lavfi: add aeval filter

Changelog

@@ -12,6 +12,7 @@ version <next>
 - complete Voxware MetaSound decoder
 - remove mp3_header_compress bitstream filters
 - Windows resource files for shared libraries
+- aeval filter
 
 
 version 2.1:

doc/filters.texi

@@ -435,6 +435,70 @@ aecho=0.8:0.9:1000|1800:0.3|0.25
 @end example
 @end itemize
 
+@section aeval
+
+Modify an audio signal according to the specified expressions.
+
+This filter accepts one or more expressions (one for each channel),
+which are evaluated and used to modify a corresponding audio signal.
+
+This filter accepts the following options:
+
+@table @option
+@item exprs
+Set the '|'-separated expressions list for each separate channel. If
+the number of input channels is greater than the number of
+expressions, the last specified expression is used for the remaining
+output channels.
+
+@item channel_layout, c
+Set output channel layout. If not specified, the channel layout is
+specified by the number of expressions. If set to @samp{same}, it will
+use by default the same input channel layout.
+@end table
+
+Each expression in @var{exprs} can contain the following constants and functions:
+
+@table @option
+@item ch
+channel number of the current expression
+
+@item n
+number of the evaluated sample, starting from 0
+
+@item s
+sample rate
+
+@item t
+time of the evaluated sample expressed in seconds
+
+@item nb_in_channels
+@item nb_out_channels
+input and output number of channels
+
+@item val(CH)
+the value of input channel with number @var{CH}
+@end table
+
+Note: this filter is slow. For faster processing you should use a
+dedicated filter.
+
+@subsection Examples
+
+@itemize
+@item
+Half volume:
+@example
+aeval=val(ch)/2:c=same
+@end example
+
+@item
+Invert phase of the second channel:
+@example
+eval=val(0)|-val(1)
+@end example
+@end itemize
+
 @section afade
 
 Apply fade-in/out effect to input audio.

libavfilter/Makefile

@@ -53,6 +53,7 @@ OBJS-$(CONFIG_AVCODEC)                       += avcodec.o
 OBJS-$(CONFIG_ACONVERT_FILTER)               += af_aconvert.o
 OBJS-$(CONFIG_ADELAY_FILTER)                 += af_adelay.o
 OBJS-$(CONFIG_AECHO_FILTER)                  += af_aecho.o
+OBJS-$(CONFIG_AEVAL_FILTER)                  += asrc_aevalsrc.o
 OBJS-$(CONFIG_AFADE_FILTER)                  += af_afade.o
 OBJS-$(CONFIG_AFORMAT_FILTER)                += af_aformat.o
 OBJS-$(CONFIG_AINTERLEAVE_FILTER)            += f_interleave.o

libavfilter/allfilters.c

@@ -50,6 +50,7 @@ void avfilter_register_all(void)
 #endif
     REGISTER_FILTER(ADELAY,         adelay,         af);
     REGISTER_FILTER(AECHO,          aecho,          af);
+    REGISTER_FILTER(AEVAL,          aeval,          af);
     REGISTER_FILTER(AFADE,          afade,          af);
     REGISTER_FILTER(AFORMAT,        aformat,        af);
     REGISTER_FILTER(AINTERLEAVE,    ainterleave,    af);

libavfilter/asrc_aevalsrc.c

@@ -34,14 +34,20 @@
 #include "internal.h"
 
 static const char * const var_names[] = {
+    "ch",           ///< the value of the current channel
     "n",            ///< number of frame
+    "nb_in_channels",
+    "nb_out_channels",
     "t",            ///< timestamp expressed in seconds
     "s",            ///< sample rate
     NULL
 };
 
 enum var_name {
+    VAR_CH,
     VAR_N,
+    VAR_NB_IN_CHANNELS,
+    VAR_NB_OUT_CHANNELS,
     VAR_T,
     VAR_S,
     VAR_VARS_NB
@@ -53,7 +59,9 @@ typedef struct {
     int sample_rate;
     int64_t chlayout;
     char *chlayout_str;
-    int nb_channels;
+    int nb_channels;            ///< number of output channels
+    int nb_in_channels;         ///< number of input channels
+    int same_chlayout;          ///< set output as input channel layout
     int64_t pts;
     AVExpr **expr;
     char *exprs;
@@ -61,8 +69,19 @@ typedef struct {
     int64_t duration;
     uint64_t n;
     double var_values[VAR_VARS_NB];
+    double *channel_values;
+    int64_t out_channel_layout;
 } EvalContext;
 
