lavfi: add showwaves filter

Changelog

@@ -11,6 +11,7 @@ version next:
 - ffprobe -show_data option
 - RTMPT protocol support
 - iLBC encoding/decoding via libilbc
+- showwaves filter
 
 
 version 0.11:

doc/filters.texi

@@ -3826,3 +3826,48 @@ mainly useful as a template and to be employed in analysis / debugging
 tools.
 
 @c man end VIDEO SINKS
+
+@chapter Transmedia Filters
+@c man begin TRANSMEDIA FILTERS
+
+Below is a description of the currently available transmedia filters.
+
+@section showwaves
+
+Convert input audio to a video output, representing the samples waves.
+
+The filter accepts the following named parameters:
+@table @option
+
+@item n
+Set the number of samples which are printed on the same column. A
+larger value will decrease the frame rate. Must be a positive
+integer. This option can be set only if the value for @var{rate}
+is not explicitly specified.
+
+@item rate, r
+Set the (approximate) output frame rate. This is done by setting the
+option @var{n}. Default value is "25".
+
+@item size, s
+Specify the video size for the output. Default value is "600x240".
+@end table
+
+Some examples follow.
+@itemize
+@item
+Output the input file audio and the corresponding video representation
+at the same time:
+@example
+amovie=a.mp3,asplit[out0],showwaves[out1]
+@end example
+
+@item
+Create a synthetic signal and show it with showwaves, forcing a
+framerate of 30 frames per second:
+@example
+aevalsrc=sin(1*2*PI*t)*sin(880*2*PI*t):cos(2*PI*200*t),asplit[out0],showwaves=r=30[out1]
+@end example
+@end itemize
+
+@c man end TRANSMEDIA FILTERS

libavfilter/Makefile

@@ -193,6 +193,8 @@ OBJS-$(CONFIG_MP_FILTER) += libmpcodecs/vf_yuvcsp.o
 OBJS-$(CONFIG_MP_FILTER) += libmpcodecs/vf_yvu9.o
 OBJS-$(CONFIG_MP_FILTER) += libmpcodecs/pullup.o
 
+# transmedia filters
+OBJS-$(CONFIG_SHOWWAVES_FILTER)              += avf_showwaves.o
 
 TESTPROGS = drawutils formats
 

libavfilter/allfilters.c

@@ -129,6 +129,9 @@ void avfilter_register_all(void)
     REGISTER_FILTER (BUFFERSINK,  buffersink,  vsink);
     REGISTER_FILTER (NULLSINK,    nullsink,    vsink);
 
+    /* transmedia filters */
+    REGISTER_FILTER (SHOWWAVES,   showwaves,   avf);
+
     /* those filters are part of public or internal API => registered
      * unconditionally */
     {

