I was looking for something similar a while ago, and as far as I know, this is not possible using just JavaScript and html (at least not in any reliable way). Firefox and IE 9 seem to offer some support for reading local files, but for the vast majority of visitors to a public site, you will need a Flash, Java, or ActiveX control to access the buffer.
We searched for this functionality for a support service application and installed an inexpensive ActiveX control called xStandard. Thus, I never tested Java to comment on this part of your question. Hope someone else can develop this approach.
Can you provide additional information about your user base, and if running OS and browsers?
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