+static double val(void *priv, double ch)
+{
+    EvalContext *eval = priv;
+    return eval->channel_values[FFMIN((int)ch, eval->nb_in_channels-1)];
+}
+
+static double (* const aeval_func1[])(void *, double) = { val, NULL };
+static const char * const aeval_func1_names[] = { "val", NULL };
+
 #define OFFSET(x) offsetof(EvalContext, x)
 #define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
 
@@ -81,17 +100,27 @@ static const AVOption aevalsrc_options[]= {
 
 AVFILTER_DEFINE_CLASS(aevalsrc);
 
-static av_cold int init(AVFilterContext *ctx)
+static int parse_channel_expressions(AVFilterContext *ctx,
+                                     int expected_nb_channels)
 {
     EvalContext *eval = ctx->priv;
     char *args1 = av_strdup(eval->exprs);
     char *expr, *last_expr, *buf;
-    int ret;
+    double (* const *func1)(void *, double) = NULL;
+    const char * const *func1_names = NULL;
+    int i, ret = 0;
+
+    if (!args1)
+        return AVERROR(ENOMEM);
 
-    if (!args1) {
+    if (!eval->exprs) {
         av_log(ctx, AV_LOG_ERROR, "Channels expressions list is empty\n");
-        ret = eval->exprs ? AVERROR(ENOMEM) : AVERROR(EINVAL);
-        goto end;
+        return AVERROR(EINVAL);
+    }
+
+    if (!strcmp(ctx->filter->name, "aeval")) {
+        func1 = aeval_func1;
+        func1_names = aeval_func1_names;
     }
 
 #define ADD_EXPRESSION(expr_) do {                                      \
@@ -102,56 +131,79 @@ static av_cold int init(AVFilterContext *ctx)
         }                                                               \
         eval->expr[eval->nb_channels-1] = NULL;                         \
         ret = av_expr_parse(&eval->expr[eval->nb_channels - 1], expr_,  \
-                            var_names, NULL, NULL,                      \
+                            var_names, func1_names, func1,              \
                             NULL, NULL, 0, ctx);                        \
         if (ret < 0)                                                    \
             goto end;                                                   \
     } while (0)
 
-    /* parse expressions */
+    /* reset expressions */
+    for (i = 0; i < eval->nb_channels; i++) {
+        av_expr_free(eval->expr[i]);
+        eval->expr[i] = NULL;
+    }
+    av_freep(&eval->expr);
+    eval->nb_channels = 0;
+
     buf = args1;
     while (expr = av_strtok(buf, "|", &buf)) {
         ADD_EXPRESSION(expr);
         last_expr = expr;
     }
 
-    if (eval->chlayout_str) {
-        int i, n;
-        ret = ff_parse_channel_layout(&eval->chlayout, NULL, eval->chlayout_str, ctx);
-        if (ret < 0)
-            goto end;
-
-        n = av_get_channel_layout_nb_channels(eval->chlayout);
-        if (n > eval->nb_channels) {
-            for (i = eval->nb_channels; i < n; i++)
-                ADD_EXPRESSION(last_expr);
-        }
+    if (expected_nb_channels > eval->nb_channels)
+        for (i = eval->nb_channels; i < expected_nb_channels; i++)
+            ADD_EXPRESSION(last_expr);
+
+    if (expected_nb_channels > 0 && eval->nb_channels != expected_nb_channels) {
+        av_log(ctx, AV_LOG_ERROR,
+               "Mismatch between the specified number of channel expressions '%d' "
+               "and the number of expected output channels '%d' for the specified channel layout\n",
+               eval->nb_channels, expected_nb_channels);
+        ret = AVERROR(EINVAL);
+        goto end;
+    }
+
+end:
+    av_free(args1);
+    return ret;
+}
 
