H265 / VP9 for 1080p?

[marauder]

Hey there,
this might seem out of place among the very technical threads in this board but:
I'm running out of space on my dedicated video drive. Most videos are 1080p h264 at 14000 kbps recorded using my cellphone during holiday trips / important events. My questions are

1. Given the newest encoders, would transcoding from h264 to h265 while (mostly) retaining image fidelity yield disk space benefit ?
It is often quoted that h265 is twice as effective in compressing the data, would love to use it to tide me over until 8tb portable drives are cheaper.
These are for personal and extended family usage, none of whom are anal about video quality.

2. My googling skill failed me in this but : are current gen cellphones capable of recording video straight to h265 format ?

[birdie]

1. You'd better recode them using x264 which is currently much better at retaining fine details than x265 but then it all depends on your preferred bitrate/quality settings. If you're ready to sacrifice quite a lot of details, then x265 might be better.

The truth is it all boils down to your source material. If it's grainy and shaky then there's a great chance no reencoding will help you. If your hands are steady, video is well lit (so there isn't much noise) then x264 can easily save up to 70% of bitrate while preserving almost all the fine details.

For instance I have several very noisy clips in MJPG which neither x264, nor x265 can efficiently reencode. At the same time I have several videos in H.264 made by my smartphone which I was able to compress to roughly 33% of their original size and the loss of detail is negligible.

VP9 and x265 encoders are currently very very slow.

2. No. Besides the H.265 codec currently shines only at low bitrates. At high bitrates x264/H.264 easily outperforms it.

[marauder]

Could you please clarify what you meant by low and high bitrate ?
Cos I'm thinking a Doom9 regular might have a different standard than a layman.

E.g. More than 5 mbps is high bitrate and below that I should use x265

[Asmodian]

This is completely source dependent, "low bitrate" can change really a lot depending on the source.

An easier way to think about it: If you want as small as possible use x265 if you want transparent (as small as possible without being able to tell it was re-compressed) use x264.

I suggest you play with x264 a bit to get an idea of how well it can compresses your videos, usually software H.264 is much more efficient than the hardware encorder in your phone. That said generation loss can also be an issue so there are a lot of factors to consider. Run a test encode with x265 as well to see if you like the result (and can handle the speed), x265 is still pretty young, it is quickly maturing but it has still not reached its full potential.

[marauder]

Ah gotcha

Now that Google is using VP9 as default for Youtube I got the impression that both H265 and VP9 are ready for everyday user and better than h264 especially at lower bitrate. Guess not ...

[benwaggoner]

Of course, cell phone video is typically quite quantized and smoothed-out already. There typically isn't much hard-to-encode detail left. I wouldn't be surprised if a reasonable --crf with x264 could preserve the existing quality in ~5 Mbps.