Re: [FFmpeg-devel] [PATCH v3] libavfi/dnn: add LibTorch as one of DNN backend

["Jean-Baptiste Kempf" <jb@videolan.org>]

Hello,

On Tue, 20 Feb 2024, at 05:48, wenbin.chen-at-intel.com@ffmpeg.org wrote:
> From: Wenbin Chen <wenbin.chen@intel.com>
>
> PyTorch is an open source machine learning framework that accelerates

OK for me

> the path from research prototyping to production deployment. Official
> websit: https://pytorch.org/. We call the C++ library of PyTorch as

websitE

> LibTorch, the same below.
>
> To build FFmpeg with LibTorch, please take following steps as reference:
> 1. download LibTorch C++ library in 
> https://pytorch.org/get-started/locally/,
> please select C++/Java for language, and other options as your need.
> 2. unzip the file to your own dir, with command
> unzip libtorch-shared-with-deps-latest.zip -d your_dir
> 3. export libtorch_root/libtorch/include and
> libtorch_root/libtorch/include/torch/csrc/api/include to $PATH
> export libtorch_root/libtorch/lib/ to $LD_LIBRARY_PATH
> 4. config FFmpeg with ../configure --enable-libtorch 
> --extra-cflag=-I/libtorch_root/libtorch/include 
> --extra-cflag=-I/libtorch_root/libtorch/include/torch/csrc/api/include 
> --extra-ldflags=-L/libtorch_root/libtorch/lib/
> 5. make
>
> To run FFmpeg DNN inference with LibTorch backend:
> ./ffmpeg -i input.jpg -vf 
> dnn_processing=dnn_backend=torch:model=LibTorch_model.pt -y output.jpg
> The LibTorch_model.pt can be generated by Python with 
> torch.jit.script() api. Please note, torch.jit.trace() is not 
> recommanded, since it does not support ambiguous input size.
>
> Signed-off-by: Ting Fu <ting.fu@intel.com>
> Signed-off-by: Wenbin Chen <wenbin.chen@intel.com>
> ---
>  configure                             |   5 +-
>  libavfilter/dnn/Makefile              |   1 +
>  libavfilter/dnn/dnn_backend_torch.cpp | 597 ++++++++++++++++++++++++++
>  libavfilter/dnn/dnn_interface.c       |   5 +
>  libavfilter/dnn_filter_common.c       |  15 +-
>  libavfilter/dnn_interface.h           |   2 +-
>  libavfilter/vf_dnn_processing.c       |   3 +
>  7 files changed, 624 insertions(+), 4 deletions(-)
>  create mode 100644 libavfilter/dnn/dnn_backend_torch.cpp
>
> diff --git a/configure b/configure
> index 2c635043dd..450ef54a80 100755
> --- a/configure
> +++ b/configure
> @@ -279,6 +279,7 @@ External library support:
>    --enable-libtheora       enable Theora encoding via libtheora [no]
>    --enable-libtls          enable LibreSSL (via libtls), needed for 
> https support
>                             if openssl, gnutls or mbedtls is not used 
> [no]
> +  --enable-libtorch        enable Torch as one DNN backend [no]
>    --enable-libtwolame      enable MP2 encoding via libtwolame [no]
>    --enable-libuavs3d       enable AVS3 decoding via libuavs3d [no]
>    --enable-libv4l2         enable libv4l2/v4l-utils [no]
> @@ -1901,6 +1902,7 @@ EXTERNAL_LIBRARY_LIST="
>      libtensorflow
>      libtesseract
>      libtheora
> +    libtorch
>      libtwolame
>      libuavs3d
>      libv4l2
> @@ -2781,7 +2783,7 @@ cbs_vp9_select="cbs"
>  deflate_wrapper_deps="zlib"
>  dirac_parse_select="golomb"
>  dovi_rpu_select="golomb"
> -dnn_suggest="libtensorflow libopenvino"
> +dnn_suggest="libtensorflow libopenvino libtorch"
>  dnn_deps="avformat swscale"
>  error_resilience_select="me_cmp"
>  evcparse_select="golomb"
> @@ -6886,6 +6888,7 @@ enabled libtensorflow     && require 
> libtensorflow tensorflow/c/c_api.h TF_Versi
>  enabled libtesseract      && require_pkg_config libtesseract tesseract 
> tesseract/capi.h TessBaseAPICreate
>  enabled libtheora         && require libtheora theora/theoraenc.h 
> th_info_init -ltheoraenc -ltheoradec -logg
>  enabled libtls            && require_pkg_config libtls libtls tls.h 
