X-Git-Url: http://git.tdb.fi/?a=blobdiff_plain;f=source%2Fmp3decoder.cpp;h=cc3235683db098cc5782ef11ba2b7094678f9bb1;hb=1e7141871d33e3e184456ba063fcf3448a8cc12a;hp=00fc9181bd69a2a2d6318d7d13153c3a71fce363;hpb=227da1e7a20432e056e7ab42444cb56f197c53d6;p=libs%2Fal.git

diff --git a/source/mp3decoder.cpp b/source/mp3decoder.cpp
index 00fc918..cc32356 100644
--- a/source/mp3decoder.cpp
+++ b/source/mp3decoder.cpp
@@ -54,7 +54,9 @@ Mp3Decoder::Mp3Decoder(IO::Seekable &io):
 
 	try
 	{
-		decode_frame();
+		if(!fill_input() || !decode(false))
+			throw runtime_error("no mp3 data");
+
 		format = create_format(2, MAD_NCHANNELS(&priv->frame.header));
 		freq = priv->frame.header.samplerate;
 	}
@@ -82,12 +84,35 @@ bool Mp3Decoder::detect(const string &sig)
 	static const char id3_sig[] = { 'I', 'D', '3' };
 	if(sig.size()<sizeof(id3_sig))
 		return false;
-	return !sig.compare(0, sizeof(id3_sig), id3_sig);
+	return !sig.compare(0, sizeof(id3_sig), id3_sig, sizeof(id3_sig));
 }
 
-void Mp3Decoder::rewind()
+void Mp3Decoder::seek(unsigned pos)
 {
+	unsigned unit = get_unit_size(format);
+	pos /= unit;
+
 	in.seek(0, IO::S_BEG);
+	mad_stream_buffer(&priv->stream, 0, 0);
+	fill_input();
+	if(!pos)
+	{
+		priv->synth.pcm.length = 0;
+		return;
+	}
+
+	while(decode(false))
+	{
+		unsigned frame_len = 32*MAD_NSBSAMPLES(&priv->frame.header);
+		if(frame_len>pos)
+		{
+			decode(true);
+			read_pos = pos;
+			break;
+		}
+
+		pos -= frame_len;
+	}
 }
 
 unsigned Mp3Decoder::read(char *buf, unsigned len)
@@ -98,11 +123,8 @@ unsigned Mp3Decoder::read(char *buf, unsigned len)
 	unsigned pos = 0;
 	while(pos+2*nchan<=len)
 	{
-		if(read_pos>=pcm.length)
-		{
-			if(!decode_frame())
-				break;
-		}
+		if(read_pos>=pcm.length && !decode(true))
+			break;
 
 		for(unsigned i=0; i<nchan; ++i)
 		{
@@ -135,26 +157,34 @@ bool Mp3Decoder::fill_input()
 	return len;
 }
 
-bool Mp3Decoder::decode_frame()
+bool Mp3Decoder::try_decode(bool full)
+{
+	if(full)
+		return !mad_frame_decode(&priv->frame, &priv->stream);
+	else
+		return !mad_header_decode(&priv->frame.header, &priv->stream);
+}
+
+bool Mp3Decoder::decode(bool full)
 {
-	while(1)
+	while(!try_decode(full))
 	{
-		if(!priv->stream.buffer || priv->stream.error==MAD_ERROR_BUFLEN)
+		if(priv->stream.error==MAD_ERROR_BUFLEN)
+		{
 			if(!fill_input())
 				return false;
-
-		if(!mad_frame_decode(&priv->frame, &priv->stream))
-		{
-			mad_synth_frame(&priv->synth, &priv->frame);
-			read_pos = 0;
-			return true;
 		}
-
-		if(priv->stream.error==MAD_ERROR_BUFLEN)
-			continue;
 		else if(!MAD_RECOVERABLE(priv->stream.error))
 			throw mp3_error("mad_frame_decode", priv->stream.error);
 	}
+
+	if(full)
+	{
+		read_pos = 0;
+		mad_synth_frame(&priv->synth, &priv->frame);
+	}
+
+	return true;
 }
 
 } // namespace AL