From 4d05c7add94c6ca55dda08226f74bc68da0b2c53 Mon Sep 17 00:00:00 2001
From: Robin Gareus <robin@gareus.org>
Date: Tue, 6 Dec 2022 05:34:18 +0100
Subject: [PATCH] Map sndfile/opus quality to bitrate

---
 libs/ardour/ardour/export_formats.h        |  2 +-
 libs/ardour/export_format_specification.cc | 10 +++++++++-
 libs/ardour/export_formats.cc              | 16 +++++++++++-----
 3 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/libs/ardour/ardour/export_formats.h b/libs/ardour/ardour/export_formats.h
index 97cebc10c9..eecec5e21e 100644
--- a/libs/ardour/ardour/export_formats.h
+++ b/libs/ardour/ardour/export_formats.h
@@ -373,7 +373,7 @@ public:
 	}
 	int default_codec_quality () const
 	{
-		return 40;
+		return 49;
 	}
 	virtual bool supports_tagging () const
 	{
diff --git a/libs/ardour/export_format_specification.cc b/libs/ardour/export_format_specification.cc
index b2cd76e244..6d9f1c523e 100644
--- a/libs/ardour/export_format_specification.cc
+++ b/libs/ardour/export_format_specification.cc
@@ -449,7 +449,15 @@ ExportFormatSpecification::set_state (const XMLNode & root)
 			_codec_quality = -2;
 		}
 		else if (format_id() == F_Ogg) {
-			_codec_quality = 40;
+			switch (sample_format ()) {
+				default:
+				case SF_Vorbis:
+					_codec_quality = 40;
+					break;
+				case SF_Opus:
+					_codec_quality = 49;
+					break;
+			}
 		}
 	}
 
diff --git a/libs/ardour/export_formats.cc b/libs/ardour/export_formats.cc
index 0c4ece2a68..9e550bdff0 100644
--- a/libs/ardour/export_formats.cc
+++ b/libs/ardour/export_formats.cc
@@ -401,11 +401,17 @@ ExportFormatOggOpus::ExportFormatOggOpus ()
 	set_format_id (F_Ogg);
 	sample_formats.insert (SF_Opus);
 
-	// libsndfile doesn't expose direct quality control - use these coarse approximations
-	add_codec_quality ("Low (0%)",            0);
-	add_codec_quality ("Default (40%)",      40);
-	add_codec_quality ("High (60%)",         60);
-	add_codec_quality ("Very High (100%)",  100);
+	/* libsndfile doesn't expose direct quality control,
+	 * bitrate = (((1.0 - quality) * (250000.0)) + 6000.0)
+	 */
+	add_codec_quality ("6 kb/s/channel",   0);
+	add_codec_quality ("32 kb/s/channel",  10); // 10.4
+	add_codec_quality ("64 kb/s/channel",  23); // 23.2
+	add_codec_quality ("96 kb/s/channel",  36);
+	add_codec_quality ("128 kb/s/channel", 49); // 48.8
+	add_codec_quality ("160 kb/s/channel", 61); // 61.6
+	add_codec_quality ("192 kb/s/channel", 74); // 74.42
+	add_codec_quality ("256 kb/s/channel", 100);
 
 	set_extension ("opus");
 	set_quality (Q_LossyCompression);