PeerTube/shared/models/videos/video-resolution.enum.ts

90 lines
3.2 KiB
TypeScript
Raw Normal View History

import { VideoTranscodingFPS } from './video-transcoding-fps.model'
export enum VideoResolution {
H_NOVIDEO = 0,
H_240P = 240,
H_360P = 360,
H_480P = 480,
H_720P = 720,
H_1080P = 1080,
H_4K = 2160
}
/**
2018-10-10 00:46:26 +02:00
* Bitrate targets for different resolutions, at VideoTranscodingFPS.AVERAGE.
*
* Sources for individual quality levels:
* Google Live Encoder: https://support.google.com/youtube/answer/2853702?hl=en
* YouTube Video Info: youtube-dl --list-formats, with sample videos
*/
2018-10-10 09:39:34 +02:00
function getBaseBitrate (resolution: VideoResolution) {
switch (resolution) {
case VideoResolution.H_NOVIDEO:
// audio-only
return 64 * 1000
2019-07-19 10:37:35 +02:00
case VideoResolution.H_240P:
// quality according to Google Live Encoder: 300 - 700 Kbps
// Quality according to YouTube Video Info: 285 Kbps
return 320 * 1000
2019-07-19 10:37:35 +02:00
case VideoResolution.H_360P:
// quality according to Google Live Encoder: 400 - 1,000 Kbps
// Quality according to YouTube Video Info: 700 Kbps
return 780 * 1000
2019-07-19 10:37:35 +02:00
case VideoResolution.H_480P:
// quality according to Google Live Encoder: 500 - 2,000 Kbps
// Quality according to YouTube Video Info: 1300 Kbps
return 1500 * 1000
2019-07-19 10:37:35 +02:00
case VideoResolution.H_720P:
// quality according to Google Live Encoder: 1,500 - 4,000 Kbps
// Quality according to YouTube Video Info: 2680 Kbps
return 2800 * 1000
2019-07-19 10:37:35 +02:00
case VideoResolution.H_1080P:
// quality according to Google Live Encoder: 3000 - 6000 Kbps
// Quality according to YouTube Video Info: 5081 Kbps
2019-12-05 15:12:58 +01:00
return 5200 * 1000
2019-07-19 10:37:35 +02:00
case VideoResolution.H_4K: // fallthrough
default:
// quality according to Google Live Encoder: 13000 - 34000 Kbps
2019-12-05 15:12:58 +01:00
return 22000 * 1000
}
}
2018-10-10 00:46:26 +02:00
/**
* Calculate the target bitrate based on video resolution and FPS.
2018-10-10 01:53:16 +02:00
*
* The calculation is based on two values:
* Bitrate at VideoTranscodingFPS.AVERAGE is always the same as
* getBaseBitrate(). Bitrate at VideoTranscodingFPS.MAX is always
* getBaseBitrate() * 1.4. All other values are calculated linearly
* between these two points.
2018-10-10 00:46:26 +02:00
*/
2018-10-17 13:10:58 +02:00
export function getTargetBitrate (resolution: VideoResolution, fps: number, fpsTranscodingConstants: VideoTranscodingFPS) {
2018-10-10 00:46:26 +02:00
const baseBitrate = getBaseBitrate(resolution)
// The maximum bitrate, used when fps === VideoTranscodingFPS.MAX
// Based on numbers from Youtube, 60 fps bitrate divided by 30 fps bitrate:
2018-10-10 01:53:16 +02:00
// 720p: 2600 / 1750 = 1.49
// 1080p: 4400 / 3300 = 1.33
2018-10-10 00:46:26 +02:00
const maxBitrate = baseBitrate * 1.4
const maxBitrateDifference = maxBitrate - baseBitrate
const maxFpsDifference = fpsTranscodingConstants.MAX - fpsTranscodingConstants.AVERAGE
// For 1080p video with default settings, this results in the following formula:
// 3300 + (x - 30) * (1320/30)
2018-10-10 01:22:35 +02:00
// Example outputs:
// 1080p10: 2420 kbps, 1080p30: 3300 kbps, 1080p60: 4620 kbps
2018-10-10 01:53:16 +02:00
// 720p10: 1283 kbps, 720p30: 1750 kbps, 720p60: 2450 kbps
2018-10-10 00:46:26 +02:00
return baseBitrate + (fps - fpsTranscodingConstants.AVERAGE) * (maxBitrateDifference / maxFpsDifference)
}
/**
* The maximum bitrate we expect to see on a transcoded video in bytes per second.
*/
2018-10-17 13:10:58 +02:00
export function getMaxBitrate (resolution: VideoResolution, fps: number, fpsTranscodingConstants: VideoTranscodingFPS) {
return getTargetBitrate(resolution, fps, fpsTranscodingConstants) * 2
}