Can someone help me understand the differences?

[AndyD]

I just finished ripping Underworld Awakening using Ripbot (CRF 16 / Flac) and I'm trying to understand why the movie would end up at 7gb when Underworld Rise of the Lycans ended up at 13gb. I'm pretty sure I used the same settings but can you guys tell what would cause such a different in size?


Awakening

General
Unique ID : 234738787616615036123581296188777672661 (0xB0990BC7D5EAB15FB8E785F54BEDAFD5)
Complete name : \\HOMESERVER\Videos\Movies\HD\Underworld Collection\Underworld - Awakening\Underworld - Awakening.mkv
Format : Matroska
Format version : Version 2
File size : 6.47 GiB
Duration : 1h 28mn
Overall bit rate mode : Variable
Overall bit rate : 10.5 Mbps
Movie name : Tempvideo
Encoded date : UTC 2012-05-26 18:07:28
Writing application : mkvmerge v5.5.0 ('Healer') built on Apr 6 2012 21:43:24
Writing library : libebml v1.2.3 + libmatroska v1.3.0

Video
ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : High@L4.0
Format settings, CABAC : Yes
Format settings, ReFrames : 3 frames
Codec ID : V_MPEG4/ISO/AVC
Duration : 1h 28mn
Bit rate mode : Variable
Maximum bit rate : 25.0 Mbps
Width : 1 920 pixels
Height : 1 080 pixels
Display aspect ratio : 16:9
Frame rate : 23.976 fps
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Writing library : x264 core 124 r2197 69a0443
Encoding settings : cabac=1 / ref=3 / deblock=1:0:0 / analyse=0x3:0x113 / me=hex / subme=7 / psy=1 / psy_rd=1.00:0.00 / mixed_ref=1 / me_range=16 / chroma_me=1 / trellis=1 / 8x8dct=1 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=-2 / threads=6 / 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=1 / weightb=1 / open_gop=0 / weightp=2 / keyint=240 / keyint_min=24 / scenecut=40 / intra_refresh=0 / rc_lookahead=40 / rc=crf / mbtree=1 / crf=16.0 / qcomp=0.60 / qpmin=0 / qpmax=69 / qpstep=4 / vbv_maxrate=25000 / vbv_bufsize=25000 / crf_max=0.0 / nal_hrd=vbr / ip_ratio=1.40 / aq=1:1.00
Default : Yes
Forced : No

Audio
ID : 2
Format : FLAC
Format/Info : Free Lossless Audio Codec
Codec ID : A_FLAC
Duration : 1h 28mn
Bit rate mode : Variable
Channel(s) : 8 channels
Sampling rate : 48.0 KHz
Bit depth : 16 bits
Writing library : libFLAC 1.2.1 (UTC 2007-09-17)
Language : English
Default : Yes
Forced : No

Rise of the Lycans

General
Unique ID : 174642265645910312932654550874226438902 (0x8362E07C46C8AC8EBFC09F592AC032F6)
Complete name : \\HOMESERVER\Videos\Movies\HD\Underworld Collection\Underworld - Rise of the Lycans\Underworld - Rise of the Lycans.mkv
Format : Matroska
Format version : Version 2
File size : 12.3 GiB
Duration : 1h 32mn
Overall bit rate mode : Variable
Overall bit rate : 19.1 Mbps
Movie name : 00262
Encoded date : UTC 2010-09-05 06:56:17
Writing application : mkvmerge v4.1.1 ('Bouncin' Back') built on Jul 3 2010 22:54:08
Writing library : libebml v1.0.0 + libmatroska v1.0.0

Video
ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : High@L4.0
Format settings, CABAC : Yes
Format settings, ReFrames : 3 frames
Codec ID : V_MPEG4/ISO/AVC
Duration : 1h 32mn
Bit rate mode : Variable
Bit rate : 18.1 Mbps
Maximum bit rate : 25.0 Mbps
Width : 1 920 pixels
Height : 1 080 pixels
Display aspect ratio : 16:9
Frame rate : 23.976 fps
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.364
Stream size : 11.7 GiB (95%)
Writing library : x264 core 104 r1683 62997d6
Encoding settings : cabac=1 / ref=3 / deblock=1:0:0 / analyse=0x3:0x133 / me=umh / subme=7 / psy=1 / psy_rd=1.00:0.00 / mixed_ref=1 / me_range=16 / chroma_me=1 / trellis=1 / 8x8dct=1 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=-2 / threads=6 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / constrained_intra=0 / bframes=3 / b_pyramid=0 / b_adapt=1 / b_bias=0 / direct=1 / weightb=1 / open_gop=0 / weightp=2 / keyint=240 / keyint_min=24 / scenecut=40 / intra_refresh=0 / rc_lookahead=40 / rc=crf / mbtree=1 / crf=18.0 / qcomp=0.60 / qpmin=10 / qpmax=51 / qpstep=4 / vbv_maxrate=25000 / vbv_bufsize=25000 / crf_max=0.0 / ip_ratio=1.40 / aq=1:1.00 / nal_hrd=vbr
Default : Yes
Forced : No

Audio
ID : 2
Format : AC-3
Format/Info : Audio Coding 3
Mode extension : CM (complete main)
Format settings, Endianness : Big
Codec ID : A_AC3
Duration : 1h 32mn
Bit rate mode : Constant
Bit rate : 640 Kbps
Channel(s) : 6 channels
Channel positions : Front: L C R, Side: L R, LFE
Sampling rate : 48.0 KHz
Bit depth : 16 bits
Compression mode : Lossy
Stream size : 423 MiB (3%)
Language : English
Default : Yes
Forced : No

[goodyuop]

The file's size is based on the bitrate of video stream..

[jman98]

If you used the same setting for CQ on both movies then the larger one has more action scenes. If you don't know what I'm talking about then I would guess based on the above that somehow you ended up setting the bit rate on the larger one to almost twice the value of the smaller one without realizing it.

[Cornucopia]

And using CRF encoding, the bitrate is determined by the complexity of the video. IOW, your 2nd video is more visually complex than your 1st.

Scott

[intracube]

To complicate things, the first movie has FLAC audio vs AC3 for the second.

I roughly calculated the FLAC audio bitrate as 3.7Mbps:
8 * 48000 * 16 * 0.6 = 3,686,400
(assuming the FLAC stream is 60% size of uncompressed audio)

This compares to 640Kbps for AC3. So the FLAC audio is nearly 6x higher bitrate. That's ~2.4 gigabytes vs ~420 megabytes for the whole film.

If anything this should make Underworld Awakening bigger, so there are obviously other factors at work such as the video complexity. If one of the films was letterboxed 2.39:1, the black bars would compress more easily than a full frame image - but imdb says both films are 2.39:1.

[poisondeathray]

Also "CRF" values were rebalanced several times in x264 development history

CRF18 r1683 cannot be compared to CRF18 from r2197 (Even though you used CRF 18 and 16)

If you encoded using the same x264 version, same settings, ignored the audio, then the differences would be attributable to content complexity differences

[intracube]

From looking at the trailers:
http://www.movie-list.com/trailers.php?id=underworldriseofthelycans
http://www.movie-list.com/trailers.php?id=underworld4
- AOL 1080p versions

Rise of the Lycans has a lot more noise in some scenes compared to Awakening. The former also has scenes with lots of rain. This could account for the higher bitrate required to achieve the same 'quality'.

[AndyD]

Ok thanks guys. I thought I might have messed something up along the way. I was assuming file size to be around the same but I guess that was a silly assumption

I was initially expecting the newer rip to be larger if only because of the FLAC