Give the real-audio quality test a corpus

.github/scripts/fetch-quality-corpus.sh

@@ -0,0 +1,83 @@
+1#!/usr/bin/env bash
+
+# SPDX-FileCopyrightText: 2026 The Pion community <https://pion.ly>
+# SPDX-License-Identifier: MIT
+
+# Builds the real-audio corpus that TestEncoderQualityRealCorpus measures
+# against. The clips are live recordings from the Internet Archive's Live Music
+# Archive, whose taping policies allow free redistribution; only their URLs and
+# checksums live in this repo, never the audio.
+#
+# Every clip was checked to be free of prior codec damage two ways: its spectrum
+# descends to Nyquist with no plateau at the dither floor, and its round-trip
+# score is flat across framing offsets. Material that has already been through a
+# codec fails one or both, and scores about a dB high when re-encoded on the
+# grid it already carries, which makes it useless as a quality reference.
+#
+#   ./.github/scripts/fetch-quality-corpus.sh [output-dir]
+
+set -euo pipefail
+
+OUT_DIR="${1:-${OPUS_QUALITY_CORPUS:-corpus}}"
+
+# item|file|sha1|start seconds|duration seconds
+MANIFEST="
+oar2006-01-14.mix.flac16|oar2006-01-14d2t09.mix.flac|54e85d4f7a90afd5d9e1ccf8a4ee4d39b2c60b62|60|30
+jj2008-06-14.mk4|jj2008-06-14d2t02.flac|90682e3425e1fd516e1c44190457f8745e60db23|60|30
+tlg2006-10-21.mk4v.flac16|tlg2006-10-21d2t04.flac|5c7a4872e056d294a9303674ff7ae6dd272a0734|60|30
+gd1977-05-08.shure57.stevenson.29303.flac16|gd1977-05-08d03t05.flac|2182ce0c10de3e6c5760982944f4ca0cf1c5eb51|60|30
+pattersonh2006-01-07.184.flac16|pattersonh2006-01-07d2t08.flac|5830b37cc92ac915cae58d32f5515fc602623885|60|30
+moe2004-10-29.at4051a.flac|moe2004-10-29set2t09.flac|fddde10084bc760b0f0ae5d8ef726d8058fb0a69|60|30
+SOMS2004-11-13.flac|SOMS2004-11-13D2T06.flac|2b7a44350021077690b2533f8925bc737d220baf|60|30
+mss2003-12-31.flac16f|mss2003-12-31d3.flac16/mss2003-12-31d3t02.flac|56ea71e19e61e160e5bfdd1126182ac18c5d576c|60|30
+maroon5-2004-10-21.flac16|maroon5-2004-10-21t05.flac|0cf9e7d771d05f01988e4ae66117df8e81ef8252|60|30
+johnmayer2008-08-02.DPA4023.flac16|John_Mayer_2008-08-02_t05.flac|b80d8191f6fba32d38b81a9e8b871fd070665d4c|60|30
+ryanadams2006-10-17.sbd.flac16|ryanadams2006-10-17.sbd.d2t05.flac|2ef12d80888f6a9188e913f905107f4c18a839ce|60|30
+esmith2003-01-31.flac16|es2003-01-31d1t12.flac|e556a82cedfc3c3d3e3ca00c3b3730ed8bff53e9|60|30
+"
+
+for tool in curl ffmpeg sha1sum; do
+    command -v "${tool}" >/dev/null 2>&1 || {
+        echo "missing ${tool}" >&2
+        exit 1
+    }
+done
+
+mkdir -p "${OUT_DIR}"
+WORK_DIR="$(mktemp -d)"
+trap 'rm -rf "${WORK_DIR}"' EXIT
+
+while IFS='|' read -r item file sha start dur; do
+    if [ -z "${item}" ]; then
+        continue
+    fi
+    name="${item%%.*}"
+    target="${OUT_DIR}/${name}.pcm"
+    if [ -s "${target}" ]; then
+        echo "have ${name}"
+
+        continue
+    fi
+
+    src="${WORK_DIR}/src.flac"
+    url="https://archive.org/download/${item}/$(echo "${file}" | sed 's/ /%20/g')"
+    curl -sL --retry 3 -m 600 -o "${src}" "${url}"
+
+    got="$(sha1sum "${src}" | cut -d' ' -f1)"
+    if [ "${got}" != "${sha}" ]; then
+        echo "checksum mismatch for ${name}: ${got} != ${sha}" >&2
+        exit 1
+    fi
+
+    # soxr is pinned because these masters are 44.1 kHz and a different
+    # resampler would move the baseline for reasons that are not the encoder.
+    ffmpeg -v error -ss "${start}" -t "${dur}" -i "${src}" \
+        -af aresample=resampler=soxr:precision=28:out_sample_rate=48000 \
+        -ac 2 -f s16le "${target}" -y
+    rm -f "${src}"
+    echo "built ${name}"
+done <<<"${MANIFEST}"
+
+echo
+echo "corpus ready in ${OUT_DIR}"
+echo "  export OPUS_QUALITY_CORPUS=$(cd "${OUT_DIR}" && pwd)"

