If they're omitted, it's reasonable to assume it's because
they were uninteresting (i.e. sample data always tightly
packed at the start of the mdat). This is an issue for some
SmoothStreaming streams.
We actually already play such streams successfully, but
that's only due to another bug to be fixed in a following CL.
The same is true for V1, but given the low impact nature,
the fix will be V2 only.
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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=131191975
0b6a93b468