Sometimes a video player can display the images of a video but the sound is completely silent or an error message box appears. For example on the Dreambox or VU+ video boxes you can get an error message like "Gstreamer can't decode stream of type '<Codec>'". This means that the type of video stream inside the media file is supported but the audio stream is not. Multimedia Xpert can repair this by converting such a file by only converting the audio stream and copying the other streams 1:1. Since the video conversion of a media is a much bigger task converting just the audio saves a lot of time. The conversion time for a typical episode is only about 3 minutes (depending on your computer).
To convert only the audio you need to configure an output specification that transfers video and subtitle streams directly without processing. For MP4 there is already a predefined one named "Video MP4 only Audio Conversion to AAC", but for other formats you need to do the following:
- Switch to the Output Specifications tab.
- Select the output specification that is closest to your desired output format.
- Enter the name for a new specification under 'Name', e.g. "Video H.264 without video conversion", and press . This will duplicate all previous values to the new specification.
- Empty the 'Output Video Codec' field. This is the crucial one.
- Since now the video stream is copied 1:1 to the output, you must clear all option fields that are related to video streams or set them to the default value. Without this a conversion would have to take place, and ffmpeg will report this contradiction with the error message "Filtering and streamcopy cannot be used together".
If this does not result in a playable video, the video stream or other streams inside are probably the problem. In this case you can try to disable streams other than the video and audio stream in the Stream Selection column and convert again or else doing a full conversion.