Atrac: Move buffer offset only if needed.

Hmm, need to manage this buffer smarter, though, when streaming.  Right
now it's only getting it right enough to ask for the right amount of data,
really...

Fixes #8498.

Core/HLE/sceAtrac.cpp

@@ -1258,8 +1258,12 @@ u32 _AtracDecodeData(int atracID, u8 *outbuf, u32 outbufPtr, u32 *SamplesNum, u3
 				}
 				if ((atrac->bufferState_ & ATRAC_STATUS_STREAMED_MASK) == ATRAC_STATUS_STREAMED_MASK) {
 					// Whatever bytes we have left were added from the loop.
-					atrac->first_.fileoffset = atrac->FileOffsetBySample(atrac->loopStartSample_ - atrac->FirstOffsetExtra() - atrac->firstSampleOffset_ - atrac->SamplesPerFrame() * 2);
-					// Skip the initial frame at the start.
+					u32 loopOffset = atrac->FileOffsetBySample(atrac->loopStartSample_ - atrac->FirstOffsetExtra() - atrac->firstSampleOffset_ - atrac->SamplesPerFrame() * 2);
+					// TODO: Hmm, need to manage the buffer better.  But don't move fileoffset if we already have valid data.
+					if (loopOffset > atrac->first_.fileoffset || loopOffset + atrac->bufferValidBytes_ < atrac->first_.fileoffset) {
+						// Skip the initial frame at the start.
+						atrac->first_.fileoffset = atrac->FileOffsetBySample(atrac->loopStartSample_ - atrac->FirstOffsetExtra() - atrac->firstSampleOffset_ - atrac->SamplesPerFrame() * 2);
+					}
 				}
 			} else if (hitEnd) {
 				finishFlag = 1;