[FFmpeg-devel] [PATCH 1/3] lavc/srtenc: fix invalid read in case of SubRip.

[Philip Langdale]

On 2012-10-25 10:03, Clément Bœsch wrote:
> Regression since 6057de19b. The ptr-2 is used to eat the \r\n and add
> the position information on the timing line. This can't be done in 
> case
> of SubRip where the timing isn't present in the payload.
>
> Note that we can't use yet the side data to transmit the position
> information since the encode subtitles API is still using buffer+size
> instead AVPacket as input.
> ---
>  libavcodec/srtenc.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/libavcodec/srtenc.c b/libavcodec/srtenc.c
> index 473c88f..56f29e9 100644
> --- a/libavcodec/srtenc.c
> +++ b/libavcodec/srtenc.c
> @@ -203,6 +203,8 @@ static void srt_move_cb(void *priv, int x1, int
> y1, int x2, int y2,
>                          int t1, int t2)
>  {
>      SRTContext *s = priv;
> +
> +    if (s->avctx->codec->id == CODEC_ID_SRT) {
>      char buffer[32];
>      int len = snprintf(buffer, sizeof(buffer),
>                         "  X1:%03u X2:%03u Y1:%03u Y2:%03u", x1, x2, 
> y1, y2);
> @@ -211,6 +213,7 @@ static void srt_move_cb(void *priv, int x1, int
> y1, int x2, int y2,
>          memcpy(s->dialog_start, buffer, len);
>          s->ptr += len;
>      }
> +    }
>  }
>
>  static void srt_end_cb(void *priv)
> @@ -262,9 +265,9 @@ static int srt_encode_frame(AVCodecContext 
> *avctx,
>                  es = ec/   1000;  ec -=    1000*es;
>                  srt_print(s,"%d\r\n%02d:%02d:%02d,%03d -->
> %02d:%02d:%02d,%03d\r\n",
>                            ++s->count, sh, sm, ss, sc, eh, em, es, 
> ec);
> +                s->dialog_start = s->ptr - 2;
>              }
>              s->alignment_applied = 0;
> -            s->dialog_start = s->ptr - 2;
>              srt_style_apply(s, dialog->style);
>              ff_ass_split_override_codes(&srt_callbacks, s, 
> dialog->text);
>          }

Looks good to me.

--phil