mtmd : add ultravox audio input (#13623)

* convert ok, load ok

* warmup ok

* test

* still does not work?

* fix padding

* temporary give up

* fix merge conflict

* build_ultravox()

* rm test

* fix merge conflict

* add necessary mtmd APIs

* first working version (only 4s of audio)

* will this monster compile?

* fix compile

* please compile

* fPIC

* fix windows

* various fixes

* clean up audio_helpers

* fix conversion

* add some debug stuff

* long audio input ok

* adapt the api

* add --audio arg

* final touch UX

* add miniaudio to readme

* fix typo

* refactor kv metadata

* mtmd_default_marker()

tools/mtmd/mtmd-audio.h

@@ -0,0 +1,62 @@
+#pragma once
+
+#include "ggml.h"
+
+#include <cstdint>
+#include <vector>
+#include <string>
+
+#define WHISPER_ASSERT GGML_ASSERT
+
+#define WHISPER_SAMPLE_RATE 16000
+#define WHISPER_N_FFT       400
+#define WHISPER_HOP_LENGTH  160
+#define WHISPER_CHUNK_SIZE  30
+
+#define COMMON_SAMPLE_RATE 16000
+
+namespace whisper_preprocessor {
+
+struct whisper_mel {
+    int n_len;
+    int n_len_org;
+    int n_mel;
+
+    std::vector<float> data;
+};
+
+struct whisper_filters {
+    int32_t n_mel;
+    int32_t n_fft;
+
+    std::vector<float> data;
+};
+
+extern bool preprocess_audio(
+        const float * samples,
+        size_t n_samples,
+        const whisper_filters & filters,
+        std::vector<whisper_mel> & output);
+
+} // namespace whisper_preprocessor
+
+
+// TODO @ngxson : move this helper to mtmd-helpers.cpp
+namespace audio_helpers {
+
+extern bool is_audio_file(const char * buf, size_t len);
+
+extern bool decode_audio_from_buf(
+        const unsigned char * buf_in,
+        size_t len,
+        int target_sampler_rate,
+        std::vector<float> & pcmf32_mono);
+
+} // namespace audio_helpers
+
+
+namespace whisper_precalc_filters {
+
+extern whisper_preprocessor::whisper_filters get_128_bins();
+
+} // namespace whisper_precalc_filters