File README of Package libvdpau

DEBUGGING AND TRACING

The VDPAU wrapper library supports tracing VDPAU function calls, and their
parameters. This tracing is controlled by the following environment variables:

VDPAU_TRACE

    Enables tracing. Set to 1 to trace function calls. Set to 2 to trace all
    arguments passed to the function.

VDPAU_TRACE_FILE

    Filename to write traces to. By default, traces are sent to stderr. This
    variable may either contain a plain filename, or a reference to an
    existing open file-descriptor in the format "&N" where N is the file
    descriptor number.


The VDPAU wrapper library is responsible for determining which vendor-specific
driver to load for a given X11 display/screen. At present, it hard-codes
"nvidia" as the driver. The environment variable VDPAU_DRIVER may be set to
override this default. The actual library loaded will be
libvdpau_${VDPAU_DRIVER}.so. Setting VDPAU_DRIVER to "trace" is not advised.