这个问题困扰我很久了
MPEG4的avi，在PM6中打开，拖到Timeline中就没了声音，虽然音轨中有声音显示，无论怎样选择输出设置，都没用。处理其它视频没一点问题。
这是我的原avi文件的信息。其中音频采用MPEG Layer-3 Codec 压缩，而我的pm6的音频输出无此选项，不知是否是这个原因：
File Size: 264.37MB bytes
Total Duration: 0:49:14:00
Average Data Rate: 91.64KB per second
Image Size: 352 x 288
Pixel Depth: 24 bits
Frame Rate: 25.00 fps

Audio: 44100 Hz - 16 bit - Stereo

AVI File details:
Contains 1 video track(s) and 1 audio track(s).

Video track 1:
Total duration is 0:49:14:00
Size is 227.14MB bytes (average frame = 3.61KB bytes)
There are 297 keyframes, 73553 delta frames.
Frame rate is 25.00 fps
Frame size is 352 x 288
Depth is 24 bits.
Compressor: 'DIV3', DivX ;-) MPEG-4 Low-Motion

Audio track 1:
Size is 33.75MB bytes
Rate is 44100 samples/sec, stereo
Sample size is 16 bits
Compatible compressor: MPEG Layer-3 Codec
Compression ratio is -3.-12:1