x264 with manually setted "ref" parameter and MediaInfo report not the same

[aleaksunder]

Hello!

I've file encoded with x264 with parameters:

--profile main --level 3.1 --bluray-compat --preset veryslow --tune film --crf 24.0 --ref 2 --slices 4 --qpmin 3 --vbv-bufsize 14000 --vbv-maxrate 14000 --colorprim bt709 --transfer bt709 --colormatrix bt709 --sar 1:1

But MediaInfo shows some strange thing:

Video
ID                             	: 1
Format                         	: AVC
Format/Info                    	: Advanced Video Codec
Format profile                 	: Main@L3.1
Format settings                	: CABAC / 3 Ref Frames
Format settings, CABAC         	: Yes
Format settings, ReFrames      	: 3 frames
Codec ID                       	: avc1
Codec ID/Info                  	: Advanced Video Coding
Duration                       	: 2 h 58 min
Bit rate mode                  	: Variable
Bit rate                       	: 2 548 kb/s
Maximum bit rate               	: 14.0 Mb/s
Width                          	: 1 280 pixels
Height                         	: 720 pixels
Display aspect ratio           	: 16:9
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)             	: 0.115
Stream size                    	: 3.17 GiB (100%)
Writing library                	: x264 core 157 r2935 545de2f
Encoding settings              	: cabac=1 / ref=2 / deblock=1:-1:-1 / analyse=0x1:0x131 / me=umh / subme=10 / psy=1 / psy_rd=1.00:0.15 / mixed_ref=1 / me_range=24 / chroma_me=1 / trellis=2 / 8x8dct=0 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=-3 / threads=6 / lookahead_threads=1 / sliced_threads=0 / slices=4 / nr=0 / decimate=1 / interlaced=0 / bluray_compat=1 / constrained_intra=0 / bframes=3 / b_pyramid=1 / b_adapt=2 / b_bias=0 / direct=3 / weightb=1 / open_gop=0 / weightp=1 / keyint=240 / keyint_min=1 / scenecut=40 / intra_refresh=0 / rc_lookahead=60 / rc=crf / mbtree=1 / crf=24.0 / qcomp=0.60 / qpmin=3 / qpmax=69 / qpstep=4 / vbv_maxrate=14000 / vbv_bufsize=14000 / crf_max=0.0 / nal_hrd=vbr / filler=0 / ip_ratio=1.40 / aq=1:1.00
Encoded date                   	: UTC 2019-02-18 00:11:30
Tagged date                    	: UTC 2019-02-18 00:15:06
Color range                    	: Limited
Color primaries                	: BT.709
Transfer characteristics       	: BT.709
Matrix coefficients            	: BT.709

As you can see in "Format settings", "Format settings, ReFrames" shows that there is actually 3 ref ReFrames, but "Encoding settings" shows that parameter "ref" was set to "2"... where is the truth? =) Why it shows that?

And even if I encode with manually set "ref" to "3"... MediaInfo do not shows that "Format settings", "Format settings, ReFrames" set to 4... in that situation all string reports that "ref" was set to "3"

[poisondeathray]

x264 string is correct. The method in which mediainfo counts "reference frames" is different (it's adding frame reordering)

[LigH.de]

I believe the size of the reference frames storage is increased by 1 when the B frame pyramid is enabled...