mtmd: refactor audio preprocessing (#17978)

* mtmd: refactor audio preprocessing

* refactor

Co-authored-by: Tarek <tdakhran@users.noreply.github.com>

* wip

* wip (2)

* improve constructor

* fix use_natural_log

* fix padding for short input

* clean up

* remove need_chunking

---------

Co-authored-by: Tarek <tdakhran@users.noreply.github.com>

Author: ngxson

tools/mtmd/clip-model.h

@@ -65,6 +65,13 @@ struct clip_hparams {
     int32_t n_mel_bins = 0; // whisper preprocessor
     int32_t proj_stack_factor = 0; // ultravox
 
+    // audio-to-mel preprocessor params
+    int32_t audio_chunk_len   = -1; // in seconds
+    int32_t audio_sample_rate = -1;
+    int32_t audio_n_fft       = -1;
+    int32_t audio_window_len  = -1;
+    int32_t audio_hop_len     = -1;
+
     // legacy
     bool has_llava_projector = false;
     int minicpmv_version = 0;
@@ -278,3 +285,5 @@ struct clip_model {
             || proj_type == PROJECTOR_TYPE_VOXTRAL;
     }
 };
+
+const clip_hparams * clip_get_hparams(const struct clip_ctx * ctx);

tools/mtmd/clip.cpp

@@ -1170,11 +1170,15 @@ struct clip_model_loader {
                                              model.proj_type == PROJECTOR_TYPE_VOXTRAL ||
                                              model.proj_type == PROJECTOR_TYPE_GLMA;
                         get_u32(KEY_A_PROJ_STACK_FACTOR, hparams.proj_stack_factor, require_stack);
-                        if (hparams.n_mel_bins != 128) {
-                            throw std::runtime_error(string_format("%s: only 128 mel bins are supported for ultravox\n", __func__));
-                        }
                         hparams.ffn_op = FFN_GELU_ERF;
                         log_ffn_op = "gelu_erf"; // temporary solution for logging
+
+                        // audio preprocessing params
+                        hparams.audio_chunk_len    = 30; // in seconds
+                        hparams.audio_sample_rate  = 16000;
+                        hparams.audio_n_fft        = 400;
+                        hparams.audio_window_len   = 400;
+                        hparams.audio_hop_len      = 160;
                     } break;
                 default:
                     break;
@@ -1212,6 +1216,11 @@ struct clip_model_loader {
                 LOG_INF("\n--- audio hparams ---\n");
                 LOG_INF("%s: n_mel_bins:         %d\n", __func__, hparams.n_mel_bins);
                 LOG_INF("%s: proj_stack_factor:  %d\n", __func__, hparams.proj_stack_factor);
+                LOG_INF("%s: audio_chunk_len:    %d\n", __func__, hparams.audio_chunk_len);
+                LOG_INF("%s: audio_sample_rate:  %d\n", __func__, hparams.audio_sample_rate);
+                LOG_INF("%s: audio_n_fft:        %d\n", __func__, hparams.audio_n_fft);
+                LOG_INF("%s: audio_window_len:   %d\n", __func__, hparams.audio_window_len);
+                LOG_INF("%s: audio_hop_len:      %d\n", __func__, hparams.audio_hop_len);
             }
             LOG_INF("\n");
             LOG_INF("%s: model size:         %.2f MiB\n", __func__, model_size / 1024.0 / 1024.0);
@@ -3478,3 +3487,7 @@ void clip_image_f32_batch_add_mel(struct clip_image_f32_batch * batch, int n_mel
     batch->entries.push_back(clip_image_f32_ptr(audio));
     batch->is_audio = true;
 }
+
+const clip_hparams * clip_get_hparams(const struct clip_ctx * ctx) {
+    return &ctx->model.hparams;
+}