> tls_configure
> +enabled libtorch          && check_cxxflags -std=c++14 && require_cpp 
> libtorch torch/torch.h "torch::Tensor" -ltorch -lc10 -ltorch_cpu 
> -lstdc++ -lpthread
>  enabled libtwolame        && require libtwolame twolame.h twolame_init 
> -ltwolame &&
>                               { check_lib libtwolame twolame.h 
> twolame_encode_buffer_float32_interleaved -ltwolame ||
>                                 die "ERROR: libtwolame must be 
> installed and version must be >= 0.3.10"; }
> diff --git a/libavfilter/dnn/Makefile b/libavfilter/dnn/Makefile
> index 5d5697ea42..3d09927c98 100644
> --- a/libavfilter/dnn/Makefile
> +++ b/libavfilter/dnn/Makefile
> @@ -6,5 +6,6 @@ OBJS-$(CONFIG_DNN)                           += 
> dnn/dnn_backend_common.o
> 
>  DNN-OBJS-$(CONFIG_LIBTENSORFLOW)             += dnn/dnn_backend_tf.o
>  DNN-OBJS-$(CONFIG_LIBOPENVINO)               += dnn/dnn_backend_openvino.o
> +DNN-OBJS-$(CONFIG_LIBTORCH)                  += dnn/dnn_backend_torch.o
> 
>  OBJS-$(CONFIG_DNN)                           += $(DNN-OBJS-yes)
> diff --git a/libavfilter/dnn/dnn_backend_torch.cpp 
> b/libavfilter/dnn/dnn_backend_torch.cpp
> new file mode 100644
> index 0000000000..54d3b309a1
> --- /dev/null
> +++ b/libavfilter/dnn/dnn_backend_torch.cpp
> @@ -0,0 +1,597 @@
> +/*
> + * Copyright (c) 2024
> + *
> + * This file is part of FFmpeg.
> + *
> + * FFmpeg is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public
> + * License as published by the Free Software Foundation; either
> + * version 2.1 of the License, or (at your option) any later version.
> + *
> + * FFmpeg is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with FFmpeg; if not, write to the Free Software
> + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 
> 02110-1301 USA
> + */
> +
> +/**
> + * @file
> + * DNN Torch backend implementation.
> + */
> +
> +#include <torch/torch.h>
> +#include <torch/script.h>
> +
> +extern "C" {
> +#include "../internal.h"
> +#include "dnn_io_proc.h"
> +#include "dnn_backend_common.h"
> +#include "libavutil/opt.h"
> +#include "queue.h"
> +#include "safe_queue.h"
> +}
> +
> +typedef struct THOptions{
> +    char *device_name;
> +    int optimize;
> +} THOptions;
> +
> +typedef struct THContext {
> +    const AVClass *c_class;
> +    THOptions options;
> +} THContext;
> +
> +typedef struct THModel {
> +    THContext ctx;
> +    DNNModel *model;
> +    torch::jit::Module *jit_model;
> +    SafeQueue *request_queue;
> +    Queue *task_queue;
> +    Queue *lltask_queue;
> +} THModel;
> +
> +typedef struct THInferRequest {
> +    torch::Tensor *output;
> +    torch::Tensor *input_tensor;
> +} THInferRequest;
> +
> +typedef struct THRequestItem {
> +    THInferRequest *infer_request;
> +    LastLevelTaskItem *lltask;
> +    DNNAsyncExecModule exec_module;
> +} THRequestItem;
> +
> +
> +#define OFFSET(x) offsetof(THContext, x)
> +#define FLAGS AV_OPT_FLAG_FILTERING_PARAM
> +static const AVOption dnn_th_options[] = {
> +    { "device", "device to run model", OFFSET(options.device_name), 
> AV_OPT_TYPE_STRING, { .str = "cpu" }, 0, 0, FLAGS },
> +    { "optimize", "turn on graph executor optimization", 
> OFFSET(options.optimize), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 1, FLAGS},
> +    { NULL }
> +};
> +
> +AVFILTER_DEFINE_CLASS(dnn_th);
> +
> +static int extract_lltask_from_task(TaskItem *task, Queue 
> *lltask_queue)
> +{
> +    THModel *th_model = (THModel *)task->model;
> +    THContext *ctx = &th_model->ctx;
> +    LastLevelTaskItem *lltask = (LastLevelTaskItem 
> *)av_malloc(sizeof(*lltask));
> +    if (!lltask) {
> +        av_log(ctx, AV_LOG_ERROR, "Failed to allocate memory for 
> LastLevelTaskItem\n");
> +        return AVERROR(ENOMEM);
> +    }
