Optimize transcoding

Skip transcoding if audio/video already has desired encoding

src/main/kotlin/com/pischule/memevizor/bot/BotConfiguration.kt

@@ -46,6 +46,7 @@ class BotConfiguration(
         photos { handleMedia() }
         video { handleMedia() }
         videoNote { handleMedia() }
+        document { handleMedia() }
         command("whoami") {
             handleMessage(message) {
                 bot.sendMessage(

src/main/kotlin/com/pischule/memevizor/util/TelegramHelper.kt

@@ -7,10 +7,20 @@ fun Message.getMedia(): MessageMedia? {
         return MessageMedia(fileId, MessageMedia.Type.PHOTO)
     }
 
-    (video?.fileId ?: videoNote?.fileId)?.let { fileId ->
-        return MessageMedia(fileId, MessageMedia.Type.VIDEO)
+    video?.let {
+        return MessageMedia(it.fileId, MessageMedia.Type.VIDEO)
     }
 
+    videoNote?.let {
+        return MessageMedia(it.fileId, MessageMedia.Type.VIDEO)
+    }
+
+    document
+        ?.takeIf { it.mimeType?.startsWith("video/") == true }
+        ?.let {
+            return MessageMedia(it.fileId, MessageMedia.Type.VIDEO)
+        }
+
     return null
 }
 

src/main/kotlin/com/pischule/memevizor/video/VideoTranscoderService.kt

@@ -1,6 +1,7 @@
 package com.pischule.memevizor.video
 
 import io.github.oshai.kotlinlogging.KotlinLogging
+import java.nio.file.Path
 import kotlin.io.path.createTempFile
 import kotlin.io.path.deleteIfExists
 import kotlin.io.path.readBytes
@@ -14,62 +15,32 @@ private val logger = KotlinLogging.logger {}
 class VideoTranscoderService {
 
     fun transcode(inputVideo: ByteArray): ByteArray {
-        logger.info { "Started transcoding a file" }
+        logger.info { "Started transcoding a video" }
 
         val inputFile = createTempFile()
         val outputFile = createTempFile()
 
-        val command: List<String> =
-            listOf(
-                "ffmpeg",
-                "-nostdin",
-                "-nostats",
-                "-hide_banner",
-                // input
-                "-i",
-                "$inputFile",
-                // video
-                "-map",
-                "0:v",
-                "-c:v",
-                "libsvtav1",
-                "-preset",
-                "6",
-                "-crf",
-                "35",
-                "-svtav1-params",
-                "film-grain=10",
-                // audio
-                "-map",
-                "0:a?",
-                "-c:a",
-                "libopus",
-                "-b:a",
-                "96k",
-                "-vbr",
-                "on",
-                "-compression_level",
-                "10",
-                // output
-                "-f",
-                "webm",
-                "-y",
-                "$outputFile",
-            )
-
         try {
             inputFile.writeBytes(inputVideo)
 
-            val process = ProcessBuilder(command).redirectErrorStream(true).start()
-            val exitCode: Int
-            val timeTaken = measureTime { exitCode = process.waitFor() }
-            val processOutput = process.inputStream.bufferedReader().use { it.readText() }
-            if (exitCode != 0) {
-                throw VideoTranscodingException(exitCode, processOutput)
+            val copyVideo = hasDesiredVideoEncoding(inputFile)
+            val copyAudio = hasDesiredAudioEncoding(inputFile)
+
+            val processOutput: String
+            val timeTaken = measureTime {
+                processOutput =
+                    launchCommand(
+                        transcodeCommand(
+                            inputFile = inputFile,
+                            outputFile = outputFile,
+                            copyVideo = copyVideo,
+                            copyAudio = copyAudio,
+                        )
+                    )
             }
 
             logger.atInfo {
-                message = "Finished transcoding a file"
+                message = "Finished transcoding a video"
                 payload =
                     mapOf(
                         "processOutput" to processOutput,
@@ -82,4 +53,106 @@ class VideoTranscoderService {
             outputFile.deleteIfExists()
         }
     }
+
+    private fun launchCommand(command: List<String>): String {
+        val process = ProcessBuilder(command).redirectErrorStream(true).start()
+        val exitCode = process.waitFor()
+        val processOutput = process.inputStream.bufferedReader().use { it.readText() }
+        if (exitCode != 0) {
+            throw VideoTranscodingException(exitCode, processOutput)
+        }
+        return processOutput.trim()
+    }
+
+    private fun hasDesiredVideoEncoding(inputFile: Path): Boolean {
+        val videoCodec = launchCommand(getVideoCodecCommand(inputFile))
+        return videoCodec == "av1"
+    }
+
+    private fun hasDesiredAudioEncoding(inputFile: Path): Boolean {
+        val audioCodec = launchCommand(getAudioCodecCommand(inputFile))
+        return audioCodec == "opus" || audioCodec == ""
+    }
+
+    private fun getVideoCodecCommand(inputFile: Path) =
+        listOf(
+            "ffprobe",
+            "-v",
+            "error",
+            "-select_streams",
+            "v:0",
+            "-show_entries",
+            "stream=codec_name",
+            "-of",
+            "default=noprint_wrappers=1:nokey=1",
+            "$inputFile",
+        )
+
+    private fun getAudioCodecCommand(inputFile: Path) =
+        listOf(
+            "ffprobe",
+            "-v",
+            "error",
+            "-select_streams",
+            "a:0",
+            "-show_entries",
+            "stream=codec_name",
+            "-of",
+            "default=noprint_wrappers=1:nokey=1",
+            "$inputFile",
+        )
+
+    private fun transcodeCommand(
+        inputFile: Path,
+        outputFile: Path,
+        copyVideo: Boolean,
+        copyAudio: Boolean,
+    ): List<String> = buildList {
+        add("ffmpeg")
+        add("-nostdin")
+        add("-nostats")
+        add("-hide_banner")
+
+        // input
+        add("-i")
+        add("$inputFile")
+
+        // video
+        add("-map")
+        add("0:v")
+        add("-c:v")
+        if (copyVideo) {
+            add("copy")
+        } else {
+            add("libsvtav1")
+            add("-preset")
+            add("6")
+            add("-crf")
+            add("35")
+            add("-svtav1-params")
+            add("film-grain=10")
+        }
+
+        // audio
+        add("-map")
+        add("0:a?")
+        add("-c:a")
+        if (copyAudio) {
+            add("copy")
+        } else {
+            add("libopus")
+            add("-b:a")
+            add("96k")
+            add("-vbr")
+            add("on")
+            add("-compression_level")
+            add("10")
+        }
+
+        // output
+        add("-f")
+        add("webm")
+        add("-y")
+        add("$outputFile")
+    }
 }