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fix(decoder): lots of fixes for sample prediction. stereo correlation. other fixes

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Illusion
2024-06-12 20:09:09 +02:00
parent 5c69629872
commit f90d1c477e
2 changed files with 249 additions and 116 deletions
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TODO.md
+29 -9
View File
@@ -1,15 +1,35 @@
Files:-
14 -> MD5 mismatch
23 -> MD5 mismatch
27 -> This one uses the old format of specifying a variable block strategy. Look into it.
The way to know the blocking strategy for this old format FLACs is to see if min_block_size and max_block_size are different,
if they are, then the blocking strategy is VARIABLE, if not, then it's FIXED.
61 -> I suspect the predictor DOES overflow here. check it
62 -> I suspect the predictor DOES overflow here. check it
63 -> I suspect the predictor DOES overflow here. check it
Also MD5 mismatch
28 -> MD5 mismatch
29 -> MD5 mismatch
30 -> MD5 mismatch
31 -> MD5 mismatch
32 -> MD5 mismatch
33 -> MD5 mismatch
34 -> MD5 mismatch
35 -> MD5 mismatch
36 -> MD5 mismatch
38 -> MD5 mismatch
39 -> MD5 mismatch
40 -> MD5 mismatch
44 -> MD5 mismatch + High memory and CPU usage. needs optimization.
--- 40s and 50s have a lot of MD5 mismatches too, too lazy to write them.
60 -> MD5 mismatch
61 -> MD5 mismatch
63 -> MD5 mismatch
64 -> MD5 mismatch
uncommon/01 -> This one decodes fine but the expected MD5 is 0x00 * 16 which doesn't match the calculated MD5. not sure what to do about this.
uncommon/02 -> We fail a CRC check
uncommon/03 -> We fail so hard we end up reading an invalid residual coding method
uncommon/02 -> No MD5
uncommon/03 -> No MD5
uncommon/04 -> We get a bits per sample mismatch
uncommon/05 -> MD5 mismatch
uncommon/06 -> MD5 mismatch
uncommon/10 -> We error with Invalid Signature. I assume for these two I should look for the frame sync bits. But maybe my decoder should reject these. idk.
uncommon/11 -> We error with Invalid Signature
@@ -18,21 +38,21 @@ faulty/02 -> This one works when it shouldn't (Wrong max framesize)
faulty/04 -> We fail on Invalid_Coefficient_Precision. This one has a wrong number of channels (whatever that means)
faulty/05 -> This one works when it shouldn't. (Wrong number of samples)
faulty/08 -> This one works when it shouldn't. (Blocksize 65536, exceeds the allowed max of 65535)
faulty/09 -> This one works when it shouldn't. (Blocksize 1, below the allowed min of 16 (last frame is allowed to have less than 16))
faulty/09 -> This one works when it shouldn't. (Blocksize 1, below the allowed min of 16 (last frame(subframe?) is allowed to have less than 16))
Things:-
[ ] Stereo Decorrelation
[ ] Lots of checks (look at the TODOs in flac.odin)
[ ] MD5 checksums (depends on stereo decorrelation)
- [ ] VERBATIM subframe
- [x] VERBATIM subframe (seems to work fine if all frames are verbatim, might not work if mixed with other frames)
- [ ] CONSTANT subframe
- [ ] FIXED subframe
- [x] FIXED subframe
- [ ] LPC subframe
[ ] Seeking
[x] RICE2
[x] Add check for mismatched bits per sample
[x] Unencoded BPS is zero
[x] CONSTANT subframe
[x] Stereo Decorrelation
[ ] Encoder (low priority for now)
flac.odin
+216 -103
View File
@@ -85,6 +85,13 @@ crc16_lookup := [256]u16 {
0x8213, 0x0216, 0x021C, 0x8219, 0x0208, 0x820D, 0x8207, 0x0202,
}
fixed_coefficients := [4][]i32 {
{1},
{2, -1},
{3, -3, 1},
{4, -6, 4, -1},
}
md5_ctx: md5.Context
decoded_samples: [dynamic]byte
output_file: os.Handle
@@ -189,7 +196,7 @@ SampleSize :: enum {
ChannelAssignment :: enum {
MONO,
_2CHANNEL,
_2CHANNELS,
_3CHANNELS,
_4CHANNELS,
_5CHANNELS,
@@ -274,7 +281,7 @@ CueSheetTrackIndex :: struct #packed {
reserved: [3]byte,
}
decode_subframe :: proc(r: ^Reader, bps: u8, block_size: u16) -> Error {
