Merge pull request 'WavPack decoding and seeking speed improvements' (#342) from ayumi/tangara-fw:wavpack into main

Reviewed-on: https://codeberg.org/cool-tech-zone/tangara-fw/pulls/342

2 files changed, 23 insertions, 9 deletions

diff --git a/src/codecs/sample.cpp b/src/codecs/sample.cpp
index 63d14203..faf8b0f9 100644
--- a/src/codecs/sample.cpp
+++ b/src/codecs/sample.cpp
@@ -13,13 +13,17 @@
 
 namespace sample {
 
-static uint64_t sSeed1{0};
-static uint64_t sSeed2{0};
-
 auto shiftWithDither(int64_t src, uint_fast8_t bits) -> Sample {
   // FIXME: Use a better dither.
-  int16_t noise = static_cast<int16_t>(komirand(&sSeed1, &sSeed2) & 1);
-  return (src >> bits) ^ noise;
+  static uint64_t sSeed1{0};
+  static uint64_t sSeed2{0};
+  static uint64_t noise;
+  static uint_fast8_t pos = 0;
+  if (pos++ % 64 == 0)
+    noise = komirand(&sSeed1, &sSeed2);
+  else
+    noise >>= 1;
+  return (src >> bits) ^ (noise & 1);
 }
 
 }  // namespace sample
diff --git a/src/codecs/wavpack.cpp b/src/codecs/wavpack.cpp
index 21865785..709302e6 100644
--- a/src/codecs/wavpack.cpp
+++ b/src/codecs/wavpack.cpp
@@ -73,7 +73,7 @@ auto WavPackDecoder::OpenStream(std::shared_ptr<IStream> input, uint32_t offset)
         );
   const auto rate = WavpackGetSampleRate(&wavpack_);
   if (offset && total && input_.get()->CanSeek()) {
-    const uint32_t want = offset * rate - 1;
+    const uint32_t want = offset * rate;
     if (total < want) {
       ESP_LOGE(kTag, "seeking: offset points beyond the end of the file");
       return cpp::fail(Error::kInternalError);
@@ -96,7 +96,11 @@ auto WavPackDecoder::OpenStream(std::shared_ptr<IStream> input, uint32_t offset)
       }
       const uint32_t blockIndex = loadLe32(header + 16);
       const uint32_t blockSamples = loadLe32(header + 20);
-      if (want >= blockIndex && want <= blockIndex + blockSamples) {
+      if (want >= blockIndex && want == blockIndex + blockSamples) {
+        input_->SeekTo(size - 24, IStream::SeekFrom::kCurrentPosition);
+        target = 0;
+        break;
+      } else if (want >= blockIndex && want < blockIndex + blockSamples) {
         input_->SeekTo(-32, IStream::SeekFrom::kCurrentPosition);
         target = want - blockIndex;
         break;
@@ -150,8 +154,14 @@ auto WavPackDecoder::DecodeTo(std::span<sample::Sample> output)
     ESP_LOGE(kTag, "CRC error");
     return cpp::fail(Error::kMalformedData);
   }
-  for (size_t i = 0; i < samples; i++)
-    output[i] = sample::FromSigned(buf_[i], bitdepth_);
+  if (bitdepth_ == 16)
+    for (size_t i = 0; i < samples; i++)
+      output[i] = buf_[i];
+  else if (bitdepth_ > 16)
+    for (size_t i = 0; i < samples; i++)
+      output[i] = sample::shiftWithDither(buf_[i], bitdepth_ - 16);
+  else for (size_t i = 0; i < samples; i++)
+    output[i] = buf_[i] << (16 - bitdepth_);
   return OutputInfo{
       .samples_written = samples,
       .is_stream_finished = samples == 0,