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MP3_Source.cpp
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MP3_Source.cpp
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/***************************************************************************
* This file is part of last.fm fingerprint app *
* Last.fm Ltd <mir@last.fm> *
* *
* This library is free software; you can redistribute it and/or *
* modify it under the terms of the GNU Lesser General Public *
* License as published by the Free Software Foundation; either *
* version 2.1 of the License, or (at your option) any later version. *
* *
* This library is distributed in the hope that it will be useful, *
* but WITHOUT ANY WARRANTY; without even the implied warranty of *
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU *
* Lesser General Public License for more details. *
* *
* You should have received a copy of the GNU Lesser General Public *
* License along with this library; if not, write to the Free Software *
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 *
* USA *
***************************************************************************/
#include <iostream>
#include <fstream>
#include <limits>
#include <sstream>
#include <cassert>
#include <stdexcept>
#include <cmath>
#include <cstdlib>
#include <climits>
#include <cstring>
#include "MP3_Source.h"
#undef max // was definded in mad
// -----------------------------------------------------------
MP3_Source::MP3_Source()
: m_pMP3_Buffer ( new unsigned char[m_MP3_BufferSize+MAD_BUFFER_GUARD] )
{}
// -----------------------------------------------------------
MP3_Source::~MP3_Source()
{
if (m_pMP3_Buffer) delete [] m_pMP3_Buffer;
}
// ---------------------------------------------------------------------
inline short f2s(mad_fixed_t f)
{
/* A fixed point number is formed of the following bit pattern:
*
* SWWWFFFFFFFFFFFFFFFFFFFFFFFFFFFF
* MSB LSB
* S ==> Sign (0 is positive, 1 is negative)
* W ==> Whole part bits
* F ==> Fractional part bits
*
* This pattern contains MAD_F_FRACBITS fractional bits, one
* should alway use this macro when working on the bits of a fixed
* point number. It is not guaranteed to be constant over the
* different platforms supported by libmad.
*
* The signed short value is formed, after clipping, by the least
* significant whole part bit, followed by the 15 most significant
* fractional part bits. Warning: this is a quick and dirty way to
* compute the 16-bit number, madplay includes much better
* algorithms.
*/
/* Clipping */
if(f >= MAD_F_ONE)
return(SHRT_MAX);
if(f <= -MAD_F_ONE)
return(-SHRT_MAX);
/* Conversion. */
f = f >> (MAD_F_FRACBITS-15);
return (signed short)f;
}
// ---------------------------------------------------------------------
string MP3_Source::MadErrorString(const mad_error& error)
{
switch(error)
{
/* Generic unrecoverable errors. */
case MAD_ERROR_BUFLEN:
return("input buffer too small (or EOF)");
case MAD_ERROR_BUFPTR:
return("invalid (null) buffer pointer");
case MAD_ERROR_NOMEM:
return("not enough memory");
/* Frame header related unrecoverable errors. */
case MAD_ERROR_LOSTSYNC:
return("lost synchronization");
case MAD_ERROR_BADLAYER:
return("reserved header layer value");
case MAD_ERROR_BADBITRATE:
return("forbidden bitrate value");
case MAD_ERROR_BADSAMPLERATE:
return("reserved sample frequency value");
case MAD_ERROR_BADEMPHASIS:
return("reserved emphasis value");
/* Recoverable errors */
case MAD_ERROR_BADCRC:
return("CRC check failed");
case MAD_ERROR_BADBITALLOC:
return("forbidden bit allocation value");
case MAD_ERROR_BADSCALEFACTOR:
return("bad scalefactor index");
case MAD_ERROR_BADFRAMELEN:
return("bad frame length");
case MAD_ERROR_BADBIGVALUES:
return("bad big_values count");
case MAD_ERROR_BADBLOCKTYPE:
return("reserved block_type");
case MAD_ERROR_BADSCFSI:
return("bad scalefactor selection info");
case MAD_ERROR_BADDATAPTR:
return("bad main_data_begin pointer");
case MAD_ERROR_BADPART3LEN:
return("bad audio data length");
case MAD_ERROR_BADHUFFTABLE:
return("bad Huffman table select");
case MAD_ERROR_BADHUFFDATA:
return("Huffman data overrun");
case MAD_ERROR_BADSTEREO:
return("incompatible block_type for JS");
/* Unknown error. This switch may be out of sync with libmad's
* defined error codes.
*/
default:
return("Unknown error code");
}
}
// -----------------------------------------------------------------------------
bool MP3_Source::isRecoverable(const mad_error& error, bool log)
{
if (MAD_RECOVERABLE (error))
{
/* Do not print a message if the error is a loss of
* synchronization and this loss is due to the end of
* stream guard bytes. (See the comments marked {3}
* supra for more informations about guard bytes.)
