Fixes some files from Ticket679
This also changes subtitles to 4:2:0 matching the output format and thus simplifying the blend code. This restricts placement to the chroma sample resolution though, speak up if you consider this a problem, say so, the code could be changed to use YUV444 for subtitles and scaling them down while blending, this would be slower though. The current code only uses a single swscale context and reinitializes it as needed, this could be changed as well if needed
d64ba25 ffplay: Use sws_scale to scale subtitles
ffplay.c | 284 ++++++++++++++++----------------------------------------------
1 file changed, 71 insertions(+), 213 deletions(-)