = 0
-    r.box_pos = 0
+    r.box.pos = 0
 }
 
-read_header :: proc(r: ^Reader) -> (err: BoxError) {
+read_header :: proc(r: ^Reader) -> (err: Error) {
-    r.box_pos = 0
+    r.box.pos = 0
-    r.size = read_u32be(r) or_return
+    r.box.size = read_u32be(r) or_return
     type := read_u32be(r) or_return
-    r.type = transmute(BoxType)type
+    r.box.type = transmute(BoxType)type
 
     return err
 }
 
-read_byte :: proc(r: ^Reader) -> (byte, BoxError) {
+read_bit :: proc(r: ^Reader) -> (bit: byte, err: Error) {
     if r.i >= i64(len(r.s)) {
         return 0, .EOF
     }
-    if r.box_pos >= i64(r.size) {
+    if r.box.size != 0 && r.box.pos >= i64(r.box.size) {
+        return 0, .ReadExceedsBox
+    }
+    byte := r.s[r.i]
+
+    // Get the bit that's after however many bits read starting from the MSB in the byte
+    bits := 8 - (r.bits_read_in_byte + 1)
+    b := (r.s[r.i:r.i+1][0] & auto_cast math.pow2_f32(bits)) >> bits
+    r.bits_read_in_byte += 1
+
+    if r.bits_read_in_byte == 8 {
+        r.i += 1
+        r.box.pos += 1
+        r.bits_read_in_byte = 0
+    }
+
+    return b, nil
+}
+
+read_byte :: proc(r: ^Reader) -> (byte, Error) {
+    if r.i >= i64(len(r.s)) {
+        return 0, .EOF
+    }
+    if r.box.size != 0 && r.box.pos >= i64(r.box.size) {
         return 0, .ReadExceedsBox
     }
     b := r.s[r.i]
     r.i += 1
-    r.box_pos += 1
+    r.box.pos += 1
     return b, nil
 }
 
-read_u16be :: proc(r: ^Reader) -> (u16, BoxError) {
+read_u16be :: proc(r: ^Reader) -> (u16, Error) {
     if r.i >= i64(len(r.s)) {
         return 0, .EOF
     }
-    if r.box_pos + 2 > i64(r.size) {
+    if r.box.size != 0 && r.box.pos + 2 > i64(r.box.size) {
         return 0, .ReadExceedsBox
     }
     b := endian.unchecked_get_u16be(r.s[r.i:])
     r.i += 2
-    r.box_pos += 2
+    r.box.pos += 2
     return b, nil
 }
 
-read_u32be :: proc(r: ^Reader) -> (u32, BoxError) {
+read_u32be :: proc(r: ^Reader) -> (u32, Error) {
     if r.i >= i64(len(r.s)) {
         return 0, .EOF
     }
-    if r.size != 0 && r.box_pos + 4 > i64(r.size) {
+    if r.box.size != 0 && r.box.pos + 4 > i64(r.box.size) {
         return 0, .ReadExceedsBox
     }
     b := endian.unchecked_get_u32be(r.s[r.i:])
     r.i += 4
-    r.box_pos += 4
+    r.box.pos += 4
     return b, nil
 }
 
-read_u64be :: proc(r: ^Reader) -> (u64, BoxError) {
+read_u64be :: proc(r: ^Reader) -> (u64, Error) {
     if r.i >= i64(len(r.s)) {
         return 0, .EOF
     }
-    if r.size != 0 && r.box_pos + 8 > i64(r.size) {
+    if r.box.size != 0 && r.box.pos + 8 > i64(r.box.size) {
         return 0, .ReadExceedsBox
     }
     b := endian.unchecked_get_u64be(r.s[r.i:])
     r.i += 8
-    r.box_pos += 8
+    r.box.pos += 8
     return b, nil
 }
 
-read_slice :: proc(r: ^Reader, s: []byte) -> (n: int, err: BoxError) {
+read_slice :: proc(r: ^Reader, s: []byte) -> (n: int, err: Error) {
     if r.i >= i64(len(r.s)) {
         return 0, .EOF
     }
     n = copy(s, r.s[r.i:])
-    if r.box_pos + i64(n) > i64(r.size) {
+    if r.box.pos + i64(n) > i64(r.box.size) {
         return 0, .ReadExceedsBox
     }
     r.i += i64(n)
-    r.box_pos += i64(n)
+    r.box.pos += i64(n)
     return
 }
 
