halsboss
26th November 2008, 23:03
Neuron2's information here http://forum.doom9.org/showthread.php?p=1216590#post1216590 has made an incredible difference to increasing the quality of my PAL HDTV 1080i50 (supposedly 1080i50 !) --> 576i/576p DVD resizing.
I'd mistakenly assumed that Aus over-the-air broadcast PAL 1080i was, well, 1080i. Gong. Wrong assumption. It can be and is various things wrapped in what consistently looks to be an interlaced frame (but where the actual content can be other than 1080i).
Here http://forum.doom9.org/showthread.php?p=1216590#post1216590 describes the types of content that can be inside what's supposed to by a 1080i OTA broadcast ... truly 1080i50, 1080p25, 1080p25-field-shifted, and whatnot. Neuron2 describes how to tell the types of content apart. Unfortunately it's a manual process, however it's a "must do" if you want any sort of decent output from the resizing process.
Once you can tell which type of content it really is then you can then use AviSynth apply the right correction (eg if field shifted 1080p25) and the right type of interlaced or progressive resizing method to get it to DVD spec which in my case is either 567i or 576p depending on whether the content was actually interlaced or progressive.
In just 2 days I've come across various of PAL 1080i50, 1080p25, and field-shifted 1080p25 so far (no field-blending although it's early days since discovering OTA content isn't what I thought it was). There does not appear to be noticeable consistency in which programs are broadcast in which content type although I'd venture a guess that series could possibly be of the same type.
Resizing and other avisynth processing, appropriate to the nature of the source, really improved the quality of the result for me... so I thought I'd drop a post here for others that may have made the same unfortunate assumption as me.
I'd mistakenly assumed that Aus over-the-air broadcast PAL 1080i was, well, 1080i. Gong. Wrong assumption. It can be and is various things wrapped in what consistently looks to be an interlaced frame (but where the actual content can be other than 1080i).
Here http://forum.doom9.org/showthread.php?p=1216590#post1216590 describes the types of content that can be inside what's supposed to by a 1080i OTA broadcast ... truly 1080i50, 1080p25, 1080p25-field-shifted, and whatnot. Neuron2 describes how to tell the types of content apart. Unfortunately it's a manual process, however it's a "must do" if you want any sort of decent output from the resizing process.
Once you can tell which type of content it really is then you can then use AviSynth apply the right correction (eg if field shifted 1080p25) and the right type of interlaced or progressive resizing method to get it to DVD spec which in my case is either 567i or 576p depending on whether the content was actually interlaced or progressive.
In just 2 days I've come across various of PAL 1080i50, 1080p25, and field-shifted 1080p25 so far (no field-blending although it's early days since discovering OTA content isn't what I thought it was). There does not appear to be noticeable consistency in which programs are broadcast in which content type although I'd venture a guess that series could possibly be of the same type.
Resizing and other avisynth processing, appropriate to the nature of the source, really improved the quality of the result for me... so I thought I'd drop a post here for others that may have made the same unfortunate assumption as me.