stream : add "max_tokens" cli arg

Controls the max tokens per segment for the stream example

examples/stream/stream.cpp

@@ -40,6 +40,8 @@ struct whisper_params {
     int32_t step_ms    = 3000;
     int32_t length_ms  = 10000;
     int32_t capture_id = -1;
+    int32_t max_tokens = 32;
+    int32_t audio_ctx  = 0;
 
     bool speed_up             = false;
     bool verbose              = false;
@@ -69,6 +71,10 @@ bool whisper_params_parse(int argc, char ** argv, whisper_params & params) {
             params.length_ms = std::stoi(argv[++i]);
         } else if (arg == "-c" || arg == "--capture") {
             params.capture_id = std::stoi(argv[++i]);
+        } else if (arg == "-mt" || arg == "--max_tokens") {
+            params.max_tokens = std::stoi(argv[++i]);
+        } else if (arg == "-ac" || arg == "--audio_ctx") {
+            params.audio_ctx = std::stoi(argv[++i]);
         } else if (arg == "-su" || arg == "--speed-up") {
             params.speed_up = true;
         } else if (arg == "-v" || arg == "--verbose") {
@@ -116,6 +122,8 @@ void whisper_print_usage(int argc, char ** argv, const whisper_params & params)
     fprintf(stderr, "            --step N         audio step size in milliseconds (default: %d)\n", params.step_ms);
     fprintf(stderr, "            --length N       audio length in milliseconds (default: %d)\n", params.length_ms);
     fprintf(stderr, "  -c ID,    --capture ID     capture device ID (default: -1)\n");
+    fprintf(stderr, "  -mt N,    --max_tokens N   maximum number of tokens per audio chunk (default: %d)\n", params.max_tokens);
+    fprintf(stderr, "  -ac N,    --audio_ctx N    audio context size (default: %d, 0 - all)\n", params.audio_ctx);
     fprintf(stderr, "  -su,      --speed-up       speed up audio by factor of 2 (faster processing, reduced accuracy, default: %s)\n", params.speed_up ? "true" : "false");
     fprintf(stderr, "  -v,       --verbose        verbose output\n");
     fprintf(stderr, "            --translate      translate from source language to english\n");
@@ -221,6 +229,7 @@ int main(int argc, char ** argv) {
     const int n_samples = (params.step_ms/1000.0)*WHISPER_SAMPLE_RATE;
     const int n_samples_len = (params.length_ms/1000.0)*WHISPER_SAMPLE_RATE;
     const int n_samples_30s = 30*WHISPER_SAMPLE_RATE;
+    const int n_samples_keep = 0.2*WHISPER_SAMPLE_RATE;
 
     std::vector<float> pcmf32(n_samples_30s, 0.0f);
     std::vector<float> pcmf32_old;
@@ -303,7 +312,7 @@ int main(int argc, char ** argv) {
         //const int n_samples_take = std::min((int) pcmf32_old.size(), std::max(0, n_samples_30s/30 - n_samples_new));
 
         // take up to params.length_ms audio from previous iteration
-        const int n_samples_take = std::min((int) pcmf32_old.size(), std::max(0, n_samples_len - n_samples_new));
+        const int n_samples_take = std::min((int) pcmf32_old.size(), std::max(0, n_samples_keep + n_samples_len - n_samples_new));
 
         //printf("processing: take = %d, new = %d, old = %d\n", n_samples_take, n_samples_new, (int) pcmf32_old.size());
 
@@ -327,9 +336,12 @@ int main(int argc, char ** argv) {
             wparams.print_timestamps     = !params.no_timestamps;
             wparams.translate            = params.translate;
             wparams.no_context           = params.no_context;
+            wparams.single_segment       = true;
+            wparams.max_tokens           = params.max_tokens;
             wparams.language             = params.language.c_str();
             wparams.n_threads            = params.n_threads;
 
+            wparams.audio_ctx            = params.audio_ctx;
             wparams.speed_up             = params.speed_up;
 
             if (whisper_full(ctx, wparams, pcmf32.data(), pcmf32.size()) != 0) {
@@ -379,7 +391,8 @@ int main(int argc, char ** argv) {
             if ((n_iter % n_new_line) == 0) {
                 printf("\n");
 
