Video transcoding allows you to change coding formats, adjust resolution and bitrate, modify container formats, and alter video parameters to meet various business requirements
Feature overview
Video transcoding is the process of converting a compressed video stream into another format, adjusting elements such as video format, container format, resolution, frame rate, and bitrate. This ensures compatibility for playback on various devices and platforms while also reducing file size to enhance transmission efficiency.
Scenarios
Cross-device compatibility: To ensure smooth playback of videos across various devices, such as mobile phones, tablets, computers, and smart TVs, transcoding technology can convert videos into formats that are compatible with each specific device.
Streaming media playback: Streaming services must transcode videos into multiple formats and bitrates to dynamically adapt to users' network conditions, enhancing the overall viewing experience.
Video compression: Video transcoding can reduce file size while preserving video quality, making it easier to store and transmit, particularly in environments with limited network bandwidth.
Data archiving: Transcoding converts high-quality videos into optimized formats for efficient long-term storage and management, minimizing storage requirements.
Resolution adaptation: Transcoding reduces video resolution to support diverse playback devices and network conditions, ensuring a smoother playback experience.
Video format compatibility: Transcoding converts less common video formats into widely adopted ones, ensuring compatibility with media playback software and enabling broader accessibility.
Usage
Prerequisites
Intelligent Media Management (IMM) is activated. For more information, see Activate IMM.
The corresponding Object Storage Service (OSS) bucket is bound to an IMM project.
For information about binding in the OSS console, see Get started.
For information about binding using the IMM API, see AttachOSSBucket.
The required permissions are granted to the Resource Access Management (RAM) user that you use to use IMM features. For more information, see Permissions.
Use OSS SDKs
Video transcoding is asynchronous. Among OSS SDKs for all supported languages, only the Java, Python, and Go SDKs support this feature.
Java
OSS SDK for Java 3.17.4 or later is required.
import com.aliyun.oss.ClientBuilderConfiguration;
import com.aliyun.oss.OSS;
import com.aliyun.oss.OSSClientBuilder;
import com.aliyun.oss.common.auth.CredentialsProviderFactory;
import com.aliyun.oss.common.auth.EnvironmentVariableCredentialsProvider;
import com.aliyun.oss.common.comm.SignVersion;
import com.aliyun.oss.model.AsyncProcessObjectRequest;
import com.aliyun.oss.model.AsyncProcessObjectResult;
import com.aliyuncs.exceptions.ClientException;
import java.util.Base64;
public class Demo {
public static void main(String[] args) throws ClientException {
// Specify the endpoint of the region in which the bucket is located.
String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
// Specify the ID of the Alibaba Cloud region in which the bucket is located. Example: cn-hangzhou.
String region = "cn-hangzhou";
// Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured.
EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
// Specify the name of the bucket. Example: examplebucket.
String bucketName = "examplebucket";
// Specify the name of the output video.
String targetKey = "dest.avi";
// Specify the name of the source video.
String sourceKey = "src.mp4";
// Create an OSSClient instance.
// When the OSSClient instance is no longer used, call the shutdown method to release resources.
ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);
OSS ossClient = OSSClientBuilder.create()
.endpoint(endpoint)
.credentialsProvider(credentialsProvider)
.clientConfiguration(clientBuilderConfiguration)
.region(region)
.build();
try {
// Create a style variable of the string type to store video transcoding parameters.
String style = String.format("video/convert,f_avi,vcodec_h265,s_1920x1080,vb_2000000,fps_30,acodec_aac,ab_100000,sn_1");
// Create an asynchronous processing instruction.
String bucketEncoded = Base64.getUrlEncoder().withoutPadding().encodeToString(bucketName.getBytes());
String targetEncoded = Base64.getUrlEncoder().withoutPadding().encodeToString(targetKey.getBytes());
String process = String.format("%s|sys/saveas,b_%s,o_%s", style, bucketEncoded, targetEncoded);
// Create an AsyncProcessObjectRequest object.
AsyncProcessObjectRequest request = new AsyncProcessObjectRequest(bucketName, sourceKey, process);
// Execute the asynchronous processing task.
AsyncProcessObjectResult response = ossClient.asyncProcessObject(request);
System.out.println("EventId: " + response.getEventId());
System.out.println("RequestId: " + response.getRequestId());
System.out.println("TaskId: " + response.getTaskId());
} finally {
// Shut down the OSSClient instance.
ossClient.shutdown();
}
}
}Python
OSS SDK for Python V2.18.4 or later is required.
