avfilter/asrc_anullsrc: fix allowed range for sample_rate

Reviewed-by: Paul B Mahol <onemda@gmail.com>
Signed-off-by: James Almer <jamrial@gmail.com>

libavfilter/asrc_anullsrc.c

@@ -51,8 +51,8 @@ typedef struct ANullContext {
 static const AVOption anullsrc_options[]= {
     { "channel_layout", "set channel_layout", OFFSET(ch_layout), AV_OPT_TYPE_CHLAYOUT, {.str = "stereo"}, 0, 0, FLAGS },
     { "cl",             "set channel_layout", OFFSET(ch_layout), AV_OPT_TYPE_CHLAYOUT, {.str = "stereo"}, 0, 0, FLAGS },
-    { "sample_rate",    "set sample rate",    OFFSET(sample_rate)   , AV_OPT_TYPE_INT, {.i64 = 44100}, 0, 0, FLAGS },
-    { "r",              "set sample rate",    OFFSET(sample_rate)   , AV_OPT_TYPE_INT, {.i64 = 44100}, 0, 0, FLAGS },
+    { "sample_rate",    "set sample rate",    OFFSET(sample_rate)   , AV_OPT_TYPE_INT, {.i64 = 44100}, 1, INT_MAX, FLAGS },
+    { "r",              "set sample rate",    OFFSET(sample_rate)   , AV_OPT_TYPE_INT, {.i64 = 44100}, 1, INT_MAX, FLAGS },
     { "nb_samples",     "set the number of samples per requested frame", OFFSET(nb_samples), AV_OPT_TYPE_INT, {.i64 = 1024}, 1, UINT16_MAX, FLAGS },
     { "n",              "set the number of samples per requested frame", OFFSET(nb_samples), AV_OPT_TYPE_INT, {.i64 = 1024}, 1, UINT16_MAX, FLAGS },
     { "duration",       "set the audio duration",                        OFFSET(duration),   AV_OPT_TYPE_DURATION, {.i64 = -1}, -1, INT64_MAX, FLAGS },