- fixed a few issues with libmpg123 not correctly reporting the sound's length and issues with repeatedly rewinding the song.

src/sound/i_soundinternal.h

@@ -132,7 +132,7 @@ struct SoundDecoder
 
     virtual size_t read(char *buffer, size_t bytes) = 0;
     virtual TArray<char> readAll();
-    virtual bool seek(size_t ms_offset, bool ms) = 0;
+    virtual bool seek(size_t ms_offset, bool ms, bool mayrestart) = 0;
     virtual size_t getSampleOffset() = 0;
     virtual size_t getSampleLength() { return 0; }
 

src/sound/mpg123_decoder.cpp

@@ -190,23 +190,38 @@ size_t MPG123Decoder::read(char *buffer, size_t bytes)
     return amt;
 }
 
-bool MPG123Decoder::seek(size_t ms_offset, bool ms)
+bool MPG123Decoder::seek(size_t ms_offset, bool ms, bool mayrestart)
 {
 	int enc, channels;
 	long srate;
 
-    if(mpg123_getformat(MPG123, &srate, &channels, &enc) == MPG123_OK)
+	if (!mayrestart || ms_offset > 0)
 	{
-        size_t smp_offset = ms? (size_t)((double)ms_offset / 1000. * srate) : ms_offset;
-        if(mpg123_seek(MPG123, (off_t)smp_offset, SEEK_SET) >= 0)
+		if (mpg123_getformat(MPG123, &srate, &channels, &enc) == MPG123_OK)
+		{
+			size_t smp_offset = ms ? (size_t)((double)ms_offset / 1000. * srate) : ms_offset;
+			if (mpg123_seek(MPG123, (off_t)smp_offset, SEEK_SET) >= 0)
 			{
 				Done = false;
 				return true;
 			}
 		}
 		return false;
+	}
+	else
+	{
+		// Restart the song instead of rewinding. A rewind seems to cause distortion when done repeatedly.
+		// offset is intentionally ignored here.
+		if (MPG123)
+		{
+			mpg123_close(MPG123);
+			mpg123_delete(MPG123);
+			MPG123 = 0;
+		}
+		Reader->Seek(0, SEEK_SET);
+		return open(Reader);
+	}
 }
-
 size_t MPG123Decoder::getSampleOffset()
 {
     return mpg123_tell(MPG123);

src/sound/mpg123_decoder.h

@@ -21,7 +21,7 @@ struct MPG123Decoder : public SoundDecoder
     virtual void getInfo(int *samplerate, ChannelConfig *chans, SampleType *type);
 
     virtual size_t read(char *buffer, size_t bytes);
-    virtual bool seek(size_t ms_offset, bool ms);
+    virtual bool seek(size_t ms_offset, bool ms, bool mayrestart);
     virtual size_t getSampleOffset();
     virtual size_t getSampleLength();
 

src/sound/musicformats/music_libsndfile.cpp

@@ -326,16 +326,39 @@ bool SndFileSong::Read(SoundStream *stream, void *vbuff, int ilen, void *userdat
 	}
 	else
 	{
+		// This looks a bit more complicated than necessary because libmpg123 will not read the full requested length for the last block in the file.
 		if (currentpos + framestoread > song->Loop_End)
 		{
 			size_t endblock = (song->Loop_End - currentpos) * song->Channels * 2;
-			err = (song->Decoder->read(buff, endblock) != endblock);
+			size_t endlen = song->Decoder->read(buff, endblock);
+			if (endlen != 0)
+			{
 				buff = buff + endblock;
 				len -= endblock;
-			song->Decoder->seek(song->Loop_Start, false);
+				song->Decoder->seek(song->Loop_Start, false, true);
+			}
+			else
+			{
+				song->CritSec.Leave();
+				return false;
+			}
+		}
+		while (len > 0)
+		{
+			size_t readlen = song->Decoder->read(buff, len);
+			if (readlen == 0)
+			{
+				song->CritSec.Leave();
+				return false;
+			}
+			buff += readlen;
+			len -= readlen;
+			if (len > 0)
+			{
+				song->Decoder->seek(song->Loop_Start, false, true);
+			}
 		}
-		err |= song->Decoder->read(buff, len) != len;
 	}
 	song->CritSec.Leave();
-	return !err;
+	return true;
 }

src/sound/oalsound.cpp

@@ -215,7 +215,7 @@ class OpenALSoundStream : public SoundStream
 		size_t got = self->Decoder->read((char*)ptr, length);
 		if(got < (unsigned int)length)
 		{
-			if(!self->Looping || !self->Decoder->seek(0, false))
+			if(!self->Looping || !self->Decoder->seek(0, false, true))
 				return false;
 			got += self->Decoder->read((char*)ptr+got, length-got);
 		}
@@ -364,7 +364,7 @@ public:
 	virtual bool SetPosition(unsigned int ms_pos)
 	{
 		std::unique_lock<std::mutex> lock(Renderer->StreamLock);
-		if(!Decoder->seek(ms_pos, true))
+		if(!Decoder->seek(ms_pos, true, false))
 			return false;
 
 		if(!Playing.load())

src/sound/sndfile_decoder.cpp

@@ -190,7 +190,7 @@ TArray<char> SndFileDecoder::readAll()
     return output;
 }
 
-bool SndFileDecoder::seek(size_t ms_offset, bool ms)
+bool SndFileDecoder::seek(size_t ms_offset, bool ms, bool /*mayrestart*/)
 {
     size_t smp_offset = ms? (size_t)((double)ms_offset / 1000. * SndInfo.samplerate) : ms_offset;
     if(sf_seek(SndFile, smp_offset, SEEK_SET) < 0)

src/sound/sndfile_decoder.h

@@ -17,7 +17,7 @@ struct SndFileDecoder : public SoundDecoder
 
     virtual size_t read(char *buffer, size_t bytes);
     virtual TArray<char> readAll();
-    virtual bool seek(size_t ms_offset, bool ms);
+    virtual bool seek(size_t ms_offset, bool ms, bool mayrestart);
 	virtual size_t getSampleOffset();
     virtual size_t getSampleLength();