Cannot compress over 20 Mbps

[bob77]

Hello,
I'm using Xmedia Recode (latest version).
Compressing remux bluray that's at 32 Mbps. Wanted to get it down to 25 Mbps. But for some reason it ended up being 20 Mbps.
Here is what media info shows:

General
Format : Matroska
Format version : Version 4 / Version 2
File size : 16.5 GiB
Duration : 2 h 0 min
Overall bit rate : 19.5 Mb/s
Encoded date : UTC 2016-03-26 22:40:33
Writing application : Lavf57.29.101
Writing library : Lavf57.29.101 / Lavf57.29.101

Video
ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : Main@L4.1
Format settings, CABAC : Yes
Format settings, ReFrames : 2 frames
Codec ID : V_MPEG4/ISO/AVC
Duration : 2 h 0 min
Nominal bit rate : 25.0 Mb/s
Width : 1 920 pixels
Height : 804 pixels
Display aspect ratio : 2.40:1
Original display aspect ratio : 2.40:1
Frame rate mode : Constant
Frame rate : 23.976 (24000/1001) FPS
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.675
Writing library : x264 core 148 r2665
Encoding settings : cabac=1 / ref=2 / deblock=1:0:0 / analyse=0x1:0x131 / me=hex / subme=7 / psy=1 / psy_rd=1.00:0.00 / mixed_ref=0 / me_range=16 / chroma_me=1 / trellis=1 / 8x8dct=0 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=-2 / threads=6 / lookahead_threads=1 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / bluray_compat=0 / constrained_intra=0 / bframes=3 / b_pyramid=0 / b_adapt=1 / b_bias=0 / direct=3 / weightb=1 / open_gop=0 / weightp=2 / keyint=239 / keyint_min=23 / scenecut=40 / intra_refresh=0 / rc_lookahead=40 / rc=2pass / mbtree=1 / bitrate=25000 / ratetol=1.0 / qcomp=0.60 / qpmin=10 / qpmax=69 / qpstep=4 / cplxblur=20.0 / qblur=0.5 / vbv_maxrate=25500 / vbv_bufsize=1063 / nal_hrd=none / filler=0 / ip_ratio=1.40 / aq=3:1.00
Language : English
Default : Yes
Forced : No
DURATION : 02:00:51.203000000

Audio
ID : 2
Format : DTS
Format/Info : Digital Theater Systems
Format profile : MA / Core
Mode : 16
Format settings, Endianness : Big
Codec ID : A_DTS
Duration : 2 h 0 min
Bit rate mode : Variable / Constant
Bit rate : Unknown / 1 509 kb/s
Channel(s) : 8 channels / 6 channels
Channel positions : Front: L C R, Side: L R, Back: L R, LFE / Front: L C R, Side: L R, LFE
Sampling rate : 48.0 kHz
Frame rate : 93.750 FPS (512 spf)
Bit depth : 24 bits
Compression mode : Lossless / Lossy
Language : English
Default : Yes
Forced : No
DURATION : 02:00:51.209000000


Overall bitrate is 20 yet nominal for video is 25. And size (16GB) corresponds to 20 not 25.
I made the mistake to use Main profile and not High, and was thinking of redoing it when I noticed the bitrate thing.
Xmedia recode has a bitrate calculator option. When I use that and blow up the bitrate, no matter how high I get it it always ends up calculating for 20 Mbps and doesn't want to go higher. I thought it's because of the profile but changing it does not make a difference.

Question 1:
What am I missing? Why cant I get it to go to 25 Mbps.

Question 2:
As far as I understand Main@L4.1 allows up to 50 Mbps. But I noticed that everybody else uses High profile for that kind of compression. Should I reencode using High or does it not matter?

Thank you!!!

[theewizard]

IDK
But why recode to only 25% size reduction
I would
Either keep the original, or recode to a significant reduction, your 20mbps is a 30% reduction
I don't see anything to complain about, Blu Ray is about quality

I guess I don't understand the logic, to compressing bd to the point it approaches DVD

[sneaker]

vbv_maxrate=25500 / vbv_bufsize=1063

That's probably your problem. Set to something sane, e.g. --vbv-maxrate 40000 --vbv-bufsize 30000 --level 4.1 with High Profile like on BluRay or --vbv-maxrate 62500 --vbv-bufsize 78125 --level 4.1 for generic H.264 High Profile level 4.1.

[bob77]

theewizard,
I want to keep the original quality but still get some compression out of it because I need the space. Less than 20 is visibly worse. More is practically indistinguishable.

sneaker,
Where do I find an option for that? What is vbv anyway?
All I have in Xmedia Recode is stuff like codec, framerate, color mode, bitrate, profile, level, tune (for movies or animation, etc. probably a cool option but I've never tried it), frame packing, open GOP, keyframe, Min GOP, Display mode (progressive), Threads (which is set at 0).

PS: Remux doesn't run smooth for me. Recoded version @20 is smooth. - Another reason why I compress.

[sneaker]

You can find them in the "Rate Control" section of the "Video" tab.

vbv limits the video bitrate at any given time to ensure neither decoder nor connection or disk speed are overloaded during playback. You set it too low.
https://en.wikipedia.org/wiki/Video_buffering_verifier

[bob77]

You can find them in the "Rate Control" section of the "Video" tab.

vbv limits the video bitrate at any given time to ensure neither decoder nor connection or disk speed are overloaded during playback. You set it too low.
https://en.wikipedia.org/wiki/Video_buffering_verifier

I found it. It doesn't allow anything higher than 50000 on either of those two. Reset button makes it 24000 buffer and 50000 max rate.
Anyway it doesn't work. Using just default settings Ive changed only profile and level to High 4.1 and bitrate 25 Mbps 2pass average. I click on the calculator, use the little arrows to go above 20000 and it increases in that field but the calculation stays at 20000 and doesn't go any higher.

[sneaker]

I found it. It doesn't allow anything higher than 50000 on either of those two.

You can set to 62,500/62,500 if you first set to high profile level 4.1. Setting to 78,125 doesn't work, I assume this is a bug.

I click on the calculator, use the little arrows to go above 20000 and it increases in that field but the calculation stays at 20000 and doesn't go any higher.

Yes, the calculator seems to be buggy and values above 20,000 aren't copied. Solution? Don't use the calculator. Easy.

If it still doesn't go higher it may compress too well. Set "Minimum Quantizer" (under "Quantizers") to "0" and set "Tune" to "Grain".

[bob77]

I found it. It doesn't allow anything higher than 50000 on either of those two.

You can set to 62,500/62,500 if you first set to high profile level 4.1. Setting to 78,125 doesn't work, I assume this is a bug.

I click on the calculator, use the little arrows to go above 20000 and it increases in that field but the calculation stays at 20000 and doesn't go any higher.

Yes, the calculator seems to be buggy and values above 20,000 aren't copied. Solution? Don't use the calculator. Easy.

If it still doesn't go higher it may compress too well. Set "Minimum Quantizer" (under "Quantizers") to "0" and set "Tune" to "Grain".

That worked and I was finally able to get it up to 25 Mbps. Thank you. You have been very kind!