decode_subframe :: proc(r: ^Reader, bps: u8, block_size: u16) -> (samples: []i32, err: Error) {
subframe_type_str := ""
// TODO: temp allocator?? so we copy the slice of data into the _actual_ sample buffer
// Maybe even a static arena with a size of 32MB by default (and configurable using #config) or something
@@ -282,13 +289,13 @@ decode_subframe :: proc(r: ^Reader, bps: u8, block_size: u16) -> Error {
// is probably noticibly slower)
subframe_samples := make([dynamic]i32, 0, block_size)
fmt.println("cur offset", r.i)
fmt.println("cur offset bits", r.bits_read_in_byte)
fmt.println("SUBFRAME START AT OFFSET:", r.i)
fmt.println("SUBFRAME offset bits", r.bits_read_in_byte)
data := read_byte(r) or_return
fmt.println("First subframe byte:", data)
fmt.printfln("First subframe byte: 0b%b", data)
//fmt.println("First subframe byte:", data)
//fmt.printfln("First subframe byte: 0b%b", data)
subframe_type := (data & 0x7E) >> 1
low_3_bits := subframe_type & 7
@@ -306,7 +313,7 @@ decode_subframe :: proc(r: ^Reader, bps: u8, block_size: u16) -> Error {
}
if subframe_type == 0 { // CONSTANT
fmt.println("SUBFRAME: CONSTANT")
//fmt.println("SUBFRAME: CONSTANT")
subframe_type_str = "CONSTANT"
bits_to_read := int(bps) - wasted_bits
// TODO: should we shift to the left by the number of wasted bits??
@@ -316,31 +323,32 @@ decode_subframe :: proc(r: ^Reader, bps: u8, block_size: u16) -> Error {
}
append(&subframe_samples, sample)
} else if subframe_type == 1 { // VERBATIM
fmt.println("SUBFRAME: VERBATIM")
//fmt.println("SUBFRAME: VERBATIM")
subframe_type_str = "VERBATIM"
// We loop over the samples in the block here because each sample is BPS bits long.
// Which I assume is always 16 but that's wrong because BPS can go as high as 32 bits
// TODO: this will break if bits per sample is anything BUT 16
if bps < 16 || bps > 17 {
fmt.println("UNSUPPORTED BPS FOR VERBATIM SUBFRAME")
return .Unsupported_BPS
return nil, .Unsupported_BPS
}
for sample in 0..<block_size {
bits_to_read := int(bps) - wasted_bits
fmt.printfln("reading %d bits", bits_to_read)
unencoded_subblock := u16((read_bits(r, bits_to_read) or_return)) << uint(wasted_bits)
unencoded_subblock := i32((read_bits(r, bits_to_read) or_return)) << uint(wasted_bits)
fmt.printfln("unencoded_subblock: %b", unencoded_subblock)
fmt.println("unencoded_subblock:", unencoded_subblock)
fmt.printfln("unencoded_subblock: 0x%X", unencoded_subblock)
//fmt.printfln("unencoded_subblock: %b", unencoded_subblock)
//fmt.println("unencoded_subblock:", unencoded_subblock)
//fmt.printfln("unencoded_subblock: 0x%X", unencoded_subblock)
unencoded_subblock_arr := transmute([2]byte)unencoded_subblock
fmt.printfln("arr: %X", unencoded_subblock_arr)
fmt.printfln("arr as u16: %X", transmute(u16)unencoded_subblock_arr)
//unencoded_subblock_arr := transmute([2]byte)unencoded_subblock
//fmt.printfln("arr: %X", unencoded_subblock_arr)
//fmt.printfln("arr as u16: %X", transmute(u16)unencoded_subblock_arr)
// TODO: I think we'll want to append these samples to a local slice and return that (or a slice we pass in)
append(&decoded_samples, ..unencoded_subblock_arr[:])
append(&subframe_samples, unencoded_subblock)
//append(&decoded_samples, ..unencoded_subblock_arr[:])
}
} else if (subframe_type >> 5) & 1 == 1 { // LPC
fmt.println("SUBFRAME: LPC")
@@ -349,9 +357,9 @@ decode_subframe :: proc(r: ^Reader, bps: u8, block_size: u16) -> Error {
predictor_order := (subframe_type & 0x1F) + 1
fmt.println("predictor_order:", predictor_order)
bits_to_read := int(bps) - wasted_bits
for sample in 0..<predictor_order {
// NOTE: samples are signed so we do 2's complement
bits_to_read := int(bps) - wasted_bits
// TODO: should we shift to the left by the number of wasted bits??
