Audio can sometimes lag behind video on the BBC iPlayer media streaming app if the computer's processor is too slow, if the streaming connection is too slow or if the download file contains an error. Quitting other apps on your PC or tablet is one way to ease the burden on an overstretched processor. Refreshing and reconnecting to iPlayer can sometimes also fix audio/video synch issues.
Slower computers can't always handle the video decoding necessary for high-quality video. You might get smoother playback by downloading a lower-quality video with a smaller file size. However, computers of a certain age are simply unable to perform quickly enough to decode the video and keep the audio synchronized. According to the BBC, if your computer's processor was made before 2003, then it won't be able to handle the iPlayer's demands.
Streamed video files also depend on fast Internet connection speeds. The BBC estimates that connections below 3.5 Megabytes-per-second won't handle high definition video. If the connection is below 0.5 Mbps you won't be able to view any streaming video on your computer. Use the iPlayer's speed diagnostic tool to test the speed of your Internet connection.
Downloaded File Error
Downloaded video and audio can sometimes fall out of sych due to file download errors. Try deleting and redownloading the file, or playing a different downloaded file. If you cannot play the downloaded file, stream the video content instead.
You might be able to increase the performance of the iPlayer application by closing all other applications to prevent other programs using processor power. Also try increasing the priority level for the iPlayer application. Press Ctrl, Shift and Esc to launch the Windows Task Manager. Click to select the iPlayer app from the list on the Applications tab. Right-click and select Go to Process. Right-click on the highlighted process that appears, point to Set Priority and then click Realtime. Windows now allocates all available processor power to the iPlayer application to give the best performance possible.