Video bitrate Air 2S question DLOG/HLG

[pommy]

Hey all,

Can someone clarify something for me? I thought the video bitrate for the Air 2S was 150MBits/s but I’ve been playing with some DLOG vs HLG stuff and noticed that they both have low bitrates?

I know there’s no setting for this, so how does it work? Am I mistaken? Misunderstanding something?

I‘ve attached a pic, same clip taken one after the other, one DLOG, one HLG - showing the bitrate of the video…

 

[Saladshooter]

Hey all,

Can someone clarify something for me? I thought the video bitrate for the Air 2S was 150MBits/s but I’ve been playing with some DLOG vs HLG stuff and noticed that they both have low bitrates?

I know there’s no setting for this, so how does it work? Am I mistaken? Misunderstanding something?

I‘ve attached a pic, same clip taken one after the other, one DLOG, one HLG - showing the bitrate of the video…

The 150MBits/s is a maximum. The h265 codec you are using will encode using a variable bitrate based on what is needed to render the scene. Complex scenery and rapid movement will use higher bitrates.

 

[pommy]

The 150MBits/s is a maximum. The h265 codec you are using will encode using a variable bitrate based on what is needed to render the scene. Complex scenery and rapid movement will use higher bitrates.

Sounds logical. Thanks

 

[karlblessing]

From what I've seen in mine it's about 126Mbps maximum in h265.

However keep in mind that H265 126Mbps is superior visual quality to 150Mbps H264, the compression on h265 is much more complicated and visually speaking can hold about twice the data to h264 when at the same bit rate. So h265 75Mbps is about the same visual quality as h264 150mbps.

I knew this from questions I had towards shooting modes on my Panasonic gh5 at 10 bit (can do 10bit at h264 and h265). 400Mbps h264 all intra , 150mbps h264 long-gop, and 75mbps h265 all have about the same quality of information, long-gop being the type most devices will use for h264 now days.

H264 All-intra : older simpler compression algorithm, frames saved independently, much more bandwidth/storage cost, lower computing power needed to decode (easier for video editors without transcoding)

H264 long-gop : the current compression algorithm for most devices using h624 codec, frames are saved in such a way that is predictive from one frame to the next (each frame contains data of it's neighbor), better compression ratio saving space. Higher computing requirements to decode/edit (better to transcode to ProRes or dnxhr before editing).

H265 HEVC (high efficiency video codec) compression ratio is much much better saving much more space for the same visual quality. Computing requirements for decoding to edit with increased nearly 8x over h264. Transcoding highly recommended for editing even if you have software utilizing h264/h265 hw accelerated decoding.

 

[SethB]

…H265 HEVC (high efficiency video codec) compression ratio is much much better saving much more space for the same visual quality. Computing requirements for decoding to edit with increased nearly 8x over h264. Transcoding highly recommended for editing even if you have software utilizing h264/h265 hw accelerated decoding.

Good info from @karlblessing!

h.265/HEVC continues the proud “we’re not a standard” standard begun with h.264. Meaning, that the standard is a loose framework within which individual manufacturers may custom cook their compression / decoding math. A bit.

In practice this means that decoding for the video editor is a bit of a moving target. While transcoding *will* work, computer and GPU manufacturers have been quietly adding hardware decoding, which is the best! (when it works)

If hardware decoding is working then usually there is no need for a transcoding/proxy workflow. All it does is needlessly take additional time and storage.

I do some filming with an Insta360 Pro 2 360 video camera, which lays down 8k resolution in h.265. It was a pleasant surprise to find out that a recent iMac! (pre M1) could play it back in full resolution in Premiere.

If you have a recent (2 years? 4 years?) computer/GPU it’s likely it has a chip dedicated to h.265 decoding. Unfortunately this is very difficult to find specs on - just try it!