More sampling rate checks and tests.

Signed-off-by: Michal Zientkiewicz <michalz@nvidia.com>

dali/operators/decoder/audio/audio_decoder_op.cc

@@ -166,6 +166,9 @@ void AudioDecoderCpu::DecodeBatch(workspace_t<Backend> &ws) {
     tp.DoWorkWithID([&, i](int thread_id) {
       try {
         DecodeSample<OutputType>(decoded_output[i], thread_id, i);
+        sample_rate_output[i].data[0] = use_resampling_
+          ? target_sample_rates_[i]
+          : sample_meta_[i].sample_rate;
       } catch (const DALIException &e) {
         DALI_FAIL(make_string("Error decoding file.\nError: ", e.what(), "\nFile: ",
                               files_names_[i], "\n"));

dali/test/python/test_operator_audio_decoder.py

@@ -59,11 +59,12 @@ def __init__(self):
 
   def define_graph(self):
     self.raw_file = self.file_source()
-    dec_plain,_ = self.plain_decoder(self.raw_file)
-    dec_res,_ = self.resampling_decoder(self.raw_file)
-    dec_mix,_ = self.downmixing_decoder(self.raw_file)
-    dec_res_mix,_ = self.resampling_downmixing_decoder(self.raw_file)
-    out = [dec_plain, dec_res, dec_mix, dec_res_mix]
+    dec_plain, rates_plain = self.plain_decoder(self.raw_file)
+    dec_res, rates_res = self.resampling_decoder(self.raw_file)
+    dec_mix, rates_mix = self.downmixing_decoder(self.raw_file)
+    dec_res_mix, rates_res_mix = self.resampling_downmixing_decoder(self.raw_file)
+    out = [dec_plain, dec_res, dec_mix, dec_res_mix,
+           rates_plain, rates_res, rates_mix, rates_res_mix]
     return out
 
   def iter_setup(self):
@@ -113,6 +114,11 @@ def test_decoded_vs_generated():
       ref3 = generate_waveforms(ref_len[3], freqs[idx] * (rates[idx] / rate2))
       ref3 = ref3.mean(axis = 1, keepdims = 1)
 
+      assert(out[4].at(i)[0] == rates[idx])
+      assert(out[5].at(i)[0] == rate1)
+      assert(out[6].at(i)[0] == rates[idx])
+      assert(out[7].at(i)[0] == rate2)
+
       # just reading - allow only for rounding
       assert np.allclose(plain, ref0, rtol = 0, atol=0.5)
       # resampling - allow for 1e-3 dynamic range error