unencoded_warmup_sample := i32(read_bits(r, bits_to_read) or_return)
if (unencoded_warmup_sample >> (uint(bits_to_read) - 1)) & 1 == 1 {
@@ -359,14 +367,14 @@ decode_subframe :: proc(r: ^Reader, bps: u8, block_size: u16) -> Error {
}
//fmt.printfln("unencoded warmup sample: 0b%b", unencoded_warmup_sample)
//fmt.println("unencoded warmup sample:", unencoded_warmup_sample)
fmt.println("unencoded warmup sample:", unencoded_warmup_sample)
//fmt.printfln("unencoded warmup sample: 0x%X", unencoded_warmup_sample)
append(&subframe_samples, unencoded_warmup_sample)
}
coeff_precision_minus_one := u8(read_bits(r, 4) or_return)
if coeff_precision_minus_one == 0xF {
return .Invalid_Coefficient_Precision
return nil, .Invalid_Coefficient_Precision
}
coeff_precision := coeff_precision_minus_one + 1
@@ -390,26 +398,26 @@ decode_subframe :: proc(r: ^Reader, bps: u8, block_size: u16) -> Error {
unencoded_coefficient = -(((~unencoded_coefficient) & i32(math.pow2_f32(coeff_precision) - 1)) + 1)
}
coefficients[i] = unencoded_coefficient
//fmt.println("unencoded_coefficient", unencoded_coefficient)
fmt.println("unencoded_coefficient", unencoded_coefficient)
}
residual_coding_method := ResidualCodingMethod(read_bits(r, 2) or_return)
if residual_coding_method != .RICE && residual_coding_method != .RICE2 {
return .Invalid_Residual_Coding_Method
return nil, .Invalid_Residual_Coding_Method
}
fmt.println(residual_coding_method)
partition_order := read_bits(r, 4) or_return
//fmt.println("parition order", partition_order)
fmt.println("parition order", partition_order)
partitions := int(math.pow2_f32(partition_order))
//fmt.println("partitions:", partitions)
//fmt.println("block_size:", block_size)
fmt.println("partitions:", partitions)
fmt.println("block_size:", block_size)
lpc_partitions_loop: for i in 0..<partitions {
rice_parameter := read_bits(r, residual_coding_method == .RICE ? 4 : 5) or_return
if (residual_coding_method == .RICE && rice_parameter == 15) || (residual_coding_method == .RICE2 && rice_parameter == 31) {
unencoded_bps := u8(read_bits(r, 5) or_return)
//fmt.println("unencoded_bps:", unencoded_bps)
fmt.println("unencoded_bps:", unencoded_bps)
num_samples := 0
if partition_order == 0 {
@@ -453,18 +461,18 @@ decode_subframe :: proc(r: ^Reader, bps: u8, block_size: u16) -> Error {
//fmt.println("shifting by", coeff_bits_to_shift)
// NOTE: Apply arithmetic right shift in case the bits to shift are negative
predictor := int(math.floor(f32(predictor_before_shift) / math.pow2_f32(coeff_bits_to_shift)))
//predictor := predictor_before_shift >> u8(coeff_bits_to_shift)
//predictor := int(math.floor(f32(predictor_before_shift) / math.pow2_f32(coeff_bits_to_shift)))
predictor := predictor_before_shift >> u32(coeff_bits_to_shift)
//fmt.println("predictor:", predictor)
sample := i32(predictor) + residual_sample_value
append(&subframe_samples, sample)
//fmt.println("residual sample value:", residual_sample_value)
//fmt.printfln(" residual[%d]=%d", s, residual_sample_value)
//fmt.println("sample value:", sample)
sample_i += 1
}
} else {
//fmt.println("rice parameter:", rice_parameter)
fmt.println("rice parameter:", rice_parameter)
num_samples := 0
if partition_order == 0 {
@@ -480,7 +488,7 @@ decode_subframe :: proc(r: ^Reader, bps: u8, block_size: u16) -> Error {
// Undo the RICE coding
//
previous_sample_value := 0
for j in 0..<num_samples {
for s in 0..<num_samples {
quotient := 0
// Read bits until we encounter a 1 (also called unary encoding). That's our quotient.
