[FFmpeg-devel] [PATCH 1/2] avcodec/msmpeg4dec: Don't check for errors for complete VLCs

Andreas Rheinhardt andreas.rheinhardt at gmail.com
Thu Jan 28 15:16:22 EET 2021


Andreas Rheinhardt:
> This also affected other users of VLCs from msmpeg4dec, namely vc1_block
> and wmv2dec.
> 
> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at gmail.com>
> ---
>  libavcodec/msmpeg4.h    |  2 +-
>  libavcodec/msmpeg4dec.c | 20 ++------------------
>  libavcodec/vc1_block.c  | 12 ------------
>  libavcodec/wmv2dec.c    | 20 +++-----------------
>  4 files changed, 6 insertions(+), 48 deletions(-)
> 
> diff --git a/libavcodec/msmpeg4.h b/libavcodec/msmpeg4.h
> index bcdb967401..f9c63b5022 100644
> --- a/libavcodec/msmpeg4.h
> +++ b/libavcodec/msmpeg4.h
> @@ -59,7 +59,7 @@ void ff_msmpeg4_encode_mb(MpegEncContext *s, int16_t block[6][64],
>  int ff_msmpeg4_decode_init(AVCodecContext *avctx);
>  int ff_msmpeg4_decode_picture_header(MpegEncContext *s);
>  int ff_msmpeg4_decode_ext_header(MpegEncContext *s, int buf_size);
> -int ff_msmpeg4_decode_motion(MpegEncContext * s, int *mx_ptr, int *my_ptr);
> +void ff_msmpeg4_decode_motion(MpegEncContext * s, int *mx_ptr, int *my_ptr);
>  int ff_msmpeg4_decode_block(MpegEncContext * s, int16_t * block,
>                              int n, int coded, const uint8_t *scan_table);
>  int ff_msmpeg4_pred_dc(MpegEncContext *s, int n,
> diff --git a/libavcodec/msmpeg4dec.c b/libavcodec/msmpeg4dec.c
> index d059e8eecc..9501b101ca 100644
> --- a/libavcodec/msmpeg4dec.c
> +++ b/libavcodec/msmpeg4dec.c
> @@ -228,8 +228,6 @@ static int msmpeg4v34_decode_mb(MpegEncContext *s, int16_t block[6][64])
>          }
>  
>          code = get_vlc2(&s->gb, ff_mb_non_intra_vlc[DEFAULT_INTER_INDEX].table, MB_NON_INTRA_VLC_BITS, 3);
> -        if (code < 0)
> -            return -1;
>          //s->mb_intra = (code & 0x40) ? 0 : 1;
>          s->mb_intra = (~code & 0x40) >> 6;
>  
> @@ -237,8 +235,6 @@ static int msmpeg4v34_decode_mb(MpegEncContext *s, int16_t block[6][64])
>      } else {
>          s->mb_intra = 1;
>          code = get_vlc2(&s->gb, ff_msmp4_mb_i_vlc.table, MB_INTRA_VLC_BITS, 2);
> -        if (code < 0)
> -            return -1;
>          /* predict coded block pattern */
>          cbp = 0;
>          for(i=0;i<6;i++) {
> @@ -259,8 +255,7 @@ static int msmpeg4v34_decode_mb(MpegEncContext *s, int16_t block[6][64])
>              s->rl_chroma_table_index = s->rl_table_index;
>          }
>          ff_h263_pred_motion(s, 0, 0, &mx, &my);
> -        if (ff_msmpeg4_decode_motion(s, &mx, &my) < 0)
> -            return -1;
> +        ff_msmpeg4_decode_motion(s, &mx, &my);
>          s->mv_dir = MV_DIR_FORWARD;
>          s->mv_type = MV_TYPE_16X16;
>          s->mv[0][0][0] = mx;
> @@ -612,11 +607,6 @@ static int msmpeg4_decode_dc(MpegEncContext * s, int n, int *dir_ptr)
>          } else {
>              level = get_vlc2(&s->gb, ff_msmp4_dc_chroma_vlc[s->dc_table_index].table, DC_VLC_BITS, 3);
>          }
> -        if (level < 0){
> -            av_log(s->avctx, AV_LOG_ERROR, "illegal dc vlc\n");
> -            *dir_ptr = 0;
> -            return -1;
> -        }
>  
>          if (level == DC_MAX) {
>              level = get_bits(&s->gb, 8);
> @@ -838,8 +828,7 @@ int ff_msmpeg4_decode_block(MpegEncContext * s, int16_t * block,
>      return 0;
>  }
>  
> -int ff_msmpeg4_decode_motion(MpegEncContext * s,
> -                                 int *mx_ptr, int *my_ptr)
> +void ff_msmpeg4_decode_motion(MpegEncContext *s, int *mx_ptr, int *my_ptr)
>  {
>      MVTable *mv;
>      int code, mx, my;
> @@ -847,10 +836,6 @@ int ff_msmpeg4_decode_motion(MpegEncContext * s,
>      mv = &ff_mv_tables[s->mv_table_index];
>  
>      code = get_vlc2(&s->gb, mv->vlc.table, MV_VLC_BITS, 2);
> -    if (code < 0){
> -        av_log(s->avctx, AV_LOG_ERROR, "illegal MV code at %d %d\n", s->mb_x, s->mb_y);
> -        return -1;
> -    }
>      if (code == mv->n) {
>          mx = get_bits(&s->gb, 6);
>          my = get_bits(&s->gb, 6);
> @@ -873,7 +858,6 @@ int ff_msmpeg4_decode_motion(MpegEncContext * s,
