lavfi: add perms and aperms filters.

libavfilter/f_perms.c

@@ -0,0 +1,187 @@
+/*
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "libavutil/lfg.h"
+#include "libavutil/opt.h"
+#include "libavutil/random_seed.h"
+#include "audio.h"
+#include "video.h"
+
+enum mode {
+    MODE_NONE,
+    MODE_RO,
+    MODE_RW,
+    MODE_TOGGLE,
+    MODE_RANDOM,
+    NB_MODES
+};
+
+typedef struct {
+    const AVClass *class;
+    AVLFG lfg;
+    enum mode mode;
+} PermsContext;
+
+#define OFFSET(x) offsetof(PermsContext, x)
+#define FLAGS AV_OPT_FLAG_FILTERING_PARAM
+
+static const AVOption options[] = {
+    { "mode", "select permissions mode", OFFSET(mode), AV_OPT_TYPE_INT, {.i64 = MODE_NONE}, MODE_NONE, NB_MODES-1, FLAGS, "mode" },
+        { "none",   "do nothing",                       0, AV_OPT_TYPE_CONST, {.i64 = MODE_NONE},       INT_MIN, INT_MAX, FLAGS, "mode" },
+        { "ro",     "set all output frames read-only",  0, AV_OPT_TYPE_CONST, {.i64 = MODE_RO},         INT_MIN, INT_MAX, FLAGS, "mode" },
+        { "rw",     "set all output frames writable",   0, AV_OPT_TYPE_CONST, {.i64 = MODE_RW},         INT_MIN, INT_MAX, FLAGS, "mode" },
+        { "toggle", "switch permissions",               0, AV_OPT_TYPE_CONST, {.i64 = MODE_TOGGLE},     INT_MIN, INT_MAX, FLAGS, "mode" },
+        { "random", "set permissions randomly",         0, AV_OPT_TYPE_CONST, {.i64 = MODE_RANDOM},     INT_MIN, INT_MAX, FLAGS, "mode" },
+    { NULL }
+};
+
+static av_cold int init(AVFilterContext *ctx, const char *args, const AVClass *class)
+{
+    int ret;
+    PermsContext *perms = ctx->priv;
+    static const char *shorthand[] = { "mode", NULL };
+
+    perms->class = class;
+    av_opt_set_defaults(perms);
+
+    if ((ret = av_opt_set_from_string(perms, args, shorthand, "=", ":")) < 0)
+        return ret;
+
+    // TODO: add a seed option
+    if (perms->mode == MODE_RANDOM)
+        av_lfg_init(&perms->lfg, av_get_random_seed());
+
+    av_opt_free(perms);
+    return 0;
+}
+
+enum perm                        {  RO,   RW  };
+static const char *perm_str[2] = { "RO", "RW" };
+
+static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
+{
+    int ret;
+    AVFilterContext *ctx = inlink->dst;
+    PermsContext *perms = ctx->priv;
+    AVFrame *out = frame;
+    enum perm in_perm = av_frame_is_writable(frame) ? RW : RO;
+    enum perm out_perm;
+
+    switch (perms->mode) {
+    case MODE_TOGGLE:   out_perm = in_perm == RO ? RW : RO;                 break;
+    case MODE_RANDOM:   out_perm = av_lfg_get(&perms->lfg) & 1 ? RW : RO;   break;
+    case MODE_RO:       out_perm = RO;                                      break;
+    case MODE_RW:       out_perm = RW;                                      break;
+    default:            out_perm = in_perm;                                 break;
+    }
+
+    av_log(ctx, AV_LOG_VERBOSE, "%s -> %s%s\n",
+           perm_str[in_perm], perm_str[out_perm],
+           in_perm == out_perm ? " (no-op)" : "");
+
+    if (in_perm == RO && out_perm == RW) {
+        if ((ret = av_frame_make_writable(frame)) < 0)
+            return ret;
+    } else if (in_perm == RW && out_perm == RO) {
+        out = av_frame_clone(frame);
+        if (!out)
+            return AVERROR(ENOMEM);
+    }
+
+    ret = ff_filter_frame(ctx->outputs[0], out);
+
+    if (in_perm == RW && out_perm == RO)
+        av_frame_free(&frame);
+    return ret;
+}
+
+#if CONFIG_APERMS_FILTER
+
+#define aperms_options options
+AVFILTER_DEFINE_CLASS(aperms);
+
+static av_cold int aperms_init(AVFilterContext *ctx, const char *args)
+{
+    return init(ctx, args, &aperms_class);
+}
+
+static const AVFilterPad aperms_inputs[] = {
+    {
+        .name         = "default",
+        .type         = AVMEDIA_TYPE_AUDIO,
+        .filter_frame = filter_frame,
+    },
+    { NULL }
+};
+
+static const AVFilterPad aperms_outputs[] = {
+    {
+        .name = "default",
+        .type = AVMEDIA_TYPE_AUDIO,
+    },
+    { NULL }
+};
+
+AVFilter avfilter_af_aperms = {
+    .name        = "aperms",
+    .description = NULL_IF_CONFIG_SMALL("Set permissions for the output audio frame."),
+    .init        = aperms_init,
+    .priv_size   = sizeof(PermsContext),
+    .inputs      = aperms_inputs,
+    .outputs     = aperms_outputs,
+    .priv_class  = &aperms_class,
+};
+#endif /* CONFIG_APERMS_FILTER */
+
+#if CONFIG_PERMS_FILTER
+
+#define perms_options options
+AVFILTER_DEFINE_CLASS(perms);
+
+static av_cold int perms_init(AVFilterContext *ctx, const char *args)
+{
+    return init(ctx, args, &perms_class);
+}
+
+static const AVFilterPad perms_inputs[] = {
+    {
+        .name         = "default",
+        .type         = AVMEDIA_TYPE_VIDEO,
+        .filter_frame = filter_frame,
+    },
+    { NULL }
+};
+
+static const AVFilterPad perms_outputs[] = {
+    {
+        .name = "default",
+        .type = AVMEDIA_TYPE_VIDEO,
+    },
+    { NULL }
+};
+
+AVFilter avfilter_vf_perms = {
+    .name        = "perms",
+    .description = NULL_IF_CONFIG_SMALL("Set permissions for the output video frame."),
+    .init        = perms_init,
+    .priv_size   = sizeof(PermsContext),
+    .inputs      = perms_inputs,
+    .outputs     = perms_outputs,
+    .priv_class  = &perms_class,
+};
+#endif /* CONFIG_PERMS_FILTER */