In these cases, only drop dts. Because if we drop both we have no timestamps at all for some files.
This improves playback of HLS streams from GoPro cameras.
bd239c9 lavf: Don't drop both pts and dts if timestamps are invalid
libavformat/utils.c | 2 +-
tests/ref/fate/vc1-ism | 182 +++++++++++++++++-------------------------------
2 files changed, 63 insertions(+), 121 deletions(-)