tools/mtmd/mtmd-helper-gen.cpp

#include "mtmd.h"
#include "mtmd-helper.h"
#include "mtmd-helper-common.h"
#include "llama.h"
#include "../src/llama-ext.h"

#include <algorithm>
#include <cstring>
#include <memory>
#include <string>
#include <unordered_map>
#include <vector>

#ifdef MTMD_INTERNAL_HEADER
#error "mtmd-helper is a public library outside of mtmd. it must not include internal headers"
#endif

//
// Audio generation helpers
//

// --tts-lang codes -> language names used by the codec_language special tokens
static const std::unordered_map<std::string, std::string> tts_lang_codes = {
    { "zh", "chinese"    },
    { "en", "english"    },
    { "de", "german"     },
    { "it", "italian"    },
    { "pt", "portuguese" },
    { "es", "spanish"    },
    { "ja", "japanese"   },
    { "ko", "korean"     },
    { "fr", "french"     },
    { "ru", "russian"    },
};

static std::string tts_resolve_lang(const std::string & lang) {
    auto it = tts_lang_codes.find(lang);
    return it != tts_lang_codes.end() ? it->second : lang;
}

static llama_token find_special_token(const llama_vocab * vocab, const std::string & piece) {
    const int32_t n = llama_vocab_n_tokens(vocab);
    for (llama_token t = 0; t < n; t++) {
        if (piece == llama_vocab_get_text(vocab, t)) {
            return t;
        }
    }
    return LLAMA_TOKEN_NULL;
}

static bool write_wav16(std::vector<char> & buf, const std::vector<float> & pcm, int32_t rate) {
    // RIFF chunk sizes are 32-bit; refuse to emit a file with a truncated header
    if (pcm.size() > ((size_t) UINT32_MAX - 36) / 2) {
        return false;
    }
    const uint32_t data_sz   = (uint32_t) (pcm.size() * 2);
    const uint32_t riff_sz   = 36 + data_sz;
    const uint32_t fmt_sz    = 16, byte_rate = (uint32_t) rate * 2;
    const uint16_t fmt = 1, ch = 1, align = 2, bits = 16;
    const uint32_t rate32    = (uint32_t) rate;
    auto put = [&](const void * p, size_t n) {
        const char * c = (const char *) p;
        buf.insert(buf.end(), c, c + n);
    };
    put("RIFF", 4); put(&riff_sz, 4); put("WAVE", 4);
    put("fmt ", 4); put(&fmt_sz, 4);
    put(&fmt, 2); put(&ch, 2); put(&rate32, 4);
    put(&byte_rate, 4); put(&align, 2); put(&bits, 2);
    put("data", 4); put(&data_sz, 4);
    for (float v : pcm) {
        int16_t s = (int16_t) (std::max(-1.0f, std::min(1.0f, v)) * 32767.0f);
        put(&s, 2);
    }
    return true;
}

class mtmd_gen_audio_pipeline {
public:
    mtmd_gen_audio_pipeline(llama_context * lctx, mtmd_context * mctx)
        : lctx(lctx), mctx(mctx), model(llama_get_model(lctx)), vocab(llama_model_get_vocab(model)),
          n_embd(llama_model_n_embd(model)), info(mtmd_gen_audio_get_info(mctx)) {}
    virtual ~mtmd_gen_audio_pipeline() = default;

    virtual void reset() = 0;
    virtual int32_t set_input(const mtmd_helper_gen_audio_inp * inp) = 0;
    // decodes at most n_batch prompt tokens; returns remaining count (0 = done), <0 on error
    virtual int32_t step_prompt(int32_t n_batch) = 0;
    // sampled can be LLAMA_TOKEN_NULL for pipelines with no discrete backbone token,
    // those read what they need from h_state_in instead
    virtual int32_t step_gen(llama_token sampled, const float * h_state_in, const float ** h_state_out) = 0;
    virtual int32_t get_output(int32_t * out_sample_rate, const char ** out_data, size_t * out_data_len, int64_t * out_n_samples) = 0;

protected:
    llama_context * lctx;
    mtmd_context  * mctx;
    const llama_model * model;
    const llama_vocab  * vocab;
    int n_embd;
    mtmd_gen_audio_info info;
};

