Commit bd161c61 authored by Josh Coalson's avatar Josh Coalson
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Improve decoder's ability to distinguish between a FLAC sync code and an MPEG...

Improve decoder's ability to distinguish between a FLAC sync code and an MPEG one (SF #2491433 https://sourceforge.net/tracker2/?func=detail&aid=2491433&group_id=13478&atid=113478
parent ee51fc0b
......@@ -121,6 +121,7 @@
<ul>
<li>libFLAC encoder was defaulting to level 0 compression instead of 5 (<a href="https://sourceforge.net/tracker2/?func=detail&aid=1816825&group_id=13478&atid=113478">SF #1816825</a>).</li>
<li>Fix bug in bitreader handling of read callback returning a short count (<a href="https://sourceforge.net/tracker2/?func=detail&aid=2490454&group_id=13478&atid=113478">SF #2490454</a>).</li>
<li>Improve decoder's ability to distinguish between a FLAC sync code and an MPEG one (<a href="https://sourceforge.net/tracker2/?func=detail&aid=2491433&group_id=13478&atid=113478">SF #2491433</a>).</li>
</ul>
</li>
<li>
......
......@@ -1121,7 +1121,7 @@
&lt;1&gt;
</td>
<td>
Reserved:<br />
Reserved: <a href="#frame_header_notes">[1]</a><br />
<ul>
<li>
<tt>0</tt> : mandatory value
......@@ -1137,7 +1137,7 @@
&lt;1&gt;
</td>
<td>
Blocking strategy:<br />
Blocking strategy: <a href="#frame_header_notes">[2]</a> <a href="#frame_header_notes">[3]</a><br />
<ul>
<li>
<tt>0</tt> : fixed-blocksize stream; frame header encodes the frame number
......@@ -1325,9 +1325,9 @@
</td>
<td>
if(variable blocksize)<br />
&nbsp;&nbsp;&nbsp;&lt;8-56&gt;:"UTF-8" coded sample number (decoded number is 36 bits)<br />
&nbsp;&nbsp;&nbsp;&lt;8-56&gt;:"UTF-8" coded sample number (decoded number is 36 bits) <a href="#frame_header_notes">[4]</a><br />
else<br />
&nbsp;&nbsp;&nbsp;&lt;8-48&gt;:"UTF-8" coded frame number (decoded number is 31 bits)
&nbsp;&nbsp;&nbsp;&lt;8-48&gt;:"UTF-8" coded frame number (decoded number is 31 bits) <a href="#frame_header_notes">[4]</a>
</td>
</tr>
<tr>
......@@ -1360,8 +1360,11 @@
<td>
</td>
<td bgcolor="#F4F4CC">
<font size="+1">NOTES</font><br />
<ul>
<a name="frame_header_notes"><font size="+1">NOTES</font></a><br />
<ol>
<li>
This bit must remain reserved for <tt>0</tt> in order for a FLAC frame's initial 15 bits to be distinguishable from the start of an MPEG audio frame (<a href="http://lists.xiph.org/pipermail/flac-dev/2008-December/002607.html">see also</a>).
</li>
<li>
The "blocking strategy" bit must be the same throughout the entire stream.
</li>
......@@ -1371,7 +1374,7 @@
<li>
The "UTF-8" coding used for the sample/frame number is the same variable length code used to store compressed UCS-2, extended to handle larger input.
</li>
</ul>
</ol>
</td>
</tr>
</table>
......
......@@ -1407,7 +1407,7 @@ FLAC__bool find_metadata_(FLAC__StreamDecoder *decoder)
decoder->private_->lookahead = (FLAC__byte)x;
decoder->private_->cached = true;
}
else if(x >> 2 == 0x3e) { /* MAGIC NUMBER for the last 6 sync bits */
else if(x >> 1 == 0x7c) { /* MAGIC NUMBER for the last 6 sync bits and reserved 7th bit */
decoder->private_->header_warmup[1] = (FLAC__byte)x;
decoder->protected_->state = FLAC__STREAM_DECODER_READ_FRAME;
return true;
......@@ -1977,7 +1977,7 @@ FLAC__bool frame_sync_(FLAC__StreamDecoder *decoder)
decoder->private_->lookahead = (FLAC__byte)x;
decoder->private_->cached = true;
}
else if(x >> 2 == 0x3e) { /* MAGIC NUMBER for the last 6 sync bits */
else if(x >> 1 == 0x7c) { /* MAGIC NUMBER for the last 6 sync bits and reserved 7th bit */
decoder->private_->header_warmup[1] = (FLAC__byte)x;
decoder->protected_->state = FLAC__STREAM_DECODER_READ_FRAME;
return true;
......
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