Progressive and 1080

M

massimo.03

Member
I've read (thank you Barry Green) that when shooting progressive in 1080 (in my case, 1080i/25p), the camera captures an entire frame all at once and then each frame is divided into fields for recording. Does this division into fields involve some compression or some conversion or some degrade of quality?
Same question for the inverse process that happens in post production: I've read that some non linear editing programs (like mine Edius Broadcast) can reconstitute the fields back into their full progressive frames. Is there, in this process, some compression or some conversion or some degrade of quality?
I apologize for my ignorance and for my English.
Thank you in advance.
Massimo
 
I've read (thank you Barry Green) that when shooting progressive in 1080 (in my case, 1080i/25p), the camera captures an entire frame all at once and then each frame is divided into fields for recording. Does this division into fields involve some compression or some conversion or some degrade of quality?
Click to expand...

Yes, the signal is compressed into the DVCPro HD format. At 1080 resolution, the DVCPro HD format stores the video data in interlaced fields.

Same question for the inverse process that happens in post production: I've read that some non linear editing programs (like mine Edius Broadcast) can reconstitute the fields back into their full progressive frames. Is there, in this process, some compression or some conversion or some degrade of quality?
Click to expand...
No, at this point your NLE timeline needs only to be properly set up for progressive video and then it assembles the fields and throws away the duplicate frames without having to recompress anything.
 
There is something that I don't understand.
If shooting 1080i/25p there's a compression that doesn't happen shooting 720p, does this mean that 1080 is more compressed than 720?
If NLE timeline assembles the fiedld and throws away the duplicate frames, does this mean that it can eliminate the compression due to the interlaced recording?
Almost surely I have understood badly.
I apologize again for my ignorance and for my English.
 
Whether you shoot 1080i or 720p, both settings involve compressing the footage to DVCPro HD, so 720p does not have an advantage there. There's no compression in 1080i that doesn't happen in 720p.

When recording to an interlaced format (1080i) rather than progressive (720p), there is no added compression by interlacing the frames into fields. And there is no quality loss involved when the NLE rebuilds the fields back into whole frames. The way that the PA setting works is that it simply figures out an effective way to store the progressive frames accurately into fields so that it may be reconstructed back into whole frames again later in the NLE.

I hope that helps. This can be a really confusing area to try and understand :)
 
You must log in or register to reply here.
Back
Top