How to calculate the average bitrate of video

[einstein1969]

Hi, I'm using Mediainfo to take the average bitrate of a video but I've found that many times it's not there.

I have two questions:

1) what other ways are there to get the average bitrate?

2) If there are more than one way, what parameters can you count on? That is, what parameters are definitely present?

[lollo]

1) what about taking your calculator and do size / duration?

2) what parameters are you referring to?

[Swedaniel]

Hi, I'm using Mediainfo to take the average bitrate of a video but I've found that many times it's not there.

I have two questions:

1) what other ways are there to get the average bitrate?

2) If there are more than one way, what parameters can you count on? That is, what parameters are definitely present?

Hi, it took some time for me to realise, but this one program called 'Avanti' have an feature called Bitrate/Filesize Calculator. Ive been using v.0.9.2 together with FFMpeg Essentials v.6.0 and it is working pretty good! This bitrate calculator will display the source files duration (time in hour/minute/seconds), and allso it is possible to click 'Calc bitrate' and it will display the source files bitrate, the video i tested the bitrate calc with have variable bitrate (VBR) and it display an pretty accurate estimate of the bitrate that ive compared the bitrate with an other program, ellse it say in the program it is mostly reliable with CBR (Constant Bitrate), it seem to be working fine with VBR allso!.. (You can find this function on the right side of 'Bitrate Kbit/s and it is an button 'C' to click on which wil load the Bitrate calculator).

The program is avalible for download here on VideoHelp, it is allso required to aqquire FFMpeg for this program to function which can be found here (FFMpeg) aswell in many different version.

[einstein1969]

1) what about taking your calculator and do size / duration?

2) what parameters are you referring to?

1) Yes, I had thought about it, but sometimes the size of the video is not there.

2) I'm referring to the parameters returned by Mediainfo. Which of these are definitely present and come back with the mediainfo command? Of course, those that allow me to calculate the bitrate.

[davexnet]

Assuming you know the filesize and running time, see here for an example
https://forum.videohelp.com/threads/397023-why-does-file-size-increase-so-much-when-tr...rn#post2581789

[lollo]

but sometimes the size of the video is not there.

It is always there, mouse right click on the video file and select properties

Which of these are definitely present and come back with the mediainfo command?

Why don't you try?

[einstein1969]

Hi, I'm using Mediainfo to take the average bitrate of a video but I've found that many times it's not there.

I have two questions:

1) what other ways are there to get the average bitrate?

2) If there are more than one way, what parameters can you count on? That is, what parameters are definitely present?

Hi, it took some time for me to realise, but this one program called 'Avanti' have an feature called Bitrate/Filesize Calculator. Ive been using v.0.9.2 together with FFMpeg Essentials v.6.0 and it is working pretty good! This bitrate calculator will display the source files duration (time in hour/minute/seconds), and allso it is possible to click 'Calc bitrate' and it will display the source files bitrate, the video i tested the bitrate calc with have variable bitrate (VBR) and it display an pretty accurate estimate of the bitrate that ive compared the bitrate with an other program, ellse it say in the program it is mostly reliable with CBR (Constant Bitrate), it seem to be working fine with VBR allso!.. (You can find this function on the right side of 'Bitrate Kbit/s and it is an button 'C' to click on which wil load the Bitrate calculator).

The program is avalible for download here on VideoHelp, it is allso required to aqquire FFMpeg for this program to function which can be found here (FFMpeg) aswell in many different version.

sorry I forgot to mention that I'm using mediainfo CLI. I need to create a cmd batch.

[einstein1969]

but sometimes the size of the video is not there.

It is always there, mouse right click on the video file and select properties

Which of these are definitely present and come back with the mediainfo command?

Why don't you try?

I need to do these calculations in a batch and I'm using mediainfo CLI. Let me explain, so you understand. I need to calculate the bitrate of the video alone. If I query the file, in the Video section sometimes both the bitrate and the Video size are missing.

[einstein1969]

Why don't you try?

I tried but didn't come to a conclusion. I thought someone here knew about fixed parameters. I'm not very experienced.