// Qwen3-TTS: backbone samples codec_0, code_predictor gives the other 15 codebooks,
// then code2wav decodes them to PCM
class qwen3tts_gen_audio_pipeline : public mtmd_gen_audio_pipeline {
public:
    using mtmd_gen_audio_pipeline::mtmd_gen_audio_pipeline;

    void reset() override {
        seq_id = 0;
        pos = 0;
        codes_buf.clear();
        c2w_state.clear();
        audio_pcm.clear();
        overlay.clear();
        h_state_buf.clear();
        out_buf.clear();
        prompt_embd_buf.clear();
        prompt_batch.reset();
        n_prompt = 0;
        prompt_pos = 0;
    }

    int32_t set_input(const mtmd_helper_gen_audio_inp * inp) override {
        reset();
        seq_id = inp->seq_id;

        if (!ensure_cache()) {
            return 1;
        }

        const std::string lang   = tts_resolve_lang((inp->lang && inp->lang[0]) ? inp->lang : "english");
        const llama_token c_lang = find_special_token(vocab, ("<|codec_language_" + lang + "|>").c_str());
        if (c_lang == LLAMA_TOKEN_NULL) {
            LOG_ERR("mtmd_helper_gen_audio: unknown language '%s'\n", lang.c_str());
            return 1;
        }

        std::vector<float> speaker_embd;
        if (inp->speaker_ref) {
            if (!encode_speaker(inp->speaker_ref, speaker_embd)) {
                return 1;
            }
        }

        const int n_e = n_embd;
        auto row = [&](llama_token t) {
            return std::vector<float>(tok_embd.begin() + (size_t) t * n_e,
                                       tok_embd.begin() + (size_t) (t + 1) * n_e);
        };
        auto sum_row = [&](llama_token a, llama_token b) {
            std::vector<float> va = row(a), vb = row(b);
            for (int i = 0; i < n_e; i++) va[(size_t) i] += vb[(size_t) i];
            return va;
        };
        auto sum_vec = [&](llama_token a, const std::vector<float> & vb) {
            std::vector<float> va = row(a);
            for (int i = 0; i < n_e; i++) va[(size_t) i] += vb[(size_t) i];
            return va;
        };

        // upstream chat wrap, then slices: [0:3] role, [3:-5] utterance body
        const std::string full = "<|im_start|>assistant\n" + std::string(inp->prompt, inp->prompt_len) +
                                  "<|im_end|>\n<|im_start|>assistant\n";
        std::vector<llama_token> ids(full.size() + 16);
        int n_ids = llama_tokenize(vocab, full.c_str(), (int32_t) full.size(), ids.data(), (int32_t) ids.size(),
                                   false, true);
        if (n_ids < 8) {
            LOG_ERR("mtmd_helper_gen_audio: tokenization failed\n");
            return 1;
        }
        ids.resize((size_t) n_ids);

        std::vector<std::vector<float>> prompt;
        for (int i = 0; i < 3; i++) prompt.push_back(row(ids[(size_t) i]));
        prompt.push_back(sum_row(tts_pad, c_think));
        prompt.push_back(sum_row(tts_pad, c_think_b));
        prompt.push_back(sum_row(tts_pad, c_lang));
        prompt.push_back(sum_row(tts_pad, c_think_e));
        if (!speaker_embd.empty()) prompt.push_back(sum_vec(tts_pad, speaker_embd));
        prompt.push_back(sum_row(tts_bos, codec_pad));
        for (int i = 3; i < n_ids - 5; i++) prompt.push_back(sum_row(ids[(size_t) i], codec_pad));
        prompt.push_back(sum_row(tts_eos, codec_pad));
        prompt.push_back(sum_row(tts_pad, codec_bos));

        n_prompt = (int) prompt.size();

        // the talker uses the qwen3vl interleaved mrope, all sections are equal for a text/codec stream
        mrope = llama_model_rope_type(model) == LLAMA_ROPE_TYPE_MROPE ||
                llama_model_rope_type(model) == LLAMA_ROPE_TYPE_IMROPE;
        const int n_pos_per_embd = mrope ? 4 : 1;

        prompt_embd_buf.resize((size_t) n_prompt * (size_t) n_e);
        for (int i = 0; i < n_prompt; i++) {
            memcpy(prompt_embd_buf.data() + (size_t) i * n_e, prompt[(size_t) i].data(), (size_t) n_e * sizeof(float));
        }

        prompt_batch.reset(new decode_embd_batch(prompt_embd_buf.data(), n_prompt, n_pos_per_embd, n_e));
        if (mrope) prompt_batch->set_position_mrope_1d(0, seq_id);
        else       prompt_batch->set_position_normal  (0, seq_id);
        prompt_pos = 0;

        pos = 0;
        top_k = inp->top_k > 0 ? inp->top_k : 50;
        top_p = inp->top_p > 0 ? inp->top_p : 1.0f;
        out_type = inp->out_type;