-                pcmf32_old.clear();
+                // keep part of the audio for next iteration to try to mitigate word boundary issues
+                pcmf32_old = std::vector<float>(pcmf32.end() - n_samples_keep, pcmf32.end());
             }
         }
     }

whisper.cpp

@@ -424,6 +424,9 @@ struct whisper_context {
     int64_t t_last;
     whisper_token tid_last;
     std::vector<float> energy; // PCM signal energy
+
+    // [EXPERIMENTAL] speed-up techniques
+    int32_t exp_n_audio_ctx; // 0 - use default
 };
 
 // load the model from a ggml file
@@ -1076,13 +1079,11 @@ static bool whisper_encode(
     const auto & mel_inp = wctx.mel;
     const auto & hparams = model.hparams;
 
-    const int n_ctx   = hparams.n_audio_ctx;
+    const int n_ctx   = wctx.exp_n_audio_ctx > 0 ? wctx.exp_n_audio_ctx : hparams.n_audio_ctx;
     const int n_state = hparams.n_audio_state;
     const int n_head  = hparams.n_audio_head;
     const int n_layer = hparams.n_audio_layer;
 
-    const int N = n_ctx;
-
     const int n_mels = hparams.n_mels;
     assert(mel_inp.n_mel == n_mels);
 
@@ -1132,7 +1133,30 @@ static bool whisper_encode(
         cur = ggml_gelu(ctx0, cur);
     }
 
-    cur = ggml_add(ctx0, model.e_pe, ggml_transpose(ctx0, cur));
+    // ===================================================================
+    // NOTE: experimenting with partial evaluation of the encoder (ignore)
+    //static int iter = -1;
+    //const int n_iter = 1500/n_ctx;
+
+    //iter = (iter + 1) % n_iter;
+
+    //if (iter == 0) {
+    //    memset(model.memory_cross_k->data, 0, ggml_nbytes(model.memory_cross_k));
+    //    memset(model.memory_cross_v->data, 0, ggml_nbytes(model.memory_cross_v));
+    //}
+
+    static int iter = 0;
+
+    const size_t e_pe_stride = model.e_pe->ne[0]*ggml_element_size(model.e_pe);
+    const size_t e_pe_offset = model.e_pe->ne[0]*ggml_element_size(model.e_pe)*n_ctx*iter;
+
+    struct ggml_tensor * e_pe = ggml_view_2d(ctx0, model.e_pe, model.e_pe->ne[0], n_ctx, e_pe_stride, e_pe_offset);
+
+    cur = ggml_add(ctx0, e_pe, ggml_transpose(ctx0, cur));
+    // ===================================================================
+
+    // original:
+    //cur = ggml_add(ctx0, model.e_pe, ggml_transpose(ctx0, cur));
 
     struct ggml_tensor * inpL = cur;
 
@@ -1198,14 +1222,14 @@ static bool whisper_encode(
                 ggml_permute(ctxL,
                         ggml_cpy(ctxL,
                             Qcur,
-                            ggml_new_tensor_3d(ctxL, GGML_TYPE_F16, n_state/n_head, n_head, N)),
+                            ggml_new_tensor_3d(ctxL, GGML_TYPE_F16, n_state/n_head, n_head, n_ctx)),
                         0, 2, 1, 3);
 
             struct ggml_tensor * K =
                 ggml_permute(ctxL,
                         ggml_cpy(ctxL,
                             Kcur,
-                            ggml_new_tensor_3d(ctxL, GGML_TYPE_F16, n_state/n_head, n_head, N)),
+                            ggml_new_tensor_3d(ctxL, GGML_TYPE_F16, n_state/n_head, n_head, n_ctx)),
                         0, 2, 1, 3);
 
             struct ggml_tensor * V =
@@ -1213,9 +1237,9 @@ static bool whisper_encode(
                         ggml_permute(ctxL,
                             ggml_reshape_3d(ctxL,
                                 Vcur,
-                                n_state/n_head, n_head, N),
+                                n_state/n_head, n_head, n_ctx),
                             1, 2, 0, 3),
-                        ggml_new_tensor_3d(ctxL, GGML_TYPE_F16, N, n_state/n_head, n_head)
+                        ggml_new_tensor_3d(ctxL, GGML_TYPE_F16, n_ctx, n_state/n_head, n_head)
                         );
 