[einstein1969]

Assuming you know the filesize and running time, see here for an example
https://forum.videohelp.com/threads/397023-why-does-file-size-increase-so-much-when-tr...rn#post2581789

Thanks for the formula, I had already thought about it only that sometimes there is not the size of either the video part or the audio part (where there can be even more tracks)

[einstein1969]

Maybe with an example

mediainfo "video.mkv" -f
General
Count                                    : 350
Count of stream of this kind             : 1
Kind of stream                           : General
Kind of stream                           : General
Stream identifier                        : 0
Unique ID                                : 219964994478558908138968093440097951937
Unique ID                                : 219964994478558908138968093440097951937 (0xA57BB78A94A5B53CFFC7FE173FD4A0C1)
Count of video streams                   : 1
Count of audio streams                   : 1
Video_Format_List                        : AVC
Video_Format_WithHint_List               : AVC
Codecs Video                             : AVC
Audio_Format_List                        : AAC LC
Audio_Format_WithHint_List               : AAC LC
Audio codecs                             : AAC LC
Audio_Channels_Total                     : 2
Complete name                            : ...
File name extension                      : ...
File name                                : ...
File extension                           : mkv
Format                                   : Matroska
Format                                   : Matroska
Format/Url                               : https://matroska.org/downloads/windows.html
Format/Extensions usually used           : mkv mk3d mka mks
Commercial name                          : Matroska
Format version                           : Version 4
File size                                : 998829184
File size                                : 953 MiB
File size                                : 953 MiB
File size                                : 953 MiB
File size                                : 953 MiB
File size                                : 952.6 MiB
Duration                                 : 6535675
Duration                                 : 1 h 48 min
Duration                                 : 1 h 48 min 55 s 675 ms
Duration                                 : 1 h 48 min
Duration                                 : 01:48:55.675
Duration                                 : 01:48:57;07
Duration                                 : 01:48:55.675 (01:48:57;07)
Overall bit rate                         : 1222618
Overall bit rate                         : 1 223 kb/s
Frame rate                               : 23.976
Frame rate                               : 23.976 FPS
Frame count                              : 156699
IsStreamable                             : Yes
Encoded date                             : 2022-08-15 12:11:21 UTC
File creation date                       : 2023-11-14 11:28:40.610 UTC
File creation date (local)               : 2023-11-14 12:28:40.610
File last modification date              : 2023-10-12 20:38:32.773 UTC
File last modification date (local)      : 2023-10-12 21:38:32.773
Writing application                      : HandBrake 1.4.0 2021071800
Writing application                      : HandBrake 1.4.0 2021071800
Writing library                          : Lavf58.76.100
Writing library                          : Lavf58.76.100
ErrorDetectionType                       : Per level 1

Video
Count                                    : 381
Count of stream of this kind             : 1
Kind of stream                           : Video
Kind of stream                           : Video
Stream identifier                        : 0
StreamOrder                              : 0
ID                                       : 1
ID                                       : 1
Unique ID                                : 14949589773543386298
Format                                   : AVC
Format                                   : AVC
Format/Info                              : Advanced Video Codec
Format/Url                               : http://developers.videolan.org/x264.html
Commercial name                          : AVC
Format profile                           : Main@L3.1
Format settings                          : CABAC / 4 Ref Frames
Format settings, CABAC                   : Yes
Format settings, CABAC                   : Yes
Format settings, Reference frames        : 4
Format settings, Reference frames        : 4 frames
Internet media type                      : video/H264
Codec ID                                 : V_MPEG4/ISO/AVC
Codec ID/Url                             : http://ffdshow-tryout.sourceforge.net/
Duration                                 : 6535654.000000
Duration                                 : 1 h 48 min
Duration                                 : 1 h 48 min 55 s 654 ms
Duration                                 : 1 h 48 min
Duration                                 : 01:48:55.654
Duration                                 : 01:48:57;07
Duration                                 : 01:48:55.654 (01:48:57;07)
Width                                    : 720
Width                                    : 720 pixels
Height                                   : 304
Height                                   : 304 pixels
Sampled_Width                            : 720
Sampled_Height                           : 304
Pixel aspect ratio                       : 1.000
Display aspect ratio                     : 2.368
Display aspect ratio                     : 2.35:1
Frame rate mode                          : CFR
Frame rate mode                          : Constant
FrameRate_Mode_Original                  : VFR
Frame rate                               : 23.976
Frame rate                               : 23.976 (24000/1001) FPS
FrameRate_Num                            : 24000
FrameRate_Den                            : 1001
Frame count                              : 156699
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Chroma subsampling                       : 4:2:0
Bit depth                                : 8
Bit depth                                : 8 bits
Scan type                                : Progressive
Scan type                                : Progressive
Delay                                    : 21
Delay                                    : 21 ms
Delay                                    : 21 ms
Delay                                    : 21 ms
Delay                                    : 00:00:00.021
Delay                                    : 00:00:00;00
Delay                                    : 00:00:00.021 (00:00:00;00)
Delay, origin                            : Container
Delay, origin                            : Container
Writing library                          : x264 - core 163 r3059 b684ebe0
Writing library                          : x264 core 163 r3059 b684ebe0
Encoded_Library_Name                     : x264
Encoded_Library_Version                  : core 163 r3059 b684ebe0
Encoding settings                        : cabac=1 / ref=2 / deblock=1:0:0 / analyse=0x1:0x111 / me=hex / subme=6 / psy=1 / psy_rd=1.00:0.00 / mixed_ref=1 / me_range=16 / chroma_me=1 / trellis=1 / 8x8dct=0 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=-2 / threads=6 / lookahead_threads=1 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / bluray_compat=0 / constrained_intra=0 / bframes=3 / b_pyramid=2 / b_adapt=1 / b_bias=0 / direct=1 / weightb=1 / open_gop=0 / weightp=1 / keyint=240 / keyint_min=24 / scenecut=40 / intra_refresh=0 / rc_lookahead=30 / rc=crf / mbtree=1 / crf=20.0 / qcomp=0.60 / qpmin=0 / qpmax=69 / qpstep=4 / vbv_maxrate=14000 / vbv_bufsize=14000 / crf_max=0.0 / nal_hrd=none / filler=0 / ip_ratio=1.40 / aq=1:1.00
Default                                  : Yes
Default                                  : Yes
Forced                                   : No
Forced                                   : No
colour_description_present               : Yes
colour_description_present_Source        : Container / Stream
Color range                              : Limited
colour_range_Source                      : Container / Stream
Color primaries                          : BT.601 NTSC
colour_primaries_Source                  : Container / Stream
Transfer characteristics                 : BT.709
transfer_characteristics_Source          : Container / Stream
Matrix coefficients                      : BT.601
matrix_coefficients_Source               : Container / Stream

Audio
Count                                    : 285
Count of stream of this kind             : 1
Kind of stream                           : Audio
Kind of stream                           : Audio
Stream identifier                        : 0
StreamOrder                              : 1
ID                                       : 2
ID                                       : 2
Unique ID                                : 7924595837062408030
Format                                   : AAC
Format                                   : AAC LC
Format/Info                              : Advanced Audio Codec Low Complexity
Commercial name                          : AAC
Format settings, SBR                     : No (Explicit)
Format settings, SBR                     : No (Explicit)
Format_AdditionalFeatures                : LC
Codec ID                                 : A_AAC-2
Duration                                 : 6535658.000000
Duration                                 : 1 h 48 min
Duration                                 : 1 h 48 min 55 s 658 ms
Duration                                 : 1 h 48 min
Duration                                 : 01:48:55.658
Duration                                 : 01:48:55.658
Channel(s)                               : 2
Channel(s)                               : 2 channels
Channel positions                        : Front: L R
Channel positions                        : 2/0/0
Channel layout                           : L R
Samples per frame                        : 1024
Sampling rate                            : 48000
Sampling rate                            : 48.0 kHz
Samples count                            : 313711584
Frame rate                               : 46.875
Frame rate                               : 46.875 FPS (1024 SPF)
Compression mode                         : Lossy
Compression mode                         : Lossy
Delay                                    : 0
Delay                                    : 00:00:00.000
Delay                                    : 00:00:00.000
Delay, origin                            : Container
Delay, origin                            : Container
Delay relative to video                  : -21
Delay relative to video                  : -21 ms
Delay relative to video                  : -21 ms
Delay relative to video                  : -21 ms
Delay relative to video                  : -00:00:00.021
Delay relative to video                  : -00:00:00.021
Title                                    : Stereo
Default                                  : Yes
Default                                  : Yes
Forced                                   : No
Forced                                   : No

