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Bug 1579136 - do not read content from null NAL. r=jya

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Dealing with a case where `DecodeNALUnit()` returns nullptr which we should not try to create bit reader and decode anything.

In addition, wrap these logic to `DecodedISlice()` in order to keep consistent with a case where we decode SEI.

Differential Revision: https://phabricator.services.mozilla.com/D44875

--HG--
extra : moz-landing-system : lando
This commit is contained in:
alwu 2019-09-06 20:11:22 +00:00
parent c843481e4b
commit 677f012080
2 changed files with 21 additions and 9 deletions
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27
dom/media/platforms/agnostic/bytestreams/H264.cpp
View File

@ -985,16 +985,8 @@ uint32_t H264::ComputeMaxRefFrames(const mozilla::MediaByteBuffer* aExtraData) {
return FrameType::I_FRAME;
}
} else if (nalType == H264_NAL_SLICE) {
// According to ITU-T Rec H.264 Table 7.3.3, read the slice type from
// slice_header, and the slice type 2 and 7 are representing I slice.
RefPtr<mozilla::MediaByteBuffer> decodedNAL = DecodeNALUnit(p, nalLen);
BitReader br(decodedNAL);
// Skip `first_mb_in_slice`
br.ReadUE();
// The value of slice type can go from 0 to 9, but the value between 5 to
// 9 are actually equal to 0 to 4.
const uint32_t sliceType = br.ReadUE() % 5;
if (sliceType == SLICE_TYPES::I_SLICE || sliceType == SI_SLICE) {
if (DecodeISlice(decodedNAL)) {
return FrameType::I_FRAME;
}
}
@ -1187,6 +1179,23 @@ static inline Result<Ok, nsresult> ReadSEIInt(BufferReader& aBr,
return Ok();
}
/* static */
bool H264::DecodeISlice(const mozilla::MediaByteBuffer* aSlice) {
if (!aSlice) {
return false;
}
// According to ITU-T Rec H.264 Table 7.3.3, read the slice type from
// slice_header, and the slice type 2 and 7 are representing I slice.
BitReader br(aSlice);
// Skip `first_mb_in_slice`
br.ReadUE();
// The value of slice type can go from 0 to 9, but the value between 5 to
// 9 are actually equal to 0 to 4.
const uint32_t sliceType = br.ReadUE() % 5;
return sliceType == SLICE_TYPES::I_SLICE || sliceType == SI_SLICE;
}
/* static */
bool H264::DecodeRecoverySEI(const mozilla::MediaByteBuffer* aSEI,
SEIRecoveryData& aDest) {

3
dom/media/platforms/agnostic/bytestreams/H264.h
View File

@ -510,6 +510,9 @@ class H264 {
// point.
static bool DecodeRecoverySEI(const mozilla::MediaByteBuffer* aSEI,
SEIRecoveryData& aDest);
// Decode NAL Slice payload and return true if its slice type is I slice or SI
// slice.
static bool DecodeISlice(const mozilla::MediaByteBuffer* aSlice);
};
} // namespace mozilla