Showing posts with label denoise. Show all posts
Showing posts with label denoise. Show all posts

Thursday, May 14, 2009

Preprocessing

There are great benefits from processing videos prior to encoding. The right preprocessing can gain you time, bandwidth and increase the image quality of your final video.
There are six important processes that you should consider applying to your source video prior to encoding:

1) De-interlacing. Will avoid creating line crawling artifacts.

2) Noise reduction. Motion adaptive noise reduction can greatly improve the performance of your encoder as random noise in images produce artifacts in the encoded image.

3) Color Space Conversion. Use of high quality color space conversion algorithms can reduce color bands and “blotches” as bit reduction and color plane decimation (going from RGB or 4:4:4 to 4:2:0 for example.)

4) Resampling and resizing. Will greatly reduce encoding time and improve quality. Specially true if you are down sampling or reducing sizes.

5) Cropping. Same as above.

6) Frame Rate Conversion. Will allow you to use high quality frame rate conversion algorithms. If you are reducing the frame rate, you’ll have the added benefit of faster encodes.

Tuesday, April 21, 2009

AviSynth

AviSynth is a frame server –it feeds uncompressed frames to other applications directly- that can be scripted to automate image processing and editing of videos.

It is not a video editing or special effects workstation. Its strengths lie on allowing the video professional to pre-process videos to resize, crop or remove noise and to conform video sources with simple cuts. Basically you create a script that indicates AviSynth which filters to apply in what order. If you are not comfortable with writing scripts in text form, you could use VirtualDubMod or MeGUI graphic user interfaces to create them.

AviSynth comes very handy when preparing videos for compression in an automated and streamlined fashion. In particular, you can perform noise reduction, resizing and color conversions to ensure that the compressed video looks as best as possible.
It is an open source project that has many followers. Check it out: