Re: [Cellar] Matroska Format Version 4 / Version 2

[Dave Rice <[e-mail]>]

> On Mar 22, 2018, at 4:09 PM, Kieran O Leary <[e-mail]> wrote:
> 
> Hi,
> 
> I am wondering about the format_version value that mediainfo produces.
> 
> mediainfo out.mkv |grep -i format
> Format                                   : Matroska
> Format version                           : Version 4 / Version 2
> Format                                   : FFV1
> Format version                           : Version 3.4
> 
> What does the Version 4/2 refer to?
> 
> When looking into the trace output, I found these values:
> mediainfo --Details=1 out.mkv |grep -i version
> 0000C  EBMLVersion - 1 (0x1) (4 bytes)
> 00010  EBMLReadVersion - 1 (0x1) (4 bytes)
> 00027  DocTypeVersion - 4 (0x4) (4 bytes)
> 0002B  DocTypeReadVersion - 2 (0x2) (4 bytes)
> 001FB        version:                         3 (0x00000003)
> 001FC        micro_version:                   4 (0x00000004)
> 
> 
> Is it possibly referring to the DocTypeVersion being 4, and the
> DocTypeReadVersion being 2? Which, from my reading of the specs, means
> that software supporting Matroska version 2 is enough the play back
> the file, though there may be features present that require a reading
> application to support version 4?

That’s correct. See the first and last lines highlighted here: https://github.com/MediaArea/MediaInfoLib/blob/d8fd88a1c282d1c09388c55ee0b46029e7330690/Source/MediaInfo/Multiple/File_Mk.cpp#L2063-L2076 <https://github.com/MediaArea/MediaInfoLib/blob/d8fd88a1c282d1c09388c55ee0b46029e7330690/Source/MediaInfo/Multiple/File_Mk.cpp#L2063-L2076>.
Dave Rice