Can anyone clarify why all the Canon DSLRs are so soft? I recall someone shooting a res chart, indicating that the cameras produce resolutions roughly similar to SD pictures, in 1080 mode.
How does the line binning work or is there an upres happening from a more limited image buffer?
Are the images intentionally soft to obscure the limited resolution due to binning?
For a T2i the feed into the encoder is assumed to be 1056x704, it then gets upsampled/uprezzed to 1920x1088. have a look at a uncompressed 4:2:2 silent pic captured in movie mode, but whilst not recording and see how much sharper it is.
Encoder feed is 1720x974 (550D) and 1904x1072 (5D3).
Line skipping is one cause, upsampling is another, 422 to 420 is another, compression is another. Bitrate control only reduces compression artifacts.
On 5D3 there's no line skipping and we might get 422 video, which should be pretty good.
Quote from: a1ex on September 18, 2012, 02:40:18 PM
Encoder feed is 1720x974 (550D) and 1904x1072 (5D3).
Line skipping is one cause, upsampling is another, 422 to 420 is another, compression is another. Bitrate control only reduces compression artifacts.
On 5D3 there's no line skipping and we might get 422 video, which should be pretty good.
So the 5DIII is still "upsampling" the LV image altough by a few pixels.
From their point of view, why couldn't they go for true 1920*1080 as it was just a few pixels away?
I can't understand this and the stupid resolution of the other cameras.
Have you come up with an explanation?
I'm not a Canon engineer, so I can't explain why they did that.
The encoder has a "realtime" constraint so it was probably too slow to encode FULL HD
Or maybe they couldn't reliably sample a full HD frame from the sensor at 30p ...who knows
QuoteBitrate control only reduces compression artifacts.
Qscale sets QP though so at QP10 (slice <= 112) you you get more of what little was originally going in. I've recorded some 8 megabit video... I think worst ever seen (qp of 51). So low qp should be most of the data - line skip - color data and with resize.
1720x974
Isn't this also crop mode size for 600D. I thought others had lower resolution even while recording. Or do they just control ratio of real size to recorded size with the line skips. So "viewing window" is smaller on crop mode and pixels are more or less 1:1. If so then maybe other cameras could get a real crop mode like 600D? Just set Jpcore like it sets it up dzoom mode on 600D.
For 600D, sizes are 1728x972 (crop) and 1680x945 (non-crop). Canon calls this data "craw" (look for strings). See vram.c for all the other cameras.
Although I think this data sometimes has some up/down sampling too, see 720p modes where pixel ratio is not 1:1.
re T2i feed to encoder.
1056x704 when not recording uprezzed whilst recording and as a result softened to 1728x972 to feed the encoder? Would that be more accurate assumption?
No, check with silent pics.
I had done on a number of silent pics whilst recording / not recording, is why I said what I said. :-)
To my eyes the larger of the two resolutions looks softer but ok I stand corrected. :-)