[x264-devel] x264 bug: interlaced video missing grain/detail in top 32 lines

[Adam Warner]

Hi all,

I have found a bug in x264's interlacing. I have compiled x264 from
source with the x264_NAL-HRD.1.32.patch available from:
<http://forum.doom9.org/showthread.php?p=1379904#post1379904>

Input source is a segment of a PAL version of ABBA's Mamma Mia. The x264
result includes a 32-pixel band at the top of the image that is almost
devoid of grain/detail. Here are two before/after stills:

Source (a): <http://i.imgur.com/A9UrU.png>
Result (a): <http://i.imgur.com/kHq4r.png>

Source (b): <http://i.imgur.com/j2CDl.png>
Result (b): <http://i.imgur.com/Of8Us.png>

I invoked my compiled version of x264 with the options:
my-x264 --pass 1 --ref 16 --bframes 8 --bitrate 2735 --trellis 2 --subme 10 --tune grain test.y4m -o test.264
my-x264 --pass 2 --ref 16 --bframes 8 --bitrate 2735 --trellis 2 --subme 10 --tune grain test.y4m -o test.264

Here is a copy of the input source (20 seconds, 170MB compressed) in
yuv4mpeg format:
<http://www.mediafire.com/file/jtttzonmggy/x264_interlacing_bug_demo_20_sec_yuv4mpeg_clip.y4m.gz>

Result (20 seconds, H264-ES, 7MB):
<http://www.mediafire.com/file/nknbvz3z2zy/x264_interlacing_bug_demo_20_sec_clip.264>

Regards,
Adam