From 824ad247ec3d3312078ca0dfd492892d2e169148 Mon Sep 17 00:00:00 2001
From: Mattias Wadman <mattias.wadman@gmail.com>
Date: Mon, 30 Oct 2023 12:31:18 +0100
Subject: [PATCH] flac: Add option to see sample details like residuals and
 verbatim values

---
 format/flac/flac_frame.go | 64 +++++++++++++++++++++++++++++++--------
 format/format.go          |  3 +-
 2 files changed, 54 insertions(+), 13 deletions(-)

diff --git a/format/flac/flac_frame.go b/format/flac/flac_frame.go
index 2e63f4d493..bb0ea31335 100644
--- a/format/flac/flac_frame.go
+++ b/format/flac/flac_frame.go
@@ -20,6 +20,7 @@ func init() {
 			DecodeFn:    frameDecode,
 			DefaultInArg: format.FLAC_Frame_In{
 				BitsPerSample: 16, // TODO: maybe should not have a default value?
+				SampleDetails: false,
 			},
 		})
 }
@@ -466,7 +467,15 @@ func frameDecode(d *decode.D) any {
 										n += count
 									} else {
 										d.RangeFn(d.Pos(), int64(count*escapeSampleSize), func(d *decode.D) {
-											d.FieldRawLen("samples", int64(count*escapeSampleSize))
+											if ffi.SampleDetails {
+												d.FieldArray("residuals", func(d *decode.D) {
+													for i := 0; i < count; i++ {
+														d.FieldS("residual", escapeSampleSize)
+													}
+												})
+											} else {
+												d.FieldRawLen("residuals", int64(count*escapeSampleSize))
+											}
 										})
 										for j := 0; j < count; j++ {
 											samples[n] = d.S(escapeSampleSize)
@@ -474,17 +483,32 @@ func frameDecode(d *decode.D) any {
 										}
 									}
 								} else {
-									samplesStart := d.Pos()
-									for j := 0; j < count; j++ {
-										high := d.Unary(0)
-										low := d.U(riceParameter)
-										samples[n] = mathex.ZigZag[uint64, int64](high<<riceParameter | low)
-										n++
+									if ffi.SampleDetails {
+										d.FieldArray("residuals", func(d *decode.D) {
+											for i := 0; i < count; i++ {
+												d.FieldStruct("residual", func(d *decode.D) {
+													high := d.FieldUnary("high", 0)
+													low := d.FieldU("low", riceParameter)
+													residual := mathex.ZigZag[uint64, int64](high<<riceParameter | low)
+													d.FieldValueSint("value", residual)
+													samples[n] = residual
+												})
+												n++
+											}
+										})
+									} else {
+										samplesStart := d.Pos()
+										for j := 0; j < count; j++ {
+											high := d.Unary(0)
+											low := d.U(riceParameter)
+											samples[n] = mathex.ZigZag[uint64, int64](high<<riceParameter | low)
+											n++
+										}
+										samplesStop := d.Pos()
+										d.RangeFn(samplesStart, samplesStop-samplesStart, func(d *decode.D) {
+											d.FieldRawLen("residuals", d.BitsLeft())
+										})
 									}
-									samplesStop := d.Pos()
-									d.RangeFn(samplesStart, samplesStop-samplesStart, func(d *decode.D) {
-										d.FieldRawLen("samples", d.BitsLeft())
-									})
 								}
 							})
 						}
@@ -516,7 +540,15 @@ func frameDecode(d *decode.D) any {
 					// <n*i> Unencoded subblock; n = frame's bits-per-sample, i = frame's blocksize.
 					// TODO: refactor into some kind of FieldBitBufLenFn?
 					d.RangeFn(d.Pos(), int64(blockSize*subframeSampleSize), func(d *decode.D) {
-						d.FieldRawLen("samples", d.BitsLeft())
+						if ffi.SampleDetails {
+							d.FieldArray("samples", func(d *decode.D) {
+								for i := 0; i < subframeSampleSize; i++ {
+									d.FieldS("sample", subframeSampleSize)
+								}
+							})
+						} else {
+							d.FieldRawLen("samples", d.BitsLeft())
+						}
 					})
 
 					for i := 0; i < blockSize; i++ {
@@ -565,6 +597,14 @@ func frameDecode(d *decode.D) any {
 					}
 				}
 
+				if ffi.SampleDetails {
+					d.FieldArray("samples", func(d *decode.D) {
+						for i := 0; i < len(samples); i++ {
+							d.FieldValueSint("sample", samples[i])
+						}
+					})
+				}
+
 				channelSamples = append(channelSamples, samples)
 			})
 		}
diff --git a/format/format.go b/format/format.go
index b87fa4b212..bb4cef9ea7 100644
--- a/format/format.go
+++ b/format/format.go
@@ -199,7 +199,8 @@ type CAFF_In struct {
 
 type FLAC_Frame_In struct {
 	SamplesBuf    []byte
-	BitsPerSample int `doc:"Bits per sample"`
+	BitsPerSample int  `doc:"Bits per sample"`
+	SampleDetails bool `doc:"Decode more sample details like residuals etc"`
 }
 
 type FLAC_Frame_Out struct {