undersize with beta2 using hdtv

[eng3]

So far beta2 has worked very well for me encoding 640x480 tv captures.

I recently got a HDTV card and started geting 1920x1080i video.
using YV12InterlaceReduceBy2(), it works fine, but I feel the video size may still be too high because playback is alittle choppy and blocky. I left all other settings at default except used VHQ1.
I did a two pass, 50mb for a 2.7min clip.

I tried not using YV12interlacereduceby2 and converted to YUY2 and used lancose resize and pixiedust. I reduced the resolution alittle more to 768x432.

this resulted in a 26mb file.

I tried it withough pixiedust and get 32mb file.

I did a search and only found 4 topics about undersize. two only said "use search", the other two were relating to someone using the wrong settings

[Zep]

Originally posted by Enrico Ng


50mb for a 2.7min clip.

I tried not using YV12interlacereduceby2 and converted to YUY2 and used lancose resize and pixiedust. I reduced the resolution alittle more to 768x432.

this resulted in a 26mb file.

I tried it withough pixiedust and get 32mb file.

I did a search and only found 4 topics about undersize. two only said "use search", the other two were relating to someone using the wrong settings


at 768 x 432 you will be undersized on 44 minutes at 350 megs for most stuff
with 2 b-frames on.

so.... 50MB for a 2.7min clip you do the math :)

At that rez all you need to hit Q=2 on every frame is about 2000kb rate.
if you turn on 2 b-frames you can do it at 1000kb and hit i2 p2 b3 b3
no problem. which is what i encode at, at 768 x 432.

look at the video.stats file. I bet all your frames are Q maxed.

[eng3]

Originally posted by Zep
at 768 x 432 you will be undersized on 44 minutes at 350 megs for most stuff
with 2 b-frames on.

so.... 50MB for a 2.7min clip you do the math :)

At that rez all you need to hit Q=2 on every frame is about 2000kb rate.
if you turn on 2 b-frames you can do it at 1000kb and hit i2 p2 b3 b3
no problem. which is what i encode at, at 768 x 432.

look at the video.stats file. I bet all your frames are Q maxed.

ah, I did noticed that they were all Q=2.
I guess I don't know that much about how xvid choses between Q=2 and Q>2
I did not use any bframes.
I notice that the video does look quite "blocky".

I find it curious that when I used the pixiedust filter, the file size drops even more.

[Imperial Llama]

The whole purpose of filters like pixie dust is to reduce the amount of detail in a video so that when you encode it the bitrate needed for each quant will be lower. Therefore the maximum file size should always be smaller when you use filter like dust then when you don't.

IMO if your source is of a high quality and you are encoding at very high bitrates, there is no need to use filters like dust. From what I've read elsewhere on this forum I believe dust can sometimes cause blocking, which may explain why your videos look blocky.

[eng3]

Originally posted by Imperial Llama
The whole purpose of filters like pixie dust is to reduce the amount of detail in a video so that when you encode it the bitrate needed for each quant will be lower. Therefore the maximum file size should always be smaller when you use filter like dust then when you don't.

IMO if your source is of a high quality and you are encoding at very high bitrates, there is no need to use filters like dust. From what I've read elsewhere on this forum I believe dust can sometimes cause blocking, which may explain why your videos look blocky.

well, for some reason, the video looks blocky after compression.
pixie dust seemed to make it look slightly less blocky.

I'm just not sure why it is blocky.

the orig. video is not blocky.