-read_rune :: proc(r: ^Reader) -> (ch: rune, size: int, err: BoxError) {
+read_rune :: proc(r: ^Reader) -> (ch: rune, size: int, err: Error) {
     if r.i >= i64(len(r.s)) {
         return 0, 0, .EOF
     }
     if c := r.s[r.i]; c < utf8.RUNE_SELF {
-        if r.box_pos >= i64(r.size) {
+        if r.box.pos >= i64(r.box.size) {
             return 0, 0, .ReadExceedsBox
         }
         r.i += 1
-        r.box_pos += 1
+        r.box.pos += 1
         return rune(c), 1, nil
     }
     ch, size = utf8.decode_rune(r.s[r.i:])
-    if r.box_pos + i64(size) > i64(r.size) {
+    if r.box.pos + i64(size) > i64(r.box.size) {
         return 0, 0, .ReadExceedsBox
     }
     r.i += i64(size)
-    r.box_pos += i64(size)
+    r.box.pos += i64(size)
     return
 }
 
-read_string :: proc(r: ^Reader) -> (str: string, err: BoxError) {
+read_string :: proc(r: ^Reader) -> (str: string, err: Error) {
     if r.i >= i64(len(r.s)) {
         return "", .EOF
     }
@@ -173,32 +201,39 @@ read_string :: proc(r: ^Reader) -> (str: string, err: BoxError) {
 }
 
 @(private = "file")
-read_bitfield_u32 :: proc(r: ^Reader, $T: typeid) -> (T, BoxError) where size_of(T) == 4 {
+read_bitfield_u32 :: proc(r: ^Reader, $T: typeid) -> (T, Error) where size_of(T) == 4 {
     b, err := read_u32be(r)
     return T(b), err
 }
 
 @(private = "file")
-read_bitfield_u16 :: proc(r: ^Reader, $T: typeid) -> (T, BoxError) where size_of(T) == 2 {
+read_bitfield_u16 :: proc(r: ^Reader, $T: typeid) -> (T, Error) where size_of(T) == 2 {
     b, err := read_u16be(r)
     return T(b), err
 }
 
+@(private = "file")
+read_bitfield_u8 :: proc(r: ^Reader, $T: typeid) -> (T, Error) where size_of(T) == 1 {
+    b, err := read_byte(r)
+    return T(b), err
+}
+
 read_bitfield :: proc {
+    read_bitfield_u8,
     read_bitfield_u16,
     read_bitfield_u32,
 }
 
 skip_box :: proc(r: ^Reader) {
-    fmt.printfln("SKIPPED! %v with size %d", r.type, r.size)
+    fmt.printfln("SKIPPED! %v with size %d", r.box.type, r.box.size)
-    reader_seek(r, auto_cast r.size - BOX_HEADER_SIZE, .Current)
+    reader_seek(r, auto_cast r.box.size - BOX_HEADER_SIZE, .Current)
 }
 
 remaining_box_size :: proc(r: ^Reader) -> i64 {
-    return i64(r.size) - r.box_pos
+    return i64(r.box.size) - r.box.pos
 }
 
-reader_seek :: proc(r: ^Reader, offset: i64, whence: io.Seek_From) -> (i64, BoxError) {
+reader_seek :: proc(r: ^Reader, offset: i64, whence: io.Seek_From) -> (i64, Error) {
     abs: i64
     switch whence {
         case .Start:

obu.odin

@@ -1,5 +1,6 @@
 package avif
 
+import "core:fmt"
 import "core:io"
 
 OBUType :: enum u8 {
@@ -14,17 +15,76 @@ OBUType :: enum u8 {
     PADDING                = 15,
 }
 
