Fix live FPS limit

4 files changed, 67 insertions, 42 deletions

diff --git a/server/helpers/ffmpeg-utils.ts b/server/helpers/ffmpeg-utils.ts
index 9755dd67c..3cc062b8c 100644
--- a/server/helpers/ffmpeg-utils.ts
+++ b/server/helpers/ffmpeg-utils.ts
@@ -1,11 +1,11 @@
 import * as ffmpeg from 'fluent-ffmpeg'
 import { readFile, remove, writeFile } from 'fs-extra'
 import { dirname, join } from 'path'
-import { FFMPEG_NICE, VIDEO_LIVE, VIDEO_TRANSCODING_ENCODERS, VIDEO_TRANSCODING_FPS } from '@server/initializers/constants'
+import { FFMPEG_NICE, VIDEO_LIVE, VIDEO_TRANSCODING_ENCODERS } from '@server/initializers/constants'
 import { VideoResolution } from '../../shared/models/videos'
 import { checkFFmpegEncoders } from '../initializers/checker-before-init'
 import { CONFIG } from '../initializers/config'
-import { getAudioStream, getClosestFramerateStandard, getVideoFileFPS } from './ffprobe-utils'
+import { computeFPS, getAudioStream, getVideoFileFPS } from './ffprobe-utils'
 import { processImage } from './image-utils'
 import { logger } from './logger'
 
@@ -223,7 +223,17 @@ async function getLiveTranscodingCommand (options: {
 
   for (let i = 0; i < resolutions.length; i++) {
     const resolution = resolutions[i]
-    const baseEncoderBuilderParams = { input, availableEncoders, profile, fps, resolution, streamNum: i, videoType: 'live' as 'live' }
+    const resolutionFPS = computeFPS(fps, resolution)
+
+    const baseEncoderBuilderParams = {
+      input,
+      availableEncoders,
+      profile,
+      fps: resolutionFPS,
+      resolution,
+      streamNum: i,
+      videoType: 'live' as 'live'
+    }
 
     {
       const builderResult = await getEncoderBuilderResult(Object.assign({}, baseEncoderBuilderParams, { streamType: 'VIDEO' }))
@@ -233,7 +243,7 @@ async function getLiveTranscodingCommand (options: {
 
       command.outputOption(`-map [vout${resolution}]`)
 
-      addDefaultEncoderParams({ command, encoder: builderResult.encoder, fps, streamNum: i })
+      addDefaultEncoderParams({ command, encoder: builderResult.encoder, fps: resolutionFPS, streamNum: i })
 
       logger.debug('Apply ffmpeg live video params from %s.', builderResult.encoder, builderResult)
 
@@ -249,7 +259,7 @@ async function getLiveTranscodingCommand (options: {
 
       command.outputOption('-map a:0')
 
-      addDefaultEncoderParams({ command, encoder: builderResult.encoder, fps, streamNum: i })
+      addDefaultEncoderParams({ command, encoder: builderResult.encoder, fps: resolutionFPS, streamNum: i })
 
       logger.debug('Apply ffmpeg live audio params from %s.', builderResult.encoder, builderResult)
 
@@ -387,15 +397,7 @@ function addDefaultLiveHLSParams (command: ffmpeg.FfmpegCommand, outPath: string
 
 async function buildx264VODCommand (command: ffmpeg.FfmpegCommand, options: TranscodeOptions) {
   let fps = await getVideoFileFPS(options.inputPath)
-  if (
-    // On small/medium resolutions, limit FPS
-    options.resolution !== undefined &&
-    options.resolution < VIDEO_TRANSCODING_FPS.KEEP_ORIGIN_FPS_RESOLUTION_MIN &&
-    fps > VIDEO_TRANSCODING_FPS.AVERAGE
-  ) {
-    // Get closest standard framerate by modulo: downsampling has to be done to a divisor of the nominal fps value
-    fps = getClosestFramerateStandard(fps, 'STANDARD')
-  }
+  fps = computeFPS(fps, options.resolution)
 
   command = await presetVideo(command, options.inputPath, options, fps)
 
@@ -408,12 +410,6 @@ async function buildx264VODCommand (command: ffmpeg.FfmpegCommand, options: Tran
     command = command.size(size)
   }
 
-  // Hard FPS limits
-  if (fps > VIDEO_TRANSCODING_FPS.MAX) fps = getClosestFramerateStandard(fps, 'HD_STANDARD')
-  else if (fps < VIDEO_TRANSCODING_FPS.MIN) fps = VIDEO_TRANSCODING_FPS.MIN
-
-  command = command.withFPS(fps)
-
   return command
 }
 
@@ -422,13 +418,6 @@ async function buildAudioMergeCommand (command: ffmpeg.FfmpegCommand, options: M
 
   command = await presetVideo(command, options.audioPath, options)
 
-  /*
-  MAIN reference: https://slhck.info/video/2017/03/01/rate-control.html
-  Our target situation is closer to a livestream than a stream,
-  since we want to reduce as much a possible the encoding burden,
-  although not to the point of a livestream where there is a hard
-  constraint on the frames per second to be encoded.
-  */
   command.outputOption('-preset:v veryfast')
 
   command = command.input(options.audioPath)
diff --git a/server/helpers/ffprobe-utils.ts b/server/helpers/ffprobe-utils.ts
index 16b295bbd..1cf397767 100644
--- a/server/helpers/ffprobe-utils.ts
+++ b/server/helpers/ffprobe-utils.ts
@@ -247,6 +247,26 @@ function getClosestFramerateStandard (fps: number, type: 'HD_STANDARD' | 'STANDA
                                     .sort((a, b) => fps % a - fps % b)[0]
 }
 