-        if (n != eval->nb_channels) {
-            av_log(ctx, AV_LOG_ERROR,
-                   "Mismatch between the specified number of channels '%d' "
-                   "and the number of channels '%d' in the specified channel layout '%s'\n",
-                   eval->nb_channels, n, eval->chlayout_str);
-            ret = AVERROR(EINVAL);
-            goto end;
+static av_cold int init(AVFilterContext *ctx)
+{
+    EvalContext *eval = ctx->priv;
+    int ret;
+
+    if (eval->chlayout_str) {
+        if (!strcmp(eval->chlayout_str, "same") && !strcmp(ctx->filter->name, "aeval")) {
+            eval->same_chlayout = 1;
+        } else {
+            ret = ff_parse_channel_layout(&eval->chlayout, NULL, eval->chlayout_str, ctx);
+            if (ret < 0)
+                return ret;
+
+            ret = parse_channel_expressions(ctx, av_get_channel_layout_nb_channels(eval->chlayout));
+            if (ret < 0)
+                return ret;
         }
     } else {
         /* guess channel layout from nb expressions/channels */
+        if ((ret = parse_channel_expressions(ctx, -1)) < 0)
+            return ret;
+
         eval->chlayout = av_get_default_channel_layout(eval->nb_channels);
         if (!eval->chlayout && eval->nb_channels <= 0) {
             av_log(ctx, AV_LOG_ERROR, "Invalid number of channels '%d' provided\n",
                    eval->nb_channels);
-            ret = AVERROR(EINVAL);
-            goto end;
+            return AVERROR(EINVAL);
         }
     }
 
-    if ((ret = ff_parse_sample_rate(&eval->sample_rate, eval->sample_rate_str, ctx)))
-        goto end;
+    if (eval->sample_rate_str)
+        if ((ret = ff_parse_sample_rate(&eval->sample_rate, eval->sample_rate_str, ctx)))
+            return ret;
     eval->n = 0;
 
-end:
-    av_free(args1);
     return ret;
 }
 
@@ -176,6 +228,8 @@ static int config_props(AVFilterLink *outlink)
     outlink->sample_rate = eval->sample_rate;
 
     eval->var_values[VAR_S] = eval->sample_rate;
+    eval->var_values[VAR_NB_IN_CHANNELS] = NAN;
+    eval->var_values[VAR_NB_OUT_CHANNELS] = outlink->channels;
 
     av_get_channel_layout_string(buf, sizeof(buf), 0, eval->chlayout);
 
@@ -232,6 +286,7 @@ static int request_frame(AVFilterLink *outlink)
     return ff_filter_frame(outlink, samplesref);
 }
 