*/
if (error != MAD_ERROR_LOSTSYNC /*|| mad_stream.this_frame != pGuard */ && log)
{
cerr << "Recoverable frame level error: "
<< MadErrorString(error) << endl;
}
return true;
}
else
{
if (error == MAD_ERROR_BUFLEN)
return true;
else
{
stringstream ss;
ss << "Unrecoverable frame level error: "
<< MadErrorString (error) << endl;
throw ss.str();
}
}
return false;
}
// -----------------------------------------------------------
void MP3_Source::release()
{
if ( m_inputFile.is_open() )
{
m_inputFile.close();
m_inputFile.clear();
mad_synth_finish(&m_mad_synth);
mad_frame_finish(&m_mad_frame);
mad_stream_finish(&m_mad_stream);
}
}
// -----------------------------------------------------------
void MP3_Source::init(const string& fileName)
{
m_inputFile.open( fileName.c_str() , ios::binary);
m_fileName = fileName;
if ( !m_inputFile.is_open() )
{
m_inputFile.clear();
throw std::runtime_error ("Cannot load mp3 file!");
}
mad_stream_init(&m_mad_stream);
mad_frame_init (&m_mad_frame);
mad_synth_init (&m_mad_synth);
mad_timer_reset(&m_mad_timer);
m_pcmpos = m_mad_synth.pcm.length;
}
// -----------------------------------------------------------------------------
void MP3_Source::getInfo( const string& fileName, int& lengthSecs, int& samplerate, int& bitrate, int& nchannels )
{
// get the header plus some other stuff..
ifstream inputFile(fileName.c_str(), ios::binary);
if ( !inputFile.is_open() )
{
cerr << "ERROR: Cannot load file for getInfo!" << endl;
return;
}
unsigned char* pMP3_Buffer = new unsigned char[m_MP3_BufferSize+MAD_BUFFER_GUARD];
mad_stream madStream;
mad_header madHeader;
mad_timer_t madTimer;
mad_stream_init(&madStream);
mad_timer_reset(&madTimer);
double avgSamplerate = 0;
double avgBitrate = 0;
double avgNChannels = 0;
int nFrames = 0;
while ( fetchData( inputFile, pMP3_Buffer, m_MP3_BufferSize, madStream) )
{
if ( mad_header_decode(&madHeader, &madStream) != 0 )
{
if ( isRecoverable(madStream.error) )
continue;
else
break;
}
mad_timer_add(&madTimer, madHeader.duration);
avgSamplerate += madHeader.samplerate;
avgBitrate += madHeader.bitrate;
if ( madHeader.mode == MAD_MODE_SINGLE_CHANNEL )
++avgNChannels;
else
avgNChannels += 2;
++nFrames;
}
inputFile.close();
inputFile.clear();
mad_stream_finish(&madStream);
mad_header_finish(&madHeader);
lengthSecs = static_cast<int>(madTimer.seconds);
samplerate = static_cast<int>( (avgSamplerate/nFrames) + 0.5 );
bitrate = static_cast<int>( (avgBitrate/nFrames) + 0.5 );
nchannels = static_cast<int>( (avgNChannels/nFrames) + 0.5 );
}
// -----------------------------------------------------------
bool MP3_Source::fetchData( ifstream& mp3File,
unsigned char* pMP3_Buffer,
const int MP3_BufferSize,
mad_stream& madStream )
{
unsigned char *pReadStart = NULL;
unsigned char *pGuard = NULL;
if ( madStream.buffer == NULL ||
madStream.error == MAD_ERROR_BUFLEN )
{
size_t readSize;
size_t remaining;
/* {2} libmad may not consume all bytes of the input
* buffer. If the last frame in the buffer is not wholly
* contained by it, then that frame's start is pointed by
* the next_frame member of the Stream structure. This
* common situation occurs when mad_frame_decode() fails,
* sets the stream error code to MAD_ERROR_BUFLEN, and
* sets the next_frame pointer to a non NULL value. (See
* also the comment marked {4} bellow.)
*
* When this occurs, the remaining unused bytes must be
* put back at the beginning of the buffer and taken in
* account before refilling the buffer. This means that
* the input buffer must be large enough to hold a whole
* frame at the highest observable bit-rate (currently 448
* kb/s). XXX=XXX Is 2016 bytes the size of the largest
* frame? (448000*(1152/32000))/8
*/
if (madStream.next_frame != NULL)
{
remaining = madStream.bufend - madStream.next_frame;
memmove (pMP3_Buffer, madStream.next_frame, remaining);
pReadStart = pMP3_Buffer + remaining;
readSize = MP3_BufferSize - remaining;
}
else
{
readSize = MP3_BufferSize;
pReadStart = pMP3_Buffer;
remaining = 0;
}
mp3File.read ( reinterpret_cast<char*>(pReadStart),
static_cast <std::streamsize> (readSize));
readSize = mp3File.gcount();
// nothing else to read!
if (readSize <= 0)
return false;
if ( mp3File.eof() )
{
pGuard = pReadStart + readSize;
memset (pGuard, 0, MAD_BUFFER_GUARD);
readSize += MAD_BUFFER_GUARD;
}
// Pipe the new buffer content to libmad's stream decoder facility.