for (read_bit(r) or_return) != 1 {
@@ -513,15 +521,15 @@ decode_subframe :: proc(r: ^Reader, bps: u8, block_size: u16) -> Error {
//fmt.println("shifting by", coeff_bits_to_shift)
// NOTE: Apply arithmetic right shift in case the bits to shift are negative
predictor := int(math.floor(f32(predictor_before_shift) / math.pow2_f32(coeff_bits_to_shift)))
//predictor := predictor_before_shift >> u8(coeff_bits_to_shift)
//predictor := int(math.floor(f32(predictor_before_shift) / math.pow2_f32(coeff_bits_to_shift)))
predictor := predictor_before_shift >> u32(coeff_bits_to_shift)
//fmt.println("predictor:", predictor)
sample := predictor + residual_sample_value
append(&subframe_samples, i32(sample))
sample_i += 1
//fmt.println("residual sample value:", residual_sample_value)
//fmt.printfln(" residual[%d]=%d", s, residual_sample_value)
//fmt.println("sample value:", sample)
}
}
@@ -532,6 +540,7 @@ decode_subframe :: proc(r: ^Reader, bps: u8, block_size: u16) -> Error {
} else if (subframe_type >> 3) & 1 == 1 && low_3_bits <= 4 { // FIXED
fmt.println("SUBFRAME: FIXED")
subframe_type_str = "FIXED"
sample_i := 0
predictor_order := low_3_bits
fmt.println("predictor_order:", predictor_order)
@@ -541,22 +550,24 @@ decode_subframe :: proc(r: ^Reader, bps: u8, block_size: u16) -> Error {
// few samples in each subframe cannot be predicted. Therefore, a
// number of so-called warm-up samples equal to the predictor order is
// stored"
bits_to_read := bps - u8(wasted_bits)
unencoded_samples_n := bits_to_read * predictor_order
//fmt.println("unencoded warmup samples n:", unencoded_samples_n)
bits_to_read := int(bps) - wasted_bits
// NOTE: samples can be negative
// TODO: should we shift to the left by the number of wasted bits??
unencoded_warmup_sample := i32(read_bits(r, int(unencoded_samples_n)) or_return)
for sample in 0..<predictor_order {
unencoded_warmup_sample := i32(read_bits(r, bits_to_read) or_return)
if (unencoded_warmup_sample >> (uint(bits_to_read) - 1)) & 1 == 1 {
unencoded_warmup_sample = -(((~unencoded_warmup_sample) & i32(math.pow2_f32(bits_to_read) - 1)) + 1)
}
fmt.println("unencoded warmup sample:", unencoded_warmup_sample)
fmt.printfln("unencoded warmup sample: 0x%X", unencoded_warmup_sample)
//fmt.printfln("unencoded warmup sample: 0x%X", unencoded_warmup_sample)
append(&subframe_samples, unencoded_warmup_sample)
}
residual_coding_method := ResidualCodingMethod(read_bits(r, 2) or_return)
if residual_coding_method != .RICE && residual_coding_method != .RICE2 {
return .Invalid_Residual_Coding_Method
return nil, .Invalid_Residual_Coding_Method
}
fmt.println(residual_coding_method)
@@ -564,7 +575,7 @@ decode_subframe :: proc(r: ^Reader, bps: u8, block_size: u16) -> Error {
fmt.println("parition order", partition_order)
partitions := int(math.pow2_f32(partition_order))
fmt.println("partitions:", partitions)
//fmt.println("block_size:", block_size)
fmt.println("block_size:", block_size)
fixed_partitions_loop: for i in 0..<partitions {
rice_parameter := read_bits(r, residual_coding_method == .RICE ? 4 : 5) or_return
@@ -588,40 +599,39 @@ decode_subframe :: proc(r: ^Reader, bps: u8, block_size: u16) -> Error {
continue fixed_partitions_loop
}
fmt.printfln("reading %d samples for residual", num_samples)
//fmt.printfln("reading %d samples for residual", num_samples)