This is just an example, MediaInfo does not come out with the video bitrate, nor with the video dimension, nor with the audio dimension. Sometimes the overall bitrate would be sufficient, but if the audio tracks are many and consistent, it doesn't match at all.

[pandy]

You can extract elementary streams and calculate average bitrate based on this, containers always add some overhead so overall file size is bigger than sum of all elementary streams sizes - there is many reasons for this - for example packetization, metadata, container structure etc.
So whenever you need to know average video bitrate go for video elementary stream and calculate it by yourself.
Btw mediainfo frequently may provide inaccurate informations.

[_Al_]

if mediainfo does not provide some values, try ffprobe:

@echo off
SETLOCAL ENABLEDELAYEDEXPANSION
set "ffprobe=F:\tools\ffprobe.exe"

set "arg[0]=width"
set "arg[1]=height"
set "arg[2]=bit_rate"
ffprobe -v quiet -select_streams v:0 -show_entries stream=%arg[0]%,%arg[1]%,%arg[2]%  -of default=noprint_wrappers=1:nokey=1 "%~1" >video.txt
set "index=0"
for /f "delims=" %%x in (video.txt) do call :set_value %%x
echo %width%
echo %height%
echo %bit_rate%


set "arg[0]=bit_rate"
ffprobe -v quiet -select_streams a:0 -show_entries stream=%arg[0]% -of default=noprint_wrappers=1:nokey=1 "%~1" >audio.txt
set "index=0"
for /f "delims=" %%x in (audio.txt) do call :set_value %%x
echo %bit_rate%

ENDLOCAL&echo press any key to exit&pause>nul&exit

:set_value  <value>
set "!arg[%index%]!=%1"
set /A index=%index%+1
goto :eof

[einstein1969]

if mediainfo does not provide some values, try ffprobe:

@echo off
SETLOCAL ENABLEDELAYEDEXPANSION
set "ffprobe=F:\tools\ffprobe.exe"

set "arg[0]=width"
set "arg[1]=height"
set "arg[2]=bit_rate"
ffprobe -v quiet -select_streams v:0 -show_entries stream=%arg[0]%,%arg[1]%,%arg[2]%  -of default=noprint_wrappers=1:nokey=1 "%~1" >video.txt
set "index=0"
for /f "delims=" %%x in (video.txt) do call :set_value %%x
echo %width%
echo %height%
echo %bit_rate%


set "arg[0]=bit_rate"
ffprobe -v quiet -select_streams a:0 -show_entries stream=%arg[0]% -of default=noprint_wrappers=1:nokey=1 "%~1" >audio.txt
set "index=0"
for /f "delims=" %%x in (audio.txt) do call :set_value %%x
echo %bit_rate%

ENDLOCAL&echo press any key to exit&pause>nul&exit

:set_value  <value>
set "!arg[%index%]!=%1"
set /A index=%index%+1
goto :eof

Thank you for the script, you saved me so much time.

Unfortunately my videos are strange. You can't do that with ffprobe either.

[einstein1969]

You can extract elementary streams and calculate average bitrate based on this, containers always add some overhead so overall file size is bigger than sum of all elementary streams sizes - there is many reasons for this - for example packetization, metadata, container structure etc.
So whenever you need to know average video bitrate go for video elementary stream and calculate it by yourself.
Btw mediainfo frequently may provide inaccurate informations.

Thanks to you, your solution is the one that should work. It's heavy in terms of pc work, but I don't see any other solution. Since I don't need a precise value, I'm undecided whether to extract the audio tracks, to do it first, and make the difference. I have to do some tests... Thank you, thank you, thank you.

