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-rw-r--r--media/libstagefright/avc_utils.cpp38
1 files changed, 37 insertions, 1 deletions
diff --git a/media/libstagefright/avc_utils.cpp b/media/libstagefright/avc_utils.cpp
index c6ac0da..38a1f6b 100644
--- a/media/libstagefright/avc_utils.cpp
+++ b/media/libstagefright/avc_utils.cpp
@@ -40,6 +40,25 @@ unsigned parseUE(ABitReader *br) {
return x + (1u << numZeroes) - 1;
}
+signed parseSE(ABitReader *br) {
+ unsigned codeNum = parseUE(br);
+
+ return (codeNum & 1) ? (codeNum + 1) / 2 : -(codeNum / 2);
+}
+
+static void skipScalingList(ABitReader *br, size_t sizeOfScalingList) {
+ size_t lastScale = 8;
+ size_t nextScale = 8;
+ for (size_t j = 0; j < sizeOfScalingList; ++j) {
+ if (nextScale != 0) {
+ signed delta_scale = parseSE(br);
+ nextScale = (lastScale + delta_scale + 256) % 256;
+ }
+
+ lastScale = (nextScale == 0) ? lastScale : nextScale;
+ }
+}
+
// Determine video dimensions from the sequence parameterset.
void FindAVCDimensions(
const sp<ABuffer> &seqParamSet,
@@ -63,7 +82,24 @@ void FindAVCDimensions(
parseUE(&br); // bit_depth_luma_minus8
parseUE(&br); // bit_depth_chroma_minus8
br.skipBits(1); // qpprime_y_zero_transform_bypass_flag
- CHECK_EQ(br.getBits(1), 0u); // seq_scaling_matrix_present_flag
+
+ if (br.getBits(1)) { // seq_scaling_matrix_present_flag
+ for (size_t i = 0; i < 8; ++i) {
+ if (br.getBits(1)) { // seq_scaling_list_present_flag[i]
+
+ // WARNING: the code below has not ever been exercised...
+ // need a real-world example.
+
+ if (i < 6) {
+ // ScalingList4x4[i],16,...
+ skipScalingList(&br, 16);
+ } else {
+ // ScalingList8x8[i-6],64,...
+ skipScalingList(&br, 64);
+ }
+ }
+ }
+ }
}
parseUE(&br); // log2_max_frame_num_minus4