             struct ggml_tensor * KQV = ggml_flash_attn(ctxL, Q, K, V, false);
@@ -1224,14 +1248,14 @@ static bool whisper_encode(
                 ggml_permute(ctxL,
                         ggml_cpy(ctxL,
                             Qcur,
-                            ggml_new_tensor_3d(ctxL, GGML_TYPE_F32, n_state/n_head, n_head, N)),
+                            ggml_new_tensor_3d(ctxL, GGML_TYPE_F32, n_state/n_head, n_head, n_ctx)),
                         0, 2, 1, 3);
 
             struct ggml_tensor * K =
                 ggml_permute(ctxL,
                         ggml_cpy(ctxL,
                             Kcur,
-                            ggml_new_tensor_3d(ctxL, GGML_TYPE_F16, n_state/n_head, n_head, N)),
+                            ggml_new_tensor_3d(ctxL, GGML_TYPE_F16, n_state/n_head, n_head, n_ctx)),
                         0, 2, 1, 3);
 
             // K * Q
@@ -1249,7 +1273,7 @@ static bool whisper_encode(
             //    ggml_permute(ctxL,
             //            ggml_cpy(ctxL,
             //                Vcur,
-            //                ggml_new_tensor_3d(ctxL, GGML_TYPE_F16, n_state/n_head, n_head, N)),
+            //                ggml_new_tensor_3d(ctxL, GGML_TYPE_F16, n_state/n_head, n_head, n_ctx)),
             //            1, 2, 0, 3);
 
             //struct ggml_tensor * KQV = ggml_mul_mat(ctxL, V_trans, KQ_soft_max);
@@ -1259,9 +1283,9 @@ static bool whisper_encode(
                         ggml_permute(ctxL,
                             ggml_reshape_3d(ctxL,
                                 Vcur,
-                                n_state/n_head, n_head, N),
+                                n_state/n_head, n_head, n_ctx),
                             0, 2, 1, 3),
-                        ggml_new_tensor_3d(ctxL, GGML_TYPE_F16, n_state/n_head, N, n_head)
+                        ggml_new_tensor_3d(ctxL, GGML_TYPE_F16, n_state/n_head, n_ctx, n_head)
                         );
 
             struct ggml_tensor * KQV = ggml_mul_mat(ctxL, ggml_transpose(ctxL, V), KQ_soft_max);
@@ -1271,7 +1295,7 @@ static bool whisper_encode(
 
             cur = ggml_cpy(ctxL,
                     KQV_merged,
-                    ggml_new_tensor_2d(ctxL, GGML_TYPE_F32, n_state, N));
+                    ggml_new_tensor_2d(ctxL, GGML_TYPE_F32, n_state, n_ctx));
         }
 
         // projection
@@ -1425,6 +1449,8 @@ static bool whisper_encode(
                         Vcross),
                     Vcross);
 
+            //struct ggml_tensor * k = ggml_view_1d(ctx0, model.memory_cross_k, n_state*n_ctx, (ggml_element_size(model.memory_cross_k)*n_state)*(il*hparams.n_audio_ctx + iter*n_ctx));
+            //struct ggml_tensor * v = ggml_view_1d(ctx0, model.memory_cross_v, n_state*n_ctx, (ggml_element_size(model.memory_cross_v)*n_state)*(il*hparams.n_audio_ctx + iter*n_ctx));
             struct ggml_tensor * k = ggml_view_1d(ctx0, model.memory_cross_k, n_state*n_ctx, (ggml_element_size(model.memory_cross_k)*n_state)*(il*n_ctx));
             struct ggml_tensor * v = ggml_view_1d(ctx0, model.memory_cross_v, n_state*n_ctx, (ggml_element_size(model.memory_cross_v)*n_state)*(il*n_ctx));
 
