Use context instead of NULL for logging.

Originally committed as revision 20085 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/dv.c

@@ -631,7 +631,7 @@ static int dv_decode_video_segment(AVCodecContext *avctx, void *arg)
                 dv_decode_ac(&gb, mb, block);
             }
             if (mb->pos >= 64 && mb->pos < 127)
-                av_log(NULL, AV_LOG_ERROR, "AC EOB marker is absent pos=%d\n", mb->pos);
+                av_log(avctx, AV_LOG_ERROR, "AC EOB marker is absent pos=%d\n", mb->pos);
             block += 64;
             mb++;
         }
@@ -1099,7 +1099,7 @@ static int dv_encode_video_segment(AVCodecContext *avctx, void *arg)
        if (enc_blks[j].partial_bit_count)
            pb = dv_encode_ac(&enc_blks[j], pb, &pbs[s->sys->bpm*5]);
        if (enc_blks[j].partial_bit_count)
-            av_log(NULL, AV_LOG_ERROR, "ac bitstream overflow\n");
+            av_log(avctx, AV_LOG_ERROR, "ac bitstream overflow\n");
     }
 
     for (j=0; j<5*s->sys->bpm; j++) {