encoder_corpus_test.go

@@ -62,6 +62,10 @@ type corpusBaseline struct {
 // Set OPUS_QUALITY_CORPUS to a directory of 48 kHz stereo s16le .pcm files and
 // OPUS_RFC6716_REFERENCE to a libopus checkout. Set OPUS_QUALITY_CORPUS_UPDATE
 // to rewrite the baseline instead of asserting against it.
+//
+// The committed baseline was measured on the corpus that
+// .github/scripts/fetch-quality-corpus.sh builds; a different corpus needs its
+// own baseline.
 func TestEncoderQualityRealCorpus(t *testing.T) {
 	if runtime.GOOS == conformanceWindowsGOOS {
 		t.Skip("the reference tools use a POSIX-oriented Makefile")

testdata/encoder-quality-corpus-baseline.json

@@ -0,0 +1,66 @@
+{
+  "version": 1,
+  "bitrate": 96000,
+  "clips": {
+    "SOMS2004-11-13": {
+      "weightedError": 0.624648,
+      "badWindows": 1,
+      "totalWindows": 2999
+    },
+    "esmith2003-01-31": {
+      "weightedError": 0.680949,
+      "badWindows": 0,
+      "totalWindows": 2999
+    },
+    "gd1977-05-08": {
+      "weightedError": 0.395929,
+      "badWindows": 0,
+      "totalWindows": 2999
+    },
+    "jj2008-06-14": {
+      "weightedError": 0.485416,
+      "badWindows": 0,
+      "totalWindows": 2999
+    },
+    "johnmayer2008-08-02": {
+      "weightedError": 0.563283,
+      "badWindows": 0,
+      "totalWindows": 2999
+    },
+    "maroon5-2004-10-21": {
+      "weightedError": 1.043867,
+      "badWindows": 0,
+      "totalWindows": 2999
+    },
+    "moe2004-10-29": {
+      "weightedError": 0.804476,
+      "badWindows": 0,
+      "totalWindows": 2999
+    },
+    "mss2003-12-31": {
+      "weightedError": 0.579516,
+      "badWindows": 0,
+      "totalWindows": 2999
+    },
+    "oar2006-01-14": {
+      "weightedError": 1.146483,
+      "badWindows": 0,
+      "totalWindows": 2999
+    },
+    "pattersonh2006-01-07": {
+      "weightedError": 0.413035,
+      "badWindows": 0,
+      "totalWindows": 2999
+    },
+    "ryanadams2006-10-17": {
+      "weightedError": 0.569696,
+      "badWindows": 0,
+      "totalWindows": 2999
+    },
+    "tlg2006-10-21": {
+      "weightedError": 0.281118,
+      "badWindows": 0,
+      "totalWindows": 2999
+    }
+  }
+}

testdata/encoder-quality-corpus-baseline.json.license

@@ -0,0 +1,2 @@
+SPDX-FileCopyrightText: 2026 The Pion community <https://pion.ly>
+SPDX-License-Identifier: MIT