        // the prompt above holds the whole text stream up to tts_eos, so every generated
        // frame adds tts_pad on top of the codes embedding
        overlay = row(tts_pad);

        return 0;
    }

    int32_t step_prompt(int32_t n_batch) override {
        GGML_ASSERT(n_batch > 0);
        if (prompt_pos >= n_prompt) {
            return 0;
        }
        const int32_t n_tokens_batch = std::min(n_batch, n_prompt - prompt_pos);
        llama_batch batch_view = prompt_batch->get_view(prompt_pos, n_tokens_batch);

        const bool is_last_batch = (prompt_pos + n_tokens_batch) == n_prompt;
        if (is_last_batch) {
            batch_view.logits[n_tokens_batch - 1] = 1;
        }

        if (llama_decode(lctx, batch_view) != 0) {
            LOG_ERR("mtmd_helper_gen_audio: prompt decode failed\n");
            return -1;
        }

        pos        += n_tokens_batch;
        prompt_pos += n_tokens_batch;

        if (prompt_pos >= n_prompt) {
            // prompt fully processed, its embedding buffer is no longer needed
            prompt_batch.reset();
            prompt_embd_buf.clear();
            return 0;
        }
        return n_prompt - prompt_pos;
    }

    int32_t step_gen(llama_token sampled, const float * h_state_in, const float ** h_state_out) override {
        mtmd_gen_inp inp{};
        inp.type  = MTMD_GEN_PROCESS_TYPE_GEN_CODE;
        inp.code0 = sampled - codec_0;
        inp.embd  = const_cast<float *>(h_state_in);
        inp.top_k = top_k;
        inp.top_p = top_p;
        mtmd_gen_out out{};
        if (mtmd_gen_audio_process(mctx, &inp, &out) != 0) {
            LOG_ERR("mtmd_helper_gen_audio: gen_code process failed\n");
            return 1;
        }

        codes_buf.insert(codes_buf.end(), out.codes, out.codes + out.n_codes);
        if (out.n_codes > 0 && codes_buf.size() / out.n_codes >= window_frames) {
            if (!flush_gen_wav()) {
                return 1;
            }
        }

        std::vector<float> fb(out.embd, out.embd + n_embd);
        for (int i = 0; i < n_embd; i++) fb[(size_t) i] += overlay[(size_t) i];

        const int n_pos_per_embd = mrope ? 4 : 1;
        decode_embd_batch batch_embd(fb.data(), 1, n_pos_per_embd, n_embd);
        if (mrope) batch_embd.set_position_mrope_1d(pos, seq_id);
        else       batch_embd.set_position_normal  (pos, seq_id);
        batch_embd.batch.logits[0] = 1;
        pos++;

        if (llama_decode(lctx, batch_embd.batch) != 0) {
            LOG_ERR("mtmd_helper_gen_audio: decode failed\n");
            return 1;
        }

        const float * he = llama_get_embeddings_ith(lctx, -1);
        h_state_buf.assign(he, he + n_embd);
        *h_state_out = h_state_buf.data();

        return 0;
    }

    int32_t get_output(int32_t * out_sample_rate, const char ** out_data, size_t * out_data_len, int64_t * out_n_samples) override {
        if (!flush_gen_wav()) {
            return 1;
        }

        *out_sample_rate = info.sample_rate;
        if (out_n_samples) {
            *out_n_samples = (int64_t) audio_pcm.size();
        }

        if (out_type == MTMD_HELPER_GEN_AUDIO_OUTTYPE_PCM) {
            *out_data     = (const char *) audio_pcm.data();
            *out_data_len = audio_pcm.size() * sizeof(float);
            return 0;
        }

        out_buf.clear();
        if (!write_wav16(out_buf, audio_pcm, info.sample_rate)) {
            LOG_ERR("mtmd_helper_gen_audio: output too large for WAV\n");
            return 1;
        }
        *out_data     = out_buf.data();
        *out_data_len = out_buf.size();
        return 0;
    }

