Is there a way to batch split a file by chapter with ffmpeg and then reassemble with mkvmerge in windows?

Question

So I made a batch script originally with the ability to relatively precision trim a video into chapters without having to run by keyframes, but the code looks horrible and I can't get it to loop through all mp4 files nor get mkvmerge to append the files after splitting them. Code is below but be gentle it is my first try.

@echo off
setlocal enableDelayedExpansion

REM CODE BELOW CREATES JSON FILES FOR ALL MP4 FILES WITHIN THE SAME DIRECTORY
ffprobe -v quiet -print_format json -show_chapters -loglevel error "01x01.mp4" > "01x01.json"

REM CODE BELOW SETS VARIABLES FROM EACH SPECIFIC JSON
FOR /F "delims=" %%i in ('jq .chapters[2].start ^< 01x01.json') DO SET /A start1=%%i
FOR /F "delims=" %%j in ('jq .chapters[2].end ^< 01x01.json') DO SET /A end1=%%j

FOR /F "delims=" %%k in ('jq .chapters[4].start ^< 01x01.json') DO SET /A start2=%%k
FOR /F "delims=" %%l in ('jq .chapters[4].end ^< 01x01.json') DO SET /A end2=%%l

FOR /F "delims=" %%m in ('jq .chapters[6].start ^< 01x01.json') DO SET /A start3=%%m
FOR /F "delims=" %%n in ('jq .chapters[6].end ^< 01x01.json') DO SET /A end3=%%n

FOR /F "delims=" %%o in ('jq .chapters[8].start ^< 01x01.json') DO SET /A start4=%%o
FOR /F "delims=" %%p in ('jq .chapters[8].end ^< 01x01.json') DO SET /A end4=%%p

REM SETS THE DURATION OF EACH FILE TO USE PRECISION TIMING FOR START AND STOP TIMES
CALL vbs (%end1%-%start1%)/1000
SET duration1=%val%
CALL vbs (%end2%-%start2%)/1000
SET duration2=%val%
CALL vbs (%end3%-%start3%)/1000
SET duration3=%val%
CALL vbs (%end4%-%start4%)/1000
SET duration4=%val%

REM SETS THE START TIME IN SECONDS VS MILLISECONDS
CALL vbs (%start1%)/1000
SET start1=%val%
CALL vbs (%start2%)/1000
SET start2=%val%
CALL vbs (%start3%)/1000
SET start3=%val%
CALL vbs (%start4%)/1000
SET start4=%val%

REM TRIM AND SPLIT ORIGINAL FILE INTO SEPERATE SECTIONS BASED ON CHAPTER MARKERS
ffmpeg -ss %START1% -i 01x01.mp4 -ss 0 -c copy -to %DURATION1% -avoid_negative_ts make_zero 01x01-1.mp4
ffmpeg -ss %START2% -i 01x01.mp4 -ss 0 -c copy -to %DURATION2% -avoid_negative_ts make_zero 01x01-2.mp4
ffmpeg -ss %START3% -i 01x01.mp4 -ss 0 -c copy -to %DURATION3% -avoid_negative_ts make_zero 01x01-3.mp4
ffmpeg -ss %START4% -i 01x01.mp4 -ss 0 -c copy -to %DURATION4% -avoid_negative_ts make_zero 01x01-4.mp4

REM DELETES UNNEEDED JSON AFTER USE
del /s *.json

REM APPEND ALL MP4 FILES INTO COHESIVE MKV
for /d /r %%D in (*) do (
    pushd %%D
    set files=
    for %%F in (*.mp4) do set files=!files! + ^( "%%F" ^)
    if not "!files!"=="" %mkvmerge% -o "01x01-FINAL.mkv" !files:~2!
    popd
)

REM DELETE UNNEEDED MP4 ORIGINALS AND SPLIT FILES
del /s *.mp4

I know it is super long and every time I try to use a variable or a loop to run through all files it can't read the json file. I've been at this all day and I can use the script as is but I have to make a file for each iteration.

I was also hoping to be able to have it only pull chapters labeled as "video" but I haven't quite figured that one out yet.

I'll add the vbs batch file for the arithmetic section as well as the sample json if it will help.

@echo off
>"%temp%\VBS.vbs" echo Set fso = CreateObject("Scripting.FileSystemObject") : Wscript.echo (%*)
for /f "delims=" %%a in ('cscript /nologo "%temp%\VBS.vbs"') do set "val=%%a"
del "%temp%\VBS.vbs"

{
    "chapters": [
        {
            "id": 0,
            "time_base": "1/1000",
            "start": 0,
            "start_time": "0.000000",
            "end": 5590,
            "end_time": "5.590000",
            "tags": {
                "title": "Video"
            }
        },
        {
            "id": 1,
            "time_base": "1/1000",
            "start": 5590,
            "start_time": "5.590000",
            "end": 13994,
            "end_time": "13.994000",
            "tags": {
                "title": "Advertisement"
            }
        },
        {
            "id": 2,
            "time_base": "1/1000",
            "start": 13994,
            "start_time": "13.994000",
            "end": 163964,
            "end_time": "163.964000",
            "tags": {
                "title": "Video"
            }
        },
        {
            "id": 3,
            "time_base": "1/1000",
            "start": 163964,
            "start_time": "163.964000",
            "end": 195940,
            "end_time": "195.940000",
            "tags": {
                "title": "Advertisement"
            }
        },
        {
            "id": 4,
            "time_base": "1/1000",
            "start": 195940,
            "start_time": "195.940000",
            "end": 547849,
            "end_time": "547.849000",
            "tags": {
                "title": "Video"
            }
        },
        {
            "id": 5,
            "time_base": "1/1000",
            "start": 547849,
            "start_time": "547.849000",
            "end": 595850,
            "end_time": "595.850000",
            "tags": {
                "title": "Advertisement"
            }
        },
        {
            "id": 6,
            "time_base": "1/1000",
            "start": 595850,
            "start_time": "595.850000",
            "end": 1413588,
            "end_time": "1413.588000",
            "tags": {
                "title": "Video"
            }
        },
        {
            "id": 7,
            "time_base": "1/1000",
            "start": 1413588,
            "start_time": "1413.588000",
            "end": 1477569,
            "end_time": "1477.569000",
            "tags": {
                "title": "Advertisement"
            }
        },
        {
            "id": 8,
            "time_base": "1/1000",
            "start": 1477569,
            "start_time": "1477.569000",
            "end": 1529696,
            "end_time": "1529.696000",
            "tags": {
                "title": "Video"
            }
        }
    ]
}

I also tried using the start_time so I didn't have to do extra calculations but jq didn't like that either.

mkvmerge doesn't even try to run when I have it in here and I still need to cut 7 seconds off the end and 12 seconds off the front of it once it is all one file again.

Any help would be appreciated, I know it's a lot but I seem to have hit a roadblock or just sleep deprived at this point.

UPDATE

This works amazing I just need to figure out how to use files with spaces and I'm all set. I guess I could run a batch before hand replacing all spaces with underscores. That would probably work but I would like to not change filenames if I can help it.

@echo off

for %%i in (*.mp4) do (
FOR /F "delims=" %%A IN ('ffprobe -v quiet -print_format json -show_chapters -loglevel error "%%i" ^| xidel - -se "$json/(chapters)()[id!=0 and tags/title='Video']/concat('ffmpeg -ss ',start div 1000,' -i %%i -to ',((end - start) div 1000),' -c copy -avoid_negative_ts make_zero %%~ni-',position(),'.mp4')"') DO %%A
FOR /F "delims=" %%A IN ('xidel -s --xquery "concat('mkvmerge -o "%%~ni-FINAL.mkv" "',join(file:list(.,false(),'%%~ni-*.mp4'),'" + "'),'"')"') DO %%A
)

Answer 1

If I understand correctly, you want to remove the "Advertisement"-chapters.
This could probably be done entirely with ffmpeg, but without the source video I can't say for sure.

Anyway, let me offer you a very elegant solution for the splitting procedure with the help of xidel.

First of all, you don't have to save ffprobe's output to a JSON-file. You can just pipe it to xidel:

ffprobe -v quiet -print_format json -show_chapters -loglevel error "01x01.mp4" | xidel - -se "$json"

Select the objects/chapters labeled as "Video":

ffprobe [...] | xidel - -se "$json/(chapters)()[id!=0 and tags/title='Video']"
{
  "id": 2,
  "time_base": "1/1000",
  "start": 13994,
  "start_time": "13.994000",
  "end": 163964,
  "end_time": "163.964000",
  "tags": {
    "title": "Video"
  }
}
[...]
{
  "id": 8,
  "time_base": "1/1000",
  "start": 1477569,
  "start_time": "1477.569000",
  "end": 1529696,
  "end_time": "1529.696000",
  "tags": {
    "title": "Video"
  }
}

(I'm not sure why you don't want the first chapter. If you do, then just remove id!=0 and.)

