software::resampling::Context: add get_with method (#41)

get_with allows setting additional options not covered by swr_alloc_set_opts.

Signed-off-by: Zhiming Wang <i@zhimingwang.org>

src/software/resampling/context.rs

@@ -3,7 +3,9 @@ use std::ptr;
 use super::Delay;
 use ffi::*;
 use libc::c_int;
+use std::ffi::c_void;
 use util::format;
+use Dictionary;
 use {frame, ChannelLayout, Error};
 
 #[derive(Eq, PartialEq, Copy, Clone)]
@@ -43,6 +45,27 @@ impl Context {
         dst_format: format::Sample,
         dst_channel_layout: ChannelLayout,
         dst_rate: u32,
+    ) -> Result<Self, Error> {
+        Self::get_with(
+            src_format,
+            src_channel_layout,
+            src_rate,
+            dst_format,
+            dst_channel_layout,
+            dst_rate,
+            Dictionary::new(),
+        )
+    }
+
+    /// Create a resampler with the given definitions and custom options dictionary.
+    pub fn get_with(
+        src_format: format::Sample,
+        src_channel_layout: ChannelLayout,
+        src_rate: u32,
+        dst_format: format::Sample,
+        dst_channel_layout: ChannelLayout,
+        dst_rate: u32,
+        options: Dictionary,
     ) -> Result<Self, Error> {
         unsafe {
             let ptr = swr_alloc_set_opts(
@@ -57,6 +80,14 @@ impl Context {
                 ptr::null_mut(),
             );
 
+            let mut opts = options.disown();
+            let res = av_opt_set_dict(ptr as *mut c_void, &mut opts);
+            Dictionary::own(opts);
+
+            if res != 0 {
+                return Err(Error::from(res));
+            }
+
             if !ptr.is_null() {
                 match swr_init(ptr) {
                     e if e < 0 => Err(Error::from(e)),