ffmpeg: fix for-muxer AVCodecContext stuff

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

ffmpeg.c

@@ -845,6 +845,7 @@ static void do_video_out(AVFormatContext *s,
     int ret, format_video_sync;
     AVPacket pkt;
     AVCodecContext *enc = ost->enc_ctx;
+    AVCodecContext *mux_enc = ost->st->codec;
     int nb_frames, i;
     double sync_ipts, delta;
     double duration = 0;
@@ -945,12 +946,12 @@ static void do_video_out(AVFormatContext *s,
         /* raw pictures are written as AVPicture structure to
            avoid any copies. We support temporarily the older
            method. */
-        enc->coded_frame->interlaced_frame = in_picture->interlaced_frame;
-        enc->coded_frame->top_field_first  = in_picture->top_field_first;
-        if (enc->coded_frame->interlaced_frame)
-            enc->field_order = enc->coded_frame->top_field_first ? AV_FIELD_TB:AV_FIELD_BT;
+        mux_enc->coded_frame->interlaced_frame = in_picture->interlaced_frame;
+        mux_enc->coded_frame->top_field_first  = in_picture->top_field_first;
+        if (mux_enc->coded_frame->interlaced_frame)
+            mux_enc->field_order = mux_enc->coded_frame->top_field_first ? AV_FIELD_TB:AV_FIELD_BT;
         else
-            enc->field_order = AV_FIELD_PROGRESSIVE;
+            mux_enc->field_order = AV_FIELD_PROGRESSIVE;
         pkt.data   = (uint8_t *)in_picture;
         pkt.size   =  sizeof(AVPicture);
         pkt.pts    = av_rescale_q(in_picture->pts, enc->time_base, ost->st->time_base);
@@ -967,11 +968,11 @@ static void do_video_out(AVFormatContext *s,
 
         if (in_picture->interlaced_frame) {
             if (enc->codec->id == AV_CODEC_ID_MJPEG)
-                enc->field_order = in_picture->top_field_first ? AV_FIELD_TT:AV_FIELD_BB;
+                mux_enc->field_order = in_picture->top_field_first ? AV_FIELD_TT:AV_FIELD_BB;
             else
-                enc->field_order = in_picture->top_field_first ? AV_FIELD_TB:AV_FIELD_BT;
+                mux_enc->field_order = in_picture->top_field_first ? AV_FIELD_TB:AV_FIELD_BT;
         } else
-            enc->field_order = AV_FIELD_PROGRESSIVE;
+            mux_enc->field_order = AV_FIELD_PROGRESSIVE;
 
         in_picture->quality = enc->global_quality;
         if (!enc->me_threshold)