avfilter/asubprocess: allow setting command as filter parameter

Signed-off-by: Stefan Westerfeld <stefan@space.twc.de>

libavfilter/af_asubprocess.c

@@ -200,7 +200,7 @@ enum {
 typedef struct AndioWMarkContext {
     const AVClass *class;
 
-    double strength;
+    const char *command;
 
     int    fd;
     int    state;
@@ -208,21 +208,31 @@ typedef struct AndioWMarkContext {
     SP    *sp;
     int    nb_samples;
     int    eof;
-} AudioWMarkContext;
+} ASubProcessContext;
 
-#define OFFSET(x) offsetof(AudioWMarkContext, x)
+#define OFFSET(x) offsetof(ASubProcessContext, x)
 #define A AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
 
 static const AVOption asubprocess_options[] = {
-    { "strength",   "set watermarking strength", OFFSET(strength), AV_OPT_TYPE_DOUBLE, {.dbl=10}, 1, 100, A },
+    { "command",    "set command to run as subprocess",  OFFSET(command),  AV_OPT_TYPE_STRING, {.str=NULL},  0, 0, A},
     { NULL },
 };
 
 AVFILTER_DEFINE_CLASS(asubprocess);
 
+static av_cold int init(AVFilterContext *ctx)
+{
+    ASubProcessContext *s = ctx->priv;
+    if (!s->command) {
+        av_log(ctx, AV_LOG_ERROR, "No command provided\n");
+        return AVERROR(EINVAL);
+    }
+    return 0;
+}
+
 static av_cold void uninit(AVFilterContext *ctx)
 {
-    AudioWMarkContext *s = ctx->priv;
+    ASubProcessContext *s = ctx->priv;
 
     printf ("TODO: uninit\n");
 #if 0
@@ -234,9 +244,8 @@ static av_cold void uninit(AVFilterContext *ctx)
 static int config_input(AVFilterLink *inlink)
 {
     AVFilterContext *ctx = inlink->dst;
-    AudioWMarkContext *s = ctx->priv;
-    // TODO: use inlink->sample_rate, inlink->ch_layout.nb_channels
-    s->sp = sp_new ("audiowmark -q add - - f0");
+    ASubProcessContext *s = ctx->priv;
+    s->sp = sp_new (s->command);
     int bit_depth = 16;
     int sample_rate = inlink->sample_rate;
     int nb_channels = inlink->ch_layout.nb_channels;
@@ -285,7 +294,7 @@ static int config_input(AVFilterLink *inlink)
 static int filter_frame(AVFilterLink *inlink, AVFrame *in)
 {
     AVFilterContext *ctx = inlink->dst;
-    AudioWMarkContext *s = ctx->priv;
+    ASubProcessContext *s = ctx->priv;
     AVFilterLink *outlink = ctx->outputs[0];
     AVFrame *out;
     int ret = 0, nb_samples;
@@ -394,7 +403,7 @@ static int activate(AVFilterContext *ctx)
 {
     AVFilterLink *inlink = ctx->inputs[0];
     AVFilterLink *outlink = ctx->outputs[0];
-    AudioWMarkContext *s = ctx->priv;
+    ASubProcessContext *s = ctx->priv;
     AVFrame *in = NULL;
     int64_t pts;
     int status, ret;
@@ -454,8 +463,9 @@ static const AVFilterPad asubprocess_inputs[] = {
 const AVFilter ff_af_asubprocess = {
     .name          = "asubprocess",
     .description   = NULL_IF_CONFIG_SMALL("Filter audio stream with subprocess."),
-    .priv_size     = sizeof(AudioWMarkContext),
+    .priv_size     = sizeof(ASubProcessContext),
     .priv_class    = &asubprocess_class,
+    .init          = init,
     .uninit        = uninit,
     .activate      = activate,
     FILTER_INPUTS(asubprocess_inputs),