libavfilter/avf_showwaves.c

@@ -0,0 +1,259 @@
+/*
+ * Copyright (c) 2012 Stefano Sabatini
+ *
+ * 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
+ */
+
+/**
+ * @file
+ * audio to video transmedia filter
+ */
+
+#include "libavutil/audioconvert.h"
+#include "libavutil/opt.h"
+#include "libavutil/parseutils.h"
+#include "avfilter.h"
+#include "formats.h"
+#include "audio.h"
+#include "video.h"
+
+typedef struct {
+    const AVClass *class;
+    int w, h;
+    char *rate_str;
+    AVRational rate;
+    int buf_idx;
+    AVFilterBufferRef *outpicref;
+    int req_fullfilled;
+    int n;
+    int sample_count_mod;
+} ShowWavesContext;
+
+#define OFFSET(x) offsetof(ShowWavesContext, x)
+
+static const AVOption showwaves_options[] = {
+    { "rate", "set video rate", OFFSET(rate_str), AV_OPT_TYPE_STRING, {.str = NULL}, 0, 0 },
+    { "r",    "set video rate", OFFSET(rate_str), AV_OPT_TYPE_STRING, {.str = NULL}, 0, 0 },
+    { "size", "set video size", OFFSET(w), AV_OPT_TYPE_IMAGE_SIZE, {.str = "600x240"}, 0, 0 },
+    { "s",    "set video size", OFFSET(w), AV_OPT_TYPE_IMAGE_SIZE, {.str = "600x240"}, 0, 0 },
+    { "n",    "set how many samples to show in the same point", OFFSET(n), AV_OPT_TYPE_INT, {.dbl = 0}, 0, INT_MAX},
+    { NULL },
+};
+
+static const AVClass showwaves_class = {
+    .class_name = "showwaves",
+    .item_name  = av_default_item_name,
+    .option     = showwaves_options,
+    .version    = LIBAVUTIL_VERSION_INT,
+    .category   = AV_CLASS_CATEGORY_FILTER,
+};
+
+static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
+{
+    ShowWavesContext *showwaves = ctx->priv;
+    int err;
+
+    showwaves->class = &showwaves_class;
+    av_opt_set_defaults(showwaves);
+    showwaves->buf_idx = 0;
+
+    if ((err = av_set_options_string(showwaves, args, "=", ":")) < 0) {
+        av_log(ctx, AV_LOG_ERROR, "Error parsing options string: '%s'\n", args);
+        return err;
+    }
+
+    return 0;
+}
+
+static av_cold void uninit(AVFilterContext *ctx)
+{
+    ShowWavesContext *showwaves = ctx->priv;
+
+    av_freep(&showwaves->rate_str);
+    avfilter_unref_bufferp(&showwaves->outpicref);
+}
+
+static int query_formats(AVFilterContext *ctx)
+{
+    AVFilterFormats *formats = NULL;
+    AVFilterChannelLayouts *layouts = NULL;
+    AVFilterLink *inlink = ctx->inputs[0];
+    AVFilterLink *outlink = ctx->outputs[0];
+    static const enum AVSampleFormat sample_fmts[] = { AV_SAMPLE_FMT_S16, -1 };
+    static const enum PixelFormat pix_fmts[] = { PIX_FMT_GRAY8, -1 };
+
+    /* set input audio formats */
+    formats = ff_make_format_list(sample_fmts);
+    if (!formats)
+        return AVERROR(ENOMEM);
+    ff_formats_ref(formats, &inlink->out_formats);
+
+    layouts = ff_all_channel_layouts();
+    if (!layouts)
+        return AVERROR(ENOMEM);
+    ff_channel_layouts_ref(layouts, &inlink->out_channel_layouts);
+
+    formats = ff_all_samplerates();
+    if (!formats)
+        return AVERROR(ENOMEM);
+    ff_formats_ref(formats, &inlink->out_samplerates);
+
+    /* set output video format */
+    formats = ff_make_format_list(pix_fmts);
+    if (!formats)
+        return AVERROR(ENOMEM);
+    ff_formats_ref(formats, &outlink->in_formats);
+
+    return 0;
+}
+
+static int config_output(AVFilterLink *outlink)
+{
+    AVFilterContext *ctx = outlink->src;
+    AVFilterLink *inlink = ctx->inputs[0];
+    ShowWavesContext *showwaves = ctx->priv;
+    int err;
+
+    if (showwaves->n && showwaves->rate_str) {
+        av_log(ctx, AV_LOG_ERROR, "Options 'n' and 'rate' cannot be set at the same time\n");
+        return AVERROR(EINVAL);
+    }
+
+    if (!showwaves->n) {
+        if (!showwaves->rate_str)
+            showwaves->rate = (AVRational){25,1}; /* set default value */
+        else if ((err = av_parse_video_rate(&showwaves->rate, showwaves->rate_str)) < 0) {
+            av_log(ctx, AV_LOG_ERROR, "Invalid frame rate: '%s'\n", showwaves->rate_str);
+            return err;
+        }
+        showwaves->n = FFMAX(1, ((double)inlink->sample_rate / (showwaves->w * av_q2d(showwaves->rate))) + 0.5);
+    }
+
+    outlink->w = showwaves->w;
+    outlink->h = showwaves->h;
+    outlink->sample_aspect_ratio = (AVRational){1,1};