mad_stream_buffer( &madStream, pMP3_Buffer,
static_cast<unsigned int>(readSize + remaining));
madStream.error = MAD_ERROR_NONE;
}
return true;
}
// -----------------------------------------------------------------------------
void MP3_Source::skipSilence(double silenceThreshold /* = 0.0001 */)
{
mad_frame madFrame;
mad_synth madSynth;
mad_frame_init(&madFrame);
mad_synth_init (&madSynth);
silenceThreshold *= static_cast<double>( numeric_limits<short>::max() );
for (;;)
{
if ( !fetchData( m_inputFile, m_pMP3_Buffer, m_MP3_BufferSize, m_mad_stream) )
break;
if ( mad_frame_decode(&madFrame, &m_mad_stream) != 0 )
{
if ( isRecoverable(m_mad_stream.error) )
continue;
else
break;
}
mad_synth_frame (&madSynth, &madFrame);
double sum = 0;
switch (madSynth.pcm.channels)
{
case 1:
for (size_t j = 0; j < madSynth.pcm.length; ++j)
sum += abs((int)f2s(madSynth.pcm.samples[0][j]));
break;
case 2:
for (size_t j = 0; j < madSynth.pcm.length; ++j)
sum += abs((int)f2s(
(madSynth.pcm.samples[0][j] >> 1)
+ (madSynth.pcm.samples[1][j] >> 1)));
break;
}
if ( (sum >= silenceThreshold * madSynth.pcm.length) )
break;
}
mad_header_finish(&madHeader);
}
// -----------------------------------------------------------------------------
void MP3_Source::skip(const int mSecs)
{
if ( mSecs <= 0 )
return;
mad_header madHeader;
mad_header_init(&madHeader);
for (;;)
{
if (!fetchData( m_inputFile, m_pMP3_Buffer, m_MP3_BufferSize, m_mad_stream))
break;
if ( mad_header_decode(&madHeader, &m_mad_stream) != 0 )
{
if ( isRecoverable(m_mad_stream.error) )
continue;
else
break;
}
mad_timer_add(&m_mad_timer, madHeader.duration);
if ( mad_timer_count(m_mad_timer, MAD_UNITS_MILLISECONDS) >= mSecs )
break;
}
mad_header_finish(&madHeader);
}
// -----------------------------------------------------------
int MP3_Source::updateBuffer(signed short* pBuffer, size_t bufferSize)
{
size_t nwrit = 0; //number of samples written to the output buffer
for (;;)
{
// get a (valid) frame
// m_pcmpos == 0 could mean two things
// - we have completely decoded a frame, but the output buffer is still
// not full (it would make more sense for pcmpos == pcm.length(), but
// the loop assigns pcmpos = 0 at the end and does it this way!
// - we are starting a stream
if ( m_pcmpos == m_mad_synth.pcm.length )
{
if ( !fetchData( m_inputFile, m_pMP3_Buffer, m_MP3_BufferSize, m_mad_stream) )
{
m_mad_synth.pcm.length = 0;
break; // nothing else to read
}
// decode the frame
if (mad_frame_decode (&m_mad_frame, &m_mad_stream))
{
if ( isRecoverable(m_mad_stream.error) )
continue;
else
break;
} // if (mad_frame_decode (&madFrame, &madStream))
mad_timer_add (&m_mad_timer, m_mad_frame.header.duration);
mad_synth_frame (&m_mad_synth, &m_mad_frame);
m_pcmpos = 0;
}
size_t samples_for_mp3 = m_mad_synth.pcm.length - m_pcmpos;
size_t samples_for_buf = bufferSize - nwrit;
signed short* pBufferIt = pBuffer + nwrit;
size_t i = 0, j = 0;
switch( m_mad_synth.pcm.channels )
{
case 1:
{
size_t samples_to_use = min (samples_for_mp3, samples_for_buf);
for (i = 0; i < samples_to_use; ++i )
pBufferIt[i] = f2s( m_mad_synth.pcm.samples[0][i+m_pcmpos] );
}
j = i;
break;
case 2:
for (; i < samples_for_mp3 && j < samples_for_buf ; ++i, j+=2 )
{
pBufferIt[j] = f2s( m_mad_synth.pcm.samples[0][i+m_pcmpos] );
pBufferIt[j+1] = f2s( m_mad_synth.pcm.samples[1][i+m_pcmpos] );
}
break;
default:
cerr << "wtf kind of mp3 has " << m_mad_synth.pcm.channels << " channels??\n";
break;
}
m_pcmpos += i;
nwrit += j;
assert( nwrit <= bufferSize );
if (nwrit == bufferSize)
return static_cast<int>(nwrit);
}
// end of stream
m_pcmpos = 0;
return static_cast<int>(nwrit);
}
// -----------------------------------------------------------------------------