@@ -1474,7 +1500,7 @@ static bool whisper_decode(
     const int n_layer = hparams.n_text_layer;
 
     const int N = n_tokens;
-    const int M = hparams.n_audio_ctx;
+    const int M = wctx.exp_n_audio_ctx > 0 ? wctx.exp_n_audio_ctx : hparams.n_audio_ctx;
 
     struct ggml_init_params params = {
             .mem_size   = wctx.buf_compute.size(),
@@ -2365,6 +2391,7 @@ struct whisper_full_params whisper_full_default_params(enum whisper_sampling_str
 
                     /*.translate            =*/ false,
                     /*.no_context           =*/ false,
+                    /*.single_segment       =*/ false,
                     /*.print_special_tokens =*/ false,
                     /*.print_progress       =*/ true,
                     /*.print_realtime       =*/ false,
@@ -2374,8 +2401,10 @@ struct whisper_full_params whisper_full_default_params(enum whisper_sampling_str
                     /*.thold_pt             =*/ 0.01f,
                     /*.thold_ptsum          =*/ 0.01f,
                     /*.max_len              =*/ 0,
+                    /*.max_tokens           =*/ 0,
 
                     /*.speed_up             =*/ false,
+                    /*.audio_ctx            =*/ 0,
 
                     /*.language             =*/ "en",
 
@@ -2405,6 +2434,7 @@ struct whisper_full_params whisper_full_default_params(enum whisper_sampling_str
 
                     /*.translate            =*/ false,
                     /*.no_context           =*/ false,
+                    /*.single_segment       =*/ false,
                     /*.print_special_tokens =*/ false,
                     /*.print_progress       =*/ true,
                     /*.print_realtime       =*/ false,
@@ -2414,8 +2444,10 @@ struct whisper_full_params whisper_full_default_params(enum whisper_sampling_str
                     /*.thold_pt             =*/ 0.01f,
                     /*.thold_ptsum          =*/ 0.01f,
                     /*.max_len              =*/ 0,
+                    /*.max_tokens           =*/ 0,
 
                     /*.speed_up             =*/ false,
+                    /*.audio_ctx            =*/ 0,
 
                     /*.language             =*/ "en",
 
@@ -2546,6 +2578,9 @@ int whisper_full(
         prompt_past.clear();
     }
 
+    // overwrite audio_ctx
+    ctx->exp_n_audio_ctx = params.audio_ctx;
+
     // these tokens determine the task that will be performed
     std::vector<whisper_token> prompt_init = { whisper_token_sot(ctx) };
     if (whisper_is_multilingual(ctx)) {
@@ -2656,7 +2691,7 @@ int whisper_full(
                 //}
 
                 // end of text token
-                if (token.id == whisper_token_eot(ctx)) {
+                if (token.id == whisper_token_eot(ctx) || (params.max_tokens > 0 && i > params.max_tokens)) {
                     if (result_len == 0) {
                         if (seek + seek_delta + 100 >= seek_end) {
                             result_len = i + 1;
@@ -2665,6 +2700,12 @@ int whisper_full(
                             fprintf(stderr, "\n%s: failed to generate timestamp token - this should not happen\n\n", __func__);
                         }
                     }
+
+                    if (params.single_segment) {
+                        result_len = i + 1;
+                        seek_delta = 100*WHISPER_CHUNK_SIZE;
+                    }
+
                     break;
                 }
 

whisper.h

@@ -191,6 +191,7 @@ extern "C" {
 
         bool translate;
         bool no_context;
+        bool single_segment; // force single segment output (useful for streaming)
         bool print_special_tokens;
         bool print_progress;
         bool print_realtime;
@@ -201,9 +202,11 @@ extern "C" {
         float thold_pt;         // timestamp token probability threshold (~0.01)
         float thold_ptsum;      // timestamp token sum probability threshold (~0.01)
         int   max_len;          // max segment length in characters
+        int   max_tokens;       // max tokens per segment (0 = no limit)
 
         // [EXPERIMENTAL] speed-up techniques
         bool speed_up;  // speed-up the audio by 2x using Phase Vocoder
+        int  audio_ctx; // overwrite the audio context size (0 = use default)
 
         const char * language;