I own a Yamaha DVD-S657 player and I stumbled upon a problem while trying to play an XVID encoded movie with VBR MP3 soundtrack. The video keeps freezing-playing-freezing etc while sound plays normally. Converting the soundtrack to CBR solves the problem partially (a 'little' less video freezing going on). I haven't tried playing only the video without the MP3 sountrack muxed in.

Is it possible that my player can't handle the video encoding (I don't know the codec version used unfortunately) ?

Can my player's firmware be upgraded ? I didn't find any downloadable firmware on Yamaha's website. Is the ability to do that wide amongst the players of other manufacturers or is the ability to upgrade the firmware a rarity ? What are the solutions when a new codec version comes out so that the players will be able to handle it ? I'm a beginner in this regard so any info/explanation would really be welcome.

Thanks.