libavcodec/mpegvideo.c:1694: error: Null Dereference
  pointer `desc` last assigned on line 1693 could be null and is dereferenced at line 1694, column 21.

libavcodec/mpegvideo.c:1679:1: start of procedure ff_MPV_frame_end()
1677. /* generic function for encode/decode called after a
1678.  * frame has been coded/decoded. */
1679. void ff_MPV_frame_end(MpegEncContext *s)
      ^
1680. {
1681.     int i;

libavcodec/mpegvideo.c:1684:9: Taking false branch
1682.     /* redraw edges for the frame if decoding didn't complete */
1683.     // just to make sure that all data is rendered.
1684.     if (CONFIG_MPEG_XVMC_DECODER && s->avctx->xvmc_acceleration) {
              ^
1685.         ff_xvmc_field_end(s);
1686.    } else if ((s->er.error_count || s->encoding) &&

libavcodec/mpegvideo.c:1686:16: Taking false branch
1684.     if (CONFIG_MPEG_XVMC_DECODER && s->avctx->xvmc_acceleration) {
1685.         ff_xvmc_field_end(s);
1686.    } else if ((s->er.error_count || s->encoding) &&
                     ^
1687.               !s->avctx->hwaccel &&
1688.               !(s->avctx->codec->capabilities & CODEC_CAP_HWACCEL_VDPAU) &&

libavcodec/mpegvideo.c:1686:37: Taking true branch
1684.     if (CONFIG_MPEG_XVMC_DECODER && s->avctx->xvmc_acceleration) {
1685.         ff_xvmc_field_end(s);
1686.    } else if ((s->er.error_count || s->encoding) &&
                                          ^
1687.               !s->avctx->hwaccel &&
1688.               !(s->avctx->codec->capabilities & CODEC_CAP_HWACCEL_VDPAU) &&

libavcodec/mpegvideo.c:1687:16: Taking true branch
1685.         ff_xvmc_field_end(s);
1686.    } else if ((s->er.error_count || s->encoding) &&
1687.               !s->avctx->hwaccel &&
                     ^
1688.               !(s->avctx->codec->capabilities & CODEC_CAP_HWACCEL_VDPAU) &&
1689.               s->unrestricted_mv &&

libavcodec/mpegvideo.c:1688:17: Taking true branch
1686.    } else if ((s->er.error_count || s->encoding) &&
1687.               !s->avctx->hwaccel &&
1688.               !(s->avctx->codec->capabilities & CODEC_CAP_HWACCEL_VDPAU) &&
                      ^
1689.               s->unrestricted_mv &&
1690.               s->current_picture.reference &&

libavcodec/mpegvideo.c:1689:15: Taking true branch
1687.               !s->avctx->hwaccel &&
1688.               !(s->avctx->codec->capabilities & CODEC_CAP_HWACCEL_VDPAU) &&
1689.               s->unrestricted_mv &&
                    ^
1690.               s->current_picture.reference &&
1691.               !s->intra_only &&

libavcodec/mpegvideo.c:1690:15: Taking true branch
1688.               !(s->avctx->codec->capabilities & CODEC_CAP_HWACCEL_VDPAU) &&
1689.               s->unrestricted_mv &&
1690.               s->current_picture.reference &&
                    ^
1691.               !s->intra_only &&
1692.               !(s->flags & CODEC_FLAG_EMU_EDGE)) {

libavcodec/mpegvideo.c:1691:16: Taking true branch
1689.               s->unrestricted_mv &&
1690.               s->current_picture.reference &&
1691.               !s->intra_only &&
                     ^
1692.               !(s->flags & CODEC_FLAG_EMU_EDGE)) {
1693.        const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(s->avctx->pix_fmt);

libavcodec/mpegvideo.c:1692:17: Taking true branch
1690.               s->current_picture.reference &&
1691.               !s->intra_only &&
1692.               !(s->flags & CODEC_FLAG_EMU_EDGE)) {
                      ^
1693.        const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(s->avctx->pix_fmt);
1694.        int hshift = desc->log2_chroma_w;

