very low audio output on ripped dvd to MKV

[guymad]

I have a Antec Fusion X2 Media Centre PC running Window 7 64Bit and windows media centre soft ware.
My question is I ripped all my dvd's using "MakeMKV" software and down loaded the codex required to run MKV on windows media centre and get a great picture but the sound is really very low about 10% of where it should be- checked the sound mixer on the pc and not a problem,played a dvd which was ripped AVI and perfect, Tried playing music via itunes and works perfectly so not a hardware issue so leads me to think it is either:
- The ripping process to MKV - but do not think so as there is no area in their software to modify sound o/p level.
- Codex issues

Ideas please???

[leenuss]

Most likely, your MKV contains the original surround sound audio. Multichannel sound files with lots of headroom. Windows Media Player will perform a stereo mixdown but attenuates the volume level to not risk distortion or clipping when 6+ channels of audio will saved to 2 channels.

Your DVD ripped to AVI probably didn't have multichannel surround audio. Either it used a stereo track on the DVD, or the AVI conversion process made a stereo mixdown, then normalized the audio levels to increase the volume.

[Romansh]

Multichannel sound files with lots of headroom. Windows Media Player will perform a stereo mixdown but attenuates the volume level to not risk distortion or clipping when 6+ channels of audio will saved to 2 channels.

My experience is that multichannel audio on DVD and Blu-ray does not have that much headroom. But you are correct in that many devices will normalize Stereo downmix coefficients to avoid clipping, with the result being a low output volume.

Either it used a stereo track on the DVD, or the AVI conversion process made a stereo mixdown, then normalized the audio levels to increase the volume.

It would indeed seem likely.