model : add ASR support for LFM2-Audio-1.5B (conformer) (#18106)

* ASR with LFM2-Audio-1.5B * Set rope_theta * Fix comment * Remove rope_theta setting * Address PR feedback * rename functions to conformer * remove some redundant ggml_cont * fix missing tensor * add prefix "a." for conv tensors * remove redundant reshape * clean up * add test model --------- Co-authored-by: Tarek Dakhran <tarek@liquid.ai>
2025-12-19 00:18:01 +01:00
parent f9ec8858ed
commit 8ea958d4d9
17 changed files with 669 additions and 29 deletions
@@ -535,3 +535,56 @@ bool mtmd_audio_preprocessor_whisper::preprocess(

    return true;
 }
+
+//
+// mtmd_audio_preprocessor_conformer
+//
+
+void mtmd_audio_preprocessor_conformer::initialize() {
+    g_cache.fill_sin_cos_table(hparams.audio_n_fft);
+    g_cache.fill_hann_window(hparams.audio_window_len, true);
+    g_cache.fill_mel_filterbank_matrix(
+        hparams.n_mel_bins,
+        hparams.audio_n_fft,
+        hparams.audio_sample_rate);
+}
+
+bool mtmd_audio_preprocessor_conformer::preprocess(
+        const float * samples,
+        size_t n_samples,
+        std::vector<mtmd_audio_mel> & output) {
+    // empty audio
+    if (n_samples == 0) {
+        return false;
+    }
+
+    filter_params params;
+    params.n_mel            = hparams.n_mel_bins;
+    params.n_fft_bins       = 1 + (hparams.audio_n_fft / 2);
+    params.hann_window_size = hparams.audio_window_len;
+    params.hop_length       = hparams.audio_hop_len;
+    params.sample_rate      = hparams.audio_sample_rate;
+    params.center_padding   = true;
+    params.preemph          = 0.97f;
+    params.use_natural_log  = true;
+    params.norm_per_feature = true;
+
+    // make sure the global cache is initialized
+    GGML_ASSERT(!g_cache.sin_vals.empty());
+    GGML_ASSERT(!g_cache.cos_vals.empty());
+    GGML_ASSERT(!g_cache.filters.data.empty());
+
+    mtmd_audio_mel out_full;
+    bool ok = log_mel_spectrogram(
+                samples,
+                n_samples,
+                4, // n_threads
+                params,
+                out_full);
+    if (!ok) {
+        return false;
+    }
+
+    output.push_back(std::move(out_full));
+    return true;
+}