[FFmpeg-devel] Filter with multiple inputs, specific format on second and third input?

[F.Sluiter]

I am writing a filter that takes a video file and remaps pixels based on
second and third input.
second and third input are pgm files, which should give me a list of
integers (gray16) that I can use in the filter.
However ffmpeg by default converts my pgm files to YUV.
Is there a way to prevent that?

Should I add something to the filter code to only accept gray16 encoded
files as second (xmap) and third (ymap) input, but keep arbitray video as
input1?

Command line:
# ffmpeg -i INPUT.avi  -i feep.pgm   -i feep.pgm  -lavfi '[0][1][2]remap'
OUTPUT.avi


static int query_formats(AVFilterContext *ctx)
{
    static const enum AVPixelFormat pix_fmts[] = {
        AV_PIX_FMT_YUVA444P, AV_PIX_FMT_YUV444P, AV_PIX_FMT_YUV440P,
        AV_PIX_FMT_YUVJ444P, AV_PIX_FMT_YUVJ440P,
        AV_PIX_FMT_YUVA422P, AV_PIX_FMT_YUV422P, AV_PIX_FMT_YUVA420P,
AV_PIX_FMT_YUV420P,
        AV_PIX_FMT_YUVJ422P, AV_PIX_FMT_YUVJ420P,
        AV_PIX_FMT_YUVJ411P, AV_PIX_FMT_YUV411P, AV_PIX_FMT_YUV410P,
        AV_PIX_FMT_RGB24, AV_PIX_FMT_BGR24,
        AV_PIX_FMT_ARGB, AV_PIX_FMT_ABGR, AV_PIX_FMT_RGBA, AV_PIX_FMT_BGRA,
        AV_PIX_FMT_0RGB, AV_PIX_FMT_0BGR, AV_PIX_FMT_RGB0, AV_PIX_FMT_BGR0,
        AV_PIX_FMT_GBRP, AV_PIX_FMT_GBRAP,
        AV_PIX_FMT_GRAY8, AV_PIX_FMT_NONE
    };

    return ff_set_common_formats(ctx, ff_make_format_list(pix_fmts));
}


static const AVFilterPad remap_inputs[] = {
    {
        .name         = "source",
        .type         = AVMEDIA_TYPE_VIDEO,
        .filter_frame = filter_frame,
        .config_props = config_input,
    },
    {
        .name         = "xmap",
        .type         = AVMEDIA_TYPE_VIDEO,
        .filter_frame = filter_frame,
    },
    {
        .name         = "ymap",
        .type         = AVMEDIA_TYPE_VIDEO,
        .filter_frame = filter_frame,
    },
    { NULL }
};

static const AVFilterPad remap_outputs[] = {
    {
        .name          = "default",
        .type          = AVMEDIA_TYPE_VIDEO,
        .config_props  = config_output,
        .request_frame = request_frame,
    },
    { NULL }
};


AVFilter ff_vf_remap = {
    .name          = "remap",
    .description   = NULL_IF_CONFIG_SMALL("remap pixels."),
    .priv_size     = sizeof(remapContext),
    .uninit        = uninit,
    .query_formats = query_formats,
    .inputs        = remap_inputs,
    .outputs       = remap_outputs,
    .priv_class    = &remap_class,
    .flags         = AVFILTER_FLAG_SUPPORT_TIMELINE_INTERNAL,
};