[FFmpeg-devel] [PATCH] avformat/tty: add probe function

[James Almer]

On 1/27/2020 7:16 PM, Paul B Mahol wrote:
> Signed-off-by: Paul B Mahol <onemda at gmail.com>
> ---
>  libavformat/tty.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/libavformat/tty.c b/libavformat/tty.c
> index 8d48f2c45c..75af16a6f1 100644
> --- a/libavformat/tty.c
> +++ b/libavformat/tty.c
> @@ -24,6 +24,8 @@
>   * Tele-typewriter demuxer
>   */
>  
> +#include <ctype.h>
> +
>  #include "libavutil/intreadwrite.h"
>  #include "libavutil/avstring.h"
>  #include "libavutil/log.h"
> @@ -42,6 +44,17 @@ typedef struct TtyDemuxContext {
>      AVRational framerate; /**< Set by a private option. */
>  } TtyDemuxContext;
>  
> +static int read_probe(const AVProbeData *p)
> +{
> +    int64_t cnt = 0;
> +
> +    for (int i = 0; i < p->buf_size; i++)
> +        cnt += !!isprint(p->buf[i]);

cnt here will never be > p->buf_size, so just make it an int and cast it
to int64_t in the line below. Otherwise the above loop will be slower
than necessary on 32 bit arches.

> +
> +    return (cnt * 100 / p->buf_size) * (cnt > 500) *
> +        !!av_match_ext(p->filename, "ans,art,asc,diz,ice,nfo,txt,vt");
> +}
> +
>  /**
>   * Parse EFI header
>   */
> @@ -153,6 +166,7 @@ AVInputFormat ff_tty_demuxer = {
>      .name           = "tty",
>      .long_name      = NULL_IF_CONFIG_SMALL("Tele-typewriter"),
>      .priv_data_size = sizeof(TtyDemuxContext),
> +    .read_probe     = read_probe,
>      .read_header    = read_header,
>      .read_packet    = read_packet,
>      .extensions     = "ans,art,asc,diz,ice,nfo,txt,vt",
>