Add error handling if compute_frame_ffts runs out of space.

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

src/audiowmark.cc

@@ -307,10 +307,12 @@ gen_mix_entries (int block)
 vector<vector<complex<float>>>
 compute_frame_ffts (const WavData& wav_data, size_t start_index, size_t frame_count)
 {
-  assert (wav_data.n_values() >= (start_index + frame_count * Params::frame_size) * wav_data.n_channels());
-
   vector<vector<complex<float>>> fft_out;
 
+  /* if there is not enough space for frame_count values, return an error (empty vector) */
+  if (wav_data.n_values() < (start_index + frame_count * Params::frame_size) * wav_data.n_channels())
+    return fft_out;
+
   /* generate analysis window */
   vector<float> window (Params::frame_size);
 
@@ -939,9 +941,6 @@ public:
   vector<vector<float>>
   sync_fft (const WavData& wav_data, size_t index, size_t count)
   {
-    if (wav_data.n_values() < (index + count * Params::frame_size) * wav_data.n_channels())
-      return {};
-
     /* computing db-magnitude is expensive, so we better do it here */
     vector<vector<float>> fft_out_db;
     for (const vector<complex<float>>& spect : compute_frame_ffts (wav_data, index, count))
@@ -991,7 +990,8 @@ decode_and_report (const WavData& wav_data, const string& orig_pattern)
       const size_t index = pos + (mark_sync_frame_count() * Params::frame_size);
 
       auto fft_range_out = compute_frame_ffts (wav_data, index, count);
-
+      if (fft_range_out.size())
+        {
           vector<vector<complex<float>>> junk;
 
           vector<float> soft_bit_vec;
@@ -1003,14 +1003,9 @@ decode_and_report (const WavData& wav_data, const string& orig_pattern)
             {
               soft_bit_vec = linear_decode (fft_range_out, junk, wav_data.n_channels());
             }
-      if (soft_bit_vec.size() < conv_code_size (Params::payload_size))
-        {
-          fprintf (stderr, "audiowmark: input file too short to retrieve watermark\n");
-          fprintf (stderr, " - number of recovered raw bits %zd\n", soft_bit_vec.size());
-          fprintf (stderr, " - need at least %zd raw bits to get watermark\n", conv_code_size (Params::payload_size));
-          return 1;
-        }
+
           /* truncate to the required length */
+          assert (soft_bit_vec.size() >= conv_code_size (Params::payload_size));
           soft_bit_vec.resize (conv_code_size (Params::payload_size));
 
           vector<int> bit_vec = conv_decode_soft (randomize_bit_order (soft_bit_vec, /* encode */ false));
@@ -1031,6 +1026,7 @@ decode_and_report (const WavData& wav_data, const string& orig_pattern)
             }
           total_count++;
         }
+    }
 
   if (!orig_pattern.empty())
     printf ("match_count %d %d\n", match_count, total_count);