libavcodec/mpegvideo_parser: improve detection of progressive mpeg2
Previously many progressive mpeg2video samples were detected as interlaced
by ffmpeg/ffprobe. For example, https://tmm1.s3.amazonaws.com/720p.ts
Before:
Input #0, mpegts, from 'https://tmm1.s3.amazonaws.com/720p.ts':
Duration: 00:00:08.62, start: 18974.073233, bitrate: 9734 kb/s
Program 2
Stream #0:0[0x12eb]: Video: mpeg2video (Main), yuv420p(tv, bottom first), 1280x720 ...
After:
Input #0, mpegts, from 'https://tmm1.s3.amazonaws.com/720p.ts':
Duration: 00:00:08.62, start: 18974.073233, bitrate: 9734 kb/s
Program 2
Stream #0:0[0x12eb]: Video: mpeg2video (Main), yuv420p(tv, progressive), 1280x720 ...
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>