avconv.c:1671: error: Null Dereference
  pointer `ist` last assigned on line 1669 could be null and is dereferenced at line 1671, column 34.

avconv.c:1666:1: start of procedure init_output_stream_streamcopy()
1664. }
1665. 
1666. static int init_output_stream_streamcopy(OutputStream *ost)
      ^
1667. {
1668.     OutputFile *of = output_files[ost->file_index];

avconv.c:1668:5: 
1666. static int init_output_stream_streamcopy(OutputStream *ost)
1667. {
1668.     OutputFile *of = output_files[ost->file_index];
          ^
1669.     InputStream *ist = get_input_stream(ost);
1670.     AVCodecParameters *par_dst = ost->st->codecpar;

avconv.c:1669:5: 
1667. {
1668.     OutputFile *of = output_files[ost->file_index];
1669.     InputStream *ist = get_input_stream(ost);
          ^
1670.     AVCodecParameters *par_dst = ost->st->codecpar;
1671.     AVCodecParameters *par_src = ist->st->codecpar;

avconv.c:1604:1: start of procedure get_input_stream()
  1602. }
  1603. 
  1604. static InputStream *get_input_stream(OutputStream *ost)
        ^
  1605. {
  1606.     if (ost->source_index >= 0)

avconv.c:1606:9: Taking false branch
  1604. static InputStream *get_input_stream(OutputStream *ost)
  1605. {
  1606.     if (ost->source_index >= 0)
                ^
  1607.         return input_streams[ost->source_index];
  1608. 

avconv.c:1609:9: Taking true branch
  1607.         return input_streams[ost->source_index];
  1608. 
  1609.     if (ost->filter) {
                ^
  1610.         FilterGraph *fg = ost->filter->graph;
  1611.         int i;

avconv.c:1610:9: 
  1608. 
  1609.     if (ost->filter) {
  1610.         FilterGraph *fg = ost->filter->graph;
                ^
  1611.         int i;
  1612. 

avconv.c:1613:14: 
  1611.         int i;
  1612. 
  1613.         for (i = 0; i < fg->nb_inputs; i++)
                     ^
  1614.             if (fg->inputs[i]->ist->dec_ctx->codec_type == ost->enc_ctx->codec_type)
  1615.                 return fg->inputs[i]->ist;

avconv.c:1613:21: Loop condition is true. Entering loop body
  1611.         int i;
  1612. 
  1613.         for (i = 0; i < fg->nb_inputs; i++)
                            ^
  1614.             if (fg->inputs[i]->ist->dec_ctx->codec_type == ost->enc_ctx->codec_type)
  1615.                 return fg->inputs[i]->ist;

avconv.c:1614:17: Taking false branch
  1612. 
  1613.         for (i = 0; i < fg->nb_inputs; i++)
  1614.             if (fg->inputs[i]->ist->dec_ctx->codec_type == ost->enc_ctx->codec_type)
                        ^
  1615.                 return fg->inputs[i]->ist;
  1616.     }

avconv.c:1613:40: 
  1611.         int i;
  1612. 
  1613.         for (i = 0; i < fg->nb_inputs; i++)
                                               ^
  1614.             if (fg->inputs[i]->ist->dec_ctx->codec_type == ost->enc_ctx->codec_type)
  1615.                 return fg->inputs[i]->ist;

avconv.c:1613:21: Loop condition is false. Leaving loop
  1611.         int i;
  1612. 
  1613.         for (i = 0; i < fg->nb_inputs; i++)
                            ^
  1614.             if (fg->inputs[i]->ist->dec_ctx->codec_type == ost->enc_ctx->codec_type)
  1615.                 return fg->inputs[i]->ist;

avconv.c:1618:5: 
  1616.     }
  1617. 
  1618.     return NULL;
            ^
  1619. }
  1620. 

avconv.c:1619:1: return from a call to get_input_stream
  1617. 
  1618.     return NULL;
  1619. }
        ^
  1620. 
  1621. static int init_output_bsfs(OutputStream *ost)

avconv.c:1670:5: 
1668.     OutputFile *of = output_files[ost->file_index];
1669.     InputStream *ist = get_input_stream(ost);
1670.     AVCodecParameters *par_dst = ost->st->codecpar;
          ^
1671.     AVCodecParameters *par_src = ist->st->codecpar;
1672.     AVRational sar;

avconv.c:1671:5: 
1669.     InputStream *ist = get_input_stream(ost);
1670.     AVCodecParameters *par_dst = ost->st->codecpar;
1671.     AVCodecParameters *par_src = ist->st->codecpar;
          ^
1672.     AVRational sar;
1673.     int i;
