[FFmpeg-devel] [PATCH] audioconvert: make av_get_channel_layout accept composite names.

[Stefano Sabatini]

On date Sunday 2011-11-06 17:05:07 +0100, Nicolas George encoded:
> 
> Signed-off-by: Nicolas George <nicolas.george at normalesup.org>
> ---
>  libavutil/audioconvert.c |   47 +++++++++++++++++++++++++++++++++++++--------
>  libavutil/audioconvert.h |   12 +++++++++++
>  2 files changed, 50 insertions(+), 9 deletions(-)
> 
> diff --git a/libavutil/audioconvert.c b/libavutil/audioconvert.c
> index f4c74f6..fc03d7d 100644
> --- a/libavutil/audioconvert.c
> +++ b/libavutil/audioconvert.c
> @@ -72,23 +72,52 @@ static const struct {
>      { "5.1",         6,  AV_CH_LAYOUT_5POINT1_BACK },
>      { "7.1",         8,  AV_CH_LAYOUT_7POINT1 },
>      { "7.1(wide)",   8,  AV_CH_LAYOUT_7POINT1_WIDE },
> -    { "5.1+downmix", 8,  AV_CH_LAYOUT_5POINT1|AV_CH_LAYOUT_STEREO_DOWNMIX, },
> -    { "7.1+downmix", 10, AV_CH_LAYOUT_7POINT1|AV_CH_LAYOUT_STEREO_DOWNMIX, },
> +    { "downmix",     2,  AV_CH_LAYOUT_STEREO_DOWNMIX, },
>      { 0 }
>  };
>  
> -int64_t av_get_channel_layout(const char *name)
> +static int64_t get_channel_layout_single(const char *name, int name_len)
>  {
> -    int i = 0;
> -    do {
> -        if (!strcmp(channel_layout_map[i].name, name))
> -            return channel_layout_map[i].layout;
> -        i++;
> -    } while (channel_layout_map[i].name);

> +    int i;

maybe long int for avoiding possible warnings/problems with strtol

> +    char *end;
> +    int64_t layout;
>  
> +    for (i = 0; i < FF_ARRAY_ELEMS(channel_layout_map) - 1; i++) {
> +        if (strlen(channel_layout_map[i].name) == name_len &&
> +            !memcmp(channel_layout_map[i].name, name, name_len))
> +            return channel_layout_map[i].layout;
> +    }
> +    for (i = 0; i < FF_ARRAY_ELEMS(channel_names); i++)
> +        if (channel_names[i] &&
> +            strlen(channel_names[i]) == name_len &&
> +            !memcmp(channel_names[i], name, name_len))
> +            return (int64_t)1 << i;
> +    i = strtol(name, &end, 10);
> +    if (end - name == name_len ||
> +        (end + 1 - name == name_len && *end  == 'c'))
> +        return av_get_default_channel_layout(i);

> +    layout = strtoll(name, &end, 0);

you may want a range check to make sure that the long long int can be
contained in an int64_t if you want to be perfectly safe (I'm assuming
that long long int can contain an int64_t without checking the fine
specs).

> +    if (end - name == name_len)
> +        return layout;
>      return 0;
>  }
>  
> +int64_t av_get_channel_layout(const char *name)
> +{
> +    const char *n, *e;
> +    const char *name_end = name + strlen(name);
> +    int64_t layout = 0, layout_single;
> +
> +    for (n = name; n < name_end; n = e + 1) {
> +        for (e = n; e < name_end && *e != '+' && *e != '|'; e++);
> +        layout_single = get_channel_layout_single(n, e - n);
> +        if (!layout_single)
> +            return 0;
> +        layout |= layout_single;
> +    }
> +    return layout;
> +}
> +
>  void av_get_channel_layout_string(char *buf, int buf_size,
>                                    int nb_channels, int64_t channel_layout)
>  {
> diff --git a/libavutil/audioconvert.h b/libavutil/audioconvert.h
> index 8cef7f6..4e0e98c 100644
> --- a/libavutil/audioconvert.h
> +++ b/libavutil/audioconvert.h
> @@ -75,6 +75,18 @@
>  
>  /**
>   * Return a channel layout id that matches name, 0 if no match.
> + * name can be one or several of the following notations,
> + * separated by '+' or '|':
> + * - the name of an usual channel layout (mono, stereo, 4.0, quad, 5.0,
> + *   5.0(side), 5.1, 5.1(side), 7.1, 7.1(wide), downmix);
> + * - the name of a single channel (FL, FR, FC, LFE, BL, BR, FLC, FRC, BC,
> + *   SL, SR, TC, TFL, TFC, TFR, TBL, TBC, TBR, DL, DR);
> + * - a number of channels, in decimal, optionnally followed by 'c', yielding
> + *   the default channel layout for that number of channels (@see
> + *   av_get_default_channel_layout);
> + * - a channel layout mask, in hexadecimal starting with "0x" (see the
> + *   AV_CH_* macros).
> + + Example: "stereo+FC" = "2+FC" = "2c+1c" = "0x7"
>   */
>  int64_t av_get_channel_layout(const char *name);

looks fine to me otherwise.
-- 
FFmpeg = Formidable Freak Meaningful Pitiless Elitarian Ghost