mirror of
https://gitlab.com/mbunkus/mkvtoolnix.git
synced 2024-10-22 07:21:21 +00:00
Created Meta data fields like bitrate lost (markdown)
parent
1248e9aa29
commit
31311202dc
18
Meta-data-fields-like-bitrate-lost.md
Normal file
18
Meta-data-fields-like-bitrate-lost.md
Normal file
@ -0,0 +1,18 @@
|
||||
# Why are meta data fields like bitrate or encoder name lost when muxing to Matroska?
|
||||
|
||||
## The problem
|
||||
|
||||
You use tools like MediaInfo to show you information about source files and compare that with the information after you've muxed that file into a Matroska file. You notice that several pieces of information like e.g. the bitrate or the encoder name are not present in a Matroska file.
|
||||
|
||||
## The answer
|
||||
|
||||
The [Matroska file format](http://www.matroska.org/technical/specs/index.html) does not offer header fields for such pieces of information. In general only information that a codec might require for playback is stored in Matroska's track headers. Data that is simply informational can be stored in [Matroska tags](http://www.matroska.org/technical/specs/tagging/index.html) if you want, but mkvmerge does not do that automatically for you.
|
||||
|
||||
You might notice that MediaInfo still shows bitrate information for some Matroska files but not for others. This may have two reasons:
|
||||
|
||||
1. The bitrate might be stored on the bitstream level. This is only possible for audio/video types whose specifications provide fields for that kind of information in the bitstream.
|
||||
2. If there's only a single track in a Matroska file then the bitrate can be estimated with the following formula: `bitrate_in_kbit_per_second = (file_size_in_bytes * 8) / (file_duration_in_seconds * 1024)`
|
||||
|
||||
Note that starting with v7.0.0 mkvmerge [will create track-specific statistics](Automatic-tag-generation) and store them in tags. Newer versions of MediaInfo should be able to use that information properly.
|
||||
|
||||
Categories: [merging](Category-merging), [metadata](Category-metadata)
|
Loading…
Reference in New Issue
Block a user