15.45 drivers breaking change (bug) in H264 decoding

Hi all,

the 15.45 driver version introduces a breaking change (bug) in H264 decoding. It is the second time, that new drivers broke our app. In short, for some H264 streams the DecodeFrameAsync function now returns MFX_WRN_DEVICE_BUSY with no reason and without any changes in our code. We can reproduce the behaviour on a Win 10 Skylake computer with the driver package win64_154025.4463 (works well) and win64_154510.4542 (introduces the issue).

The sample_decode app is too complex to reproduce the problem easily, because it handles the "device busy" state and thus hides the issue. Moreover, we are always passing discrete samples for decoding, forcing the output by calling DecodeFrameAsync with a NULL bitstream if necessary and running SyncOperation immediately. So we created a minimalistic app that helps to reproduce the issue easily.

1. Unpack the small repro project (no error checking and designed mostly only for the attached h264 file). It might be necessary to update the lib directories to find the libmfx.lib to link against.

2. Run it with the attached h264 file as a command line parameter.

3. With older drivers it will decode all the frames and output the result.

4. With newer drivers it will break on MFX_WRN_DEVICE_BUSY (with no reason for it) while decoding the second frame in the file.

The (even more) interesting thing is, that this problem does happen only for some H264 bitstreams, not for all, but was never seen with the older driver testing hundreds of streams.

Thanks for looking into this.

Alex