# -*- coding: utf-8 -*-
import base64
import oss2
from oss2.credentials import EnvironmentVariableCredentialsProvider
def main():
# Specify the endpoint of the region in which the bucket is located.
# For example, if the bucket is located in the China (Hangzhou) region, set the endpoint to https://oss-cn-hangzhou.aliyuncs.com.
endpoint = 'https://oss-cn-hangzhou.aliyuncs.com'
# Obtain access credentials from environment variables.
# Before you run the sample code, ensure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured.
auth = oss2.ProviderAuthV4(EnvironmentVariableCredentialsProvider())
# Specify the name of the bucket.
bucket_name = 'examplebucket'
# Specify the ID of the Alibaba Cloud region in which the bucket is located. Example: cn-hangzhou.
region = 'cn-hangzhou'
# Create a bucket.
bucket = oss2.Bucket(auth, endpoint, bucket_name, region=region)
# Specify the name of the source video.
source_key = 'src.mp4'
# Specify the name of the output video.
target_key = 'dest.avi'
# Create a style variable of the string type to store video transcoding parameters.
style = 'video/convert,f_avi,vcodec_h265,s_1920x1080,vb_2000000,fps_30,acodec_aac,ab_100000,sn_1'
process = "{0}|sys/saveas,o_{1}".format(style,
oss2.compat.to_string(base64.urlsafe_b64encode(
oss2.compat.to_bytes(target_key))).replace('=', ''))
# Call the media processing operation.
try:
# Execute the asynchronous processing task.
result = bucket.async_process_object(source_key, process)
print(f"EventId: {result.event_id}")
print(f"RequestId: {result.request_id}")
print(f"TaskId: {result.task_id}")
except Exception as e:
print(f"Error: {e}")
if __name__ == "__main__":
main()
Go
OSS SDK for Go V3.0.2 or later is required.
package main
import (
"encoding/base64"
"fmt"
"os"
"strings"
"github.com/aliyun/aliyun-oss-go-sdk/oss"
)
func main() {
// Obtain access credentials from environment variables.
// Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured.
provider, err := oss.NewEnvironmentVariableCredentialsProvider()
if err != nil {
fmt.Println("Error:", err)
os.Exit(-1)
}
// Create an OSSClient instance.
// Specify the endpoint of the region in which the bucket is located.
// For example, if the bucket is located in the China (Hangzhou) region, set the endpoint to https://oss-cn-hangzhou.aliyuncs.com. Specify your actual endpoint.
client, err := oss.New("https://oss-cn-hangzhou.aliyuncs.com", "", "", oss.SetCredentialsProvider(&provider), oss.AuthVersion(oss.AuthV4), oss.Region("cn-hangzhou"))
if err != nil {
fmt.Println("Error:", err)
os.Exit(-1)
}
// Specify the name of the bucket in which the source video is stored. Example: examplebucket.
bucketName := "examplebucket"
bucket, err := client.Bucket(bucketName)
// Specify the name of the output video.
targetObject := "dest.avi"
if err != nil {
fmt.Println("Error:", err)
os.Exit(-1)
}
// Specify the name of the source video.
sourceObject := "src.mp4"
// Create a style variable of the string type to store video transcoding parameters.
style := "video/convert,f_avi,vcodec_h265,s_1920x1080,vb_2000000,fps_30,acodec_aac,ab_100000,sn_1"
process := fmt.Sprintf("%s|sys/saveas,b_%v,o_%v", style, strings.TrimRight(base64.URLEncoding.EncodeToString([]byte(bucketName)), "="), strings.TrimRight(base64.URLEncoding.EncodeToString([]byte(targetObject)), "="))
fmt.Printf("%#v\n", process)
rs, err := bucket.AsyncProcessObject(sourceObject, process)
if err != nil {
fmt.Println("Error:", err)
os.Exit(-1)
}
fmt.Printf("EventId:%s\n", rs.EventId)
fmt.Printf("RequestId:%s\n", rs.RequestId)
fmt.Printf("TaskId:%s\n", rs.TaskId)
}
Parameters
Action: video/convert
The following table describes the parameters for video transcoding.
