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ON24 Knowledge Center

Video Clip Specifications

This article explains the differences between video clips and presenter media, how video clips display to attendees and video clip specifications for ON24 webcasts.

 

 

Audience View

Video clips will show in the slide area for webcasts using the Live Audio (no screen share)Simu-live, or On Demand Recording present type.  The slide area can be maximized to full screen if desired.

For webcasts using the Live Video and Audio (screen share) present type, video clips will show in the media player.  The media player will auto-maximize to display the video clip and then auto-minimize once the clip is finished.  The auto-maximize and auto-minimize behavior cannot be changed.

For more information on setting up video clips for a Live Video and Audio webcast, click here.

image media player maximize.jpg

Video Clip Specifications

**It is imperative these specifications be followed so video clips play correctly for the audience.

  1. All video clips must be in an MP4 format. You may upload up to 20 video clips/webcast.

  2. Video clips cannot be the first element pushed in a webcast (this should always be a slide). Slides should also be pushed in between clips for even cleaner playback and a smoother on-demand experience.  These slides can be placeholders should you choose to add chapters to your webinar.

  3. All Video clips must have Audio and Video streams encoded (even if audio is silent).

If you need ON24 Production to re-encode an MP4, please provide 5 business days in advance of the live event.

 

SPECIFICATIONS

NOTES AND BEST PRACTICES

File

MP4 (.mp4)

 

 
Size 2 GB or lower    

Video Format

H.264 / AVC

VP6

These codecs are absolute necessities.

*MPEG4-Visual codec is not supported.

Audio Format

AAC

MP3

AAC audio format is preferred if using H.264, with MP3 the mobile stream might encounter issues.

Sample Rate 48 kHz  

Audio

32 kbps mono

32 kbps audio is sufficient and will allow the video to be encoded at a higher bit rate.

Anything over 96 kbps for the mono audio stream is superfluous unless the audio was recorded in a studio (16 kbps is the approximate audible top-end of a traditional copper telephone connection).

Frame Size

If the video clip is to be displayed in the slide area, the frame size should match the size of the slide area in the audience console.

The video clip must be a 16:9 or 4:3 aspect ratio.

We recommend 1280 x 720 pixels (or smaller) to minimize file size and bandwidth issues.

 

Dimensions:

16:9
1280x720 or 800x450

4:3
960x720 or 800x600  

Bitrate - a number of "bits per second" (bps) at which data in a video is being delivered.

1 Mbps / 1000 kbps

(Add both the audio and the video channels to get the total bit rate)

Generally speaking, the higher the bit rate, the higher the bandwidth requirement for the audience.

CONSTANT bitrate required

The size of the file and the quality of the image and sound are both controlled by the bit rate used. The higher the bit rate, the better the potential quality, and the larger the file size.

Lower bit rates should be used for international audiences or events with a large number of users on the same network that is generally more susceptible to bandwidth limitations.

Frame Rate - a number of "frames per second" (fps)

30 fps or less

 

Keyframe: 1 keyframe every 3 seconds  

Best Practices

1)  Be sure to have the video clips uploaded before your practice sessions. As a best practice, we recommend uploading your video clips at least 24 - 48 hours prior to the live event to confirm video and audio playback work as you expect before your webcast goes live.

2)  Preview your slides, video clips, polls, etc., by clicking on the Preview URL and opening the Preview Console in a separate browser tab.  If you are unable to get your video clips to play you may submit a case for assistance.

Additional Notes

During the live webinar, video clips will playback at slightly different times for audience members, depending on how strong an attendee's internet connection is.  Having a delay of a few seconds is the nature of live broadcast technology and is to be expected. 

For this reason, it’s important to wait 5 seconds before advancing to the next slide to allow the video clip to finish playing for all audience members.  If you have access to video editing software or production services, we recommend adding 10-15 seconds of silence at the end of each video clip to serve as a buffer.  You can see an example at the end of this video, https://vimeo.com/121062997.

It is not recommended to have both a video clip playing in the Slide Engagement Tool along with a video stream in the Media Player Engagement Tool as this will require attendees to have double the amount of required bandwidth.  For example, a 300K MP4 in the Slide engagement tool and a 300K video stream in the Media Player would require at least 600Kbps of bandwidth. In these cases, it's best to incorporate the MP4 content into the video stream. This is more of an issue for Simu-live events using a presenter media video.

 

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