If hwaccel is NULL, returns the first registered hardware accelerator,
if hwaccel is non-NULL, returns the next registered hardware accelerator
after hwaccel, or NULL if hwaccel is the last one.
@deprecated AVHWaccel structures contain no user-serviceable parts, so
this function should not be used.
If hwaccel is NULL, returns the first registered hardware accelerator, if hwaccel is non-NULL, returns the next registered hardware accelerator after hwaccel, or NULL if hwaccel is the last one.
@deprecated AVHWaccel structures contain no user-serviceable parts, so this function should not be used.