avfilter: add asr filter

1 files changed, 181 insertions, 0 deletions

diff --git a/libavfilter/af_asr.c b/libavfilter/af_asr.c
new file mode 100644
index 0000000000..0c08df1356
--- /dev/null
+++ b/libavfilter/af_asr.c
@@ -0,0 +1,181 @@
+/*
+ * Copyright (c) 2019 Paul B Mahol
+ *
+ * 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 <pocketsphinx/pocketsphinx.h>
+
+#include "libavutil/avassert.h"
+#include "libavutil/avstring.h"
+#include "libavutil/channel_layout.h"
+#include "libavutil/opt.h"
+#include "audio.h"
+#include "avfilter.h"
+#include "internal.h"
+
+typedef struct ASRContext {
+    const AVClass *class;
+
+    int   rate;
+    char *hmm;
+    char *dict;
+    char *lm;
+    char *lmctl;
+    char *lmname;
+    char *logfn;
+
+    ps_decoder_t *ps;
+    cmd_ln_t *config;
+
+    int utt_started;
+} ASRContext;
+
+#define OFFSET(x) offsetof(ASRContext, x)
+#define FLAGS AV_OPT_FLAG_AUDIO_PARAM | AV_OPT_FLAG_FILTERING_PARAM
+static const AVOption asr_options[] = {
+    { "rate",  "set sampling rate",                             OFFSET(rate),   AV_OPT_TYPE_INT,    {.i64=16000}, 0, INT_MAX, .flags = FLAGS },
+    { "hmm",   "set directory containing acoustic model files", OFFSET(hmm),    AV_OPT_TYPE_STRING, {.str=NULL},              .flags = FLAGS },
+    { "dict",  "set pronunciation dictionary",                  OFFSET(dict),   AV_OPT_TYPE_STRING, {.str=NULL},              .flags = FLAGS },
+    { "lm",    "set language model file",                       OFFSET(lm),     AV_OPT_TYPE_STRING, {.str=NULL},              .flags = FLAGS },
+    { "lmctl", "set language model set",                        OFFSET(lmctl),  AV_OPT_TYPE_STRING, {.str=NULL},              .flags = FLAGS },
+    { "lmname","set which language model to use",               OFFSET(lmname), AV_OPT_TYPE_STRING, {.str=NULL},              .flags = FLAGS },
+    { "logfn", "set output for log messages",                   OFFSET(logfn),  AV_OPT_TYPE_STRING, {.str="/dev/null"},       .flags = FLAGS },
+    { NULL }
+};
+
+AVFILTER_DEFINE_CLASS(asr);
+
+static int filter_frame(AVFilterLink *inlink, AVFrame *in)
+{
+    AVFilterContext *ctx = inlink->dst;
+    AVDictionary **metadata = &in->metadata;
+    ASRContext *s = ctx->priv;
+    int have_speech;
+    const char *speech;
+
+    ps_process_raw(s->ps, (const int16_t *)in->data[0], in->nb_samples, 0, 0);
+    have_speech = ps_get_in_speech(s->ps);
+    if (have_speech && !s->utt_started)
+        s->utt_started = 1;
+    if (!have_speech && s->utt_started) {
+        ps_end_utt(s->ps);
+        speech = ps_get_hyp(s->ps, NULL);
+        if (speech != NULL)
+            av_dict_set(metadata, "lavfi.asr.text", speech, 0);
+        ps_start_utt(s->ps);
+        s->utt_started = 0;
+    }
+
+    return ff_filter_frame(ctx->outputs[0], in);
+}
+
+static int config_input(AVFilterLink *inlink)
+{
+    AVFilterContext *ctx = inlink->dst;
+    ASRContext *s = ctx->priv;
+
+    ps_start_utt(s->ps);
+
+    return 0;
+}
+
+static av_cold int asr_init(AVFilterContext *ctx)
+{
+    ASRContext *s = ctx->priv;
+    const float frate = s->rate;
+    char *rate = av_asprintf("%f", frate);
+    const char *argv[] = { "-logfn",    s->logfn,
+                           "-hmm",      s->hmm,
+                           "-lm",       s->lm,
+                           "-lmctl",    s->lmctl,
+                           "-lmname",   s->lmname,
+                           "-dict",     s->dict,
+                           "-samprate", rate,
+                           NULL };
+
+    s->config = cmd_ln_parse_r(NULL, ps_args(), 14, (char **)argv, 0);
+    av_free(rate);
+    if (!s->config)
+        return AVERROR(ENOMEM);
+
+    ps_default_search_args(s->config);
+    s->ps = ps_init(s->config);
+    if (!s->ps)
+        return AVERROR(ENOMEM);
+
+    return 0;
+}
+
+static int query_formats(AVFilterContext *ctx)
+{
+    ASRContext *s = ctx->priv;
+    int sample_rates[] = { s->rate, -1 };
+    int ret;
+
+    AVFilterFormats *formats = NULL;
+    AVFilterChannelLayouts *layout = NULL;
+
+    if ((ret = ff_add_format                 (&formats, AV_SAMPLE_FMT_S16                 )) < 0 ||
+        (ret = ff_set_common_formats         (ctx     , formats                           )) < 0 ||
+        (ret = ff_add_channel_layout         (&layout , AV_CH_LAYOUT_MONO                 )) < 0 ||
+        (ret = ff_set_common_channel_layouts (ctx     , layout                            )) < 0 ||
+        (ret = ff_set_common_samplerates     (ctx     , ff_make_format_list(sample_rates) )) < 0)
+        return ret;
+
+    return 0;
+}
+
+static av_cold void asr_uninit(AVFilterContext *ctx)
+{
+    ASRContext *s = ctx->priv;
+
+    ps_free(s->ps);
+    s->ps = NULL;
+    cmd_ln_free_r(s->config);
+    s->config = NULL;
+}
+
+static const AVFilterPad asr_inputs[] = {
+    {
+        .name         = "default",
+        .type         = AVMEDIA_TYPE_AUDIO,
+        .filter_frame = filter_frame,
+        .config_props = config_input,
+    },
+    { NULL }
+};
+
+static const AVFilterPad asr_outputs[] = {
+    {
+        .name = "default",
+        .type = AVMEDIA_TYPE_AUDIO,
+    },
+    { NULL }
+};
+
+AVFilter ff_af_asr = {
+    .name          = "asr",
+    .description   = NULL_IF_CONFIG_SMALL("Automatic Speech Recognition."),
+    .priv_size     = sizeof(ASRContext),
+    .priv_class    = &asr_class,
+    .init          = asr_init,
+    .uninit        = asr_uninit,
+    .query_formats = query_formats,
+    .inputs        = asr_inputs,
+    .outputs       = asr_outputs,
+};