Parameter | Type | Required | Description |
ss | int | No | The start time of the video from which transcoding begins. Unit: milliseconds. Valid values:
|
t | int | No | The duration of video content to be transcoded after the specified start time. Unit: milliseconds. Valid values:
|
f | string | Yes | The type of the media container.
|
vn | int | No | Specifies whether to disable video stream generation. Valid values:
|
vcodec | string | No | The encoding format of the output video. Valid values:
|
fps | float | No | The video frame rate. Valid values: 0 to 240. |
fpsopt | int | No | The frame rate option. Valid values:
|
pixfmt | string | No | The target pixel format. By default, the target pixel format is the same as the source pixel format. Valid values:
|
s | string | No | The desired resolution.
|
sopt | int | No | The resolution option. Valid values:
|
scaletype | string | No | The resizing mode. Valid values:
|
arotate | int | No | Specifies whether to enable adaptive resolution orientation. Valid values:
|
g | int | No | The keyframe interval. Valid values: 1 to 100000. |
vb | int | No | The target video bitrate. Unit: bit/s. Valid values: 10000 to 100000000. |
vbopt | int | No | The video bitrate option. Valid values:
|
crf | float | No | The constant rate factor (CRF). Valid values: 0 to 51. |
maxrate | int | No | The maximum bitrate. Unit: bit/s. Valid values: 10000 to 100000000. |
bufsize | int | No | The buffer size. Unit: bit. Valid values: 10000 to 200000000. |
an | int | No | Specifies whether to disable audio stream generation. Valid values:
|
acodec | string | No | The encoding format of the audio. Valid values:
|
ar | int | No | The audio sampling rate. Valid values:
|
ac | int | No | The number of sound channels in the output audio. By default, the output audio retains the same number of channels as the source audio. Valid values: 1 to 8. |
aq | int | No | The audio compression quality. This parameter and the ab parameter are mutually exclusive. Valid values: 0 to 100. |
ab | int | No | The audio bitrate. This parameter and the aq parameter are mutually exclusive. Unit: bit/s. Valid values: 1000 to 10000000. |
abopt | int | No | The audio bitrate option. Valid values:
|
sn | int | No | Specifies whether to disable subtitle generation. Valid values:
|
adepth | int | No | The sampling bit depth of the output audio. Valid values: 16 and 24. Note This parameter takes effect only if you set the acodec parameter to flac. |
segment | string | No | The media segmentation settings. By default, no segmentation is performed. |
f | string | No | The media segmentation mode. Valid values:
Parent node: segment |
t | int | No | The length of the segment. Unit: milliseconds. Valid values: 0 to 3600000. Parent node: segment |
You may also need to use the sys/saveas and notify parameters in a video transcoding task. For more information, see sys/saveas and Message notification.
Use the OSS API
If your business requires a high level of customization, you can directly call RESTful APIs. To directly call a RESTful API, you must include the signature calculation in your code. For information about how to calculate the signature for the Authorization header, see (Recommended) Include a V4 signature.
Convert from AVI to MP4
Transcoding task information
Source object
Video format: AVI
Video name: example.avi
Processing method: video transcoding
Destination object
Video information
Video format: MP4
Video name: outobjprefix.mp4
Video stream format: H.265
Video resolution: 1920×1080
Video frame rate: 30 fps
Video bitrate: 2 Mbit/s
Audio information
Audio stream format: AAC
Audio bitrate: 100 Kbit/s
Subtitle stream: disabled
Output path: oss://outbucket/outobjprefix.mp4
Sample request
POST /example.avi?x-oss-async-process HTTP/1.1
Host: video-demo.oss-cn-hangzhou.aliyuncs.com
Date: Fri, 28 Oct 2022 06:40:10 GMT
Authorization: SignatureValue
// Transcode the example.avi object to the MP4 container format and specify H.265 as the video stream format.
// Set the resolution to 1920 x 1080, frame rate to 30 fps, and video bitrate to 2 Mbit/s. Specify AAC as the audio stream format and set the audio bitrate to 100 Kbit/s. Disable subtitle stream generation. Save the output object as oss://outbucket/outobjprefix.mp4.
x-oss-async-process=video/convert,f_mp4,vcodec_h265,s_1920x1080,vb_2000000,fps_30,acodec_aac,ab_100000,sn_1|sys/saveas,b_b3V0YnVja2V0,o_b3V0b2JqcHJlZml4LnthdXRvZXh0fQConvert from AVI to TS
Transcoding task information
Source object
Video format: AVI
Video name: example.avi
Processing task details
Length of transcoding: Transcode 60,000 milliseconds of the video, starting from the 1,000th millisecond of the video.
