lavr: make avresample_read() with NULL output discard samples.

libavresample/avresample.h

@@ -274,7 +274,8 @@ int avresample_available(AVAudioResampleContext *avr);
  * @see avresample_convert()
  *
  * @param avr         audio resample context
- * @param output      output data pointers
+ * @param output      output data pointers. May be NULL, in which case
+ *                    nb_samples of data is discarded from output FIFO.
  * @param nb_samples  number of samples to read from the FIFO
  * @return            the number of samples written to output
  */

libavresample/utils.c

@@ -385,6 +385,8 @@ int avresample_available(AVAudioResampleContext *avr)
 
 int avresample_read(AVAudioResampleContext *avr, void **output, int nb_samples)
 {
+    if (!output)
+        return av_audio_fifo_drain(avr->out_fifo, nb_samples);
     return av_audio_fifo_read(avr->out_fifo, output, nb_samples);
 }
 

libavresample/version.h

@@ -21,7 +21,7 @@
 
 #define LIBAVRESAMPLE_VERSION_MAJOR  0
 #define LIBAVRESAMPLE_VERSION_MINOR  0
-#define LIBAVRESAMPLE_VERSION_MICRO  1
+#define LIBAVRESAMPLE_VERSION_MICRO  2
 
 #define LIBAVRESAMPLE_VERSION_INT  AV_VERSION_INT(LIBAVRESAMPLE_VERSION_MAJOR, \
                                                   LIBAVRESAMPLE_VERSION_MINOR, \