[vongooB9]

If the video is an mkv and you don't care about modifying the file, you can use mkvpropedit to add all the missing statistics.

mkvpropedit --add-track-statistics-tags video.mkv

The information should then be available in mediainfo.

[einstein1969]

I did some tests. ffprobe is faster than mediainfo although in some cases mediainfo returns more information and ffprobe fails.

[einstein1969]

If the video is an mkv and you don't care about modifying the file, you can use mkvpropedit to add all the missing statistics.

mkvpropedit --add-track-statistics-tags video.mkv

The information should then be available in mediainfo.

I've tried it and it looks phenomenal. I just need to find a way to turn mp4s into mkvs painlessly. Thank you very much too.

[pandy]

You can extract elementary streams and calculate average bitrate based on this, containers always add some overhead so overall file size is bigger than sum of all elementary streams sizes - there is many reasons for this - for example packetization, metadata, container structure etc.
So whenever you need to know average video bitrate go for video elementary stream and calculate it by yourself.
Btw mediainfo frequently may provide inaccurate informations.

Thanks to you, your solution is the one that should work. It's heavy in terms of pc work, but I don't see any other solution. Since I don't need a precise value, I'm undecided whether to extract the audio tracks, to do it first, and make the difference. I have to do some tests... Thank you, thank you, thank you.

You can use ffprobe to output each frame size in bits - all bits added together and divided by duration will give average video bitrate - this can be done semiautomatically.

You can use script from here https://forum.videohelp.com/threads/412226-Losslessly-Extract-Keyframes#post2711854

pkt_duration_time and pkt_size is most interesting for you - add all pkt_duration_time together and it will give duration ; add all pkt_size together and multiply by 8 so you get bits then divide this by calculated duration and you will get correct average bitrate.

[johns0]

Use mkvmerge to turn mp4 to mkv,does this without re-encoding.

[pcspeak]

I knocked this up.
You need the following programs in the folder with the videos,
or in the System %path%
or provide the absolute path '\program path\program_name.exe' (which I did).
ffmpeg.exe
mkvpropedit.exe
MediaInfo.exe (CLI version)

if exist list.txt del /q list.txt

:: Create an MKV from all MP4 videos.
for %%a in (*.mp4) do "C:\VidAud\ffmpeg64\bin\ffmpeg.exe" -i "%%a" -c copy -y "%%~na.mkv"

:: Process each MKV video - Output to list.txt
for %%a in (*.mkv) do call :process "%%a"
goto :end

:process
:: Complete all tags in the MKV videos
"C:\Program Files\MKVToolNix\mkvpropedit.exe" --add-track-statistics-tags "%~1"
::Run MediaInfo to get the required statistics
"C:\VidAud\MediaInfoCLI\MediaInfo.exe" "--Output=General;File Name: %%FileNameExtension%%\r\nDuration: %%Duration/String3%%\r\nSize: %%FileSize/String%%" "%~1" >> list.txt
"C:\VidAud\MediaInfoCLI\MediaInfo.exe" "--Output=Video;V_bitrate: %%BitRate%%" "%~1" >> list.txt
"C:\VidAud\MediaInfoCLI\MediaInfo.exe" "--Output=Audio;A_bitrate: %%BitRate%%" "%~1" >> list.txt
echo. >> list.txt
goto :eof

:end
start /i list.txt
 pause

It will need a tweak or two to give you what you want.
Cheers.

[vongooB9]

I'm not 100% sure, but I think you don't need to convert mp4 to mkv, because I think all mp4s show that information in mediainfo. Or at least I didn't find any that didn't have it. But I'm not sure, maybe I'm wrong.

[einstein1969]

You can extract elementary streams and calculate average bitrate based on this, containers always add some overhead so overall file size is bigger than sum of all elementary streams sizes - there is many reasons for this - for example packetization, metadata, container structure etc.
So whenever you need to know average video bitrate go for video elementary stream and calculate it by yourself.
Btw mediainfo frequently may provide inaccurate informations.

Thanks to you, your solution is the one that should work. It's heavy in terms of pc work, but I don't see any other solution. Since I don't need a precise value, I'm undecided whether to extract the audio tracks, to do it first, and make the difference. I have to do some tests... Thank you, thank you, thank you.