private:
    bool ensure_cache() {
        if (specials_ok) {
            return true;
        }
        codec_0   = find_special_token(vocab, "<|codec_0|>");
        codec_bos = find_special_token(vocab, "<|codec_bos|>");
        codec_eos = find_special_token(vocab, "<|codec_eos_token|>");
        codec_pad = find_special_token(vocab, "<|codec_pad|>");
        c_think   = find_special_token(vocab, "<|codec_think|>");
        c_think_b = find_special_token(vocab, "<|codec_think_bos|>");
        c_think_e = find_special_token(vocab, "<|codec_think_eos|>");
        tts_pad   = find_special_token(vocab, "<tts_pad>");
        tts_bos   = find_special_token(vocab, "<tts_text_bos>");
        tts_eos   = find_special_token(vocab, "<tts_text_eod>");
        for (llama_token t : { codec_0, codec_bos, codec_eos, codec_pad,
                               c_think, c_think_b, c_think_e,
                               tts_pad, tts_bos, tts_eos }) {
            if (t == LLAMA_TOKEN_NULL) {
                LOG_ERR("mtmd_helper_gen_audio: missing a required special token in vocab\n");
                return false;
            }
        }
        const uint32_t n_tok_embd = llama_model_get_tok_embd(model, nullptr);
        if (n_tok_embd == 0) {
            LOG_ERR("mtmd_helper_gen_audio: model has no token embeddings\n");
            return false;
        }
        tok_embd.resize(n_tok_embd);
        if (llama_model_get_tok_embd(model, tok_embd.data()) != n_tok_embd) {
            LOG_ERR("mtmd_helper_gen_audio: token embedding copy failed\n");
            return false;
        }
        specials_ok = true;
        return true;
    }

    // runs the reference wav through the speaker encoder, returns one x-vector embedding row
    bool encode_speaker(mtmd_bitmap * bitmap, std::vector<float> & out) {
        if (!mtmd_support_audio(mctx)) {
            LOG_ERR("mtmd_helper_gen_audio: mmproj has no speaker/audio encoder\n");
            return false;
        }
        const std::string  marker = mtmd_default_marker();
        mtmd_input_text     text{ marker.c_str(), marker.size(), false, true };
        mtmd_input_chunks * chunks = mtmd_input_chunks_init();
        const mtmd_bitmap * bptr = bitmap;
        bool ok = mtmd_tokenize(mctx, chunks, &text, &bptr, 1) == 0;
        if (ok) {
            ok = false;
            for (size_t i = 0; i < mtmd_input_chunks_size(chunks); i++) {
                const mtmd_input_chunk * chunk = mtmd_input_chunks_get(chunks, i);
                if (mtmd_input_chunk_get_type(chunk) != MTMD_INPUT_CHUNK_TYPE_AUDIO) {
                    continue;
                }
                if (mtmd_encode_chunk(mctx, chunk) != 0) {
                    LOG_ERR("mtmd_helper_gen_audio: speaker encode failed\n");
                    break;
                }
                const float * embd = mtmd_get_output_embd(mctx);
                const size_t  n = (size_t) llama_model_n_embd_inp(model) * mtmd_input_chunk_get_n_tokens(chunk);
                out.assign(embd, embd + n);
                ok = true;
                break;
            }
        }
        mtmd_input_chunks_free(chunks);
        return ok;
    }

    // one GEN_WAV process() call over the buffered codes, state is carried across batches
    bool flush_gen_wav() {
        if (codes_buf.empty()) {
            return true;
        }
        mtmd_gen_inp inp{};
        inp.type       = MTMD_GEN_PROCESS_TYPE_GEN_WAV;
        inp.codes      = codes_buf.data();
        inp.n_codes    = codes_buf.size();
        inp.state_data = c2w_state.empty() ? nullptr : (const char *) c2w_state.data();
        inp.state_size = c2w_state.size();
        mtmd_gen_out out{};
        if (mtmd_gen_audio_process(mctx, &inp, &out) != 0) {
            LOG_ERR("mtmd_helper_gen_audio: gen_wav process failed\n");
            return false;
        }
        audio_pcm.insert(audio_pcm.end(), out.audio, out.audio + out.n_samples);
        c2w_state.assign(out.state_data, out.state_data + out.state_size);
        codes_buf.clear();
        return true;
    }

