WebM

Encode VP9 video and optional Opus audio into a WebM file.

Use webm_vp9 to create a VP9 video file. When the Source has audio, Chunkify encodes it as Opus at 48 kHz. Set disable_audio: true for video only.

Default video settings are CRF 24, quality: realtime, cpu_used: "5", and pixfmt: yuv420p. The cpu_used option controls VP9 encoding effort and its speed-quality tradeoff.

Create a WebM transcode

The example sets a height of 720 pixels and CRF 24. Width follows the Source aspect ratio.

Run these examples on your server after setting up your SDK and Source. Replace the token and Source ID.

These examples save the file in your Project's output storage. Set storage.path to the filename you want to use.

import Chunkify from '@chunkify/chunkify';

async function main() {
    const client = new Chunkify({
        projectAccessToken: 'My Project Access Token',
    });

    const transcoding = await client.transcodings.create({
        source_id: 'src_2G6MJiNz71bHQGNzGwKx5cJwPFS',
        format: {
            id: "webm_vp9",
            height: 720,
            crf: 24,
        },
        storage: {
            path: 'exports/video-720p.webm',
        },
    });

    console.log(transcoding.id, transcoding.status);
}

main().catch((error) => {
    console.error(error);
    process.exitCode = 1;
});
from chunkify import Chunkify

client = Chunkify(
    project_access_token="My Project Access Token",
)

transcoding = client.transcodings.create(
    source_id="src_2G6MJiNz71bHQGNzGwKx5cJwPFS",
    format={
        "id": "webm_vp9",
        "height": 720,
        "crf": 24,
    },
    storage={
        "path": "exports/video-720p.webm",
    },
)

print(transcoding.id, transcoding.status)
<?php

use Chunkify\Client;

require_once __DIR__ . '/vendor/autoload.php';

$client = new Client(
    projectAccessToken: 'My Project Access Token',
);

$transcoding = $client->transcodings->create(
    sourceID: 'src_2G6MJiNz71bHQGNzGwKx5cJwPFS',
    format: [
        'id' => 'webm_vp9',
        'height' => 720,
        'crf' => 24,
    ],
    storage: [
        'path' => 'exports/video-720p.webm',
    ],
);

var_dump($transcoding->id, $transcoding->status);
package main

import (
	"context"
	"fmt"
	"log"

	"github.com/chunkifydev/chunkify-go"
	"github.com/chunkifydev/chunkify-go/option"
)

func main() {
	client := chunkify.NewClient(
		option.WithProjectAccessToken("My Project Access Token"),
	)

	transcoding, err := client.Transcodings.New(
		context.Background(),
		chunkify.TranscodingNewParams{
			SourceID: "src_2G6MJiNz71bHQGNzGwKx5cJwPFS",
			Format: chunkify.TranscodingNewParamsFormatUnion{
				OfWebmVp9: &chunkify.TranscodingWebmVp9Param{
					Height: chunkify.Int(720),
					Crf:    chunkify.Int(24),
				},
			},
			Storage: chunkify.TranscodingNewParamsStorage{
				Path: chunkify.String("exports/video-720p.webm"),
			},
		},
	)
	if err != nil {
		log.Fatal(err)
	}
	fmt.Println(transcoding.ID, transcoding.Status)
}

Rate control

Set per_title: true to select a bitrate from the video content, or supply video_bitrate for an explicit target. Do not combine either with a manual CRF.

VP9 maxrate and bufsize require a target video_bitrate. minrate is supported only when it equals both video_bitrate and maxrate, selecting constant bitrate encoding.

Encoding parameters

webm_vp9 standalone file encoding settings.

"webm_vp9"

string

required

Id specifies the output format.

audio_bitrate

default: 128000

integer

AudioBitrate specifies the output audio bitrate in bits per second. Defaults to 128000.

Required range: 32000 <= x <= 512000

audio_samplerate

default: 48000

integer

AudioSamplerate specifies the output sample rate in Hz. Defaults to 48000. WebM Opus audio uses 48000.

