Merge branch 'v0.21.x'

NEWS

@@ -46,6 +46,11 @@ ver 0.21.25 (not yet released)
 * input
   - file: detect premature end of file
   - smbclient: don't send credentials to MPD clients
+* decoder
+  - opus: apply pre-skip and end trimming
+  - opus: fix memory leak
+* output
+  - osx: improve sample rate selection
 * Windows/Android:
   - fix Boost detection after breaking change in Meson 0.54
 

src/decoder/plugins/OpusDecoderPlugin.cxx

@@ -75,6 +75,19 @@ class MPDOpusDecoder final : public OggDecoder {
 	OpusDecoder *opus_decoder = nullptr;
 	opus_int16 *output_buffer = nullptr;
 
+	/**
+	 * The pre-skip value from the Opus header.  Initialized by
+	 * OnOggBeginning().
+	 */
+	unsigned pre_skip;
+
+	/**
+	 * The number of decoded samples which shall be skipped.  At
+	 * the beginning of the file, this gets set to #pre_skip (by
+	 * OnOggBeginning()), and may also be set while seeking.
+	 */
+	unsigned skip;
+
 	/**
 	 * If non-zero, then a previous Opus stream has been found
 	 * already with this number of channels.  If opus_decoder is
@@ -85,6 +98,13 @@ class MPDOpusDecoder final : public OggDecoder {
 
 	size_t frame_size;
 
+	/**
+	 * The granulepos of the next sample to be submitted to
+	 * DecoderClient::SubmitData().  Negative if unkown.
+	 * Initialized by OnOggBeginning().
+	 */
+	ogg_int64_t granulepos;
+
 public:
 	explicit MPDOpusDecoder(DecoderReader &reader)
 		:OggDecoder(reader) {}
@@ -101,6 +121,13 @@ public:
 	bool Seek(uint64_t where_frame);
 
 private:
+	void AddGranulepos(ogg_int64_t n) noexcept {
+		assert(n >= 0);
+
+		if (granulepos >= 0)
+			granulepos += n;
+	}
+
 	void HandleTags(const ogg_packet &packet);
 	void HandleAudio(const ogg_packet &packet);
 
@@ -137,10 +164,13 @@ MPDOpusDecoder::OnOggBeginning(const ogg_packet &packet)
 		throw std::runtime_error("BOS packet must be OpusHead");
 
 	unsigned channels;
-	if (!ScanOpusHeader(packet.packet, packet.bytes, channels) ||
+	if (!ScanOpusHeader(packet.packet, packet.bytes, channels, pre_skip) ||
 	    !audio_valid_channel_count(channels))
 		throw std::runtime_error("Malformed BOS packet");
 
+	granulepos = 0;
+	skip = pre_skip;
+
 	assert(opus_decoder == nullptr);
 	assert(IsInitialized() == (output_buffer != nullptr));
 
@@ -177,8 +207,12 @@ MPDOpusDecoder::OnOggBeginning(const ogg_packet &packet)
 	client.Ready(audio_format, eos_granulepos > 0, duration);
 	frame_size = audio_format.GetFrameSize();
 
-	output_buffer = new opus_int16[opus_output_buffer_frames
-				       * audio_format.channels];
+	if (output_buffer == nullptr)
+		/* note: if we ever support changing the channel count
+		   in chained streams, we need to reallocate this
+		   buffer instead of keeping it */
+		output_buffer = new opus_int16[opus_output_buffer_frames
+					       * audio_format.channels];
 
 	auto cmd = client.GetCommand();
 	if (cmd != DecoderCommand::NONE)
@@ -231,22 +265,58 @@ MPDOpusDecoder::HandleAudio(const ogg_packet &packet)
 				  packet.bytes,
 				  output_buffer, opus_output_buffer_frames,
 				  0);
-	if (nframes < 0)
-		throw FormatRuntimeError("libopus error: %s",
-					 opus_strerror(nframes));
-
-	if (nframes > 0) {
-		const size_t nbytes = nframes * frame_size;
-		auto cmd = client.SubmitData(input_stream,
-					     output_buffer, nbytes,
-					     0);
-		if (cmd != DecoderCommand::NONE)
-			throw cmd;
-
-		if (packet.granulepos > 0)
-			client.SubmitTimestamp(FloatDuration(packet.granulepos)
-					       / opus_sample_rate);
+	if (gcc_unlikely(nframes <= 0)) {
+		if (nframes < 0)
+			throw FormatRuntimeError("libopus error: %s",
+						 opus_strerror(nframes));
+		else
+			return;
 	}
+
+	/* apply the "skip" value */
+	if (skip >= (unsigned)nframes) {
+		skip -= nframes;
+		AddGranulepos(nframes);
+		return;
+	}
+
+	const opus_int16 *data = output_buffer;
+	data += skip * previous_channels;
+	nframes -= skip;
+	AddGranulepos(skip);
+	skip = 0;
+
+	if (packet.e_o_s && packet.granulepos > 0 && granulepos >= 0) {
+		/* End Trimming (RFC7845 4.4): "The page with the 'end
+		   of stream' flag set MAY have a granule position
+		   that indicates the page contains less audio data
+		   than would normally be returned by decoding up
+		   through the final packet.  This is used to end the
+		   stream somewhere other than an even frame
+		   boundary. [...] The remaining samples are
+		   discarded. */
+		ogg_int64_t remaining = packet.granulepos - granulepos;
+		if (remaining <= 0)
+			return;
+
+		if (remaining < nframes)
+			nframes = remaining;
+	}
+
+	/* submit decoded samples to the DecoderClient */
+	const size_t nbytes = nframes * frame_size;
+	auto cmd = client.SubmitData(input_stream,
+				     data, nbytes,
+				     0);
+	if (cmd != DecoderCommand::NONE)
+		throw cmd;
+
+	if (packet.granulepos > 0) {
+		granulepos = packet.granulepos;
+		client.SubmitTimestamp(FloatDuration(granulepos - pre_skip)
+				       / opus_sample_rate);
+	} else
+		AddGranulepos(nframes);
 }
 
