[FFmpeg-devel] [PATCH] make mpeg-ps probe less happy with random data

[Måns Rullgård]

Michael Niedermayer <michaelni at gmx.at> writes:

> currently the mpeg-ps probe code will detect various random things
> as mpeg-ps
> for example the O-MP3-5.mp3 posted by someone today
>
> i think returning AVPROBE_SCORE_MAX/2+2 for random data with 0 bytes
> more frequently occuring is not good
>
> the attached patch reduces this problem and besides the extra complexity
> is i think harmless
> ill apply it in 3 days or so if noone objects
>
> Index: libavformat/mpeg.c
> ===================================================================
> --- libavformat/mpeg.c	(revision 11117)
> +++ libavformat/mpeg.c	(working copy)
> @@ -67,7 +67,7 @@
>  static int mpegps_probe(AVProbeData *p)
>  {
>      uint32_t code= -1;
> -    int sys=0, pspack=0, priv1=0, vid=0, audio=0;
> +    int sys=0, pspack=0, priv1=0, vid=0, audio=0, invalid=0;
>      int i;
>      int score=0;
>  
> @@ -85,16 +85,19 @@
>              else if(code == PACK_START_CODE)     pspack++;
>              else if((code & 0xf0) == VIDEO_ID && pes) vid++;
>              else if((code & 0xe0) == AUDIO_ID && pes) audio++;
> +
> +            else if((code & 0xf0) == VIDEO_ID && !pes) invalid++;
> +            else if((code & 0xe0) == AUDIO_ID && !pes) invalid++;
>          }
>      }
>  
> -    if(vid || audio)            /* invalid VDR files nd short PES streams */
> +    if(vid+audio > invalid)            /* invalid VDR files nd short PES streams */
                                   ^^^^^^^
Please remove that excess whitespace to make the line of proper
length.

>          score= AVPROBE_SCORE_MAX/4;
>  
>  //av_log(NULL, AV_LOG_ERROR, "%d %d %d %d %d len:%d\n", sys, priv1, pspack,vid, audio, p->buf_size);
> -    if(sys && sys*9 <= pspack*10)
> +    if(sys>invalid && sys*9 <= pspack*10)
>          return AVPROBE_SCORE_MAX/2+2; // +1 for .mpg
> -    if((priv1 || vid || audio) && (priv1+vid+audio)*9 <= pspack*10)
> +    if(priv1 + vid + audio > invalid && (priv1+vid+audio)*9 <= pspack*10)
>          return AVPROBE_SCORE_MAX/2+2; // +1 for .mpg
>      if((!!vid ^ !!audio) && (audio+vid > 1) && !sys && !pspack && p->buf_size>2048) /* PES stream */
>          return AVPROBE_SCORE_MAX/2+2;

Looks OK, commit anytime.

-- 
M?ns Rullg?rd
mans at mansr.com