Called to open further IO contexts when needed for demuxing.
This can be set by the user application to perform security checks on
the URLs before opening them.
The function should behave like avio_open2(), AVFormatContext is provided
as contextual information and to reach AVFormatContext.opaque.
If NULL then some simple checks are used together with avio_open2().
Must not be accessed directly from outside avformat.
@See av_format_set_open_cb()
Called to open further IO contexts when needed for demuxing.
This can be set by the user application to perform security checks on the URLs before opening them. The function should behave like avio_open2(), AVFormatContext is provided as contextual information and to reach AVFormatContext.opaque.
If NULL then some simple checks are used together with avio_open2().
Must not be accessed directly from outside avformat. @See av_format_set_open_cb()
Demuxing: Set by user.
@deprecated Use io_open and io_close.