Transcoding
Transcoding is the process of converting audio and video files into other formats to suit different network bandwidths, playback devices, and user needs. The transcoding service in VOD Media Processing includes regular transcoding, subtitle burning, audio and video enhancement, and watermarking. This topic details these features and their usage.
Create a transcoding task
Create a task in the console
Standard transcoding
Log on to theIntelligent Media Services (IMS) console.
In the left-side navigation pane, choose .
On the Transcoding tab, create a transcoding task.
When selecting a template, choose a transcoding type (Narrowband HD™ 1.0 transcoding, Narrowband HD™ 2.0 transcoding, regular transcoding, audio transcoding, or container format conversion), set a transcoding scenario (such as General, Short Drama, Education, UGC Content, HD Film & TV, or E-commerce), and a transcoding policy (Bitrate First, Balanced, or Quality First). Then, select a specific preset template from the template list. A preview on the right side of the page shows a comparison of the bitrate and compression ratio before and after transcoding.
Parameter
Description
Basic parameters
Task Name
Enter a name for the transcoding task.
File Source
Select media assets from OSS or IMS Media Asset Management.
OSS Path
If the file source is OSS, select the OSS path of the media asset.
Storage Address
If the file source is Media Asset Management, select a storage address in the IMS system and click Add File to add a media asset from that address.
Select Template
Select a transcoding template.
Watermark configuration
Watermark
Specifies whether to enable the watermark feature.
Watermark Template
Select a watermark template.
Output information
Output Location
Original Storage Location: If the file source is Media Asset Management, the processed file is saved to the original storage location by default.
Custom: Specify a custom output location.
Output Address
If the output location is set to Custom, select an output address.
Output File Name
Enter a name for the transcoded file. You must add a file extension for all file types except M3U8.
Query transcoding task details
Callbacks
Query transcoding task usage
Log on to theIntelligent Media Services (IMS) console.
In the left-side navigation pane, choose Data Center > Usage Statistics.
On the VOD Tasks tab, select Transcoding to query details and export the usage duration for the corresponding tasks.
NoteTo ensure data security, the download link for the exported file is valid for 30 minutes. If the link expires, refresh the page to generate a new one.
AI Transcoding Assistant
The AI Transcoding Assistant improves the efficiency of template creation, filtering, and parameter tuning, helping you achieve precise output quality faster. It supports the following use cases:
Generate templates from natural language: Generate a template from your description, and then validate and use it.
Adjust template parameters: Modify the parameters of a specified template based on your requirements.
Query templates: Search for a list of templates or parameter details that match your needs.
Generate a template
Log on to theIntelligent Media Services (IMS) console.
In the left-side navigation pane, choose to go to the Task Management page.
Click the AI Assistant icon to open the IMS Assistant.
In the IMS Assistant dialog box, enter your business transcoding requirements. For example: "How do I improve video quality and reduce costs?"
Follow the prompts to select a scenario and transcoding policy, and enter the corresponding technical parameters. The IMS Intelligent Assistant recommends a transcoding scenario (such as Short Drama, Film & TV, Education, UGC Content, or E-commerce) and a transcoding policy (such as Ultimate Compression, Balanced, Quality First, or HD Color Enhancement). Select a suitable scenario in the Scenario Policy form.
Follow the prompts to add a test video from OSS or the media library.
Wait for the transcoding to complete, preview the video, and then generate the transcoding template.
API reference
FAQ
How do I optimize transcoding quality and file size?
If the transcoded video is blurry or distorted, the source video may have a low bitrate and the task may be using a source-following ("Follow Source") bitrate strategy. To resolve this, adjust the encoding parameters: set the encoding format to CRF encoding, or specify a higher output bitrate.
Video compression is essentially a transcoding process. The size of the output file depends on parameters such as definition, resolution, and bitrate. For extreme compression (for example, compressing a 1 GB file down to 50 MB), you can call the CreateMediaConvertTask operation and configure the H.264 or H.265 encoding format, a CRF value (18 to 28 is recommended), the resolution, and the bitrate. Note that lowering these parameters reduces video quality.
How do I view the ErrorCode and ErrorMessage of a transcoding task in the console?
Log on to theIntelligent Media Services (IMS) console, and choose VOD Media Processing > Task Management > Task List. Find the corresponding task ID and click it to go to the details page, where you can view the task status and the ErrorCode and ErrorMessage details.
Do I need to activate IMS to use only traditional Media Processing (MPS) features, such as transcoding and screenshot capture?
No, you do not need to activate IMS if you only need to use traditional Media Processing (MPS) features. Log on to the VOD Media Processing console, and submit transcoding, screenshot capture, or other tasks on the Workflows or Tasks page. The system automatically deducts the usage duration from your purchased MPS resource plan. Make sure that you use the correct entry point and do not go to the IMS console by mistake.
How do I synchronize subtitles with narration in real time without manually calculating the timeline?
Use AI_ASR (speech recognition) to keep subtitles synchronized with the narration. AI_ASR converts speech to text and automatically merges the generated subtitles into the video, so you do not need to calculate the timeline. If you use a regular subtitle track instead, you must manually calculate the in and out times of each subtitle.