Date: Sun, 4 Jan 2004 23:48:19 +0100

From: Max Horn Subject: Re: Again Audio CD patch Am 04.01.2004 um 22:38 schrieb Sam Lantinga: > > Okay, I fixed the buffering problems by simply using a 4 second buffer > instead of a 1 second buffer. However, using your code I can't play an > entire CD - the playback stops after the first song. > Found the problem: FSReadFork returns eofErr when the file is finished. However, we check its return value for errors, and if anything but noErr occurs, the reader thread aborts its current iteration. That is bad, because it aborts before it can ever set the flag which tells that the file is over (also, any remaining data which FSRead did return is lost - so you'd not hear about to 4 seconds from the end of the file. Furthermore, the computed data size was 8 bytes to high (I forgot to account for the fact that the size of an (A)IFF chunk always contains the chunk header & size fields, too). This is enough to make it work. However, the end condition is rather fragile, so I tuned some other things to be pessimistic (check for <= 0 instead of == 0, when eofErr is encountered enforce mReadFilePosition == mFileLength). You never know... The attached patch fixes the issue for me.
libsdl-org · Jan 5, 2004 · 1cb6d97 · 1cb6d97
1 parent 0780836
commit 1cb6d97
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Showing 2 changed files with 8 additions and 10 deletions.
diff --git a/src/cdrom/macosx/AudioFilePlayer.cpp b/src/cdrom/macosx/AudioFilePlayer.cpp
@@ -352,7 +352,7 @@ void    AudioFilePlayer::OpenFile (const FSRef *inRef, SInt64& outFileDataSize)
        THROW_RESULT("AudioFilePlayer::OpenFile(): FSSetForkPosition")
 
     // Data size
-    outFileDataSize = chunk.ckSize - ssndData.offset;
+    outFileDataSize = chunk.ckSize - ssndData.offset - 8;
 
     // File format
     mFileDescription.mSampleRate = 44100;

diff --git a/src/cdrom/macosx/AudioFileReaderThread.cpp b/src/cdrom/macosx/AudioFileReaderThread.cpp
@@ -241,22 +241,17 @@ void    FileReaderThread::ReadNextChunk ()
             dataChunkSize = theItem->mChunkSize;
 
             // this is the exit condition for the thread
-        if (dataChunkSize == 0) {
+        if (dataChunkSize <= 0) {
             theItem->mFinishedReadingData = true;
             continue;
         }
             // construct pointer
         char* writePtr = const_cast<char*>(theItem->GetFileBuffer() + 
                                 (theItem->mWriteToFirstBuffer ? 0 : theItem->mChunkSize));
 
-/*
-        printf ("AudioFileReadBytes: theItem=%.8X fileID=%.8X pos=%.8X sz=%.8X flen=%.8X ptr=%.8X\n", 
-            (unsigned int)theItem, (unsigned int)theItem->GetFileID(),
-            (unsigned int)theItem->mReadFilePosition, (unsigned int)dataChunkSize, 
-            (unsigned int)theItem->mFileLength, (unsigned int)writePtr);
-*/            
+            // read data
         result = theItem->Read(writePtr, &dataChunkSize);
-        if (result) {
+        if (result != noErr && result != eofErr) {
             theItem->GetParent().DoNotification(result);
             continue;
         }
@@ -271,7 +266,10 @@ void    FileReaderThread::ReadNextChunk ()
 
         theItem->mWriteToFirstBuffer = !theItem->mWriteToFirstBuffer;   // switch buffers
 
-        theItem->mReadFilePosition += dataChunkSize;        // increment count
+        if (result == eofErr)
+            theItem->mReadFilePosition = theItem->mFileLength;
+        else
+            theItem->mReadFilePosition += dataChunkSize;        // increment count
     }
 }