+function computeFPS (fpsArg: number, resolution: VideoResolution) {
+  let fps = fpsArg
+
+  if (
+    // On small/medium resolutions, limit FPS
+    resolution !== undefined &&
+    resolution < VIDEO_TRANSCODING_FPS.KEEP_ORIGIN_FPS_RESOLUTION_MIN &&
+    fps > VIDEO_TRANSCODING_FPS.AVERAGE
+  ) {
+    // Get closest standard framerate by modulo: downsampling has to be done to a divisor of the nominal fps value
+    fps = getClosestFramerateStandard(fps, 'STANDARD')
+  }
+
+  // Hard FPS limits
+  if (fps > VIDEO_TRANSCODING_FPS.MAX) fps = getClosestFramerateStandard(fps, 'HD_STANDARD')
+  else if (fps < VIDEO_TRANSCODING_FPS.MIN) fps = VIDEO_TRANSCODING_FPS.MIN
+
+  return fps
+}
+
 // ---------------------------------------------------------------------------
 
 export {
@@ -259,6 +279,7 @@ export {
   getVideoStreamFromFile,
   getDurationFromVideoFile,
   getAudioStream,
+  computeFPS,
   getVideoFileFPS,
   ffprobePromise,
   getClosestFramerateStandard,
diff --git a/server/lib/video-transcoding-profiles.ts b/server/lib/video-transcoding-profiles.ts
index 03c26f236..3bf83d6a8 100644
--- a/server/lib/video-transcoding-profiles.ts
+++ b/server/lib/video-transcoding-profiles.ts
@@ -1,5 +1,5 @@
 import { logger } from '@server/helpers/logger'
-import { getTargetBitrate } from '../../shared/models/videos'
+import { getTargetBitrate, VideoResolution } from '../../shared/models/videos'
 import { AvailableEncoders, buildStreamSuffix, EncoderOptionsBuilder } from '../helpers/ffmpeg-utils'
 import {
   canDoQuickAudioTranscode,
@@ -23,21 +23,12 @@ import { VIDEO_TRANSCODING_FPS } from '../initializers/constants'
 //  * https://trac.ffmpeg.org/wiki/Limiting%20the%20output%20bitrate
 
 const defaultX264VODOptionsBuilder: EncoderOptionsBuilder = async ({ input, resolution, fps }) => {
-  let targetBitrate = getTargetBitrate(resolution, fps, VIDEO_TRANSCODING_FPS)
-
-  const probe = await ffprobePromise(input)
-
-  const videoStream = await getVideoStreamFromFile(input, probe)
-  if (!videoStream) {
-    return { outputOptions: [ ] }
-  }
-
-  // Don't transcode to an higher bitrate than the original file
-  const fileBitrate = await getVideoFileBitrate(input, probe)
-  targetBitrate = Math.min(targetBitrate, fileBitrate)
+  const targetBitrate = await buildTargetBitrate({ input, resolution, fps })
+  if (!targetBitrate) return { outputOptions: [ ] }
 
   return {
     outputOptions: [
+      `-r ${fps}`,
       `-maxrate ${targetBitrate}`,
       `-bufsize ${targetBitrate * 2}`
     ]
@@ -49,6 +40,7 @@ const defaultX264LiveOptionsBuilder: EncoderOptionsBuilder = async ({ resolution
 
   return {
     outputOptions: [
+      `${buildStreamSuffix('-r:v', streamNum)} ${fps}`,
       `${buildStreamSuffix('-b:v', streamNum)} ${targetBitrate}`,
       `-maxrate ${targetBitrate}`,
       `-bufsize ${targetBitrate * 2}`
@@ -115,3 +107,21 @@ export {
 }
 
 // ---------------------------------------------------------------------------
+async function buildTargetBitrate (options: {
+  input: string
+  resolution: VideoResolution
+  fps: number
+
+}) {
+  const { input, resolution, fps } = options
+  const probe = await ffprobePromise(input)
+
+  const videoStream = await getVideoStreamFromFile(input, probe)
+  if (!videoStream) return undefined
+
+  const targetBitrate = getTargetBitrate(resolution, fps, VIDEO_TRANSCODING_FPS)
+
+  // Don't transcode to an higher bitrate than the original file
+  const fileBitrate = await getVideoFileBitrate(input, probe)
+  return Math.min(targetBitrate, fileBitrate)
+}
diff --git a/server/tests/api/live/live.ts b/server/tests/api/live/live.ts
index 0786db554..4f84882ff 100644
--- a/server/tests/api/live/live.ts
+++ b/server/tests/api/live/live.ts
@@ -416,7 +416,7 @@ describe('Test live', function () {
       await waitJobs(servers)
 
       const bitrateLimits = {
-        720: 3000 * 1000,
+        720: 4000 * 1000, // 60FPS
         360: 1100 * 1000,
         240: 600 * 1000
       }
@@ -436,9 +436,14 @@ describe('Test live', function () {
           const file = hlsPlaylist.files.find(f => f.resolution.id === resolution)
 
           expect(file).to.exist
-          expect(file.fps).to.be.approximately(30, 5)
           expect(file.size).to.be.greaterThan(1)
 
+          if (resolution >= 720) {
+            expect(file.fps).to.be.approximately(60, 2)
+          } else {
+            expect(file.fps).to.be.approximately(30, 2)
+          }
+
           const filename = `${video.uuid}-${resolution}-fragmented.mp4`
           const segmentPath = buildServerDirectory(servers[0], join('streaming-playlists', 'hls', video.uuid, filename))