-// TODO: write a nice bitstream reader
+OBUError :: enum {
-// ??? Still don't know how I want this to work
+    ReservedOBU,
-BitstreamReader :: struct {
+}
-    data: []byte,
+
-    pos: i64, // Number of bits read from the data slice
+ColorPrimaries :: enum u8 {
+    BT_709 = 1,
+    UNSPECIFIED = 2,
+    BT_470_M = 4,
+    BT_470_B_G = 5,
+    BT_601 = 6,
+    SMPTE_240 = 7,
+    GENERIC_FILM = 8,
+    BT_2020 = 9,
+    XYZ = 10,
+    SMPTE_431 = 11,
+    SMPTE_432 = 12,
+    EBU_3213 = 22,
+}
+
+TransferCharacteristic :: enum u8 {
+    RESERVED_0 = 0,
+    BT_709 = 1,
+    UNSPECIFIED = 2,
+    RESERVED_3 = 3,
+    BT_470_M = 4,
+    BT_470_B_G = 5,
+    BT_601 = 6,
+    SMPTE_240 = 7,
+    LINEAR = 8,
+    LOG_100 = 9,
+    LOG_100_SQRT10 = 10,
+    IEC_61966 = 11,
+    BT_1361 = 12,
+    SRGB = 13,
+    BT_2020_10_BIT = 14,
+    BT_2020_12_BIT = 15,
+    SMPTE_2084 = 16,
+    SMPTE_428 = 17,
+    HLG = 18,
+}
+
+MatrixCoefficient :: enum u8 {
+    IDENTITY = 0,
+    BT_709 = 1,
+    UNSPECIFIED = 2,
+    RESERVED_3 = 3,
+    FCC = 4,
+    BT_470_B_G = 5,
+    BT_601 = 6,
+    SMPTE_240 = 7,
+    SMPTE_YCGCO = 8,
+    BT_2020_NCL = 9,
+    BT_2020_CL = 10,
+    SMPTE_2085 = 11,
+    CHROMAT_NCL = 12,
+    CHROMAT_CL = 13,
+    ICTCP = 14,
+}
+
+ChromeSamplePosition :: enum u8 {
+    UNKNOWN = 0,
+    VERTICAL = 1,
+    COLOCATED = 2,
+    RESERVED = 3,
 }
 
 OBUHeader :: bit_field u8 {
     obu_reserved:       u8      | 1,
-    obu_has_size_field: u8      | 1,
+    obu_has_size_field: b8      | 1,
-    obu_extension_flag: u8      | 1,
+    obu_extension_flag: b8      | 1,
     obu_type:           OBUType | 4,
     obu_forbidden_bit:  u8      | 1,
 }
@@ -35,29 +95,361 @@ OBUExtensionHeader :: bit_field u8 {
     temporal_id:               u8 | 3,
 }
 
-read_bit :: proc() -> b8 {
+read_obu :: proc(r: ^Reader) -> (err: Error) {
-    // TODO: idfk
+    header := read_bitfield(r, OBUHeader) or_return
-    // This should read a single bit from the bitstream and advance the bitstream position by 1
+    size: u64
 
-    return false
+    fmt.println(header)
+
+    if header.obu_extension_flag {
+        ext_header := read_bitfield(r, OBUExtensionHeader) or_return
+
+        fmt.println(ext_header)
+    }
+
+    if header.obu_has_size_field {
+        size = leb128(r)
+    } else {
+        // TODO: is this correct ???
+        // The spec is NOT clear about wtf sz is, so I assume it's the box size without the header.
+        // It's also possibly the remaining box size, we'll have to check how other decoders do it.
+        size = u64(r.box.size - BOX_HEADER_SIZE - 1 - u32(header.obu_extension_flag))
+    }
+
+    // TODO: get bit position
+    //start_pos := get_position()
+
+    //// TODO:
+    //if header.obu_type != .SEQUENCE_HEADER && header.obu_type != .TEMPORAL_DELIMITER && OperatingPointIdc != 0 && header.obu_extension_flag == 1 {
+    //    in_temporal_layer := (OperatingPointIdc >> temporal_id) & 1
+    //    in_spatial_layer := (OperatingPointIdc >> (spatial_id + 8)) & 1
+
+    //    if in_temporal_layer == 0 || in_spatial_layer == 0 {
+    //        drop_obu()
+    //        return
+    //    }
+    //}
+
+    fmt.println("OBU size:", size)
+
+    if header.obu_type != .SEQUENCE_HEADER &&
+       header.obu_type != .TEMPORAL_DELIMITER &&
+       header.obu_type != .FRAME_HEADER &&
+       header.obu_type != .TILE_GROUP &&
+       header.obu_type != .METADATA &&
+       header.obu_type != .FRAME &&
+       header.obu_type != .REDUNDANT_FRAME_HEADER &&
+       header.obu_type != .TILE_LIST &&
+       header.obu_type != .PADDING {
+        return .ReservedOBU
+    }
+
+    #partial switch header.obu_type {
+        case .TEMPORAL_DELIMITER:
+            // do nothing. the temporal OBU has an empty payload
+        case .SEQUENCE_HEADER:
+            parse_sequence_header_obu(r)
+        case .FRAME:
+            // TODO:
+    }
+
+    // TODO:
+    //current_pos := get_position()
+    //payload_bits := current_pos - start_pos
+
+    //if size > 0 && header.obu_type != .TILE_GROUP && header.obu_type != .TILE_LIST && header.obu_type != .FRAME {
+    //    trailing_bits(size * 8 - payload_bits)
+    //}
+
+    return nil
 }
 
-f :: proc(n: int) -> u64 {
+//timing_info :: proc(r: ^Reader) {
+//    num_units_in_display_tick = f(r, 32)
+//    time_scale = f(r, 32)
+//    equal_picture_interval = f(r, 32)
+//    if equal_picture_interval == 1 {
+//        num_ticks_per_picture_minus_1 = uvlc(r)
+//    }
+//}
+//
+//decoder_model_info :: proc(r: ^Reader) {
+//    buffer_delay_length_minus_1 = f(r, 5)
+//    num_units_in_decoding_tick = f(r, 32)
+//    buffer_removal_time_length_minus_1 = f(r, 5)
+//    frame_presentation_time_length_minus_1 = f(r, 5)
+//}
+//
+//operating_parameters_info :: proc(r: ^Reader, op: u8) {
+//    n = buffer_delay_length_minus_1 + 1
+//    decoder_buffer_delay[op] = f(r, n)
+//    encoder_buffer_delay[op] = f(r, n)
+//    low_delay_mode_flag[op] = f(r, 1)
+//}
+//
+//color_config :: proc(r: ^Reader) {
+//    high_bitdepth = f(r, 1)
+//
+//    if seq_profile == 2 && high_bitdepth == 1 {
+//        twelve_bit = f(r, 1)
+//        BitDepth = twelve_bit == 1 ? 12 : 10
+//    } else if seq_profile <= 2 {
+//        BitDepth = high_bitdepth == 1 ? 10 : 8
+//    }
+//
+//    if seq_profile == 1 {
+//        mono_chrome = 0
+//    } else {
+//        mono_chrome = f(r, 1)
+//    }
+//
+//    num_planes = mono_chrome == 1 ? 1 : 3
+//    color_description_present_flag = f(r, 1)
+//
+//    if color_description_present_flag == 1 {
+//        color_primaries = auto_cast f(r, 8)
+//        transfer_characteristic = auto_cast f(r, 8)
+//        matrix_coefficients = auto_cast f(r, 8)
+//    } else {
+//        color_primaries = .UNSPECIFIED
+//        transfer_characteristic = .UNSPECIFIED
+//        matrix_coefficients = .UNSPECIFIED
+//    }
+//
+//    if mono_chrome == 1 {
+//        color_range = f(r, 1)
+//        subsampling_x = 1
+//        subsampling_y = 1
+//        chroma_sample_position = .UNKNOWN
+//        separate_uv_delta_q = 0
+//        return
+//    } else if color_primaries == .BT_709 && transfer_characteristic == .SRGB && matrix_coefficients == .IDENTITY {
+//        color_range = 1
+//        subsampling_x = 0
+//        subsampling_y = 0
+//    } else {
+//        color_range = f(r, 1)
+//
+//        if seq_profile == 0 {
+//            subsampling_x = 1
+//            subsampling_y = 1
+//        } else if seq_profile == 1 {
+//            subsampling_x = 0
+//            subsampling_y = 0
+//        } else {
+//            if BitDepth == 12 {
+//                subsampling_x = f(r, 1)
+//
+//                if subsampling_x == 1 {
+//                    subsampling_y = f(r, 1)
+//                } else {
+//                    subsampling_y = 0
+//                }
+//            } else {
+//                subsampling_x = 1
+//                subsampling_y = 0
+//            }
+//        }
+//
+//        if subsampling_x == 1 && subsampling_y == 1 {
+//            chroma_sample_position = auto_cast f(r, 2)
+//        }
+//    }
+//
+//    separate_uv_delta_q = f(r, 1)
+//}
+
+parse_sequence_header_obu :: proc(r: ^Reader) {
+    seq_profile := f(r, 3)
+    still_picture := f(r, 1)
+    reduced_still_picture_header := f(r, 1)
+
+    timing_info_present_flag: u8
+    decoder_model_info_present_flag: u8
+    initial_display_delay_present_flag: u8
+    operating_points_cnt_minus_1: u8
+
+    if reduced_still_picture_header == 1 {
+        // TODO: should these be saved as state ??
+        timing_info_present_flag = 0
+        decoder_model_info_present_flag = 0
+        initial_display_delay_present_flag = 0
