ffmpeg WMV to MP4 keep quality

[pehje]

Hi

I want to convert some 200 hours of WMV-material to MP4 without too much quality loss. The original sources are both analog and digital video cameras captured long time ago with different types of hardware and partly using Movie Maker. Content is just family and hobby level so no high level of ambition. I´m using ffmpeg command version.

I did some simple testing with just "ffmpeg -i input.wmv output.mp4" and also tried adding -crf 18 - resulting in visible sharp lines compared to the wmv-files. With the -crf 18 addition the lines were a bit less visible, but still annoying.

What are the obvious options added to the ffmpeg-command to make these lines go away without increasing file size (too much)?

Here are some facts from the -crf 18 try:

Stream #0:0(eng): Audio: wmav2 (a[1][0][0] / 0x0161), 48000 Hz, stereo, fltp, 128 kb/s
Stream #0:1(eng): Video: vc1 (Advanced) (WVC1 / 0x31435657), yuv420p, 720x576, 4000 kb/s, SAR 16:15 DAR 4:3, 25 fps, 25 tbr, 1k tbn, 1k tbc
Stream mapping:
Stream #0:1 -> #0:0 (vc1 (native) -> h264 (libx264))
Stream #0:0 -> #0:1 (wmav2 (native) -> aac (native))

Before wmv to mp4 conversion:

[Attachment 49528 - Click to enlarge]

After - with the annoying lines:

[Attachment 49529 - Click to enlarge]

Regards, Per

[davexnet]

Looks like artifacts from interlacing. Is the source interlaced?
Perhaps you should post a short clip of your source as-is to see the
best way to handle it

[pehje]

Added deinterlacing using "-vf yadif" and that seemed to do the job. Thanks for the idea about interlacing. /Per