avconv: only apply presets when we have an encoder.

Fixes a crash when using a preset with stream copy.

CC: libav-stable@libav.org

avconv_opt.c

@@ -754,8 +754,6 @@ static OutputStream *new_output_stream(OptionsContext *o, AVFormatContext *oc, e
     char *bsf = NULL, *next, *codec_tag = NULL;
     AVBitStreamFilterContext *bsfc, *bsfc_prev = NULL;
     double qscale = -1;
-    char *buf = NULL, *arg = NULL, *preset = NULL;
-    AVIOContext *s = NULL;
 
     if (!st) {
         av_log(NULL, AV_LOG_FATAL, "Could not alloc stream.\n");
@@ -777,11 +775,10 @@ static OutputStream *new_output_stream(OptionsContext *o, AVFormatContext *oc, e
     st->codec->codec_type = type;
     choose_encoder(o, oc, ost);
     if (ost->enc) {
-        ost->opts  = filter_codec_opts(codec_opts, ost->enc->id, oc, st, ost->enc);
-    }
+        AVIOContext *s = NULL;
+        char *buf = NULL, *arg = NULL, *preset = NULL;
 
-    avcodec_get_context_defaults3(st->codec, ost->enc);
-    st->codec->codec_type = type; // XXX hack, avcodec_get_context_defaults2() sets type to unknown for stream copy
+        ost->opts  = filter_codec_opts(codec_opts, ost->enc->id, oc, st, ost->enc);
 
         MATCH_PER_STREAM_OPT(presets, str, preset, oc, st);
         if (preset && (!(ret = get_preset_file_2(preset, ost->enc->name, &s)))) {
@@ -807,6 +804,10 @@ static OutputStream *new_output_stream(OptionsContext *o, AVFormatContext *oc, e
                    preset, ost->file_index, ost->index);
             exit(1);
         }
+    }
+
+    avcodec_get_context_defaults3(st->codec, ost->enc);
+    st->codec->codec_type = type; // XXX hack, avcodec_get_context_defaults2() sets type to unknown for stream copy
 
     ost->max_frames = INT64_MAX;
     MATCH_PER_STREAM_OPT(max_frames, i64, ost->max_frames, oc, st);