ApsaraVideo VOD:FAQ about ApsaraVideo Player

Which protocol should I use for standard streaming, RTMP or HTTP-FLV?

Playback failures

How do I troubleshoot playback failures?

What do I do if videos can be played in ApsaraVideo VOD but fail to be played on other platforms?

Perform the following steps to troubleshoot the error:

1. Check whether the video still exists in ApsaraVideo VOD.

2. Check whether an accelerated domain name is added.

   • If no accelerated domain name is added, check whether the ACL of the bucket is private. If the ACL of the bucket is private, disable authentication and set the ACL to public-read. This operation may introduce risks to your bucket.

   • If an accelerated domain name is added, check whether authentication is enabled. If authentication is enabled, configure a longer validity period for the signed URL or disable authentication. Disabling authentication can expose your resources to risks.

What do I do if videos uploaded to ApsaraVideo VOD can be played on all devices except iOS devices?

Cause: The compatibility of Safari on iOS devices is limited. If a video is highly compressed or the encoding profile of the video is high, the video may fail to be played in Safari.

Solution: We recommend that you transcode the video before you play it. For more information, see Audio and video transcoding.

Long startup duration

• If the startup duration is long when you play an MP4 video, the playback error may be caused by the format of the video file. To accelerate data parsing, you must place the moov atom before the mdat atom. The mdat atom contains the media data and the moov atom acts as the index of media data. You can transcode the media file to move the moov atom ahead of the mdat atom.

  • For more information, see Recommended output formats and transcoding tools.

  • To check the location of the moov atom, run the following command:

    // The video source address can be the path of a local file or the URL of an online video. Example: http://pla****.alicdn.com/video/aliyunmedia.mp4.
    ffmpeg -v trace -i "Video source address" 2>&1 | grep -e type:\'mdat\' -e type:\'moov\'

    In the following figure, the moov atom is placed ahead of the mdat atom. In this case, the video can be played as expected.

    In the following figure, the mdat atom is placed ahead of the moov atom. In this case, playback errors may occur.

• ApsaraVideo VOD provides playback solutions for ApsaraVideo Player SDKs for Android and iOS that reduce the startup duration to milliseconds. For more information, see Use ApsaraVideo Player to perform instant loading in full screen mode.

Playback of encrypted videos

What do I do if DRM-encrypted videos cannot be played by ApsaraVideo Player for Web?

You can use ApsaraVideo Player for Web to play videos that are encrypted by using Digital rights management (DRM) only on specific browsers. For more information about the supported browsers, see Features of the HTML5 player supported by browsers.

What is MtsHlsUriToken used for when I play HLS-encrypted videos? How do I obtain MtsHlsUriToken?

MtsHlsUriToken is a user-defined parameter. In HLS encryption, an encryption string is written to the HLS stream and the URL of the decryption server is added to the M3U8 index file. If you want to limit access to the encrypted video, you can use MtsHlsUriToken for identity verification before the video is decrypted for playback.

When you configure encryption, you must set up a token issuance service to generate MtsHlsUriToken. For more information, see Step 4 in the Encrytion procedure section of the HLS encryption topic.

Cross-region playback

What do I do if videos uploaded to OSS in the UK (London) region take a long time to load from the Chinese mainland?

Access from regions in the Chinese mainland to UK (London) is cross-region access. We recommend that you activate Global Accelerator (GA) and add a domain name to accelerate video loading.

What do I do if videos take a long time to load and video stuttering frequently occurs when I access ApsaraVideo VOD from regions outside the Chinese mainland?

In most cases, stuttering occurs when the network connection is unstable. If video stuttering continues for an extended period of time and causes an error to be reported in ApsaraVideo Player, the connection to CDN may be interrupted. If video stuttering frequently occurs, check whether your network speed matches the video bitrate. If your network speed does not match the video bitrate, increase your network speed or reduce the video bitrate.

Playback of videos stored in OSS

What do I do if a large number of requests are sent when I play a video stored in OSS?

Check whether the source video is abnormal. For example, check whether a large number of requests are sent when the player decrypts the source video. We recommend that you use an ApsaraVideo VOD transcoding template to transcode the source video for playback. For more information, see Audio and video transcoding.

How do I configure to preview the image when I click the URL of an image that is uploaded to ApsaraVideo VOD?

You can preview images stored in ApsaraVideo VOD only by using custom domain names. If you use the default domain name to access an image, the image is forcibly downloaded. You can add your custom domain name to ApsaraVideo VOD. For more information, see Add a domain name for CDN.

SSL certificates

What do I do if videos cannot be played on specific PCs and the 4400 error code is returned?

The 4400 error code indicates that the resources cannot be loaded due to server or network errors, or that the video format is not supported. Check whether an SSL certificate is configured.

Playback URLs

How do I generate a short playback URL for a video stored in ApsaraVideo VOD?

Why does a non-transcoded video fail to be played after I set the transcoding format to HLS?

