[FFmpeg-devel] [PATCH] avfilter/vf_libvmaf: fix string comparison bug

[Kyle Swanson]

Hi,

On Mon, Dec 4, 2023 at 7:59 AM Nil Fons Miret via ffmpeg-devel
<ffmpeg-devel at ffmpeg.org> wrote:
>
> The libvmaf filter was doing substring checks in place of string
> equality comparisons. This led to a bug when the user specified the
> pooling method "harmonic_mean", since "mean" was checked first and the
> substring comparison returned true. This patch changes all substring
> comparisons for string equality comparisons. This is both correct and
> more efficient than the existing method.
>
> Signed-off-by: nilfm <nilf at netflix.com>
> ---
> libavfilter/vf_libvmaf.c | 30 +++++++++++++++---------------
> 1 file changed, 15 insertions(+), 15 deletions(-)
>
> diff --git a/libavfilter/vf_libvmaf.c b/libavfilter/vf_libvmaf.c
> index 12810b7267..46ff8154ef 100644
> --- a/libavfilter/vf_libvmaf.c
> +++ b/libavfilter/vf_libvmaf.c
> @@ -251,7 +251,7 @@ static int parse_features(AVFilterContext *ctx)
>         const AVDictionaryEntry *e = NULL;
>
>         while (e = av_dict_iterate(dict[i], e)) {
> -            if (av_stristr(e->key, "name")) {
> +            if (!strcmp(e->key, "name")) {
>                 feature_name = e->value;
>                 continue;
>             }
> @@ -312,29 +312,29 @@ static int parse_models(AVFilterContext *ctx)
>         char  *path = NULL;
>
>         while (e = av_dict_iterate(dict[i], e)) {
> -            if (av_stristr(e->key, "disable_clip")) {
> -                model_cfg.flags |= av_stristr(e->value, "true") ?
> +            if (!strcmp(e->key, "disable_clip")) {
> +                model_cfg.flags |= !strcmp(e->value, "true") ?
>                     VMAF_MODEL_FLAG_DISABLE_CLIP : 0;
>                 continue;
>             }
>
> -            if (av_stristr(e->key, "enable_transform")) {
> -                model_cfg.flags |= av_stristr(e->value, "true") ?
> +            if (!strcmp(e->key, "enable_transform")) {
> +                model_cfg.flags |= !strcmp(e->value, "true") ?
>                     VMAF_MODEL_FLAG_ENABLE_TRANSFORM : 0;
>                 continue;
>             }
>
> -            if (av_stristr(e->key, "name")) {
> +            if (!strcmp(e->key, "name")) {
>                 model_cfg.name = e->value;
>                 continue;
>             }
>
> -            if (av_stristr(e->key, "version")) {
> +            if (!strcmp(e->key, "version")) {
>                 version = e->value;
>                 continue;
>             }
>
> -            if (av_stristr(e->key, "path")) {
> +            if (!strcmp(e->key, "path")) {
>                 path = e->value;
>                 continue;
>             }
> @@ -529,13 +529,13 @@ static int activate(AVFilterContext *ctx)
> static enum VmafOutputFormat log_fmt_map(const char *log_fmt)
> {
>     if (log_fmt) {
> -        if (av_stristr(log_fmt, "xml"))
> +        if (!strcmp(log_fmt, "xml"))
>             return VMAF_OUTPUT_FORMAT_XML;
> -        if (av_stristr(log_fmt, "json"))
> +        if (!strcmp(log_fmt, "json"))
>             return VMAF_OUTPUT_FORMAT_JSON;
> -        if (av_stristr(log_fmt, "csv"))
> +        if (!strcmp(log_fmt, "csv"))
>             return VMAF_OUTPUT_FORMAT_CSV;
> -        if (av_stristr(log_fmt, "sub"))
> +        if (!strcmp(log_fmt, "sub"))
>             return VMAF_OUTPUT_FORMAT_SUB;
>     }
>
> @@ -545,11 +545,11 @@ static enum VmafOutputFormat log_fmt_map(const
> char *log_fmt)
> static enum VmafPoolingMethod pool_method_map(const char *pool_method)
> {
>     if (pool_method) {
> -        if (av_stristr(pool_method, "min"))
> +        if (!strcmp(pool_method, "min"))
>             return VMAF_POOL_METHOD_MIN;
> -        if (av_stristr(pool_method, "mean"))
> +        if (!strcmp(pool_method, "mean"))
>             return VMAF_POOL_METHOD_MEAN;
> -        if (av_stristr(pool_method, "harmonic_mean"))
> +        if (!strcmp(pool_method, "harmonic_mean"))
>             return VMAF_POOL_METHOD_HARMONIC_MEAN;
>     }
>
> --
> 2.37.1 (Apple Git-137.1)
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Will push this tomorrow.

Thanks,
Kyle