+        operating_points_cnt_minus_1 = 0
+        //operating_point_idc[ 0 ] = 0
+        //seq_level_idx[ 0 ]
+        //seq_tier[ 0 ] = 0
+        //decoder_model_present_for_this_op[ 0 ] = 0
+        //initial_display_delay_present_for_this_op[ 0 ] = 0
+    } else {
+        //timing_info_present_flag = auto_cast f(r, 1)
+
+        //if timing_info_present_flag == 1 {
+        //    timing_info(r)
+
+        //    decoder_model_info_present_flag = auto_cast f(r, 1)
+        //    if decoder_model_info_present_flag == 1 {
+        //        decoder_model_info(r)
+        //    }
+        //} else {
+        //    decoder_model_info_present_flag = 0
+        //}
+
+        //initial_display_delay_present_flag = auto_cast f(r, 1)
+        //operating_points_cnt_minus_1 = auto_cast f(r, 5)
+
+        //for i in 0 ..=operating_points_cnt_minus_1 {
+        //    operating_point_idc[i] = f(r, 12)
+        //    seq_level_idx[i] = f(r, 5)
+
+        //    if seq_level_idx[i] > 7 {
+        //        seq_tier[i] = f(r, 1)
+        //    } else {
+        //        seq_tier[i] = 0
+        //    }
+
+        //    if decoder_model_info_present_flag == 1 {
+        //        decoder_model_present_for_this_op[i] = f(r, 1)
+        //        if decoder_model_present_for_this_op[i] == 1 {
+        //            operating_parameters_info(r, i)
+        //        }
+        //    } else {
+        //        decoder_model_present_for_this_op[i] = 0
+        //    }
+
+        //    if initial_display_delay_present_flag == 1 {
+        //        initial_display_delay_present_for_this_op[i] = f(r, 1)
+        //        if initial_display_delay_present_for_this_op[i] == 1 {
+        //            initial_display_delay_minus_1[i] = f(r, 4)
+        //        }
+        //    }
+        //}
+    }
+
+    fmt.println("seq_profile:", seq_profile)
+    fmt.println("still_picture:", still_picture)
+    fmt.println("reduced_still_picture_header:", reduced_still_picture_header)
+
+    fmt.println("timing_info_present_flag:", timing_info_present_flag)
+    fmt.println("decoder_model_info_present_flag:", decoder_model_info_present_flag)
+    fmt.println("initial_display_delay_present_flag:", initial_display_delay_present_flag)
+    fmt.println("operating_points_cnt_minus_1:", operating_points_cnt_minus_1)
+
+    //operating_point := choose_operating_point()
+    //operating_point_idc_one := operating_point_idc[operating_point]
+    frame_width_bits_minus_1 := f(r, 4)
+    frame_height_bits_minus_1 := f(r, 4)
+    n := frame_width_bits_minus_1 + 1
+    max_frame_width_minus_1 := f(r, auto_cast n)
+    n = frame_height_bits_minus_1 + 1
+    max_frame_height_minus_1 := f(r, auto_cast n)
+
+    frame_id_numbers_present_flag: u8
+    delta_frame_id_length_minus_2: u8
+    additional_frame_id_length_minus_1: u8
+
+    if reduced_still_picture_header == 1 {
+        frame_id_numbers_present_flag = 0
+    } else {
+        frame_id_numbers_present_flag = auto_cast f(r, 1)
+    }
+
+    if frame_id_numbers_present_flag == 1 {
+        delta_frame_id_length_minus_2 = auto_cast f(r, 4)
+        additional_frame_id_length_minus_1 = auto_cast f(r, 3)
+    }
+
+    use_128x128_superblock := f(r, 1)
+    enable_filter_intra := f(r, 1)
+    enable_intra_edge_filter := f(r, 1)
+
+    fmt.println("frame_width_bits_minus_1:", frame_width_bits_minus_1)
+    fmt.println("frame_height_bits_minus_1:", frame_height_bits_minus_1)
+    fmt.println("max_frame_width_minus_1:", max_frame_width_minus_1)
