One possible issue is that QuickTime 4 introduced a new compression format for sound called "QDesign Music 2". Quicktime 3 does not support this new compression. Thus, if the movie file in question was created using the QDesign Music 2 compression format in QuickTime 4, then users of QuickTime 3 will be able to play the movie and see the video, but they will not hear any audio.
If you have a Pro version of QuickTime, and you have a local copy of the movie, here is a way to verify if this is the case:
If you are using QuickTime 3 Pro, under "Compression", if it will say "Unknown."
If you are using QuickTime 4 Pro, under Compression, it will say "QDesign Music 2"
If this is the case, there are two solutions to this issue:
If you have a Pro version of QuickTime, and you have a local copy of the movie, here is a way to verify if this is the case:
- Open the movie in Movie Player (or QuickTime Player)
- Choose Get Info from the Movie menu
- Choose Sound Track from the left pop-up menu and choose Format from the right pop-up menu.
If you are using QuickTime 3 Pro, under "Compression", if it will say "Unknown."
If you are using QuickTime 4 Pro, under Compression, it will say "QDesign Music 2"
If this is the case, there are two solutions to this issue:
- 1. Download and install QuickTime 4 on the computer where you want to play the movie, or
2. Open the movie on a computer that has QuickTime 4 Pro installed and export it using a different sound compressor that is supported by QuickTime 3.