[FFmpeg-user] Question about file size changes

David Shuman d.shuman at att.net
Tue Jun 18 13:25:45 EEST 2019


 From what I understand, I am doing a copy that should not alter the original content except to add dropped frames as necessary to sync the video and audio due to transmission errors.  Why is  the KB/S changing and by two different values depending solely on the suffix for the files.  Which conversion is more valid in this case?  MTS or M2TS?
    On Sunday, June 16, 2019, 06:36:01 PM EDT, Dennis Mungai <dmngaie at gmail.com> wrote:  
 
 On Sun, 16 Jun 2019 at 22:26, David Shuman <d.shuman at att.net> wrote:

> I have a video recorder that outputs files with an .mts suffix.  mediainfo
> identifies these files as BDAV more commonly .m2ts files  I attempt to copy
> these files with the following commands
>
> ffmpeg          -i
> "D:\Dave\Videos\010-raw\mts\Charge-05082019-2255.mts" -c
> copy
> "D:\Dave\Videos\020-fix\mts\Charge-05082019-2255.mts"                2>&1
> | wtee    "D:\Dave\Videos\log\mts\ffFIX-Charge-05082019-2255.txt"
> I renamed the file to have a .m2ts suffix and tried again
> ffmpeg          -i
> "D:\Dave\Videos\010-raw\m2ts\Charge-05082019-2255.m2ts" -c
> copy
> "D:\Dave\Videos\020-fix\m2ts\Charge-05082019-2255.m2ts"
> 2>&1  | wtee    "D:\Dave\Videos\log\m2ts\ffFIX-Charge-05082019-2255.txt"
> The resulting output files according to mediainfo have had their video bit
> rates increased    The original is 1778 kb/s regardless of file suffix,
> the .mts copy is 1817 kb/s and the .m2ts copy is 1870 kb/s.
>
> Why do the copies have higher video bit rates?  Nothing else significant
> appears to have changed  the .mts claims format is mpeg-ts  on the output,
> all other formats both input and the .m2ts output claim to be BDAV.
> Is there a way I can keep the bit rate the same so the copy matches the
> original except for corrections made during the copy for missing franes,
> etc?
>
>
>
Most likely you're seeing the effects of muxer overheads.

>From your console: muxing overhead: 9.707805%
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