Segment method: Create HTTP Live Streaming (HLS) segments at intervals of 30 seconds.
Transcoding completion notification: Send Simple Message Queue (SMQ) messages.
Destination objects
Video information
Video format: TS
Video stream format: H.264
Video bitrate: 1 Mbit/s
Audio information
Audio format: AAC
Audio bitrate: 100 Kbit/s
Output paths
TS object: oss://outbucket/outobjprefix-%d.ts
M3U8 object: oss://outbucket/outobjprefix.m3u8
Sample request
POST /example.avi?x-oss-async-process HTTP/1.1
Host: video-demo.oss-cn-hangzhou.aliyuncs.com
Date: Fri, 28 Oct 2022 06:40:10 GMT
Authorization: SignatureValue
// Transcode the example.avi video.
x-oss-async-process=video/convert,ss_10000,t_60000,f_ts,vcodec_h264,vb_1000000,acodec_mp3,ab_100000/segment,f_hls,t_30000|sys/saveas,b_b3V0YnVja2V0,o_b3V0b2JqcHJlZml4LnthdXRvZXh0fQ/notify,topic_QXVkaW9Db252ZXJ0Convert from AVI to MP3
Transcoding task information
Source object
Video name: example.avi
Video format: AVI
Processing method: Extract and transcode audio.
Destination object
Audio container format: MP3
Audio coding format: MP3
Audio bitrate: 100 Kbit/s
Video stream: disabled
Subtitle stream: disabled
Output path: oss://outbucket/outobjprefix.mp3 (If the video contains multiple audio channels, only the first channel is processed by default.)
Sample request
POST /example.avi?x-oss-async-process HTTP/1.1
Host: video-demo.oss-cn-hangzhou.aliyuncs.com
Date: Fri, 28 Oct 2022 06:40:10 GMT
Authorization: SignatureValue
// Extract audio from the example.avi object and transcode the extracted audio.
x-oss-async-process=video/convert,f_mp3,acodec_mp3,ab_100000,vn_1,sn_1|sys/saveas,b_b3V0YnVja2V0,o_b3V0b2JqcHJlZml4LnthdXRvZXh0fQNotes
Video transcoding supports only asynchronous processing (x-oss-async-process).
Video transcoding does not support anonymous access.
Video transcoding supports the following video formats: MP4, MPEG-TS, MKV, MOV, AVI, FLV, M3U8, WebM, WMV, RM, and VOB.
Using video/convert for video transcoding incurs fees. Fees for media processing are included in your IMM bills. For more information, see Billable items.
FAQ
How do I fix a ResourceNotFound error for a video transcoding task?
To fix the "ResourceNotFound, The specified resource Attachment is not found." error during video transcoding, make sure that a bucket is created and bound to your IMM project. For more information, see Step 2: Bind an OSS bucket.
Can I save the output object of a video transcoding task to the path of the source object?
No, you cannot save the output object of a video transcoding task to the same path as the source object. To prevent issues such as execution loops of triggers or accidental overwriting of the source object, do not use the input path as the prefix of the output path.
Can I specify an audio bit depth in a video transcoding task?
Yes, you can specify an audio bit depth in a video transcoding task by including the pixfmt parameter in x-oss-process.
How do I retrieve the task execution result for video transcoding by using the returned task ID?
To retrieve the task execution result for video transcoding by using the returned task ID, we recommend that you call the GetTask operation in IMM.
How does OSS handle the retrieval and deletion of objects with a specific format based on their suffix during video transcoding?
OSS does not support searching for objects by suffix, as it offers an unordered storage service.
What do I do if message pushing for video transcoding is configured but the backend does not receive messages?
Check whether the SMQ topic is created and the subscription is configured. If the SMQ topic does not exist or is deleted, reconfigure the subscription. Restart the transcoding process based on the current subscription configuration.
Can I use a specific template to transcode a video after uploading the video to OSS?
Yes, you can configure a trigger to implement this feature. Video processing tasks can be initiated manually, or automatically by using batch processors (for existing data) and triggers (for incremental data). When you create tasks, batch processors, or triggers, you can use system or custom styles. For more information, see Batch processing and Triggers.
Am I charged fees for the storage of the output video in a video transcoding task? If the output video has a different prefix than the source video, will the output video replace the source video?
The output video consumes storage space, resulting in associated charges. Using the same path for both the transcoded video and the source video may lead to looping issues.