 bool
@@ -258,8 +328,20 @@ MPDOpusDecoder::Seek(uint64_t where_frame)
 
 	const ogg_int64_t where_granulepos(where_frame);
 
+	/* we don't know the exact granulepos after seeking, so let's
+	   set it to -1 - it will be set after the next packet which
+	   declares its granulepos */
+	granulepos = -1;
+
 	try {
 		SeekGranulePos(where_granulepos);
+
+		/* since all frame numbers are offset by the file's
+		   pre-skip value, we need to apply it here as well;
+		   we could just seek to "where_frame+pre_skip" as
+		   well, but I think by decoding those samples and
+		   discard them, we're safer */
+		skip = pre_skip;
 		return true;
 	} catch (...) {
 		return false;
@@ -302,13 +384,14 @@ mpd_opus_stream_decode(DecoderClient &client,
 
 bool
 ReadAndParseOpusHead(OggSyncState &sync, OggStreamState &stream,
-		     unsigned &channels)
+		     unsigned &channels, unsigned &pre_skip)
 {
 	ogg_packet packet;
 
 	return OggReadPacket(sync, stream, packet) && packet.b_o_s &&
 		IsOpusHead(packet) &&
-		ScanOpusHeader(packet.packet, packet.bytes, channels) &&
+		ScanOpusHeader(packet.packet, packet.bytes, channels,
+			       pre_skip) &&
 		audio_valid_channel_count(channels);
 }
 
@@ -327,11 +410,12 @@ ReadAndVisitOpusTags(OggSyncState &sync, OggStreamState &stream,
 
 void
 VisitOpusDuration(InputStream &is, OggSyncState &sync, OggStreamState &stream,
-		  TagHandler &handler)
+		  ogg_int64_t pre_skip, TagHandler &handler)
 {
 	ogg_packet packet;
 
-	if (OggSeekFindEOS(sync, stream, packet, is)) {
+	if (OggSeekFindEOS(sync, stream, packet, is) &&
+	    packet.granulepos >= pre_skip) {
 		const auto duration =
 			SongTime::FromScale<uint64_t>(packet.granulepos,
 						      opus_sample_rate);
@@ -351,15 +435,15 @@ mpd_opus_scan_stream(InputStream &is, TagHandler &handler) noexcept
 
 	OggStreamState os(first_page);
 
-	unsigned channels;
-	if (!ReadAndParseOpusHead(oy, os, channels) ||
+	unsigned channels, pre_skip;
+	if (!ReadAndParseOpusHead(oy, os, channels, pre_skip) ||
 	    !ReadAndVisitOpusTags(oy, os, handler))
 		return false;
 
 	handler.OnAudioFormat(AudioFormat(opus_sample_rate,
 					  SampleFormat::S16, channels));
 
-	VisitOpusDuration(is, oy, os, handler);
+	VisitOpusDuration(is, oy, os, pre_skip, handler);
 	return true;
 }
 

src/decoder/plugins/OpusHead.cxx

@@ -18,6 +18,7 @@
  */
 
 #include "OpusHead.hxx"
+#include "util/ByteOrder.hxx"
 
 #include <cstdint>
 
@@ -31,12 +32,14 @@ struct OpusHead {
 };
 
 bool
-ScanOpusHeader(const void *data, size_t size, unsigned &channels_r)
+ScanOpusHeader(const void *data, size_t size, unsigned &channels_r,
+	       unsigned &pre_skip_r)
 {
 	const auto *h = (const OpusHead *)data;
 	if (size < 19 || (h->version & 0xf0) != 0)
 		return false;
 
 	channels_r = h->channels;
+	pre_skip_r = FromLE16(h->pre_skip);
 	return true;
 }

src/decoder/plugins/OpusHead.hxx

@@ -23,6 +23,7 @@
 #include <cstddef>
 
 bool
-ScanOpusHeader(const void *data, size_t size, unsigned &channels_r);
+ScanOpusHeader(const void *data, size_t size, unsigned &channels_r,
+	       unsigned &pre_skip_r);
 
 #endif

src/output/plugins/OSXOutputPlugin.cxx

@@ -310,7 +310,8 @@ osx_output_score_sample_rate(Float64 destination_rate, unsigned source_rate)
 	double int_portion;
 	double frac_portion = modf(source_rate / destination_rate, &int_portion);
 	// prefer sample rates that are multiples of the source sample rate
-	score += (1 - frac_portion) * 1000;
+	if (frac_portion < 0.01 || frac_portion >= 0.99)
+		score += 1000;
 	// prefer exact matches over other multiples
 	score += (int_portion == 1.0) ? 500 : 0;
 	if (source_rate == destination_rate)