for sample in 0..<num_samples {
for s in 0..<num_samples {
// NOTE: This is signed 2's complement so we check the MSB
residual_sample_value := i8(read_bits(r, int(unencoded_bps)) or_return)
if (residual_sample_value >> (unencoded_bps - 1)) & 1 == 1 {
residual_sample_value = -(((~residual_sample_value) & i8(math.pow2_f32(unencoded_bps) - 1)) + 1)
}
fmt.println("residual sample value:", residual_sample_value)
//fmt.printfln(" residual[%d]=%d", s + (i * (int(block_size - 1) / partitions)), residual_sample_value)
}
return .Unencoded_BPS_For_Fixed_Subframe_Is_Unsupported
return nil, .Unencoded_BPS_For_Fixed_Subframe_Is_Unsupported
// TODO: calculate the actual sample value by using the residual AND the previous sample value
// TODO: add the samples to something ??
} else {
fmt.println("rice parameter:", rice_parameter)
samples := 0
num_samples := 0
if partition_order == 0 {
samples = int(block_size - u16(predictor_order))
num_samples = int(block_size - u16(predictor_order))
} else if i != 0 {
samples = int(block_size / u16(math.pow2_f32(partition_order)))
num_samples = int(block_size / u16(math.pow2_f32(partition_order)))
} else {
samples = int((block_size / u16(math.pow2_f32(partition_order))) - u16(predictor_order))
num_samples = int((block_size / u16(math.pow2_f32(partition_order))) - u16(predictor_order))
}
fmt.printfln("reading %d samples for residual", samples)
//fmt.printfln("reading %d samples for residual", samples)
//
// Undo the RICE coding
//
previous_sample_value := 0
for j in 0..<samples {
for s in 0..<num_samples {
quotient := 0
// Read bits until we encounter a 1 (also called unary encoding). That's our quotient.
for (read_bit(r) or_return) != 1 {
@@ -629,64 +639,53 @@ decode_subframe :: proc(r: ^Reader, bps: u8, block_size: u16) -> Error {
}
remainder := int(read_bits(r, int(rice_parameter)) or_return)
fmt.println("quotient:", quotient)
fmt.println("remainder:", remainder)
//fmt.println("quotient:", quotient)
//fmt.println("remainder:", remainder)
zigzag_encoded_value := quotient * int(math.pow2_f32(rice_parameter)) + remainder
// Unzigzag the residual sample values
residual_sample_value := zigzag_encoded_value % 2 == 0 ? zigzag_encoded_value / 2 : (zigzag_encoded_value + 1) / -2
fmt.println("residual sample value:", residual_sample_value)
//fmt.printfln(" residual[%d]=%d", sample_i, residual_sample_value)
sample_value := 0
// Restore sample values using the predictor and the residual values
sample_value := j == 0 ? residual_sample_value + int(unencoded_warmup_sample) : residual_sample_value + previous_sample_value
previous_sample_value = sample_value
if predictor_order == 0 {
sample_value = residual_sample_value
} else {
//sample_value = residual_sample_value + int(subframe_samples[sample_i])
predictor := 0
c := 0
#reverse for coefficient in fixed_coefficients[predictor_order - 1] {
predictor += int(coefficient) * int(subframe_samples[sample_i + c])
c += 1
}
fmt.println("sample_value:", sample_value)
sample_value = predictor + residual_sample_value
}
//sample_value := residual_sample_value + (predictor_order == 0 ? 0 : int(subframe_samples[sample_i]))
append(&subframe_samples, i32(sample_value))
sample_i += 1
//fmt.printfln(" sample[%d]=%d", sample_i, sample_value)
}
}
}
}
// TODO: Maybe this is slow if we have a lot of samples??