To calculate the duration of the 4 chapters:

ffprobe [...] | xidel - -se "$json/(chapters)()[id!=0 and tags/title='Video']/round-half-to-even(end_time - start_time,3)"
#or
ffprobe [...] | xidel - -se "$json/(chapters)()[id!=0 and tags/title='Video']/((end - start) div 1000)"
149.97
351.909
817.738
52.127

Create the ffmpeg strings/commands with these values and start:

ffprobe [...] | xidel - -se "$json/(chapters)()[id!=0 and tags/title='Video']/concat('ffmpeg -ss ',start div 1000,' -i 01x01.mp4 -to ',((end - start) div 1000),' -c copy -avoid_negative_ts make_zero 01x01-',position(),'.mp4')"
ffmpeg -ss 13.994 -i 01x01.mp4 -to 149.97 -c copy -avoid_negative_ts make_zero 01x01-1.mp4
ffmpeg -ss 195.94 -i 01x01.mp4 -to 351.909 -c copy -avoid_negative_ts make_zero 01x01-2.mp4
ffmpeg -ss 595.85 -i 01x01.mp4 -to 817.738 -c copy -avoid_negative_ts make_zero 01x01-3.mp4
ffmpeg -ss 1477.569 -i 01x01.mp4 -to 52.127 -c copy -avoid_negative_ts make_zero 01x01-4.mp4

Prettified command/query:

ffprobe [...] | xidel - -se ^"^
  $json/(chapters)()[id!=0 and tags/title='Video']/concat(^
    'ffmpeg -ss ',^
    start div 1000,^
    ' -i 01x01.mp4 -to ',^
    ((end - start) div 1000),^
    ' -c copy -avoid_negative_ts make_zero 01x01-',^
    position(),^
    '.mp4'^
  )^
"

To execute these ffmpeg commands simply put the entire ffprobe/xidel command in a FOR-loop:

FOR /F "delims=" %A IN ('ffprobe [...] ^| xidel - -se "$json/(chapters)()[id!=0 and tags/title='Video']/concat('ffmpeg -ss ',start div 1000,' -i 01x01.mp4 -to ',((end - start) div 1000),' -c copy -avoid_negative_ts make_zero 01x01-',position(),'.mp4')"') DO %A

(Within a Batch-script use %%A and in case of SETLOCAL ENABLEDELAYEDEXPANSION escape the exclamationmarks; id^!=0)

With all of cmd's shortcomings I would again use xidel to create the mkvmerge string/command:

xidel -s -e "file:list(.,false(),'01x01-*.mp4')"
01x01-1.mp4
01x01-2.mp4
01x01-3.mp4
01x01-4.mp4

xidel -s -e "join(file:list(.,false(),'01x01-*.mp4'),' + ')"
01x01-1.mp4 + 01x01-2.mp4 + 01x01-3.mp4 + 01x01-4.mp4

xidel -s -e "concat('\"',join(file:list(.,false(),'01x01-*.mp4'),'\" + \"'),'\"')"
#or
xidel -s --xquery "concat('"',join(file:list(.,false(),'01x01-*.mp4'),'" + "'),'"')"
"01x01-1.mp4" + "01x01-2.mp4" + "01x01-3.mp4" + "01x01-4.mp4"

xidel -s --xquery "concat('mkvmerge -o "01x01-FINAL.mkv" "',join(file:list(.,false(),'01x01-*.mp4'),'" + "'),'"')"
mkvmerge -o "01x01-FINAL.mkv" "01x01-1.mp4" + "01x01-2.mp4" + "01x01-3.mp4" + "01x01-4.mp4"

To execute the mkvmerge command again simply put the entire xidel command in a FOR-loop:

FOR /F "delims=" %A IN ('xidel -s --xquery "concat('mkvmerge -o "01x01-FINAL.mkv" "',join(file:list(.,false(),'01x01-*.mp4'),'" + "'),'"')"') DO %A

(Why --xquery and "? Because \" will cause "escape-character-hell" in a FOR-loop)

If you use just these two FOR-loops, it also means that SETLOCAL ENABLEDELAYEDEXPANSION isn't necessary anymore.