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Comparing H.265 (HEVC) and H265 video file size

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Re: Comparing H.265 (HEVC) and H265 video file size

#21

Post by boomboomsubban »

dylan604 wrote: post #16
boomboomsubban wrote: post #8

Earlier quoted context omitted.

Can you clarify this please? Does h.265 have some better deduplication compression or does reencoding apply something that the original recording could not, meaning h.264 would have the same benefit.

h.265 makes files smaller than h.264 for a given bit rate. So an h.265 I-frame will be smaller than an h.264 I-frame. If it's a mostly static computer screen, then you can get even better encoding effeciency by using a longer GOP structure so the I-frames are spread out even futher. Of course, the trade of is seeking gets worse, but works out great for push play and watch type of deliverables. h.264 can do this as we…

Is there any reason to suspect that they used a longer GOP structure? Is the default one for ffmpeg longer than the recording software?

Re: Comparing H.265 (HEVC) and H265 video file size

#22

Post by bawolff »

boomboomsubban wrote: post #8
mrtnmcc wrote: post #3

This is compressing video recordings of a computer desktop. The frames don't change much so this isn't surprising.

Can you clarify this please? Does h.265 have some better deduplication compression or does reencoding apply something that the original recording could not, meaning h.264 would have the same benefit.

If you re-encoded to h.264 with ffmpeg it would also probably get smaller.

Video codecs have lots of options and trade-offs. Its not just quality and file size, but also cpu usage. I suspect the original was encoded in minimize cpu usage while keeping quality constant, and the new one was minimize file size while keeping quality constant and use as much cpu as you want.

Re: Comparing H.265 (HEVC) and H265 video file size

#24

Post by oplav »

eikenberry wrote: post #5

The main hurdle for adoption, aside from onerous patents, is waiting for hardware acceleration to be common place. What is the current state of h.265 hardware accel? Does it come with everything yet like h.264 does?

Most Turing and above Nvidia cards have support for hardware accelerated decode of h.265 [0]. Modern Intel chips also support hardware accelerated decode (support started with Skylake [1]). Not sure about AMD.

[0] https://developer.nvidia.com/video-encode-and-decode-gpu-sup... [1] https://en.wikipedia.org/wiki/Intel_Quick_Sync_Video#Hardwar...

Re: Comparing H.265 (HEVC) and H265 video file size

#26

Post by Dylan16807 »

azernik wrote: post #11
boomboomsubban wrote: post #8

Earlier quoted context omitted.

Can you clarify this please? Does h.265 have some better deduplication compression or does reencoding apply something that the original recording could not, meaning h.264 would have the same benefit.

A compression algorithm allows multiple different encodings of the same underlying data - spend more CPU time finding redundancies in the data, and you can make the file smaller. I strongly suspect that the difference here is between real-time compression that runs while capturing the screen recording, and less time-constrained offline compression during transcoding.

I'm willing to bet it's not about CPU time constraints. My guess is that it's bitrate settings and/or keyframe interval settings. And that you could get similar results by tweaking those, even if you're encoding at veryfast.

Re: Comparing H.265 (HEVC) and H265 video file size

#27

Post by chii »

blibble wrote: post #25
mrtnmcc wrote: post #3

This is compressing video recordings of a computer desktop. The frames don't change much so this isn't surprising.

zipping the raw avi would probably get most of the way to 95%

but can you stream a zip file compressed this way to play the video on a streaming protocol?

Re: Comparing H.265 (HEVC) and H265 video file size

#29

Post by dylan604 »

boomboomsubban wrote: post #21
dylan604 wrote: post #16

Earlier quoted context omitted.

h.265 makes files smaller than h.264 for a given bit rate. So an h.265 I-frame will be smaller than an h.264 I-frame. If it's a mostly static computer screen, then you can get even better encoding effeciency by using a longer GOP structure so the I-frames are spread out even futher. Of course, the trade of is seeking gets worse, but works out great for push play and watch type of deliverables. h.264 can do this as we…

Is there any reason to suspect that they used a longer GOP structure? Is the default one for ffmpeg longer than the recording software?

I didn't see ffmpeg command to compare. I was talking in general. Usually, it is just a value you modify. A typical GOP is 1 second. That allows decent seeking within the file. On something static, you could push it to 10 seconds. If you use ffmpeg, you can fiddle with the switches until the cows come home. For homework, you can use the same methods and use MediaInfo or ffprobe to see the GOP sizes. My money would be on 1 second GOPs from both.

Re: Comparing H.265 (HEVC) and H265 video file size

#30

Post by Dylan16807 »

chii wrote: post #27
blibble wrote: post #25

Earlier quoted context omitted.

zipping the raw avi would probably get most of the way to 95%

but can you stream a zip file compressed this way to play the video on a streaming protocol?

Yes. No commonly-used compression formats lack streaming capabilities.
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