Baseline vs High (file size)

[pooksahib]

Hi. If I have a file with a bitrate in excess of 4000 I usually encode it (just to save space) with H264. I always use the High profile except for today when I accidentally used Baseline. So I redid the vids and was very surprised to note that the High vids were a smaller size than the Baseline ones even though I used the same CQ factor for all. For example, mediainfo shows 817kbps (Baseline) and 663kbps (High)for the same vid.

As I understand it, Baseline is a basic encode to allow playback on as many devices as possible whereas High is 'the preferred choice for HD broadcast and disc storage applications'. Which I'd have thought meant a bigger filesize. Can anyone suggest why the opposite is the case?

[redwudz]

Baseline is more for older devices like mobile phones. High is used for Blu-ray and HDTV.

I found this on another site:http://superuser.com/questions/489087/what-are-the-differences-between-h-264-profiles

What does that have to do with quality?

The profile only indirectly influences the quality. Some features of higher profiles may enable you to get the same quality with lower file sizes as compared to lower profiles.

For example, CABAC entropy coding (Main and High) is more efficient than CAVLC (Baseline). It is also computationally more intensive. Thus, if you give the encoder a certain bit rate to spend, it'll be able to create a better quality video with CABAC than with CAVLC because it achieves much better compression.

This also explains why you achieved smaller file size with the High profile — obviously, you somehow set a constant quality level and the encoder could use more advanced compression techniques to create a video file that has the same quality as the Baseline profile, but with smaller size.

For just general info on H.264: https://en.wikipedia.org/wiki/H.264/MPEG-4_AVC#Profiles

[Bernix]

It is for example because baseline uses CAVLC entropy and high uses CABAC entropy. Cabac is more efective than CAVLC. And there are lots of other things that have High profile. High profil has much more compression features, and therefore is file smaller. And it doesnt mean that the video is worst.
Baseline is faster to encode, decode but the result is higher bitrate compare to high profile.

Bernix

Late

[Groucho2004]

Hi. If I have a file with a bitrate in excess of 4000 I usually encode it (just to save space) with H264. I always use the High profile except for today when I accidentally used Baseline. So I redid the vids and was very surprised to note that the High vids were a smaller size than the Baseline ones even though I used the same CQ factor for all.

Which encoder did you use? If it is x264, all you have to do is look at the documentation:

      --profile <string>      Force the limits of an H.264 profile
                                  Overrides all settings.
                                  - baseline:
                                    --no-8x8dct --bframes 0 --no-cabac
                                    --cqm flat --weightp 0
                                    No interlaced.
                                    No lossless.
                                  - main:
                                    --no-8x8dct --cqm flat
                                    No lossless.
                                  - high:
                                    No lossless.
                                  - high10:
                                    No lossless.
                                    Support for bit depth 8-10.
                                  - high422:
                                    No lossless.
                                    Support for bit depth 8-10.
                                    Support for 4:2:0/4:2:2 chroma subsampling.
                                  - high444:
                                    Support for bit depth 8-10.
                                    Support for 4:2:0/4:2:2/4:4:4 chroma subsampling.

So, the high profile is more efficient and therefore results in a smaller file.

[pandy]

Baseline use simpler compression methods (less complex) and as such is simply less efficient than high.
It is very simple - baseline can be described as book written with using only 100 basic words, very simple grammar and few other limitations - as you can imagine such book may still be readable but almost for sure it will be bigger.

[pooksahib]

Thanks for taking the time, guys, I appreciate it. Groucho2004 - it was Handbrake.

[_Al_]

Yes, filesize works the other way than you thought using CRF .... take for example --tune fastdecode setting (--no-cabac --no-deblock --no-weightb --weightp 0) in x264 setting (handbrake uses it), it is worth noticing. But you keep profile High.

You can compare that --tune fastdecode (notice no-deblock, but it keeps high profile) , and --profile baseline (uses deblock but no bframes). So you might be surprised what you get. That fastdecode with no-deblock might even "outperform" no-bframes so to speak , CPU might be the same or even lower and you keep high profile.


But if you have same setings for 2 pass with average, doing two attempts, where one time the average is set lower, then for that file with lower bitrate, CPU will be lower during decoding as well, in that case that original logic works