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From 88fae6224b54ecf92ac6e3ae5083c3f352adc798 Mon Sep 17 00:00:00 2001
From: Anuradha Suraparaju <anuradha@hoyle.rd.bbc.co.uk>
Date: Fri, 17 Apr 2009 17:47:27 +1000
Subject: [PATCH] Fix uninitialised memory read that causes the encoder to crash when using
non-overlapping blocks.
---
libdirac_common/mot_comp.cpp | 21 +++++++++++++++------
1 files changed, 15 insertions(+), 6 deletions(-)
diff --git a/libdirac_common/mot_comp.cpp b/libdirac_common/mot_comp.cpp
index aa8d37c..e0ec2ff 100644
--- a/libdirac_common/mot_comp.cpp
+++ b/libdirac_common/mot_comp.cpp
@@ -306,6 +306,8 @@ void MotionCompensator::CompensateComponent( Picture* pic ,
int save_from_row = m_bparams.Ybsep()-m_bparams.Yoffset();
+ bool row_overlap = ((m_bparams.Yblen() - m_bparams.Ybsep()) > 0);
+
// unpadded picture dimensions
const int x_end_data = pic_data_out.FirstX() + std::min(pic_data_out.LengthX(), pic_size.x );
const int y_end_data = pic_data_out.FirstY() + std::min(pic_data_out.LengthY(), pic_size.y );
@@ -489,12 +491,19 @@ void MotionCompensator::CompensateComponent( Picture* pic ,
//Increment the block vertical position
pos.y += m_bparams.Ybsep();
- // Copy the rows required to motion compensate the next row of block.
- // This is usually Yblen-Ybsep rows.
- memmove (pic_data[0], pic_data[save_from_row], (m_bparams.Yblen() - save_from_row)*pic_data.LengthX()*sizeof(ValueType));
- memset( pic_data[m_bparams.Yblen() - save_from_row], 0, save_from_row*pic_data.LengthX()*sizeof(ValueType) );
- save_from_row = m_bparams.Ybsep();
-
+ if (row_overlap)
+ {
+ // Copy the rows required to motion compensate the next row of
+ // blocks. This is usually Yblen-Ybsep rows.
+ memmove (pic_data[0], pic_data[save_from_row], (m_bparams.Yblen() - save_from_row)*pic_data.LengthX()*sizeof(ValueType));
+ memset( pic_data[m_bparams.Yblen() - save_from_row], 0, save_from_row*pic_data.LengthX()*sizeof(ValueType) );
+ save_from_row = m_bparams.Ybsep();
+ }
+ else
+ {
+ // no row overlap. So reset pic_data to 0.
+ memset( pic_data[0], 0, m_bparams.Yblen()*pic_data.LengthX()*sizeof(ValueType) );
+ }
}//yblock
if ( m_add_or_sub == SUBTRACT)
--
1.7.0.4
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