Started to implement mp3 file reading based on libmpg123.

Signed-off-by: Stefan Westerfeld <stefan@space.twc.de>

configure.ac

@@ -17,6 +17,16 @@ AC_DEFUN([AC_SNDFILE_REQUIREMENTS],
     AC_SUBST(SNDFILE_LIBS)
 ])
 
+dnl
+dnl libmpg123
+dnl
+AC_DEFUN([AC_LIBMPG123_REQUIREMENTS],
+[
+    PKG_CHECK_MODULES(LIBMPG123, [libmpg123])
+    AC_SUBST(LIBMPG123_CFLAGS)
+    AC_SUBST(LIBMPG123_LIBS)
+])
+
 dnl
 dnl zita resampler
 dnl
@@ -57,6 +67,7 @@ AC_DEFUN([AC_FFTW_CHECK],
 ])
 
 AC_SNDFILE_REQUIREMENTS
+AC_LIBMPG123_REQUIREMENTS
 AC_ZITA_REQUIREMENTS
 AC_FFTW_CHECK
 AM_PATH_LIBGCRYPT

src/Makefile.am

 bin_PROGRAMS = audiowmark
 
-COMMON_SRC = utils.hh utils.cc convcode.hh convcode.cc random.hh random.cc
+COMMON_SRC = utils.hh utils.cc convcode.hh convcode.cc random.hh random.cc mp3.cc wavdata.cc wavdata.hh
+COMMON_LIBS = $(SNDFILE_LIBS) $(FFTW_LIBS) $(LIBGCRYPT_LIBS) $(LIBMPG123_LIBS)
 
-audiowmark_SOURCES = audiowmark.cc wavdata.cc wavdata.hh fft.cc fft.hh $(COMMON_SRC)
-audiowmark_LDFLAGS = $(SNDFILE_LIBS) $(FFTW_LIBS) $(LIBGCRYPT_LIBS)
+audiowmark_SOURCES = audiowmark.cc fft.cc fft.hh $(COMMON_SRC)
+audiowmark_LDFLAGS = $(COMMON_LIBS)
 
-noinst_PROGRAMS = testconvcode testrandom
+noinst_PROGRAMS = testconvcode testrandom testmp3
 
 testconvcode_SOURCES = testconvcode.cc $(COMMON_SRC)
-testconvcode_LDFLAGS = $(LIBGCRYPT_LIBS)
+testconvcode_LDFLAGS = $(COMMON_LIBS)
 
 testrandom_SOURCES = testrandom.cc $(COMMON_SRC)
-testrandom_LDFLAGS = $(LIBGCRYPT_LIBS)
+testrandom_LDFLAGS = $(COMMON_LIBS)
+
+testmp3_SOURCES = testmp3.cc $(COMMON_SRC)
+testmp3_LDFLAGS = $(COMMON_LIBS)

src/mp3.cc

+#include "mp3.hh"
+
+#include <mpg123.h>
+#include <assert.h>
+#include <stdio.h>
+#include <vector>
+
+using std::vector;
+using std::string;
+
+bool
+mp3_try_load (const string& filename, WavData& wav_data)
+{
+  int err = mpg123_init();
+  assert (err == MPG123_OK);
+
+  mpg123_handle *mh = mpg123_new (NULL, &err);
+  assert (err == MPG123_OK);
+
+  mpg123_param (mh, MPG123_ADD_FLAGS, MPG123_QUIET, 0);
+  long rate;
+  int channels;
+  int encoding;
+  //
+  const long *rates;
+  size_t rate_count;
+  mpg123_format_none (mh);
+  mpg123_rates(&rates, &rate_count);
+  for(size_t i=0; i<rate_count; ++i)
+    {
+      err = mpg123_format (mh, rates[i], MPG123_MONO|MPG123_STEREO, MPG123_ENC_FLOAT_32);
+      assert (err == 0);
+    }
+  printf ("# format: %d\n", err);
+
+  err = mpg123_open (mh, filename.c_str());
+  assert (err == 0);
+  err = mpg123_getformat (mh, &rate, &channels, &encoding);
+  assert (err == 0);
+  printf ("# %d\n", err);
+  printf ("# %ld %d %d\n", rate, channels, encoding);
+  assert (err == MPG123_OK);
+
+  /* ensure that the format will not change */
+  mpg123_format_none (mh);
+  mpg123_format (mh, rate, channels, encoding);
+
+  printf ("# %zd\n", mpg123_outblock (mh));
+  vector<unsigned char> buffer (mpg123_outblock (mh));
+
+  size_t done = 0;
+  do
+    {
+      err = mpg123_read( mh, &buffer[0], buffer.size(), &done );
+      assert (err == 0 || err == MPG123_DONE);
+      printf ("# done=%zd err=%d\n", done, err);
+
+      float *f = reinterpret_cast<float *> (&buffer[0]);
+      for (int i = 0; i < buffer.size() / 8; i++)
+        {
+          printf ("%f\n", f[i*2]);
+        }
+    }
+  while (done);
+
+  return true;
+}

src/testmp3.cc

+#include "mp3.hh"
+
+int
+main (int argc, char **argv)
+{
+  WavData wd;
+  mp3_try_load (argv[1], wd);
+}