[FFmpeg-devel] [PATCH 1/2] lavc/srtdec: make read_ts preserve the millisecond.

[Clément Bœsch]

On Sun, Sep 02, 2012 at 10:03:17AM +0200, Nicolas George wrote:
> The times are also changed to int64_t.
> 
> Signed-off-by: Nicolas George <nicolas.george at normalesup.org>
> ---
>  libavcodec/srtdec.c |   20 ++++++++++----------
>  1 file changed, 10 insertions(+), 10 deletions(-)
> 
> diff --git a/libavcodec/srtdec.c b/libavcodec/srtdec.c
> index f32521f..12b7e0c 100644
> --- a/libavcodec/srtdec.c
> +++ b/libavcodec/srtdec.c
> @@ -184,21 +184,21 @@ static const char *srt_to_ass(AVCodecContext *avctx, char *out, char *out_end,
>      return in;
>  }
>  
> -static const char *read_ts(const char *buf, int *ts_start, int *ts_end,
> +static const char *read_ts(const char *buf, int64_t *ts_start, int64_t *ts_end,
>                             int *x1, int *y1, int *x2, int *y2)
>  {
> -    int i, hs, ms, ss, he, me, se;
> +    int i, hs, ms, ss, mss, he, me, se, mse;
>  
>      for (i=0; i<2; i++) {
>          /* try to read timestamps in either the first or second line */
>          int c = sscanf(buf, "%d:%2d:%2d%*1[,.]%3d --> %d:%2d:%2d%*1[,.]%3d"
>                         "%*[ ]X1:%u X2:%u Y1:%u Y2:%u",
> -                       &hs, &ms, &ss, ts_start, &he, &me, &se, ts_end,
> +                       &hs, &ms, &ss, &mss, &he, &me, &se, &mse,
>                         x1, x2, y1, y2);
>          buf += strcspn(buf, "\n") + 1;
>          if (c >= 8) {
> -            *ts_start = 100*(ss + 60*(ms + 60*hs)) + *ts_start/10;
> -            *ts_end   = 100*(se + 60*(me + 60*he)) + *ts_end  /10;
> +            *ts_start = (int64_t)1000*(ss + 60*(ms + 60*hs)) + mss;
> +            *ts_end   = (int64_t)1000*(se + 60*(me + 60*he)) + mse;
>              return buf;
>          }
>      }
> @@ -209,7 +209,8 @@ static int srt_decode_frame(AVCodecContext *avctx,
>                              void *data, int *got_sub_ptr, AVPacket *avpkt)
>  {
>      AVSubtitle *sub = data;
> -    int ts_start, ts_end, x1 = -1, y1 = -1, x2 = -1, y2 = -1;
> +    int64_t ts_start, ts_end;
> +    int x1 = -1, y1 = -1, x2 = -1, y2 = -1;
>      char buffer[2048];
>      const char *ptr = avpkt->data;
>      const char *end = avpkt->data + avpkt->size;
> @@ -223,17 +224,16 @@ static int srt_decode_frame(AVCodecContext *avctx,
>              if (!ptr)
>                  break;
>          } else {
> -            // Do final divide-by-10 outside rescale to force rounding down.
>              ts_start = av_rescale_q(avpkt->pts,
>                                      avctx->time_base,
> -                                    (AVRational){1,100});
> +                                    (AVRational){1,1000});
>              ts_end   = av_rescale_q(avpkt->pts + avpkt->duration,
>                                      avctx->time_base,
> -                                    (AVRational){1,100});
> +                                    (AVRational){1,1000});
>          }
>          ptr = srt_to_ass(avctx, buffer, buffer+sizeof(buffer), ptr,
>                           x1, y1, x2, y2);
> -        ff_ass_add_rect(sub, buffer, ts_start, ts_end-ts_start, 0);
> +        ff_ass_add_rect(sub, buffer, ts_start / 10, ts_end / 10 - ts_start / 10, 0);
>      }
>  

IMO the correct this is to make read_ts() just skip the TS (shift the
pointer to the payload) and always rely on the avpkt->pts (SRT demuxer and
MKV demuxer should always set the correct timing).

Then the rescale to 1/100 is correct for the ASS step.

[...]

-- 
Clément B.
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