Configure video seeking - Dynamic Content Delivery Network

Video seeking allows users to seek a specified position without the need to compromise the playback quality when they play video or audio content. This topic describes how to configure video seeking.

Background information

After video seeking is enabled, when a user seeks a specified position on the video or audio content on demand, the client sends a request to the server. The request contains the URL of the video or audio file, for example, http://www.aliyun.com/test.flv?start=10. The start parameter specifies the position that the user wants to seek. After the server receives the request, it seeks the keyframe at the specified position and then returns the content that starts from this keyframe. If no keyframe can be found at the specified position, the server seeks the last keyframe before the specified position.

Before you configure video seeking, make sure that the origin server supports HTTP range requests. If an HTTP request includes the Range header field, the origin server returns an HTTP 206 status code (partial content message).

The following table describes the file formats supported by video seeking.

File format	Metadata	Start parameter	Example
MP4	The metadata of a video file on the origin server must be contained in the file header and cannot be contained in the file tail.	The start parameter specifies the position. If the position specified by the start parameter is not a keyframe, Alibaba Cloud Content Delivery Network (CDN) automatically locates the last keyframe before the specified position. The start parameter supports only values in seconds. Decimals are supported. For example, if you specify start=1.01, the position is at 1.01 seconds after the video file starts.	The request URL `http://domain/video.mp4?start=10` specifies that the video is played from the 10th second.
FLV	Video files on the origin server must contain metadata.	The start parameter specifies the byte. If the byte specified by the start parameter is not a keyframe, Alibaba Cloud CDN automatically locates the last keyframe before the specified byte.	The request URL `http:// domain/video.flv?start=10` specifies that the video is played from the 10th byte.

Procedure

Log on to the DCDN console.
In the left-side navigation pane, click Domain Names.
On the Domain Names page, find the domain name that you want to manage, and click Configure in the Actions column.
In the left-side navigation pane of the domain name, click Optimization.
In the Drag/Drop Playback section, turn on Drag/Drop Playback.