> +    task->inference_todo = 1;
> +    task->inference_done = 0;
> +    lltask->task = task;
> +    if (ff_queue_push_back(lltask_queue, lltask) < 0) {
> +        av_log(ctx, AV_LOG_ERROR, "Failed to push back 
> lltask_queue.\n");
> +        av_freep(&lltask);
> +        return AVERROR(ENOMEM);
> +    }
> +    return 0;
> +}
> +
> +static void th_free_request(THInferRequest *request)
> +{
> +    if (!request)
> +        return;
> +    if (request->output) {
> +        delete(request->output);
> +        request->output = NULL;
> +    }
> +    if (request->input_tensor) {
> +        delete(request->input_tensor);
> +        request->input_tensor = NULL;
> +    }
> +    return;
> +}
> +
> +static inline void destroy_request_item(THRequestItem **arg)
> +{
> +    THRequestItem *item;
> +    if (!arg || !*arg) {
> +        return;
> +    }
> +    item = *arg;
> +    th_free_request(item->infer_request);
> +    av_freep(&item->infer_request);
> +    av_freep(&item->lltask);
> +    ff_dnn_async_module_cleanup(&item->exec_module);
> +    av_freep(arg);
> +}
> +
> +static void dnn_free_model_th(DNNModel **model)
> +{
> +    THModel *th_model;
> +    if (!model || !*model)
> +        return;
> +
> +    th_model = (THModel *) (*model)->model;
> +    while (ff_safe_queue_size(th_model->request_queue) != 0) {
> +        THRequestItem *item = (THRequestItem 
> *)ff_safe_queue_pop_front(th_model->request_queue);
> +        destroy_request_item(&item);
> +    }
> +    ff_safe_queue_destroy(th_model->request_queue);
> +
> +    while (ff_queue_size(th_model->lltask_queue) != 0) {
> +        LastLevelTaskItem *item = (LastLevelTaskItem 
> *)ff_queue_pop_front(th_model->lltask_queue);
> +        av_freep(&item);
> +    }
> +    ff_queue_destroy(th_model->lltask_queue);
> +
> +    while (ff_queue_size(th_model->task_queue) != 0) {
> +        TaskItem *item = (TaskItem 
> *)ff_queue_pop_front(th_model->task_queue);
> +        av_frame_free(&item->in_frame);
> +        av_frame_free(&item->out_frame);
> +        av_freep(&item);
> +    }
> +    ff_queue_destroy(th_model->task_queue);
> +    delete th_model->jit_model;
> +    av_opt_free(&th_model->ctx);
> +    av_freep(&th_model);
> +    av_freep(model);
> +}
> +
> +static int get_input_th(void *model, DNNData *input, const char 
> *input_name)
> +{
> +    input->dt = DNN_FLOAT;
> +    input->order = DCO_RGB;
> +    input->layout = DL_NCHW;
> +    input->dims[0] = 1;
> +    input->dims[1] = 3;
> +    input->dims[2] = -1;
> +    input->dims[3] = -1;
> +    return 0;
> +}
> +
> +static void deleter(void *arg)
> +{
> +    av_freep(&arg);
> +}
> +
> +static int fill_model_input_th(THModel *th_model, THRequestItem 
> *request)
> +{
> +    LastLevelTaskItem *lltask = NULL;
> +    TaskItem *task = NULL;
> +    THInferRequest *infer_request = NULL;
> +    DNNData input = { 0 };
> +    THContext *ctx = &th_model->ctx;
> +    int ret, width_idx, height_idx, channel_idx;
> +
> +    lltask = (LastLevelTaskItem 
> *)ff_queue_pop_front(th_model->lltask_queue);
> +    if (!lltask) {
> +        ret = AVERROR(EINVAL);
> +        goto err;
> +    }
> +    request->lltask = lltask;
> +    task = lltask->task;
> +    infer_request = request->infer_request;
> +
> +    ret = get_input_th(th_model, &input, NULL);
> +    if ( ret != 0) {
> +        goto err;
> +    }
> +    width_idx = dnn_get_width_idx_by_layout(input.layout);
> +    height_idx = dnn_get_height_idx_by_layout(input.layout);
> +    channel_idx = dnn_get_channel_idx_by_layout(input.layout);
> +    input.dims[height_idx] = task->in_frame->height;
> +    input.dims[width_idx] = task->in_frame->width;
> +    input.data = av_malloc(input.dims[height_idx] * 
> input.dims[width_idx] *
