Under the win7 system, there are some programs that have no sound

Computer shop news Zhang's new computer installed win7sp1 system, the sound card driver is normal and the latest, the system has sound, thousands of listening, qq music, itunes and other programs have sound. QQ video, iQiyi audio and video have pictures but no sound, and there is no display in the audio synthesizer. The video that wmp can play normally has no sound in QQ video. The audio files that can be played normally play in QQ video without sound, install There is still no sound after the storm. The sound card driver has been uninstalled and reinstalled. There is no problem with the file being played. It is the demo video that comes with win7. It should be no problem to decode this video. The main strange thing is that even if there is a problem with the video, the synthesizer should also display QQ video and audio! Do not know what's going on? Analytical answers: 1. There is a problem with the file you are playing, there is no decoding for the files you support, and you need a special plugin. 2. First confirm that there is no problem with the file being played, it is probably a problem of decoding. 3, part of the program has sound, basically can eliminate the hardware and sound card driver problems, it is likely that your program settings, or system settings, it is not good, only re-install the system.