add a function to calculate a more accurate estimate for maximum FLAC

frame size and use the function in the FLAC decoder and FLAC encoder

Originally committed as revision 18092 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 43 insertions, 0 deletions

diff --git a/libavcodec/flac.c b/libavcodec/flac.c
new file mode 100644
index 0000000000..a649e08732
--- /dev/null
+++ b/libavcodec/flac.c
@@ -0,0 +1,43 @@
+/*
+ * FLAC common code
+ * Copyright (c) 2009 Justin Ruggles
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "flac.h"
+
+int ff_flac_get_max_frame_size(int blocksize, int ch, int bps)
+{
+    /* Technically, there is no limit to FLAC frame size, but an encoder
+       should not write a frame that is larger than if verbatim encoding mode
+       were to be used. */
+
+    int count;
+
+    count = 16;                  /* frame header */
+    count += ch * ((7+bps+7)/8); /* subframe headers */
+    if (ch == 2) {
+        /* for stereo, need to account for using decorrelation */
+        count += (( 2*bps+1) * blocksize + 7) / 8;
+    } else {
+        count += ( ch*bps    * blocksize + 7) / 8;
+    }
+    count += 2; /* frame footer */
+
+    return count;
+}