You can use ffprobe to output each frame size in bits - all bits added together and divided by duration will give average video bitrate - this can be done semiautomatically.

You can use script from here https://forum.videohelp.com/threads/412226-Losslessly-Extract-Keyframes#post2711854

pkt_duration_time and pkt_size is most interesting for you - add all pkt_duration_time together and it will give duration ; add all pkt_size together and multiply by 8 so you get bits then divide this by calculated duration and you will get correct average bitrate.

Thanks for the report, I did a test and unfortunately, although it is possible to make it completely automatic, the execution time was very long. I'm considering the best method.

[pandy]

Thanks for the report, I did a test and unfortunately, although it is possible to make it completely automatic, the execution time was very long. I'm considering the best method.

True - ffprobe strangely perform such analysis slowly but at least it is reliable and free way to get such information.

[einstein1969]

Use mkvmerge to turn mp4 to mkv,does this without re-encoding.

Thanks, it was also suggested to me to use ffmpeg for conversion. Do you know which is the best in terms of reliability and speed?

[einstein1969]

I knocked this up.
You need the following programs in the folder with the videos,
or in the System %path%
or provide the absolute path '\program path\program_name.exe' (which I did).
ffmpeg.exe
mkvpropedit.exe
MediaInfo.exe (CLI version)

if exist list.txt del /q list.txt

:: Create an MKV from all MP4 videos.
for %%a in (*.mp4) do "C:\VidAud\ffmpeg64\bin\ffmpeg.exe" -i "%%a" -c copy -y "%%~na.mkv"

:: Process each MKV video - Output to list.txt
for %%a in (*.mkv) do call :process "%%a"
goto :end

:process
:: Complete all tags in the MKV videos
"C:\Program Files\MKVToolNix\mkvpropedit.exe" --add-track-statistics-tags "%~1"
::Run MediaInfo to get the required statistics
"C:\VidAud\MediaInfoCLI\MediaInfo.exe" "--Output=General;File Name: %%FileNameExtension%%\r\nDuration: %%Duration/String3%%\r\nSize: %%FileSize/String%%" "%~1" >> list.txt
"C:\VidAud\MediaInfoCLI\MediaInfo.exe" "--Output=Video;V_bitrate: %%BitRate%%" "%~1" >> list.txt
"C:\VidAud\MediaInfoCLI\MediaInfo.exe" "--Output=Audio;A_bitrate: %%BitRate%%" "%~1" >> list.txt
echo. >> list.txt
goto :eof

:end
start /i list.txt
 pause

It will need a tweak or two to give you what you want.
Cheers.

Thanks for the script. I'm adapting it to mine. Very valuable

[einstein1969]

I'm not 100% sure, but I think you don't need to convert mp4 to mkv, because I think all mp4s show that information in mediainfo. Or at least I didn't find any that didn't have it. But I'm not sure, maybe I'm wrong.

thanks , i will check and report

[einstein1969]

I'm not 100% sure, but I think you don't need to convert mp4 to mkv, because I think all mp4s show that information in mediainfo. Or at least I didn't find any that didn't have it. But I'm not sure, maybe I'm wrong.

thanks , i will check and report

unfortunately, I found mp4 files where the bitrate was missing.

[vongooB9]

unfortunately, I found mp4 files where the bitrate was missing.

Thanks for testing it, I will note it for my programs. Unfortunately I can't think of any other method that someone else hasn't already mentioned. But if you are going to convert mp4 to mkv I think it is better to use mkvmerge instead of ffmpeg, this way you don't need to use mkvpropedit, because mkvmerge already adds the bitrate directly.

mkvmerge -o output.mkv input.mp4

[einstein1969]