    // vocab specials fixed across the whole session, looked up once
    bool specials_ok = false;
    llama_token codec_0    = LLAMA_TOKEN_NULL;
    llama_token codec_bos  = LLAMA_TOKEN_NULL;
    llama_token codec_eos  = LLAMA_TOKEN_NULL;
    llama_token codec_pad  = LLAMA_TOKEN_NULL;
    llama_token c_think    = LLAMA_TOKEN_NULL;
    llama_token c_think_b  = LLAMA_TOKEN_NULL;
    llama_token c_think_e  = LLAMA_TOKEN_NULL;
    llama_token tts_pad    = LLAMA_TOKEN_NULL;
    llama_token tts_bos    = LLAMA_TOKEN_NULL;
    llama_token tts_eos    = LLAMA_TOKEN_NULL;
    std::vector<float> tok_embd; // whole token embedding matrix, n_vocab * n_embd

    // must match hparams.wav_tfm_swa hardcoded in clip.cpp
    size_t window_frames = 72;

    // per-generation state, cleared by reset()
    llama_seq_id seq_id = 0;
    bool mrope = false;
    int pos = 0;
    // prompt decode state, consumed batch-by-batch by step_prompt()
    std::vector<float> prompt_embd_buf;
    std::unique_ptr<decode_embd_batch> prompt_batch;
    int n_prompt = 0;
    int prompt_pos = 0;
    int32_t top_k = 50;
    float   top_p = 1.0f;
    std::vector<int32_t> codes_buf;
    std::vector<uint8_t> c2w_state;
    std::vector<float>   audio_pcm;
    std::vector<float> overlay;
    std::vector<float> h_state_buf;
    mtmd_helper_gen_audio_outtype out_type = MTMD_HELPER_GEN_AUDIO_OUTTYPE_WAV;
    std::vector<char> out_buf;
};

static std::unique_ptr<mtmd_gen_audio_pipeline> make_pipeline(llama_context * lctx, mtmd_context * mctx) {
    switch (mtmd_gen_audio_get_info(mctx).type) {
        case MTMD_GEN_AUDIO_TYPE_QWEN3TTS:
            return std::unique_ptr<mtmd_gen_audio_pipeline>(new qwen3tts_gen_audio_pipeline(lctx, mctx));
        default:
            return nullptr;
    }
}

struct mtmd_helper_gen_audio {
    std::unique_ptr<mtmd_gen_audio_pipeline> pipeline;
};

mtmd_helper_gen_audio * mtmd_helper_gen_audio_init(struct llama_context * lctx, struct mtmd_context * mctx) {
    auto * ctx = new mtmd_helper_gen_audio();
    ctx->pipeline = make_pipeline(lctx, mctx);
    return ctx;
}

void mtmd_helper_gen_audio_free(mtmd_helper_gen_audio * ctx) {
    delete ctx;
}

void mtmd_helper_gen_audio_reset(mtmd_helper_gen_audio * ctx) {
    if (ctx->pipeline) {
        ctx->pipeline->reset();
    }
}

int32_t mtmd_helper_gen_audio_set_input(mtmd_helper_gen_audio * ctx, const mtmd_helper_gen_audio_inp * inp) {
    if (!ctx->pipeline) {
        LOG_ERR("mtmd_helper_gen_audio: unsupported or missing gen-audio pipeline\n");
        return 1;
    }
    return ctx->pipeline->set_input(inp);
}

int32_t mtmd_helper_gen_audio_step_prompt(mtmd_helper_gen_audio * ctx, int32_t n_batch) {
    if (!ctx->pipeline) {
        return -1;
    }
    return ctx->pipeline->step_prompt(n_batch);
}

int32_t mtmd_helper_gen_audio_step_gen(mtmd_helper_gen_audio * ctx, llama_token sampled,
                                       const float * h_state_in, const float ** h_state_out) {
    if (!ctx->pipeline) {
        return 1;
    }
    return ctx->pipeline->step_gen(sampled, h_state_in, h_state_out);
}

int32_t mtmd_helper_gen_audio_get_output(mtmd_helper_gen_audio * ctx, int32_t * out_sample_rate,
                                         const char ** out_data, size_t * out_data_len, int64_t * out_n_samples) {
    if (!ctx->pipeline) {
        return 1;
    }
    return ctx->pipeline->get_output(out_sample_rate, out_data, out_data_len, out_n_samples);
}