add additional opus encoder options

doc/plugins.rst

@@ -643,11 +643,15 @@ Encodes into `Ogg Opus <http://www.opus-codec.org/>`_.
    * - Setting
      - Description
    * - **bitrate**
-     - Sets the data rate in bit per second. The special value "auto" lets libopus choose a rate (which is the default), and "max" uses the maximum possible data rate.
+     - Sets the data rate in bits per second. The special value "auto" lets libopus choose a rate (which is the default), and "max" uses the maximum possible data rate.
    * - **complexity**
      - Sets the `Opus complexity <https://wiki.xiph.org/OpusFAQ#What_is_the_complexity_of_Opus.3F>`_.
    * - **signal**
      - Sets the Opus signal type. Valid values are "auto" (the default), "voice" and "music".
+   * - **vbr yes|no|constrained**
+     - Sets the vbr mode. Setting to "yes" (default) enables variable bitrate, "no" forces constant bitrate and frame sizes, "constrained" uses constant bitrate analogous to CBR in AAC and MP3.
+   * - **packet_loss**
+     - Sets the expected packet loss percentage. This value can be increased from the default "0" for a more redundant stream at the expense of quality.
    * - **opustags yes|no**
      - Configures how metadata is interleaved into the stream. If set to yes, then metadata is inserted using ogg stream chaining, as specified in :rfc:`7845`. If set to no (the default), then ogg stream chaining is avoided and other output-dependent method is used, if available.
 

src/encoder/plugins/OpusEncoderPlugin.cxx

@@ -76,6 +76,9 @@ class PreparedOpusEncoder final : public PreparedEncoder {
 	opus_int32 bitrate;
 	int complexity;
 	int signal;
+	int packet_loss;
+	int vbr;
+	int vbr_constraint;
 	const bool chaining;
 
 public:
@@ -118,6 +121,23 @@ PreparedOpusEncoder::PreparedOpusEncoder(const ConfigBlock &block)
 		signal = OPUS_SIGNAL_MUSIC;
 	else
 		throw std::runtime_error("Invalid signal");
+
+	value = block.GetBlockValue("vbr", "yes");
+	if (strcmp(value, "yes") == 0) {
+		vbr = 1U;
+		vbr_constraint = 0U;
+	} else if (strcmp(value, "no") == 0) {
+		vbr = 0U;
+		vbr_constraint = 0U;
+	} else if (strcmp(value, "constrained") == 0) {
+		vbr = 1U;
+		vbr_constraint = 1U;
+	} else
+		throw std::runtime_error("Invalid vbr");
+
+	packet_loss = block.GetBlockValue("packet_loss", 0U);
+	if (packet_loss > 100)
+		throw std::runtime_error("Invalid packet loss");
 }
 
 PreparedEncoder *
@@ -173,6 +193,9 @@ PreparedOpusEncoder::Open(AudioFormat &audio_format)
 	opus_encoder_ctl(enc, OPUS_SET_BITRATE(bitrate));
 	opus_encoder_ctl(enc, OPUS_SET_COMPLEXITY(complexity));
 	opus_encoder_ctl(enc, OPUS_SET_SIGNAL(signal));
+	opus_encoder_ctl(enc, OPUS_SET_VBR(vbr));
+	opus_encoder_ctl(enc, OPUS_SET_VBR_CONSTRAINT(vbr_constraint));
+	opus_encoder_ctl(enc, OPUS_SET_PACKET_LOSS_PERC(packet_loss));
 
 	return new OpusEncoder(audio_format, enc, chaining);
 }