# Media Conversion Scripts

## Purpose
- To learn PowerShell 7+ (pwsh)
- Learn HandBrakeCLI
- Learn FFMPEG (CLI)
- Learn how to create multi-stream videos
  - Optimize media library for a wide range of mid-to-low bandwidth Roku devices

## Language
- PowerShell v7.2.6
  *- I'm already a "Power User" with Linux/BASH ... can do some basic things in Python, but I fall short on PowerShell, so I thought this would be a great project to introduce me to the language.  I appreciate any feedback on the code and/or tips/tricks!  Thank you!*

## Tools
- [HandBrakeCLI](https://handbrake.fr/downloads2.php)
- [FFMPEG](https://ffmpeg.org/download.html)

## Documentation
### RTFM
- https://handbrake.fr/docs/en/1.5.0/
- https://ffmpeg.org/documentation.html
  - https://trac.ffmpeg.org/

## Process
### The Bit Ladder
As outlined here (https://developer.roku.com/docs/specs/media/streaming-specifications.md), the Roku developer platform talks about how the devices can intelligently switch between the available streams within the file to best serve content.  I had always assumed that my [Plex server](https://www.plex.tv/media-server-downloads/) would do this with various versions of the media I had stored in the "[Plex Versions](https://support.plex.tv/articles/213095317-creating-optimized-versions/)" folder.  Perhaps my mistake was manually re-encoding the videos and just dropping them there, perhaps I had to use the [Plex method so the media could be "Tagged" somehow -- I'm not sure](https://github.com/ccjensen/PlexMediaTagger).

So, I decided I would follow the Roku recommendation and try to create the "[Bit Ladder](https://developer.roku.com/docs/specs/media/streaming-specifications.md#avc-1080p-encodings)."
![Roku Bit Ladder](https://i.imgur.com/B55cvjb.jpg)

## The Code
### With this information in hand, I set out to create a script that would automatically convert a movie into the requisite 8 parts:

```powershell
'%HANDBRAKECLI%' `
--preset-import-file '%HANDBRAKEPRESETS%\BITLADDER.json' `
--preset BITLADDER/STEP$_ `
--input $SOURCE `
--output $OUTPUT `
--verbose | Tee-Object -FilePath "$LOGFILE" -Append
```
The [preset file I'm passing to HandBrake](https://github.com/thisguyshouldworkforus/MediaConversions/blob/master/HandBrake_Presets/BITLADDER.json) is what's actually doing all the hard work, and it's cool to watch [if you're into that kind of thing](https://buzz.ng/wp-content/uploads/2019/01/maxresdefault-1-1.jpg).


The [PowerShell script "BitLadder.ps1"](https://github.com/thisguyshouldworkforus/MediaConversions/blob/master/bitladder.ps1) uses the new PowerShell 7+ `ForEach-Object -Parallel` which allows me to encdode all 8 Bitladder Steps at once.
It definitely hit my system like a freight train, but it handled it quite well:
![Windows Task Manager getting absolutely murdered](https://i.imgur.com/666yNnw.png)

In (*roughly*) 18 minutes, I had 8 versions of the same file!
![BitLadder Steps Output](https://i.imgur.com/AHNTZqG.png)

