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Fix handling of HTTP cameras that do not provide a Content-Length. (#59)

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ReadJpeg was not correctly parsing the SOS segment.
This commit is contained in:
Peter Johnson
2017-02-16 22:11:54 -08:00
committed by GitHub
parent 878d3a6f4f
commit 8f97637b71
1 changed files with 23 additions and 0 deletions
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23
src/JpegUtil.cpp
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@@ -161,8 +161,31 @@ bool ReadJpeg(wpi::raw_istream& is, std::string& buf, int* width,
}
pos += blockLength;
bytes = reinterpret_cast<const unsigned char*>(buf.data() + pos);
if (bytes[0] != 0xff) return false; // not a tag
if (bytes[1] == 0xda) {
// SOS: need to keep reading until we reach a normal marker.
// Byte stuffing ensures we don't get false markers.
bool maybeMarker = false;
for (;;) {
ReadInto(is, buf, 1);
if (is.has_error()) return false;
++pos;
bytes = reinterpret_cast<const unsigned char*>(buf.data() + pos);
if (maybeMarker) {
if (bytes[0] != 0x00 && bytes[0] != 0xff &&
(bytes[0] < 0xd0 || bytes[0] > 0xd7))
break;
maybeMarker = false;
} else if (bytes[0] == 0xff)
maybeMarker = true;
}
// Point back to the start of the block
--pos;
bytes = reinterpret_cast<const unsigned char*>(buf.data() + pos);
}
if (bytes[0] != 0xff) return false; // not a tag
if (bytes[1] == 0xd9) return true; // EOI, we're done
if (bytes[1] == 0xc0) sofBlock = true; // SOF