>          my -= 64;
>      *mx_ptr = mx;
>      *my_ptr = my;
> -    return 0;
>  }
>  
>  AVCodec ff_msmpeg4v1_decoder = {
> diff --git a/libavcodec/vc1_block.c b/libavcodec/vc1_block.c
> index 5c33170933..b6ace37658 100644
> --- a/libavcodec/vc1_block.c
> +++ b/libavcodec/vc1_block.c
> @@ -592,10 +592,6 @@ static int vc1_decode_i_block(VC1Context *v, int16_t block[64], int n,
>      } else {
>          dcdiff = get_vlc2(&s->gb, ff_msmp4_dc_chroma_vlc[s->dc_table_index].table, DC_VLC_BITS, 3);
>      }
> -    if (dcdiff < 0) {
> -        av_log(s->avctx, AV_LOG_ERROR, "Illegal DC VLC\n");
> -        return -1;
> -    }
>      if (dcdiff) {
>          const int m = (v->pq == 1 || v->pq == 2) ? 3 - v->pq : 0;
>          if (dcdiff == 119 /* ESC index value */) {
> @@ -740,10 +736,6 @@ static int vc1_decode_i_block_adv(VC1Context *v, int16_t block[64], int n,
>      } else {
>          dcdiff = get_vlc2(&s->gb, ff_msmp4_dc_chroma_vlc[s->dc_table_index].table, DC_VLC_BITS, 3);
>      }
> -    if (dcdiff < 0) {
> -        av_log(s->avctx, AV_LOG_ERROR, "Illegal DC VLC\n");
> -        return -1;
> -    }
>      if (dcdiff) {
>          const int m = (quant == 1 || quant == 2) ? 3 - quant : 0;
>          if (dcdiff == 119 /* ESC index value */) {
> @@ -944,10 +936,6 @@ static int vc1_decode_intra_block(VC1Context *v, int16_t block[64], int n,
>      } else {
>          dcdiff = get_vlc2(&s->gb, ff_msmp4_dc_chroma_vlc[s->dc_table_index].table, DC_VLC_BITS, 3);
>      }
> -    if (dcdiff < 0) {
> -        av_log(s->avctx, AV_LOG_ERROR, "Illegal DC VLC\n");
> -        return -1;
> -    }
>      if (dcdiff) {
>          const int m = (quant == 1 || quant == 2) ? 3 - quant : 0;
>          if (dcdiff == 119 /* ESC index value */) {
> diff --git a/libavcodec/wmv2dec.c b/libavcodec/wmv2dec.c
> index a16c4465f0..7aae11568c 100644
> --- a/libavcodec/wmv2dec.c
> +++ b/libavcodec/wmv2dec.c
> @@ -278,22 +278,16 @@ int ff_wmv2_decode_secondary_picture_header(MpegEncContext *s)
>      return 0;
>  }
>  
> -static inline int wmv2_decode_motion(Wmv2Context *w, int *mx_ptr, int *my_ptr)
> +static inline void wmv2_decode_motion(Wmv2Context *w, int *mx_ptr, int *my_ptr)
>  {
>      MpegEncContext *const s = &w->s;
> -    int ret;
> -
> -    ret = ff_msmpeg4_decode_motion(s, mx_ptr, my_ptr);
>  
> -    if (ret < 0)
> -        return ret;
> +    ff_msmpeg4_decode_motion(s, mx_ptr, my_ptr);
>  
>      if ((((*mx_ptr) | (*my_ptr)) & 1) && s->mspel)
>          w->hshift = get_bits1(&s->gb);
>      else
>          w->hshift = 0;
> -
> -    return 0;
>  }
>  
>  static int16_t *wmv2_pred_motion(Wmv2Context *w, int *px, int *py)
> @@ -409,8 +403,6 @@ int ff_wmv2_decode_mb(MpegEncContext *s, int16_t block[6][64])
>  
>          code = get_vlc2(&s->gb, ff_mb_non_intra_vlc[w->cbp_table_index].table,
>                          MB_NON_INTRA_VLC_BITS, 3);
> -        if (code < 0)
> -            return AVERROR_INVALIDDATA;
>          s->mb_intra = (~code & 0x40) >> 6;
>  
>          cbp = code & 0x3f;
> @@ -419,11 +411,6 @@ int ff_wmv2_decode_mb(MpegEncContext *s, int16_t block[6][64])
>          if (get_bits_left(&s->gb) <= 0)
>              return AVERROR_INVALIDDATA;
>          code = get_vlc2(&s->gb, ff_msmp4_mb_i_vlc.table, MB_INTRA_VLC_BITS, 2);
> -        if (code < 0) {
> -            av_log(s->avctx, AV_LOG_ERROR,
> -                   "II-cbp illegal at %d %d\n", s->mb_x, s->mb_y);
> -            return AVERROR_INVALIDDATA;
> -        }
>          /* predict coded block pattern */
>          cbp = 0;
>          for (i = 0; i < 6; i++) {
> @@ -456,8 +443,7 @@ int ff_wmv2_decode_mb(MpegEncContext *s, int16_t block[6][64])
>                  w->per_block_abt = 0;
>          }
>  
> -        if ((ret = wmv2_decode_motion(w, &mx, &my)) < 0)
> -            return ret;
> +        wmv2_decode_motion(w, &mx, &my);
>  
>          s->mv_dir      = MV_DIR_FORWARD;
>          s->mv_type     = MV_TYPE_16X16;
> 
Will apply this patchset tomorrow unless there are objections.

- Andreas


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