I have a problem, the conversions with mkvmerge and ffmpeg come with different sizes from each other and with the original. Original 587MiB, mkmerge 548 MiB, ffmpeg 568 MiB

general_FileNameExtension:aoa.mp4
general_Duration/String3:00:03:09.211
general_FileSize/String:587 MiB

video_bitrate:
video_Duration:189155
video_Bits-(Pixel*Frame):

mkvmerge v80.0 ('Roundabout') 64-bit
'aoa.mp4': Using the demultiplexer for the format 'MPEG transport stream'.
'aoa.mp4' track 0: Using the output module for the format 'HEVC/H.265 (unframed)'.
'aoa.mp4' track 1: Using the output module for the format 'AAC'.
The file 'aoa_merge.mkv' has been opened for writing.
'aoa.mp4' track 0: Extracted the aspect ratio information from the video bitstream and set the display dimensions to 3840/2160.
The cue entries (the index) are being written...
Multiplexing took 15 seconds.

general_FileNameExtension:aoa_merge.mkv
general_Duration/String3:00:03:09.162
general_FileSize/String:548 MiB

video_bitrate:24086816
video_Duration:189156.000000
video_Bits-(Pixel*Frame):0.048

ffmpeg version 6.1-full_build-www.gyan.dev Copyright (c) 2000-2023 the FFmpeg developers
  built with gcc 12.2.0 (Rev10, Built by MSYS2 project)
  configuration: --enable-gpl --enable-version3 --enable-static --pkg-config=pkgconf --disable-w32threads --disable-autodetect --enable-fontconfig --enable-iconv --enable-gnutls --enable-libxml2 --enable-gmp --enable-bzlib --enable-lzma --enable-libsnappy --enable-zlib --enable-librist --enable-libsrt --enable-libssh --enable-libzmq --enable-avisynth --enable-libbluray --enable-libcaca --enable-sdl2 --enable-libaribb24 --enable-libaribcaption --enable-libdav1d --enable-libdavs2 --enable-libuavs3d --enable-libzvbi --enable-librav1e --enable-libsvtav1 --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs2 --enable-libxvid --enable-libaom --enable-libjxl --enable-libopenjpeg --enable-libvpx --enable-mediafoundation --enable-libass --enable-frei0r --enable-libfreetype --enable-libfribidi --enable-libharfbuzz --enable-liblensfun --enable-libvidstab --enable-libvmaf --enable-libzimg --enable-amf --enable-cuda-llvm --enable-cuvid --enable-ffnvcodec --enable-nvdec --enable-nvenc --enable-dxva2 --enable-d3d11va --enable-libvpl --enable-libshaderc --enable-vulkan --enable-libplacebo --enable-opencl --enable-libcdio --enable-libgme --enable-libmodplug --enable-libopenmpt --enable-libopencore-amrwb --enable-libmp3lame --enable-libshine --enable-libtheora --enable-libtwolame --enable-libvo-amrwbenc --enable-libcodec2 --enable-libilbc --enable-libgsm --enable-libopencore-amrnb --enable-libopus --enable-libspeex --enable-libvorbis --enable-ladspa --enable-libbs2b --enable-libflite --enable-libmysofa --enable-librubberband --enable-libsoxr --enable-chromaprint
  libavutil      58. 29.100 / 58. 29.100
  libavcodec     60. 31.102 / 60. 31.102
  libavformat    60. 16.100 / 60. 16.100
  libavdevice    60.  3.100 / 60.  3.100
  libavfilter     9. 12.100 /  9. 12.100
  libswscale      7.  5.100 /  7.  5.100
  libswresample   4. 12.100 /  4. 12.100
  libpostproc    57.  3.100 / 57.  3.100
Input #0, mpegts, from 'aoa.mp4':
  Duration: 00:03:09.14, start: 1.080722, bitrate: 26034 kb/s
  Program 1
  Stream #0:0[0x101]: Video: hevc (Main) ([36][0][0][0] / 0x0024), yuv420p(tv), 3840x2160 [SAR 1:1 DAR 16:9], 59.94 fps, 59.94 tbr, 90k tbn
  Stream #0:1[0x102](und): Audio: aac (LC) ([15][0][0][0] / 0x000F), 48000 Hz, stereo, fltp, 192 kb/s
Output #0, matroska, to 'aoa.mkv':
  Metadata:
    encoder         : Lavf60.16.100
  Stream #0:0: Video: hevc (Main) ([36][0][0][0] / 0x0024), yuv420p(tv), 3840x2160 [SAR 1:1 DAR 16:9], q=2-31, 59.94 fps, 59.94 tbr, 1k tbn
  Stream #0:1(und): Audio: aac (LC) ([255][0][0][0] / 0x00FF), 48000 Hz, stereo, fltp, 192 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
  Stream #0:1 -> #0:1 (copy)
Press [q] to stop, [?] for help
[out#0/matroska @ 000001a5d3d86080] video:577256kB audio:4433kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.019352%
size=  581801kB time=00:03:09.12 bitrate=25201.5kbits/s speed=18.8x
The file is being analyzed.
The file is read in order to create track statistics.
Progress: 100%
The changes are written to the file.
Done.