+    fmt.println("max_frame_height_minus_1:", max_frame_height_minus_1)
+
+    fmt.println("frame_id_numbers_present_flag:", frame_id_numbers_present_flag)
+    fmt.println("delta_frame_id_length_minus_2:", delta_frame_id_length_minus_2)
+    fmt.println("additional_frame_id_length_minus_1:", additional_frame_id_length_minus_1)
+
+    fmt.println("use_128x128_superblock:", use_128x128_superblock)
+    fmt.println("enable_filter_intra:", enable_filter_intra)
+    fmt.println("enable_intra_edge_filter:", enable_intra_edge_filter)
+
+    //if reduced_still_picture_header == 1 {
+    //    enable_interintra_compound = 0
+    //    enable_masked_compound = 0
+    //    enable_warped_motion = 0
+    //    enable_dual_filter = 0
+    //    enable_order_hint = 0
+    //    enable_jnt_comp = 0
+    //    enable_ref_frame_mvs = 0
+    //    seq_force_screen_content_tools = SELECT_SCREEN_CONTENT_TOOLS
+    //    seq_force_integer_mv = SELECT_INTEGER_MV
+    //    OrderHintBits = 0
+    //} else {
+    //    enable_interintra_compount = f(r, 1)
+    //    enable_masked_compound = f(r, 1)
+    //    enable_warped_motion = f(r, 1)
+    //    enable_dual_filter = f(r, 1)
+    //    enable_order_hint = f(r, 1)
+    //    if enable_order_hint == 1 {
+    //        enable_jnt_comp = f(r, 1)
+    //        enable_ref_frame_mvs = f(r, 1)
+    //    } else {
+    //        enable_jnt_comp = 0
+    //        enable_ref_frame_mvs = 0
+    //    }
+
+    //    seq_choose_screen_content_tools = f(r, 1)
+    //    if seq_choose_screen_content_tools == 1 {
+    //        seq_force_screen_content_tools = SELECT_SCREEN_CONTENT_TOOLS
+    //    } else {
+    //        seq_force_screen_content_tools = f(r, 1)
+    //    }
+
+    //    if seq_force_screen_content_tools > 0 {
+    //        seq_choose_integer_mv = f(r, 1)
+    //        if seq_choose_integer_mv == 1 {
+    //            seq_force_integer_mv = SELECT_INTEGER_MV
+    //        } else {
+    //            seq_force_integer_mv = f(r, 1)
+    //        }
+    //    } else {
+    //        seq_force_integer_mv = SELECT_INTEGER_MV
+    //    }
+
+    //    if enable_order_hint == 1 {
+    //        order_hint_bits_minus_1 = f(r, 3)
+    //        OrderHintBits = order_hint_bits_minus_1 + 1
+    //    } else {
+    //        OrderHintBits = 0
+    //    }
+    //}
+
+    //enable_superres = f(r, 1)
+    //enable_cdef = f(r, 1)
+    //enable_restoration = f(r, 1)
+    //color_config()
+    //film_grain_params_present = f(r, 1)
+}
+
+f :: proc(r: ^Reader, n: int) -> u64 {
     x: u64 = 0
 
     for i in 0 ..< n {
-        x = 2 * x + auto_cast read_bit()
+        // TODO: maybe get rid of or_break and propagate the error??
+        x = 2 * x + auto_cast read_bit(r) or_break
     }
 
     return x
 }
 
-leb128 :: proc() -> u64 {
+leb128 :: proc(r: ^Reader) -> u64 {
     value: u64 = 0
     leb128_bytes := 0
 
     for i: u64 = 0; i < 8; i += 1 {
-        leb128_byte := f(8)
+        leb128_byte := f(r, 8)
         value |= ((leb128_byte & 0x7f) << (i * 7))
         leb128_bytes += 1
 
@@ -68,3 +460,22 @@ leb128 :: proc() -> u64 {
 
     return value
 }
+
+uvlc :: proc(r: ^Reader) -> u64 {
+    leading_zeros: u64 = 0
+
+    for {
+        done := f(r, 1)
+        if done == 1 {
+            break
+        }
+        leading_zeros += 1
+    }
+
+    if leading_zeros >= 32 {
+        return (1 << 32) - 1
+    }
+
+    value := f(r, auto_cast leading_zeros)
+    return value + (1 << leading_zeros) - 1
+}