+#if CONFIG_AEVALSRC_FILTER
 static const AVFilterPad aevalsrc_outputs[] = {
     {
         .name          = "default",
@@ -253,3 +308,159 @@ AVFilter ff_asrc_aevalsrc = {
     .outputs       = aevalsrc_outputs,
     .priv_class    = &aevalsrc_class,
 };
+
+#endif /* CONFIG_AEVALSRC_FILTER */
+
+#define OFFSET(x) offsetof(EvalContext, x)
+#define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
+
+static const AVOption aeval_options[]= {
+    { "exprs", "set the '|'-separated list of channels expressions", OFFSET(exprs), AV_OPT_TYPE_STRING, {.str = NULL}, .flags = FLAGS },
+    { "channel_layout", "set channel layout", OFFSET(chlayout_str), AV_OPT_TYPE_STRING, {.str = NULL}, 0, 0, FLAGS },
+    { "c",              "set channel layout", OFFSET(chlayout_str), AV_OPT_TYPE_STRING, {.str = NULL}, 0, 0, FLAGS },
+    { NULL }
+};
+
+AVFILTER_DEFINE_CLASS(aeval);
+
+static int aeval_query_formats(AVFilterContext *ctx)
+{
+    AVFilterFormats *formats = NULL;
+    AVFilterChannelLayouts *layouts;
+    AVFilterLink *inlink  = ctx->inputs[0];
+    AVFilterLink *outlink  = ctx->outputs[0];
+    EvalContext *eval = ctx->priv;
+    static const enum AVSampleFormat sample_fmts[] = {
+        AV_SAMPLE_FMT_DBLP, AV_SAMPLE_FMT_NONE
+    };
+
+    // inlink supports any channel layout
+    layouts = ff_all_channel_counts();
+    ff_channel_layouts_ref(layouts, &inlink->out_channel_layouts);
+
+    if (eval->same_chlayout) {
+        layouts = ff_all_channel_counts();
+        if (!layouts)
+            return AVERROR(ENOMEM);
+            ff_set_common_channel_layouts(ctx, layouts);
+    } else {
+        // outlink supports only requested output channel layout
+        layouts = NULL;
+        ff_add_channel_layout(&layouts,
+                              eval->out_channel_layout ? eval->out_channel_layout :
+                              FF_COUNT2LAYOUT(eval->nb_channels));
+        ff_channel_layouts_ref(layouts, &outlink->in_channel_layouts);
+    }
+
+    formats = ff_make_format_list(sample_fmts);
+    if (!formats)
+        return AVERROR(ENOMEM);
+    ff_set_common_formats(ctx, formats);
+
+    formats = ff_all_samplerates();
+    if (!formats)
+        return AVERROR(ENOMEM);
+    ff_set_common_samplerates(ctx, formats);
+
+    return 0;
+}
+
+static int aeval_config_output(AVFilterLink *outlink)
+{
+    AVFilterContext *ctx = outlink->src;
+    EvalContext *eval = ctx->priv;
+    AVFilterLink *inlink = ctx->inputs[0];
+    int ret;
+
+    if (eval->same_chlayout) {
+        eval->chlayout = inlink->channel_layout;
+
+        if ((ret = parse_channel_expressions(ctx, inlink->channels)) < 0)
+            return ret;
+    }
+
+    eval->n = 0;
+    eval->nb_in_channels = eval->var_values[VAR_NB_IN_CHANNELS] = inlink->channels;
+    eval->var_values[VAR_NB_OUT_CHANNELS] = outlink->channels;
+    eval->var_values[VAR_S] = inlink->sample_rate;
+    eval->var_values[VAR_T] = NAN;
+
+    eval->channel_values = av_realloc_f(eval->channel_values,
+                                        inlink->channels, sizeof(*eval->channel_values));
+    if (!eval->channel_values)
+        return AVERROR(ENOMEM);
+
+    return 0;
+}
+
+#define TS2T(ts, tb) ((ts) == AV_NOPTS_VALUE ? NAN : (double)(ts)*av_q2d(tb))
+
+static int filter_frame(AVFilterLink *inlink, AVFrame *in)
+{
+    EvalContext *eval     = inlink->dst->priv;
+    AVFilterLink *outlink = inlink->dst->outputs[0];
+    int nb_samples        = in->nb_samples;
+    AVFrame *out;
+    double t0;
+    int i, j;
+
+    /* do volume scaling in-place if input buffer is writable */
+    out = ff_get_audio_buffer(outlink, nb_samples);
+    if (!out)
+        return AVERROR(ENOMEM);
+    av_frame_copy_props(out, in);
+
+    t0 = TS2T(in->pts, inlink->time_base);
+
+    /* evaluate expression for each single sample and for each channel */
+    for (i = 0; i < nb_samples; i++, eval->n++) {
+        eval->var_values[VAR_N] = eval->n;
+        eval->var_values[VAR_T] = t0 + i * (double)1/inlink->sample_rate;
+
+        for (j = 0; j < inlink->channels; j++)
+            eval->channel_values[j] = *((double *) in->extended_data[j] + i);
+
+        for (j = 0; j < outlink->channels; j++) {
+            eval->var_values[VAR_CH] = j;
+            *((double *) out->extended_data[j] + i) =
+                av_expr_eval(eval->expr[j], eval->var_values, eval);
+        }
+    }
+
+    av_frame_free(&in);
+    return ff_filter_frame(outlink, out);
+}
+
+#if CONFIG_AEVAL_FILTER
+
+static const AVFilterPad aeval_inputs[] = {
+    {
+        .name           = "default",
+        .type           = AVMEDIA_TYPE_AUDIO,
+        .filter_frame   = filter_frame,
+    },
+    { NULL }
+};
+
+static const AVFilterPad aeval_outputs[] = {
+    {
+        .name          = "default",
+        .type          = AVMEDIA_TYPE_AUDIO,
+        .config_props  = aeval_config_output,
+    },
+    { NULL }
+};
+
+AVFilter ff_af_aeval = {
+    .name          = "aeval",
+    .description   = NULL_IF_CONFIG_SMALL("Filter audio signal according to a specified expression."),
+    .query_formats = aeval_query_formats,
+    .init          = init,
+    .uninit        = uninit,
+    .priv_size     = sizeof(EvalContext),
+    .inputs        = aeval_inputs,
+    .outputs       = aeval_outputs,
+    .priv_class    = &aeval_class,
+};
+
+#endif /* CONFIG_AEVAL_FILTER */

libavfilter/version.h

@@ -30,8 +30,8 @@
 #include "libavutil/avutil.h"
 
 #define LIBAVFILTER_VERSION_MAJOR  3
-#define LIBAVFILTER_VERSION_MINOR  91
-#define LIBAVFILTER_VERSION_MICRO 101
+#define LIBAVFILTER_VERSION_MINOR  92
+#define LIBAVFILTER_VERSION_MICRO 100
 
 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \
                                                LIBAVFILTER_VERSION_MINOR, \