You can use video IDs and playback credentials to play only the transcoded videos in ApsaraVideo Player. Videos that are not transcoded can only be played by using playback URLs. You can call the GetMezzanineInfo operation to obtain the source video URL or log on to the ApsaraVideo VOD console to view the video playback URL.

Does a video stored in ApsaraVideo VOD have multiple playback URLs?

If the ACL of the bucket in which the video is stored is private, the playback URL of the video has an expiration time. The authentication string included in the auth_key parameter in the playback URL varies based on the expiration time that you specify.

If you need a permanent playback URL for a video, you must change the ACL of the bucket in which the video is stored to public-read or public-read-write. Then, a playback URL is generated. The content before ? is the permanent playback URL. For more information about the read and write permissions on the storage bucket and how to change the permissions, see Manage storage buckets.

Why a video uploaded to ApsaraVideo VOD can only be played in browsers after I access the playback URL of the video from platforms such as Taobao?

Video playback depends on browsers and the transcoding capabilities of your local device. In most cases, you are redirected to a browser to play videos.

Why am I unable to play the new video after I upload the updated video?

After you update the video, you must refresh the playback URL to obtain the latest video data. For more information about how to refresh the URL by using the ApsaraVideo VOD console, see Refresh and prefetch. For more information about how to refresh the URL by using the ApsaraVideo VOD API or SDK, see PreloadVodObjectCaches or RefreshMediaPlayUrls.

How do I obtain the pixels of each video frame in ApsaraVideo Player?

• ApsaraVideo Player for Android: listen for the OnRenderFrameCallback event.

• ApsaraVideo Player for iOS: listen for the onRenderingFrame event.

  player.renderingDelegate = self;
  
  
  #pragma mark CicadaRenderingDelegate
  - (BOOL)onRenderingFrame:(CicadaFrameInfo*) frameInfo{
      if(frameInfo.frameType==Cicada_FrameType_Video){
          // Obtain the pixels of video frames.
          NSLog(@"receive HW frame:%p pts:%ld foramt %d", frameInfo.video_pixelBuffer, frameInfo.pts, CVPixelBufferGetPixelFormatType(frameInfo.video_pixelBuffer));
  
      } else if (frameInfo.frameType==Cicada_FrameType_Audio){
          // This feature is not supported for audio.
      }
      return NO;
  }

• ApsaraVideo Player for Web: You cannot obtain the pixels of video frames.

Why am I unable to obtain playback URLs of AVI videos uploaded to ApsaraVideo VOD by using the API or SDK?

You cannot obtain AVI videos by calling the GetPlayInfo operation. Therefore, you cannot use SDKs that use this operation to obtain playback URLs of AVI videos.

You can view the playback URL of an AVI video in the ApsaraVideo VOD console. For more information, see Query audio/video files.

Playback stuttering

What do I do to reduce video stuttering and improve the cache hit ratio?

You can configure the following settings: URL signing, refresh and prefetch, cache TTL, and parameter filtering.

What do I do if video stuttering occurs when I drag the progress handle to the middle of the progress bar?

When you drag the progress handle on the progress bar, ApsaraVideo Player loads the keyframes before and after the position to which you seek to display the required video image. Stuttering occurs in a video when the keyframes are insufficient and the required video image takes more time to be displayed. In this case, we recommend that you transcode the video to add more keyframes to the video. For more information about transcoding, see Audio and video transcoding.

Video thumbnails

Why am I unable to obtain video thumbnails?

By default, the ApsaraVideo VOD console uses the HTTPS protocol. The screenshots can be displayed and previewed only if HTTPS is used. You can also open the browser developer tool to view error details.

Video review

Why am I unable to play videos submitted for manual review?

Parameter parsing

What is a video ID? Why is a video ID required? How do I obtain a video ID?

After you upload a video file, ApsaraVideo VOD provides you with a video ID instead of a video URL to ensure the security of the video file. You can obtain the video URL by calling an API operation in ApsaraVideo VOD. For more information, see GetPlayInfo.

After you upload a video to ApsaraVideo VOD, you can obtain the video ID.

What are the AccessKey ID and AccessKey secret? How do I obtain an AccessKey ID and AccessKey secret?

The AccessKey ID and AccessKey secret are the only credentials that you can use to call Alibaba Cloud APIs. The AccessKey ID is used to verify your identity. The AccessKey secret is used to encrypt the signature string of your access request. This prevents data from being tampered with. The AccessKey secret is similar to a logon password. Keep the AccessKey secret confidential.

What is a playKey? How do I obtain a playKey?

What is a playAuth? How do I obtain a playAuth?

ApsaraVideo Player supports three playback modes that are suitable for different scenarios. Compared with other playback modes, playAuth-based playback is more secure. We recommend that you use the setAuthInfo mode for video playback.

playAuth is a playback credential in which the video ID, AccessKey ID, and AccessKey secret are packaged and encrypted. After you obtain the playAuth, you can use the string of data that contains various information to play videos in ApsaraVideo Player.