MKV Bitrate question

jbinkley60

I've recently started testing ripping to MKV format vs. M2TS. I've noticed where it seems that the bitrate selected in DVDFab doesn't match the actual output file as reported by Mediainfo nor does the file size. I've attached a zip file which has the DVDfab screenshot of the setting, the logfile and a Mediainfo output. In DVDfab I set the bitrate to 30 Meg but Mediainfo shows it at 22.7 Meg and the output file size is much smaller than DVDFab said it would be (corresponding to the lower bitrate). Is this normal ?

jbinkley60

So I did some more testing with MKV and see a huge difference in the bitrate and resulting file size depending upon whether I am using CUDA or IQS. IQS looks normal in that the bitrate either meets or exceeds DVDFab but CUDA is significantly lower. I don't see this behavior ripping to M2TS format, just MKV. I've attached 2 screenshots for comparison.

jbinkley60

I did a lot more testing today and here's what I've determined. When ripping to MKV format and leveraging CUDA support some resulting rips have the bitrates and file sizes match the DVDfab settings and some don't. The ones that don't match are significantly lower bit rats and smaller in size. IQS and software are fine.

When ripping normal DVDs to MKV and leveraging CUDA, the resulting bitrates and file sizes are not off intermittently like Blu-Ray sources but all of the time (at least with every regular DVD I tested). When using IQS and software they were fine.

When ripping to M2TS format, whether Blu-Ray or regular DVDs, and regardless of IQS, CUDA or software the bitrates and file sizes were fine. In fact the M2TS format was almost always 100% exact with Mediainfo. In other words if I set the bitrate to 8000 Medinfo would show it exactly 8000. MKV format was never as exacting.

I am curios if the DVDFab folks have any insight.

One other thing I noticed is that with both CUDA and IQS support, ripping to M2TS was significantly faster than MKV. In some cases 50% faster and in others up to 250% faster.

jbinkley60

I've been looking more deeply into the Mediainfo outputs for MKV rips. What I see is that when CUDA support is chosen the bitrate mode is constant, which is different from IQS and software. Below are the Mediainfo outputs of all three DVDFab uses.

CUDA support

General
Unique ID : 220770998767707026372387302962620684090 (0xA616F29EF3779DB4BA9D4CEE2806573A)
Complete name : U:\Video Library\New Releases\Blue Ray\Video\ONE_SHOT\One Shot - CUDA.mkv
Format : Matroska
Format version : Version 2
File size : 4.38 GiB
Duration : 1h 35mn
Overall bit rate mode : Constant
Overall bit rate : 6 561 Kbps
Movie name : One Shot - CUDA
Encoded date : UTC 2015-08-07 21:15:29
Writing application : DVDFab 9.2.0.7
Writing library : libebml v0.7.8 + libmatroska v0.8.1

Video
ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : High@L3
Format settings, CABAC : Yes
Format settings, ReFrames : 2 frames
Format settings, GOP : M=3, N=24
Codec ID : V_MPEG4/ISO/AVC
Duration : 1h 35mn
Bit rate mode : Constant
Bit rate : 5 983 Kbps
Nominal bit rate : 8 000 Kbps
Width : 856 pixels
Height : 480 pixels
Display aspect ratio : 16:9
Frame rate mode : Constant
Frame rate : 23.976 fps
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.607
Stream size : 3.99 GiB (91%)

Software only

General
Unique ID : 221465452876373121340349953665410913881 (0xA69CB1DA198C00D9875B385A2A19D659)
Complete name : U:\Video Library\New Releases\Blue Ray\Video\ONE_SHOT\One Shot - software.mkv
Format : Matroska
Format version : Version 2
File size : 5.55 GiB
Duration : 1h 35mn
Overall bit rate : 8 329 Kbps
Movie name : One Shot - software
Encoded date : UTC 2015-08-07 21:23:28
Writing application : DVDFab 9.2.0.7
Writing library : libebml v0.7.8 + libmatroska v0.8.1

Video
ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : High@L4.1
Format settings, CABAC : Yes
Format settings, ReFrames : 2 frames
Codec ID : V_MPEG4/ISO/AVC
Duration : 1h 35mn
Bit rate : 8 000 Kbps
Width : 856 pixels
Height : 480 pixels
Display aspect ratio : 16:9
Frame rate mode : Constant
Frame rate : 23.976 fps
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.812
Stream size : 5.14 GiB (93%)

IQS support

eneral
ID : 0 (0x0)
Complete name : U:\Video Library\New Releases\Blue Ray\Video\ONE_SHOT\One Shot - IQS.m2ts
Format : BDAV
Format/Info : Blu-ray Video
File size : 5.83 GiB
Duration : 1h 35mn
Overall bit rate mode : Variable
Overall bit rate : 8 739 Kbps
Maximum Overall bit rate : 48.0 Mbps

Video
ID : 4113 (0x1011)
Menu ID : 1 (0x1)
Format : AVC
Format/Info : Advanced Video Codec
Format profile : High@L4.1
Format settings, CABAC : Yes
Format settings, ReFrames : 2 frames
Codec ID : 27
Duration : 1h 35mn
Bit rate mode : Variable
Bit rate : 7 936 Kbps
Maximum bit rate : 12.0 Mbps
Width : 856 pixels
Height : 480 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) : 0.806
Stream size : 5.29 GiB (91%)

signals

Note that the codec settings are slightly different:
CUDA=High@Level 3
Software and IQS=High@Level 4.1
and will produce different results. The .81 b/p is pretty high for h264 video and may even be overkill.

jbinkley60

[QUOTE=signals;177626]Note that the codec settings are slightly different:
CUDA=High@Level 3
Software and IQS=High@Level 4.1
and will produce different results. The .81 b/p is pretty high for h264 video and may even be overkill.[/QUOTE]

The codec settings must be changing due to DVDfab, The only change I made between all three rips above was turning on/off CUDA/IQS and software support. I made no other changes to the DVDfab MKV settings.

jbinkley60

[QUOTE=jbinkley60;177585]I did a lot more testing today and here's what I've determined. When ripping to MKV format and leveraging CUDA support some resulting rips have the bitrates and file sizes match the DVDfab settings and some don't. The ones that don't match are significantly lower bit rats and smaller in size. IQS and software are fine.

When ripping normal DVDs to MKV and leveraging CUDA, the resulting bitrates and file sizes are not off intermittently like Blu-Ray sources but all of the time (at least with every regular DVD I tested). When using IQS and software they were fine.

When ripping to M2TS format, whether Blu-Ray or regular DVDs, and regardless of IQS, CUDA or software the bitrates and file sizes were fine. In fact the M2TS format was almost always 100% exact with Mediainfo. In other words if I set the bitrate to 8000 Medinfo would show it exactly 8000. MKV format was never as exacting.

I am curios if the DVDFab folks have any insight.

One other thing I noticed is that with both CUDA and IQS support, ripping to M2TS was significantly faster than MKV. In some cases 50% faster and in others up to 250% faster.[/QUOTE]

I've found the solution to the ripping speed question. When I rip and the output is a network drive (gigabit network) MKV is significantly slower than a local drive whereas M2TS is the same. This must have something to do with how MKV accesses the file share when ripping. I am able to obtain the same ripping speeds to local drives.

So what remains is the differences in bitrate when using CUDA and MKV vs. MKV and IQS or MKV and software. That appears to be a DVDFab bug.