avconv.c:1803: error: Null Dereference
  pointer `ist` last assigned on line 1801 could be null and is dereferenced at line 1803, column 34.

avconv.c:1798:1: start of procedure init_output_stream_streamcopy()
1796. }
1797. 
1798. static int init_output_stream_streamcopy(OutputStream *ost)
      ^
1799. {
1800.     OutputFile *of = output_files[ost->file_index];

avconv.c:1800:5: 
1798. static int init_output_stream_streamcopy(OutputStream *ost)
1799. {
1800.     OutputFile *of = output_files[ost->file_index];
          ^
1801.     InputStream *ist = get_input_stream(ost);
1802.     AVCodecParameters *par_dst = ost->st->codecpar;

avconv.c:1801:5: 
1799. {
1800.     OutputFile *of = output_files[ost->file_index];
1801.     InputStream *ist = get_input_stream(ost);
          ^
1802.     AVCodecParameters *par_dst = ost->st->codecpar;
1803.     AVCodecParameters *par_src = ist->st->codecpar;

avconv.c:1689:1: start of procedure get_input_stream()
  1687. }
  1688. 
  1689. static InputStream *get_input_stream(OutputStream *ost)
        ^
  1690. {
  1691.     if (ost->source_index >= 0)

avconv.c:1691:9: Taking false branch
  1689. static InputStream *get_input_stream(OutputStream *ost)
  1690. {
  1691.     if (ost->source_index >= 0)
                ^
  1692.         return input_streams[ost->source_index];
  1693. 

avconv.c:1694:9: Taking true branch
  1692.         return input_streams[ost->source_index];
  1693. 
  1694.     if (ost->filter) {
                ^
  1695.         FilterGraph *fg = ost->filter->graph;
  1696.         int i;

avconv.c:1695:9: 
  1693. 
  1694.     if (ost->filter) {
  1695.         FilterGraph *fg = ost->filter->graph;
                ^
  1696.         int i;
  1697. 

avconv.c:1698:14: 
  1696.         int i;
  1697. 
  1698.         for (i = 0; i < fg->nb_inputs; i++)
                     ^
  1699.             if (fg->inputs[i]->ist->dec_ctx->codec_type == ost->enc_ctx->codec_type)
  1700.                 return fg->inputs[i]->ist;

avconv.c:1698:21: Loop condition is true. Entering loop body
  1696.         int i;
  1697. 
  1698.         for (i = 0; i < fg->nb_inputs; i++)
                            ^
  1699.             if (fg->inputs[i]->ist->dec_ctx->codec_type == ost->enc_ctx->codec_type)
  1700.                 return fg->inputs[i]->ist;

avconv.c:1699:17: Taking false branch
  1697. 
  1698.         for (i = 0; i < fg->nb_inputs; i++)
  1699.             if (fg->inputs[i]->ist->dec_ctx->codec_type == ost->enc_ctx->codec_type)
                        ^
  1700.                 return fg->inputs[i]->ist;
  1701.     }

avconv.c:1698:40: 
  1696.         int i;
  1697. 
  1698.         for (i = 0; i < fg->nb_inputs; i++)
                                               ^
  1699.             if (fg->inputs[i]->ist->dec_ctx->codec_type == ost->enc_ctx->codec_type)
  1700.                 return fg->inputs[i]->ist;

avconv.c:1698:21: Loop condition is false. Leaving loop
  1696.         int i;
  1697. 
  1698.         for (i = 0; i < fg->nb_inputs; i++)
                            ^
  1699.             if (fg->inputs[i]->ist->dec_ctx->codec_type == ost->enc_ctx->codec_type)
  1700.                 return fg->inputs[i]->ist;

avconv.c:1703:5: 
  1701.     }
  1702. 
  1703.     return NULL;
            ^
  1704. }
  1705. 

avconv.c:1704:1: return from a call to get_input_stream
  1702. 
  1703.     return NULL;
  1704. }
        ^
  1705. 
  1706. /* open the muxer when all the streams are initialized */

avconv.c:1802:5: 
1800.     OutputFile *of = output_files[ost->file_index];
1801.     InputStream *ist = get_input_stream(ost);
1802.     AVCodecParameters *par_dst = ost->st->codecpar;
          ^
1803.     AVCodecParameters *par_src = ist->st->codecpar;
1804.     AVRational sar;

avconv.c:1803:5: 
1801.     InputStream *ist = get_input_stream(ost);
1802.     AVCodecParameters *par_dst = ost->st->codecpar;
1803.     AVCodecParameters *par_src = ist->st->codecpar;
          ^
1804.     AVRational sar;
1805.     int i;
