Re: [FFmpeg-devel] [PATCH 08/11] fftools/opt_common: switch to avcodec_get_supported_config()

[James Almer <jamrial@gmail.com>]

On 4/5/2024 3:57 PM, Niklas Haas wrote:
> From: Niklas Haas <git@haasn.dev>
> 
> While rewriting this macro, I decided to make it a bit more flexible so
> it can work for all of the fields (including future fields) in a more
> generic way.
> ---
>   fftools/opt_common.c | 86 ++++++++++++++++++++++----------------------
>   1 file changed, 43 insertions(+), 43 deletions(-)
> 
> diff --git a/fftools/opt_common.c b/fftools/opt_common.c
> index 947a226d8d1..1bf66580192 100644
> --- a/fftools/opt_common.c
> +++ b/fftools/opt_common.c
> @@ -262,22 +262,32 @@ int show_buildconf(void *optctx, const char *opt, const char *arg)
>       return 0;
>   }
>   
> -#define PRINT_CODEC_SUPPORTED(codec, field, type, list_name, term, get_name) \
> -    if (codec->field) {                                                      \
> -        const type *p = codec->field;                                        \
> -                                                                             \
> -        printf("    Supported " list_name ":");                              \
> -        while (*p != term) {                                                 \
> -            get_name(*p);                                                    \
> -            printf(" %s", name);                                             \
> -            p++;                                                             \
> -        }                                                                    \
> -        printf("\n");                                                        \
> -    }                                                                        \
> +#define PRINT_CODEC_SUPPORTED(codec, config, type, name, elem, cond, fmt, ...)  \
> +    do {                                                                        \
> +        const type *elem = NULL;                                                \
> +        avcodec_get_supported_config(NULL, codec, config, 0,                    \
> +                                     (const void **) &elem);                    \
> +        if (elem) {                                                             \
> +            printf("    Supported " name ":");                                  \
> +            while (cond) {                                                      \
> +                printf(" " fmt, __VA_ARGS__);                                   \
> +                elem++;                                                         \
> +            }                                                                   \
> +            printf("\n");                                                       \
> +        }                                                                       \
> +    } while (0)
> +
> +static char *get_channel_layout_desc(const AVChannelLayout *layout,
> +                                     char desc[], int desc_size)
> +{
> +    av_channel_layout_describe(layout, desc, desc_size);
> +    return desc;
> +}
>   
>   static void print_codec(const AVCodec *c)
>   {
>       int encoder = av_codec_is_encoder(c);
> +    char desc[128];
>   
>       printf("%s %s [%s]:\n", encoder ? "Encoder" : "Decoder", c->name,
>              c->long_name ? c->long_name : "");
> @@ -343,35 +353,19 @@ static void print_codec(const AVCodec *c)
>           printf("\n");
>       }
>   
> -    if (c->supported_framerates) {
> -        const AVRational *fps = c->supported_framerates;
> -
> -        printf("    Supported framerates:");
> -        while (fps->num) {
> -            printf(" %d/%d", fps->num, fps->den);
> -            fps++;
> -        }
> -        printf("\n");
> -    }
> -    PRINT_CODEC_SUPPORTED(c, pix_fmts, enum AVPixelFormat, "pixel formats",
> -                          AV_PIX_FMT_NONE, GET_PIX_FMT_NAME);
> -    PRINT_CODEC_SUPPORTED(c, supported_samplerates, int, "sample rates", 0,
> -                          GET_SAMPLE_RATE_NAME);
> -    PRINT_CODEC_SUPPORTED(c, sample_fmts, enum AVSampleFormat, "sample formats",
> -                          AV_SAMPLE_FMT_NONE, GET_SAMPLE_FMT_NAME);
> -
> -    if (c->ch_layouts) {
> -        const AVChannelLayout *p = c->ch_layouts;
> -
> -        printf("    Supported channel layouts:");
> -        while (p->nb_channels) {
> -            char name[128];
> -            av_channel_layout_describe(p, name, sizeof(name));
> -            printf(" %s", name);
> -            p++;
> -        }
> -        printf("\n");
> -    }
> +    PRINT_CODEC_SUPPORTED(c, AV_CODEC_CONFIG_FRAME_RATE, AVRational, "framerates",
> +                          fps, fps->num, "%d/%d", fps->num, fps->den);
> +    PRINT_CODEC_SUPPORTED(c, AV_CODEC_CONFIG_PIX_FORMAT, enum AVPixelFormat,
> +                          "pixel formats", fmt, *fmt != AV_PIX_FMT_NONE,
> +                          "%s", av_get_pix_fmt_name(*fmt));
> +    PRINT_CODEC_SUPPORTED(c, AV_CODEC_CONFIG_SAMPLE_RATE, int, "sample rates",
> +                          rate, *rate != 0, "%d", *rate);
> +    PRINT_CODEC_SUPPORTED(c, AV_CODEC_CONFIG_SAMPLE_FORMAT, enum AVSampleFormat,
> +                          "sample formats", fmt, *fmt != AV_SAMPLE_FMT_NONE,
> +                          "%s", av_get_sample_fmt_name(*fmt));
> +    PRINT_CODEC_SUPPORTED(c, AV_CODEC_CONFIG_CHANNEL_LAYOUT, AVChannelLayout,
> +                          "channel layouts", layout, layout->nb_channels,
> +                          "%s", get_channel_layout_desc(layout, desc, sizeof(desc)));

Since you're rewriting everything, might as well go and port this to 
AVBprint, so we're not limited to 128 bytes for the channel layout.
You can use av_bprintf() to write to the buffer using the different 
specifiers, then printf() the final bprint buffer to stdout.

>   
>       if (c->priv_class) {
>           show_help_children(c->priv_class,
> @@ -566,8 +560,14 @@ static void show_help_bsf(const char *name)
>       }
>   
>       printf("Bit stream filter %s\n", bsf->name);
> -    PRINT_CODEC_SUPPORTED(bsf, codec_ids, enum AVCodecID, "codecs",
> -                          AV_CODEC_ID_NONE, GET_CODEC_NAME);
> +    if (bsf->codec_ids) {
> +        const enum AVCodecID *id = bsf->codec_ids;
> +        printf("    Supported codecs:");
> +        while (*id != AV_CODEC_ID_NONE) {
> +            printf(" %s", avcodec_descriptor_get(*id)->name);
> +            id++;
> +        }
> +    }
>       if (bsf->priv_class)
>           show_help_children(bsf->priv_class, AV_OPT_FLAG_BSF_PARAM);
>   }
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