@end example
@end itemize
+@anchor{aformat}
@section aformat
Set output format constraints for the input audio. The framework will
The filter does not take parameters.
+@anchor{format}
@section format
Convert the input video to one of the specified pixel formats.
Below is a description of the currently available multimedia filters.
+@section aperms, perms
+
+Set read/write permissions for the output frames.
+
+These filters are mainly aimed at developers to test direct path in the
+following filter in the filtergraph.
+
+The filters accept parameters as a list of @var{key}=@var{value} pairs,
+separated by ":". If the key of the first options is omitted, the argument is
+assumed to be the @var{mode}.
+
+A description of the accepted parameters follows.
+
+@table @option
+@item mode
+Select the permissions mode.
+
+It accepts the following values:
+@table @samp
+@item none
+Do nothing. This is the default.
+@item ro
+Set all the output frames read-only.
+@item rw
+Set all the output frames directly writable.
+@item toggle
+Make the frame read-only if writable, and writable if read-only.
+@item random
+Set each output frame read-only or writable randomly.
+@end table
+@end table
+
+Note: in case of auto-inserted filter between the permission filter and the
+following one, the permission might not be received as expected in that
+following filter. Inserting a @ref{format} or @ref{aformat} filter before the
+perms/aperms filter can avoid this problem.
+
@section aselect, select
Select frames to pass in output.
--- /dev/null
+/*
+ * 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 */