libavcodec/mpegvideo.c:1693:8: 
1691.               !s->intra_only &&
1692.               !(s->flags & CODEC_FLAG_EMU_EDGE)) {
1693.        const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(s->avctx->pix_fmt);
             ^
1694.        int hshift = desc->log2_chroma_w;
1695.        int vshift = desc->log2_chroma_h;

libavutil/pixdesc.c:1464:1: start of procedure av_pix_fmt_desc_get()
  1462. }
  1463. 
  1464. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
        ^
  1465. {
  1466.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)

libavutil/pixdesc.c:1466:9: Taking false branch
  1464. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1465. {
  1466.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                ^
  1467.         return NULL;
  1468.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1466:24: Taking true branch
  1464. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1465. {
  1466.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                               ^
  1467.         return NULL;
  1468.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1467:9: 
  1465. {
  1466.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
  1467.         return NULL;
                ^
  1468.     return &av_pix_fmt_descriptors[pix_fmt];
  1469. }

libavutil/pixdesc.c:1469:1: return from a call to av_pix_fmt_desc_get
  1467.         return NULL;
  1468.     return &av_pix_fmt_descriptors[pix_fmt];
  1469. }
        ^
  1470. 
  1471. const AVPixFmtDescriptor *av_pix_fmt_desc_next(const AVPixFmtDescriptor *prev)

libavcodec/mpegvideo.c:1694:8: 
1692.               !(s->flags & CODEC_FLAG_EMU_EDGE)) {
1693.        const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(s->avctx->pix_fmt);
1694.        int hshift = desc->log2_chroma_w;
             ^
1695.        int vshift = desc->log2_chroma_h;
1696.        s->dsp.draw_edges(s->current_picture.f.data[0], s->linesize,

