Remuxing give different bitrate for video

[moth2daflame]

I'm new to REMUXing. I use mkvmergeGUI (only) and add the M2TS stream that I wanted, then I select only the video, audio, subtitle stream I want, and start MUXING.

The result gives me a files with different video bitrate (using MediaInfo). The data is below.

Is this normal, I thought its supposed to be LOSSLESS, and thus bitrate would be preserved.


FROM M2TS
Format : BDAV
Format/Info : Blu-ray Video
File size : 34.6 GiB
Duration : 2h 49mn
Overall bit rate mode : Variable
Overall bit rate : 29.2 Mbps
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 : 2h 49mn
Bit rate mode : Variable
Bit rate : 25.1 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) : 0.504
Stream size : 29.7 GiB (86%)

REMUX FILE
Overall bit rate : 26.2 Mbps
Encoded date : UTC 2013-03-12 11:57:04
Writing application : mkvmerge v6.1.0 ('Old Devil') built on Mar 2 2013 14:32:37
Writing library : libebml v1.3.0 + libmatroska v1.4.0
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 : 2h 49mn
Bit rate mode : Variable
Bit rate : 24.1 Mbps
Width : 1 920 pixels
Height : 1 080 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) : 0.484
Stream size : 28.5 GiB (92%)
Default : Yes
Forced : Nothanks in advance,

[jagabo]

MediaInfo's bitrate report isn't always accurate. Depending on the container, the codec, etc. it may only look at the bitrate value flagged in the header. Or it may calculate the bitrate based on the file size (something like video bitrate = file size / time - audio bitrate).

If you want a more accurate bitrate report use a program like Bitrate Viewer.
https://www.videohelp.com/tools/Bitrate-Viewer-2
This program actually parses all the video data to determine the bitrate.

[moth2daflame]

Anyway I can confirm that the conversion is actually done right?

I read in a couple of places where they use TSmuxer to some kind processing prior to mkvmerge, what exactly is this for and is it required? How come I got by just using mkvmerge. Or am I doing something wrong?

Thanks.

[jagabo]

If you don't notice any problems when you play the MKV file the file is fine. If you don't see audio/video sync errors, if the entire video is there, don't worry about what MediaInfo says about the bitrate. All MkvMerge does is take the tracks out of the M2TS container and put them into an MKV container.

[poisondeathray]

The filesize is going to be smaller, because .m2ts transport stream has larger overhead than .mkv container. Typically around 5-7%

If you're paranoid, demux both and examine each elementary stream without the container . They should be the same size

[hello_hello]

Yeah it's just MediaInfo not reporting accurately. If you opened the MKV file with tsmuxer and remuxed it as an M2TS file, MediaInfo will probably report it as having a slightly higher bitrate again, but it's still the same video.