// The cases are ranges because streaminfo can define unusual bits per sample
for sample in subframe_samples {
switch bps {
case 1..=8:
data := []u8{u8(sample)}
os.write(output_file, data)
md5.update(&md5_ctx, data)
case 9..=16:
first_byte := i8(sample & 0xFF)
second_byte := i8((sample >> 8) & 0xFF)
data := slice.reinterpret([]u8, []i8{first_byte, second_byte})
os.write(output_file, data)
md5.update(&md5_ctx, data)
case 17..=24:
first_byte := i8(sample & 0xFF)
second_byte := i8((sample >> 8) & 0xFF)
third_byte := i8((sample >> 16) & 0xFF)
data := slice.reinterpret([]u8, []i8{first_byte, second_byte, third_byte})
os.write(output_file, data)
md5.update(&md5_ctx, data)
case 25..=32:
first_byte := i8(sample & 0xFF)
second_byte := i8((sample >> 8) & 0xFF)
third_byte := i8((sample >> 16) & 0xFF)
fourth_byte := i8((sample >> 24) & 0xFF)
data := slice.reinterpret([]u8, []i8{first_byte, second_byte, third_byte, fourth_byte})
os.write(output_file, data)
md5.update(&md5_ctx, data)
}
}
fmt.println("cur offset", r.i)
fmt.println("cur offset bits", r.bits_read_in_byte)
//fmt.println("cur offset", r.i)
//fmt.println("cur offset bits", r.bits_read_in_byte)
fmt.println("FINISHED SUBFRAME:", subframe_type_str)
return nil
return subframe_samples[:], nil
}
// TODO: remove
@@ -698,13 +697,14 @@ decode_frame :: proc(r: ^Reader, streaminfo_bps: u8, streaminfo_sample_rate: u32
//
frame_beginning := r.i
fmt.println("STARTING FRAME", frame_num)
fmt.println("FRAME START AT OFFSET:", r.i)
data := read_data(r, u16be) or_return
sync_code := data >> 2
blocking_strategy := BlockingStrategy(data & 1)
fmt.println("blocking strategy:", blocking_strategy)
//fmt.println("blocking strategy:", blocking_strategy)
data = read_data(r, u16be) or_return
block_size := data >> 12
@@ -801,8 +801,8 @@ decode_frame :: proc(r: ^Reader, streaminfo_bps: u8, streaminfo_sample_rate: u32
fmt.printfln("block size bits: 0b%b", block_size)
fmt.printfln("actual block size: %d sample(s)", actual_block_size)
fmt.println("sample rate bits:", sample_rate)
fmt.printfln("actual sample rate: %dHz", actual_sample_rate_in_Hz)
//fmt.println("sample rate bits:", sample_rate)
//fmt.printfln("actual sample rate: %dHz", actual_sample_rate_in_Hz)
fmt.println("channel assignment:", channel_assignment)
if frame_header_crc != calculated_header_crc {
@@ -833,17 +833,51 @@ decode_frame :: proc(r: ^Reader, streaminfo_bps: u8, streaminfo_sample_rate: u32
bps = 32
}
fmt.println("channels:", channels)
fmt.println("bps:", bps)
fmt.println("sample size:", sample_size)
fmt.println("cur offset:", r.i)
fmt.println("cur offset bits:", r.bits_read_in_byte)
//fmt.println("bps:", bps)
//fmt.println("sample size:", sample_size)
//fmt.println("cur offset:", r.i)
//fmt.println("cur offset bits:", r.bits_read_in_byte)
if bps != streaminfo_bps {
return .Bits_Per_Second_Mismatch
}
for i in 0..<channels {
frame_channels := channels
switch channel_assignment {
case .MONO:
frame_channels = 1
case ._3CHANNELS:
frame_channels = 3
case ._4CHANNELS:
frame_channels = 4
case ._5CHANNELS:
frame_channels = 5
case ._6CHANNELS:
frame_channels = 6
case ._7CHANNELS:
frame_channels = 7
case ._8CHANNELS:
frame_channels = 8
case ._2CHANNELS: fallthrough
case .STEREO_LEFT_SIDE: fallthrough
case .STEREO_SIDE_RIGHT: fallthrough
case .STEREO_MID_SIDE:
frame_channels = 2
}
//fmt.println("channel assignment:", channel_assignment)
//fmt.println("channels:", channels)
if frame_channels != channels {
// TODO: warning or error?