Available options:

80001102512000160002205024000320004410048000640008820096000

bufsize

integer

Bufsize specifies the video buffer size in bits, from 100000 through 50000000. H.264 and H.265 require maxrate. AV1 and VP9 require a bitrate-controlled mode.

Required range: 100000 <= x <= 5e+07

channels

default: 2

integer

Channels specifies the output channel count. Defaults to stereo. Six channels means 5.1; eight means 7.1.

Available options:

1268

cpu_used

default: "5"

string

CpuUsed specifies the CPU usage level for VP9 encoding. Range: 0 to 8. Lower values mean better quality but slower encoding, higher values mean faster encoding but lower quality. Recommended values: 0-2 for high quality, 2-4 for good quality, 4-6 for balanced, 6-8 for speed

Available options:

012345678

Examples:

4

crf

default: 24

integer

Crf (Constant Rate Factor) controls the quality of the output video. Lower values mean better quality but larger file size. Range: 15 to 35. Recommended values: 18-28 for high quality, 23-28 for good quality, 28-35 for acceptable quality.

Required range: 15 <= x <= 35

Examples:

23

disable_audio

boolean

DisableAudio omits the audio stream. Defaults to false. A source without audio produces video only.

disable_video

boolean

DisableVideo selects an audio-only AAC M4A export. Defaults to false. The source must contain audio.

duration

number

Duration specifies the requested output length in seconds. Defaults to the remaining source duration and is capped at the source end. Audio-only output must resolve to at least 0.001 seconds after trimming and sample rounding. The accepted interval determines the fixed price.

framerate

number

Framerate specifies the output video frame rate. Defaults to the source rate and must be between 0.001 and 240 fps.

Required range: 0.001 <= x <= 240

gop

integer

Gop specifies the maximum keyframe interval in frames. Defaults to four seconds at the accepted frame rate, capped at 960 frames.

Required range: 1 <= x <= 960

height

integer

Height specifies the output dimension in pixels. Use -2 or omit one dimension to preserve the source aspect ratio. Explicit dimensions must be 2 to 7680 and even. Omitting both preserves the source dimensions rounded down to even pixels.

Required range: -2 <= x <= 7680

maxrate

integer

Maxrate specifies the video buffer maximum rate in bits per second, from 100000 through 50000000. H.264 and H.265 require bufsize. VP9 requires video_bitrate; AV1 requires CRF mode.

Required range: 100000 <= x <= 5e+07

minrate

integer

Minrate selects VP9 constant bitrate when equal to video_bitrate and maxrate. Other minimum-rate combinations are unsupported.

Required range: 100000 <= x <= 5e+07

per_title

default: false

boolean

PerTitle enables independent content-based bitrate prediction for each part of the video. Analysis uses only the selected trim interval. Defaults to false. Explicit rate-control settings cannot be combined with it.

pixfmt

default: "yuv420p"

string

Pixfmt specifies the output pixel format. Defaults to yuv420p. The selected profile must support it.

Available options:

yuv420pyuv422pyuv440pyuv444pyuv420p10leyuv422p10leyuv440p10leyuv444p10leyuv420p12leyuv422p12leyuv440p12leyuv444p12le

quality

default: "realtime"

string

Quality specifies the VP9 encoding quality preset. Valid values:

good: Balanced quality preset, good for most applications
best: Best quality preset, slower encoding
realtime: Fast encoding preset, suitable for live streaming

Available options:

goodbestrealtime

Examples:

good

seek

number

Seek specifies the start in source seconds. Defaults to zero and must precede the source end. The accepted interval uses the output frame or sample timeline. Audio-only output must retain at least 0.001 seconds after sample rounding.

Required range: x >= 0

video_bitrate

integer

VideoBitrate specifies the target video bitrate in bits per second, from 1000 through 100000000. Omit it for CRF or per-title encoding.

Required range: 1000 <= x <= 1e+08

width

integer

Width specifies the output dimension in pixels. Use -2 or omit one dimension to preserve the source aspect ratio. Explicit dimensions must be 2 to 7680 and even. Omitting both preserves the source dimensions rounded down to even pixels.

Required range: -2 <= x <= 7680