swr: allow flushing in multiple steps if the output is too small.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libswresample/swresample.c

@@ -435,6 +435,7 @@ int swr_convert(struct SwrContext *s, uint8_t *out_arg[SWR_CH_MAX], int out_coun
 
     if(!in_arg){
         if(s->in_buffer_count){
+            if (!s->flushed) {
                 AudioData *a= &s->in_buffer;
                 int i, j, ret;
                 if((ret=realloc_audio(a, s->in_buffer_index + 2*s->in_buffer_count)) < 0)
@@ -448,6 +449,8 @@ int swr_convert(struct SwrContext *s, uint8_t *out_arg[SWR_CH_MAX], int out_coun
                 }
                 s->in_buffer_count += (s->in_buffer_count+1)/2;
                 s->resample_in_constraint = 0;
+                s->flushed = 1;
+            }
         }else{
             return 0;
         }

libswresample/swresample_internal.h

@@ -64,6 +64,7 @@ struct SwrContext {
     int in_buffer_index;                            ///< cached buffer position
     int in_buffer_count;                            ///< cached buffer length
     int resample_in_constraint;                     ///< 1 if the input end was reach before the output end, 0 otherwise
+    int flushed;                                    ///< 1 if data is to be flushed and no further input is expected
 
     struct AudioConvert *in_convert;                ///< input conversion context
     struct AudioConvert *out_convert;               ///< output conversion context