## FFMPEG
### Last Step
I got learned up on using FFMPEG and learned about "[Complex Filter Maps][1]" and how I could "Map" the audio and video of my eight (8) input files into my single output file.  I wrote the automation for it with a loop so that the end command would be formatted properly:

```powershell
# Mux the 8 Bitrate Ladder steps into a single file with a common audio stream
$STEPS = @(Get-ChildItem -Path $OUTPUTDIR -Name)
$COUNT = 0
ForEach ($STEP in $STEPS){
    $INPUT_FILES += ("-i $STEP ")
    $VIDEO += ("[" + $COUNT + ":v]" + "[v" + $COUNT + "],")
    $V_ALIAS += ("[v" + $COUNT + "]")
    $AUDIO += ("[" + $COUNT + ":a]" + "[a" + $COUNT + "],")
    $A_ALIAS += ("[a" + $COUNT + "]")
    $COUNT++
}

$V_ALIAS += ("[video]")
$A_ALIAS += ("[audio]")
$FLATTEN = ('-' + "$INPUT_FILES" + "-filter_complex " + '"' + "$VIDEO" + ";" + "$AUDIO" + '"' + ';' + "$V_ALIAS" + ';' + "$A_ALIAS" + '"' + " -map [video][audio] -c:v h264 -c:a copy").Replace(',;', ';').Replace(',";', ';').Replace(',[video]', '[video]').Replace(',[audio]', '[audio]').TrimStart(' ')

D:\Applications\ffmpeg\bin\ffmpeg.exe $FLATTEN -f matroska "E:\MediaConversions\White.Boy.Rick.2018_MultiStreamTest_AAC.H264.mkv"
```
If I comment out the executable, this is the output I get and which I would correctly expect/want:
```
ffmpeg.exe \
-i White.Boy.Rick.2018.1080p.WEB-DL.H264.AC3-EVO_STEP1.mp4 \
-i White.Boy.Rick.2018.1080p.WEB-DL.H264.AC3-EVO_STEP2.mp4 \
-i White.Boy.Rick.2018.1080p.WEB-DL.H264.AC3-EVO_STEP3.mp4 \
-i White.Boy.Rick.2018.1080p.WEB-DL.H264.AC3-EVO_STEP4.mp4 \
-i White.Boy.Rick.2018.1080p.WEB-DL.H264.AC3-EVO_STEP5.mp4 \
-i White.Boy.Rick.2018.1080p.WEB-DL.H264.AC3-EVO_STEP6.mp4 \
-i White.Boy.Rick.2018.1080p.WEB-DL.H264.AC3-EVO_STEP7.mp4 \
-i White.Boy.Rick.2018.1080p.WEB-DL.H264.AC3-EVO_STEP8.mp4 \
-filter_complex "[0:v][v0],[1:v][v1],[2:v][v2],[3:v][v3],[4:v][v4],[5:v][v5],[6:v][v6],[7:v][v7];[0:a][a0],[1:a][a1],[2:a][a2],[3:a][a3],[4:a][a4],[5:a][a5],[6:a][a6],[7:a][a7];[v0][v1][v2][v3][v4][v5][v6][v7][video];[a0][a1][a2][a3][a4][a5][a6][a7][audio]" \
-map [video][audio] \
-c:v h264 \
-c:a copy \
-f matroska \
"E:\MediaConversions\White.Boy.Rick.2018_MultiStreamTest_AAC.H264.mkv"
```
## Errors
- It doesn't work
  - Because, of course, it doesn't.
- Running the code above will generate this absolutely general and unhelpful error:

```error
Unrecognized option '-i White.Boy.Rick.2018.1080p.WEB-DL.H264.AC3-EVO_STEP1.mp4 -i White.Boy.Rick.2018.1080p.WEB-DL.H264.AC3-EVO_STEP2.mp4 -i White.Boy.Rick.2018.1080p.WEB-DL.H264.AC3-EVO_STEP3.mp4 -i White.Boy.Rick.2018.1080p.WEB-DL.H264.AC3-EVO_STEP4.mp4 -i White.Boy.Rick.2018.1080p.WEB-DL.H264.AC3-EVO_STEP5.mp4 -i White.Boy.Rick.2018.1080p.WEB-DL.H264.AC3-EVO_STEP6.mp4 -i White.Boy.Rick.2018.1080p.WEB-DL.H264.AC3-EVO_STEP7.mp4 -i White.Boy.Rick.2018.1080p.WEB-DL.H264.AC3-EVO_STEP8.mp4 -filter_complex [0:v][v0],[1:v][v1],[2:v][v2],[3:v][v3],[4:v][v4],[5:v][v5],[6:v][v6],[7:v][v7];[0:a][a0],[1:a][a1],[2:a][a2],[3:a][a3],[4:a][a4],[5:a][a5],[6:a][a6],[7:a][a7];[v0][v1][v2][v3][v4][v5][v6][v7][video];[a0][a1][a2][a3][a4][a5][a6][a7][audio] -map [video][audio] -c:v h264 -c:a copy'.
Error splitting the argument list: Option not found.
```
What option?  What's wrong?  Cool, thanks -- good talk FFMPEG.


  [1]: https://trac.ffmpeg.org/wiki/Map