general_FileNameExtension:aoa.mkv
general_Duration/String3:00:03:09.156
general_FileSize/String:568 MiB

video_bitrate:25000499
video_Duration:189155.683333
video_Bits-(Pixel*Frame):0.050

code used:

@echo off
setlocal enabledelayedexpansion

echo(
call :mediainfo General "FileNameExtension Duration/String3 FileSize/String" "aoa.mp4"

echo general_FileNameExtension:%general_FileNameExtension%
echo general_Duration/String3:%general_Duration/String3%
echo general_FileSize/String:%general_FileSize/String%

echo(
call :mediainfo Video "BitRate Duration Bits-(Pixel*Frame)" "aoa.mp4"

echo video_bitrate:%video_bitrate%
echo video_Duration:%video_Duration%
echo video_Bits-(Pixel*Frame):%video_Bits-(Pixel*Frame)%

echo(
mkvmerge -o aoa_merge.mkv aoa.mp4

echo(
call :mediainfo General "FileNameExtension Duration/String3 FileSize/String" "aoa_merge.mkv"

echo general_FileNameExtension:%general_FileNameExtension%
echo general_Duration/String3:%general_Duration/String3%
echo general_FileSize/String:%general_FileSize/String%

echo(
call :mediainfo Video "BitRate Duration Bits-(Pixel*Frame)" "aoa_merge.mkv"

echo video_bitrate:%video_bitrate%
echo video_Duration:%video_Duration%
echo video_Bits-(Pixel*Frame):%video_Bits-(Pixel*Frame)%

echo(
ffmpeg.exe -i "aoa.mp4" -c copy -y "aoa.mkv"
mkvpropedit.exe --add-track-statistics-tags "aoa.mkv"

echo(
call :mediainfo General "FileNameExtension Duration/String3 FileSize/String" "aoa.mkv"

echo general_FileNameExtension:%general_FileNameExtension%
echo general_Duration/String3:%general_Duration/String3%
echo general_FileSize/String:%general_FileSize/String%

echo(
call :mediainfo Video "BitRate Duration Bits-(Pixel*Frame)" "aoa.mkv"

echo video_bitrate:%video_bitrate%
echo video_Duration:%video_Duration%
echo video_Bits-(Pixel*Frame):%video_Bits-(Pixel*Frame)%


pause

goto :eof

:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
:mediainfo "section" "parameters" "video"

  set "section=%~1"
  set "parameters=%~2"
  set "video=%~3" 

  set "cmdline=mediainfo "--inform=!section!;"

  set "i=1"
:loop1
  FOR /F "tokens=1* delims= " %%G IN ("!parameters!") DO (
	set "v[!i!]=!section!_%%G"
	set "cmdline=!cmdline!%%%%G%%\r\n"
	set "parameters=%%H"
  )
  if defined parameters set /A i+=1 & goto loop1
  set "cmdline=!cmdline:~0,-4!""

  set "i=1"
  for /f "tokens=1,* delims=]" %%f in ('%cmdline% "!Video!" ^| find /N /V ""') do (
	set "P=%%g"
	for %%G in (!i!) do ( 
		set "!v[%%G]!="
		if defined P set "!v[%%G]!=%%g"
	)
	set /A i+=1
  )

goto:eof
:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::

Is this normal?

EDIT: Going to look with the Mediainfo GUI I found out that the files that looked like MP4 actually had TS format. Could this be what created that size difference?