module TrickyCat.VideoEncoder.MediaEncoder

open MediaInfo

open System.Diagnostics

type EncodedFilePath = string

type MediaEncoderError = {

sourceFilePath: string

targetFilePath: string

error: string

}

let private getErrorDetails sourceFilePath targetFilePath error =

{

sourceFilePath = sourceFilePath

targetFilePath = targetFilePath

error = error

}

let private ``get ffmpeg encode query`` sourceFilePath targetFilePath dimensions =

$"-i \"{sourceFilePath}\" -loglevel fatal -y -c:v libx264 -crf 24 -pix_fmt yuv420p -tune film -c:a aac -b:a 192k -ar 44100 -vol 300 -strict -2 -speed fastest -s {dimensions.width}x{dimensions.height} \"{targetFilePath}\""

let private ``run ffmpeg query`` ffmpegQuery =

ProcessUtils.runProcessSuccessfully'

{

preStart = (fun process' ->

process'.StartInfo.RedirectStandardOutput <- false

process'.StartInfo.RedirectStandardError <- false

)

postStart = (fun process' ->

process'.PriorityClass <- ProcessPriorityClass.BelowNormal

)

}

"ffmpeg"

ffmpegQuery

|> Result.map ignore

let encodeFile

(sourceFilePath: string)

(targetFilePath: string)

(dimensions: Dimensions)

: Result<EncodedFilePath, MediaEncoderError> =

``get ffmpeg encode query`` sourceFilePath targetFilePath dimensions

|> ``run ffmpeg query``

|> Result.map (fun () -> targetFilePath)

|> Result.mapError (getErrorDetails sourceFilePath targetFilePath)