AVC-Intra 100: - nominally 100 Mbit/s, size of each frame is fixed - CAVLC entropy coding only. - All formats are High 4:2:2 Intra Profile, Level 4.1 - 4:2:2 chrominance sampling - 10Bit
Let's recalculate to our case (4:2:0, same CAVLC, 8Bit) keeping compression ratio : 100Mbps*(3110400/4147200)*(8/10)=100Mbps*0,75*0,8=60Mbps
100Mbps read throughput is non-issue for 7200 rpm hdd. 1:1 compression might run into disk read speed bottleneck.
If HDMI recorder can record reliably at 117Mbps, 117/24 = 4.875Mb per I-frame at GOP1. But average write speed of 7200 rpm hdd is around 12MB/s or 96Mbps. Hmmm... the speed might go lower.
If stable write at 117Mbps, 1:6 compression. Not bad. Actually that sounds pretty good if I-frame compression is better than JPEG's.
@stonebat Normally the lower the GOP - the faster is NLE :-) Compression do not matter much unless your disk or cpu are extra slow (in this case lower compression will be slower).
1920x1080 420 raw frame=2073600+2*518400=3110400 bytes I Frame size here = about 268000 bytes. Only 1:11 compression (and I frame compression in H264 is more effective than JPEG).
Hang on, Just tried my 36 GOP settings switching down to GOP 1 and got these amazing results.All intra frames, passed the Pappas chart of Death (still going after 2 minutes). Just what is wrong with the 3.62 GOP settings Chris/Vitaliy? Kae/Anyone try my settings out for me to confirm. Is 50mbps the sweet spot? Chart below were taken on pappas death chart btw. Also shot 5 minutes of footage and got nice looking images. Nice staccato!
Short GOP 1 - 50bitrate test using ptools 3.62 .png
1312 x 704 - 88K
Short GOP 1 - streamparser time mode - 50bitrate test using ptools 3.62 .png
@driftwood "Tried the new ptools 3.62, and because of the weird short GOP problems am sticking to the old ptools Kae settings."
+1 me too. These settings are great! The only thing that could top them would be GOP-1. The motion just looks too good to me to raise the GOP. I heard they were trying GOP-24 in another thread! What!!! Just take still pictures and animate them in after effects at that point! I don't get it! High-GOP motion looks like Flash animation.
Also, with Kae's extreme settings sometimes I get a weird bug where the camera will tell me that it can't play back the file... but then once I record another clip, it'll play back fine... anybody else getting something like this?
Tried the new ptools 3.62, and because of the weird short GOP problems am sticking to the old ptools Kae settings. Got some wonderful speedboat / water shots using kaes 3GOP. Any news on when the GOP fix is coming? Tried out a few 1 GOP settings and same problem Kae was getting with his latest 3GOP test - low bitrate.
loaded my GH1 using ptool 3.62 with transcend class 10 card and i have gop1 at FH 88000000 and 55000000 H am hitting 50mbps bitrate indoors and no problem so far, will test outdoors
@bwhitz Long GOP was invented for the same reason MPEG2- MPEG4- H246 etc was invented. (or part of really). As a way to distribute digital assets easily - at a low quality to fit on a DVD.
They noticed that at the end of the day - most of the motion in video is still- so no need for a new frame every frame! I think that most professional mastering houses (probably not now) used to put in markers to let the encoder know when was the best time to put in more I frames as opposed to B, P frames. (car chases etc).
And without Long-GOP even 25gig wouldn't really be enough for a Blu-ray really anyway... but that is not where the industry is at right now anyway. I believe currently the industry is still trying to work out online distro- and making money online- and what the F$*K they are going to do with 3D now that they have it...
@kae "And please don't answer 'set GOP to 12 or 6', I'm interested in 3. "
haha. me too. GOP 3 or lower... ;) I'm addicted to the blinky-sticatto film motion.
I'm wondering why long-GOP was ever implemented. What good is higher quality if the motion suffers? Did they not see that it makes everything look like 360-degree open shutter?