// we have a faulty file that says it has 5 channels but subframes all say they got 1
// we also have an two uncommon files with increasing and decreasing number of channels
// uncommon are supposed to be unusual but still valid FLAC files. why is that first one faulty then???
// so many questions...
}
subframes := make([][]i32, frame_channels)
for i in 0..<frame_channels {
frame_bps := bps
// For side channels we increase the bps by 1
// Left, mid and right channels don't need an extra bit.
@@ -853,11 +887,90 @@ decode_frame :: proc(r: ^Reader, streaminfo_bps: u8, streaminfo_sample_rate: u32
frame_bps += 1
}
decode_subframe(r, frame_bps, auto_cast actual_block_size) or_return
subframes[i] = decode_subframe(r, frame_bps, auto_cast actual_block_size) or_return
}
align_to_byte(r)
// Undo Stereo Decorrelation
#partial switch channel_assignment {
case .STEREO_MID_SIDE:
for i in 0..<len(subframes[1]) {
mid := subframes[0][i] << 1
side := subframes[1][i]
// Since side is a signed integer here. We check for oddity by looking at the LSB instead of doing a check for 1 and -1
if side & 1 == 1 {
mid += 1
}
left := i32((int(mid) + int(side)) >> 1)
right := (mid - side) >> 1
subframes[0][i] = left
subframes[1][i] = right
}
case .STEREO_SIDE_RIGHT:
for i in 0..<len(subframes[0]) {
side := subframes[0][i]
right := subframes[1][i]
subframes[0][i] = side + right
}
case .STEREO_LEFT_SIDE:
for i in 0..<len(subframes[1]) {
left := subframes[0][i]
side := subframes[1][i]
subframes[1][i] = left - side
}
}
for subframe, i in subframes {
fmt.printfln("samples in subframe %d: %d", i, len(subframe))
}
// TODO: Maybe this is slow if we have a lot of samples??
// The cases are ranges because streaminfo can define unusual bits per sample
// TODO: this crashes if we have a CONSTANT subframe because the previous subframe will have more samples
for i in 0..<len(subframes[0]) {
for subframe in subframes {
sample := subframe[0]
if len(subframe) != 1 { // non-CONSTANT subframe
sample = subframe[i]
}
switch bps {
case 1..=8:
data := []u8{u8(sample)}
os.write(output_file, data)
md5.update(&md5_ctx, data)
case 9..=16:
first_byte := i8(sample & 0xFF)
second_byte := i8((sample >> 8) & 0xFF)
data := slice.reinterpret([]u8, []i8{first_byte, second_byte})
os.write(output_file, data)
md5.update(&md5_ctx, data)
case 17..=24:
first_byte := i8(sample & 0xFF)
second_byte := i8((sample >> 8) & 0xFF)
third_byte := i8((sample >> 16) & 0xFF)
data := slice.reinterpret([]u8, []i8{first_byte, second_byte, third_byte})
os.write(output_file, data)
md5.update(&md5_ctx, data)
case 25..=32:
first_byte := i8(sample & 0xFF)
second_byte := i8((sample >> 8) & 0xFF)
third_byte := i8((sample >> 16) & 0xFF)
fourth_byte := i8((sample >> 24) & 0xFF)
data := slice.reinterpret([]u8, []i8{first_byte, second_byte, third_byte, fourth_byte})
os.write(output_file, data)
md5.update(&md5_ctx, data)
case:
fmt.println("INVALID BPS")
os.exit(1)
}
}
}
//fmt.printfln("%d", subframes)
// TODO: for stereo with side channels we must decorrelate the samples depending on the channel assignment
// otherwise we'll be saving incorrect samples.
@@ -968,7 +1081,7 @@ decode_extended_utf8 :: proc(r: ^Reader) -> (decoded_num: u64, err: Error) {
decoded_num = u64(first_byte & 0x7F)
}
fmt.println("decoded num:", decoded_num)
//fmt.println("decoded num:", decoded_num)
return decoded_num, nil
}