Questions about deinterlace

[colargol7]

Hi all

I was wondering if there were some quality loss when I encode videos (mainly h264) in that cases:
- Do I loose quality if I apply a deinterlace filter on a progressive video?
- Do I loose quality if I apply a deinterlace filter and the decoder used has already its own deinterlace?
(should I deactivate one or it doesn't matter?)

Thx for answers!

[sneaker_ger]

1. Could happen, depending on filter
2. Usually decoders only apply deinterlacing if the source is flagged as interlaced. So if you deinterlace and encode using progressive mode the decoder will detect that and turn off it's deinterlacing, so you don't lose any quality.

[colargol7]

Ok thanks!

I often use yadif (in avisynth) and divx 7.2 as decoder, and I noticed there where a small difference with interlaced sources (DVB-T 1080i) if I check deinterlace in divx or not, but I really can't tell if the image is worst or not.

[sneaker_ger]

Just make sure that you flag your encodes correctly: deinterlaced flagged as progressive and interlaced as interlaced. You can check that with MediaInfo. (Interlaced= PAFF or MBAFF, progressive = progressive)

[TheRyuu]

For further reading. (http://mod16.org/hurfdurf/?p=12)