+
+    outlink->frame_rate = av_div_q((AVRational){inlink->sample_rate,showwaves->n},
+                                   (AVRational){showwaves->w,1});
+
+    av_log(ctx, AV_LOG_INFO, "s:%dx%d r:%f n:%d\n",
+           showwaves->w, showwaves->h, av_q2d(outlink->frame_rate), showwaves->n);
+    return 0;
+}
+
+inline static void push_frame(AVFilterLink *outlink)
+{
+    ShowWavesContext *showwaves = outlink->src->priv;
+
+    ff_start_frame(outlink, showwaves->outpicref);
+    ff_draw_slice(outlink, 0, outlink->h, 1);
+    ff_end_frame(outlink);
+    showwaves->req_fullfilled = 1;
+    showwaves->outpicref = NULL;
+    showwaves->buf_idx = 0;
+}
+
+static int request_frame(AVFilterLink *outlink)
+{
+    ShowWavesContext *showwaves = outlink->src->priv;
+    AVFilterLink *inlink = outlink->src->inputs[0];
+    int ret;
+
+    showwaves->req_fullfilled = 0;
+    do {
+        ret = avfilter_request_frame(inlink);
+    } while (!showwaves->req_fullfilled && ret >= 0);
+
+    if (ret == AVERROR_EOF && showwaves->outpicref)
+        push_frame(outlink);
+    return ret;
+}
+
+#define MAX_INT16 ((1<<15) -1)
+
+static void filter_samples(AVFilterLink *inlink, AVFilterBufferRef *insamples)
+{
+    AVFilterContext *ctx = inlink->dst;
+    AVFilterLink *outlink = ctx->outputs[0];
+    ShowWavesContext *showwaves = ctx->priv;
+    const int nb_samples = insamples->audio->nb_samples;
+    AVFilterBufferRef *outpicref = showwaves->outpicref;
+    int linesize = outpicref ? outpicref->linesize[0] : 0;
+    int16_t *p = (int16_t *)insamples->data[0];
+    int nb_channels = av_get_channel_layout_nb_channels(insamples->audio->channel_layout);
+    int i, j, h;
+    const int n = showwaves->n;
+    const int x = 255 / (nb_channels * n); /* multiplication factor, pre-computed to avoid in-loop divisions */
+
+    /* draw data in the buffer */
+    for (i = 0; i < nb_samples; i++) {
+        if (showwaves->buf_idx == 0) {
+            showwaves->outpicref = outpicref =
+                ff_get_video_buffer(outlink, AV_PERM_WRITE|AV_PERM_ALIGN,
+                                    outlink->w, outlink->h);
+            outpicref->video->w = outlink->w;
+            outpicref->video->h = outlink->h;
+            outpicref->pts = insamples->pts;
+            outlink->out_buf = outpicref;
+            linesize = outpicref->linesize[0];
+            memset(outpicref->data[0], 0, showwaves->h*linesize);
+        }
+        for (j = 0; j < nb_channels; j++) {
+            h = showwaves->h/2 - av_rescale(*p++, showwaves->h/2, MAX_INT16);
+            if (h >= 0 && h < outlink->h)
+                *(outpicref->data[0] + showwaves->buf_idx + h * linesize) += x;
+        }
+        showwaves->sample_count_mod++;
+        if (showwaves->sample_count_mod == n) {
+            showwaves->sample_count_mod = 0;
+            showwaves->buf_idx++;
+        }
+        if (showwaves->buf_idx == showwaves->w)
+            push_frame(outlink);
+    }
+
+    avfilter_unref_buffer(insamples);
+}
+
+AVFilter avfilter_avf_showwaves = {
+    .name           = "showwaves",
+    .description    = NULL_IF_CONFIG_SMALL("Convert input audio to a video output."),
+    .init           = init,
+    .uninit         = uninit,
+    .query_formats  = query_formats,
+    .priv_size      = sizeof(ShowWavesContext),
+
+    .inputs  = (const AVFilterPad[]) {
+        {
+            .name           = "default",
+            .type           = AVMEDIA_TYPE_AUDIO,
+            .filter_samples = filter_samples,
+            .min_perms      = AV_PERM_READ,
+        },
+        { .name = NULL }
+    },
+
+    .outputs = (const AVFilterPad[]) {
+        {
+            .name           = "default",
+            .type           = AVMEDIA_TYPE_VIDEO,
+            .config_props   = config_output,
+            .request_frame  = request_frame,
+        },
+        { .name = NULL }
+    },
+};

libavfilter/version.h

@@ -29,7 +29,7 @@
 #include "libavutil/avutil.h"
 
 #define LIBAVFILTER_VERSION_MAJOR  2
-#define LIBAVFILTER_VERSION_MINOR 81
+#define LIBAVFILTER_VERSION_MINOR 82
 #define LIBAVFILTER_VERSION_MICRO 100
 
 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \