The bug was undetected because it accidentally fell into an error case that slept the correct amount of time. pthread_cond_timedwait takes an absolute time in the future to wait until. The value we were passing was always in the past so it was immediately failing with a TIMEDOUT error code.
This lets the decoder make decisions based on whether it is a hardware decoder or not. Specifically, hardware decoders are more strict as to which frames can be dropped in an h264 stream.
FFMpeg has an issue where png decoding will not correctly
begin until its optimal-thread-detection finishes in
multi-threaded mode. This unfortunately is after decoding
has begun.
John Bradley