Decode embedded sound in chunks of 65535 bytes

Fixes latency in lessig-freeculture.swf:
https://savannah.gnu.org/bugs/?25456

Confirms AudioDecoder is already allowed to do incremental decoding:
https://savannah.gnu.org/bugs/index.php?24638

1 files changed, 9 insertions, 1 deletions

diff --git a/libsound/EmbedSoundInst.cpp b/libsound/EmbedSoundInst.cpp
index 4c7023cb6..cecfb52f4 100644
--- a/libsound/EmbedSoundInst.cpp
+++ b/libsound/EmbedSoundInst.cpp
@@ -91,7 +91,15 @@ EmbedSoundInst::decodeNextBlock()
 {
     assert(!decodingCompleted());
 
-    const boost::uint32_t inputSize = _soundDef.size() - decodingPosition;
+    // this value is arbitrary, things would also work
+    // with a smaller value, but 2^16 seems fast enough
+    // to decode not to bother further streamlining it
+    // See https://savannah.gnu.org/bugs/?25456 for a testcase
+    // showing the benefit of chunked decoding.
+    const boost::uint32_t chunkSize = 65535;
+
+    boost::uint32_t inputSize = _soundDef.size() - decodingPosition;
+    if ( inputSize > chunkSize ) inputSize = chunkSize;
 
 #ifdef GNASH_DEBUG_SOUNDS_DECODING
     log_debug("  decoding %d bytes", inputSize);