void ff_MPV_frame_end(MpegEncContext *s)
{
    int i;
    if (CONFIG_MPEG_XVMC_DECODER && s->avctx->xvmc_acceleration) {
        ff_xvmc_field_end(s);
   } else if ((s->er.error_count || s->encoding) &&
              !s->avctx->hwaccel &&
              !(s->avctx->codec->capabilities & CODEC_CAP_HWACCEL_VDPAU) &&
              s->unrestricted_mv &&
              s->current_picture.reference &&
              !s->intra_only &&
              !(s->flags & CODEC_FLAG_EMU_EDGE)) {
       const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(s->avctx->pix_fmt);
       int hshift = desc->log2_chroma_w;
       int vshift = desc->log2_chroma_h;
       s->dsp.draw_edges(s->current_picture.f.data[0], s->linesize,
                         s->h_edge_pos, s->v_edge_pos,
                         EDGE_WIDTH, EDGE_WIDTH,
                         EDGE_TOP | EDGE_BOTTOM);
       s->dsp.draw_edges(s->current_picture.f.data[1], s->uvlinesize,
                         s->h_edge_pos >> hshift, s->v_edge_pos >> vshift,
                         EDGE_WIDTH >> hshift, EDGE_WIDTH >> vshift,
                         EDGE_TOP | EDGE_BOTTOM);
       s->dsp.draw_edges(s->current_picture.f.data[2], s->uvlinesize,
                         s->h_edge_pos >> hshift, s->v_edge_pos >> vshift,
                         EDGE_WIDTH >> hshift, EDGE_WIDTH >> vshift,
                         EDGE_TOP | EDGE_BOTTOM);
    }
    emms_c();
    s->last_pict_type                 = s->pict_type;
    s->last_lambda_for [s->pict_type] = s->current_picture_ptr->f.quality;
    if (s->pict_type!= AV_PICTURE_TYPE_B) {
        s->last_non_b_pict_type = s->pict_type;
    }
#if 0
    for (i = 0; i < MAX_PICTURE_COUNT; i++) {
        if (s->picture[i].f.data[0] == s->current_picture.f.data[0]) {
            s->picture[i] = s->current_picture;
            break;
        }
    }
    assert(i < MAX_PICTURE_COUNT);
#endif
    if (s->encoding) {
        for (i = 0; i < MAX_PICTURE_COUNT; i++) {
            if (!s->picture[i].reference)
                ff_mpeg_unref_picture(s, &s->picture[i]);
        }
    }
#if 0
    memset(&s->last_picture,    0, sizeof(Picture));
    memset(&s->next_picture,    0, sizeof(Picture));
    memset(&s->current_picture, 0, sizeof(Picture));
#endif
    s->avctx->coded_frame = &s->current_picture_ptr->f;
    if (s->current_picture.reference)
        ff_thread_report_progress(&s->current_picture_ptr->tf, INT_MAX, 0);
}
['void ff_MPV_frame_end(MpegEncContext *s)\n{\n    int i;\n    if (CONFIG_MPEG_XVMC_DECODER && s->avctx->xvmc_acceleration) {\n        ff_xvmc_field_end(s);\n   } else if ((s->er.error_count || s->encoding) &&\n              !s->avctx->hwaccel &&\n              !(s->avctx->codec->capabilities & CODEC_CAP_HWACCEL_VDPAU) &&\n              s->unrestricted_mv &&\n              s->current_picture.reference &&\n              !s->intra_only &&\n              !(s->flags & CODEC_FLAG_EMU_EDGE)) {\n       const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(s->avctx->pix_fmt);\n       int hshift = desc->log2_chroma_w;\n       int vshift = desc->log2_chroma_h;\n       s->dsp.draw_edges(s->current_picture.f.data[0], s->linesize,\n                         s->h_edge_pos, s->v_edge_pos,\n                         EDGE_WIDTH, EDGE_WIDTH,\n                         EDGE_TOP | EDGE_BOTTOM);\n       s->dsp.draw_edges(s->current_picture.f.data[1], s->uvlinesize,\n                         s->h_edge_pos >> hshift, s->v_edge_pos >> vshift,\n                         EDGE_WIDTH >> hshift, EDGE_WIDTH >> vshift,\n                         EDGE_TOP | EDGE_BOTTOM);\n       s->dsp.draw_edges(s->current_picture.f.data[2], s->uvlinesize,\n                         s->h_edge_pos >> hshift, s->v_edge_pos >> vshift,\n                         EDGE_WIDTH >> hshift, EDGE_WIDTH >> vshift,\n                         EDGE_TOP | EDGE_BOTTOM);\n    }\n    emms_c();\n    s->last_pict_type                 = s->pict_type;\n    s->last_lambda_for [s->pict_type] = s->current_picture_ptr->f.quality;\n    if (s->pict_type!= AV_PICTURE_TYPE_B) {\n        s->last_non_b_pict_type = s->pict_type;\n    }\n#if 0\n    for (i = 0; i < MAX_PICTURE_COUNT; i++) {\n        if (s->picture[i].f.data[0] == s->current_picture.f.data[0]) {\n            s->picture[i] = s->current_picture;\n            break;\n        }\n    }\n    assert(i < MAX_PICTURE_COUNT);\n#endif\n    if (s->encoding) {\n        for (i = 0; i < MAX_PICTURE_COUNT; i++) {\n            if (!s->picture[i].reference)\n                ff_mpeg_unref_picture(s, &s->picture[i]);\n        }\n    }\n#if 0\n    memset(&s->last_picture,    0, sizeof(Picture));\n    memset(&s->next_picture,    0, sizeof(Picture));\n    memset(&s->current_picture, 0, sizeof(Picture));\n#endif\n    s->avctx->coded_frame = &s->current_picture_ptr->f;\n    if (s->current_picture.reference)\n        ff_thread_report_progress(&s->current_picture_ptr->tf, INT_MAX, 0);\n}', 'const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)\n{\n    if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)\n        return NULL;\n    return &av_pix_fmt_descriptors[pix_fmt];\n}']