Now it fails at 
libavfilter/af_aformat.c.rej

... Can you see how much this file change and try to re-apply changes from patch 4?

Or May be Just skip this patch too, because i already can see same function. Uninit declare there in ffmpeg git source.. 

static av_cold void uninit(AVFilterContext *ctx)
{
    AFormatContext *s = ctx->priv;

    ff_formats_unref(&s->formats);
    ff_formats_unref(&s->sample_rates);
    ff_channel_layouts_unref(&s->channel_layouts);
}

https://git.ffmpeg.org/gitweb/ffmpeg.git/blob_plain/HEAD:/libavfilter/af_aformat.c



On Wednesday, April 28, 2021, Andrea paz via Cin <cin@lists.cinelerra-gg.org> wrote:
I attach the last part of the error logs:
1- after renaming patch2 and putting in the git-ffmpeg link.
2- after applying patch3 (not sure if I applied it properly).