@@ -74,9 +74,9 @@ static void init_slice_c(int8_t out[64][64], uint8_t h, uint8_t v,
// 64x64 inverse integer transform
for (int y = 0; y < 64; y++) {
- for (int x = 0; x < 64; x++) {
+ for (int x = 0; x <= freq_h; x++) {
int32_t sum = 0;
- for (int p = 0; p < 64; p++)
+ for (int p = 0; p <= freq_v; p++)
sum += R64T[y][p] * out[x][p];
tmp[y][x] = (sum + 128) >> 8;
}
@@ -85,7 +85,7 @@ static void init_slice_c(int8_t out[64][64], uint8_t h, uint8_t v,
for (int y = 0; y < 64; y++) {
for (int x = 0; x < 64; x++) {
int32_t sum = 0;
- for (int p = 0; p < 64; p++)
+ for (int p = 0; p <= freq_h; p++)
sum += tmp[y][p] * R64T[x][p]; // R64T^T = R64
// Renormalize and clip to [-127, 127]
out[y][x] = av_clip((sum + 128) >> 8, -127, 127);
From: Niklas Haas <git@haasn.dev> This bug flew under the radar because, in practice, these values are 0-initialized for the first invocation. But for subsequent invocations (with different h/v values), reading from the uninitialized parts of `out` is undefined behavior. Avoid this by simply adjusting the iteration range of the following loops. Has the added benefit of being a minor speedup. --- libavcodec/h274.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)