> +                           input.dims[channel_idx] * sizeof(float));
> +    if (!input.data)
> +        return AVERROR(ENOMEM);
> +    infer_request->input_tensor = new torch::Tensor();
> +    infer_request->output = new torch::Tensor();
> +
> +    switch (th_model->model->func_type) {
> +    case DFT_PROCESS_FRAME:
> +        input.scale = 255;
> +        if (task->do_ioproc) {
> +            if (th_model->model->frame_pre_proc != NULL) {
> +                th_model->model->frame_pre_proc(task->in_frame, 
> &input, th_model->model->filter_ctx);
> +            } else {
> +                ff_proc_from_frame_to_dnn(task->in_frame, &input, ctx);
> +            }
> +        }
> +        break;
> +    default:
> +        avpriv_report_missing_feature(NULL, "model function type %d", 
> th_model->model->func_type);
> +        break;
> +    }
> +    *infer_request->input_tensor = torch::from_blob(input.data,
> +        {1, 1, input.dims[channel_idx], input.dims[height_idx], 
> input.dims[width_idx]},
> +        deleter, torch::kFloat32);
> +    return 0;
> +
> +err:
> +    th_free_request(infer_request);
> +    return ret;
> +}
> +
> +static int th_start_inference(void *args)
> +{
> +    THRequestItem *request = (THRequestItem *)args;
> +    THInferRequest *infer_request = NULL;
> +    LastLevelTaskItem *lltask = NULL;
> +    TaskItem *task = NULL;
> +    THModel *th_model = NULL;
> +    THContext *ctx = NULL;
> +    std::vector<torch::jit::IValue> inputs;
> +    torch::NoGradGuard no_grad;
> +
> +    if (!request) {
> +        av_log(NULL, AV_LOG_ERROR, "THRequestItem is NULL\n");
> +        return AVERROR(EINVAL);
> +    }
> +    infer_request = request->infer_request;
> +    lltask = request->lltask;
> +    task = lltask->task;
> +    th_model = (THModel *)task->model;
> +    ctx = &th_model->ctx;
> +
> +    if (ctx->options.optimize)
> +        torch::jit::setGraphExecutorOptimize(true);
> +    else
> +        torch::jit::setGraphExecutorOptimize(false);
> +
> +    if (!infer_request->input_tensor || !infer_request->output) {
> +        av_log(ctx, AV_LOG_ERROR, "input or output tensor is NULL\n");
> +        return DNN_GENERIC_ERROR;
> +    }
> +    inputs.push_back(*infer_request->input_tensor);
> +
> +    *infer_request->output = 
> th_model->jit_model->forward(inputs).toTensor();
> +
> +    return 0;
> +}
> +
> +static void infer_completion_callback(void *args) {
> +    THRequestItem *request = (THRequestItem*)args;
> +    LastLevelTaskItem *lltask = request->lltask;
> +    TaskItem *task = lltask->task;
> +    DNNData outputs = { 0 };
> +    THInferRequest *infer_request = request->infer_request;
> +    THModel *th_model = (THModel *)task->model;
> +    torch::Tensor *output = infer_request->output;
> +
> +    c10::IntArrayRef sizes = output->sizes();
> +    outputs.order = DCO_RGB;
> +    outputs.layout = DL_NCHW;
> +    outputs.dt = DNN_FLOAT;
> +    if (sizes.size() == 5) {
> +        // 5 dimensions: [batch_size, frame_nubmer, channel, height, 
> width]
> +        // this format of data is normally used for video frame SR
> +        outputs.dims[0] = sizes.at(0); // N
> +        outputs.dims[1] = sizes.at(2); // C
> +        outputs.dims[2] = sizes.at(3); // H
> +        outputs.dims[3] = sizes.at(4); // W
> +    } else {
> +        avpriv_report_missing_feature(&th_model->ctx, "Support of this 
> kind of model");
> +        goto err;
> +    }
> +
> +    switch (th_model->model->func_type) {
> +    case DFT_PROCESS_FRAME:
> +        if (task->do_ioproc) {
> +            outputs.scale = 255;
> +            outputs.data = output->data_ptr();
> +            if (th_model->model->frame_post_proc != NULL) {
> +                th_model->model->frame_post_proc(task->out_frame, 
> &outputs, th_model->model->filter_ctx);
> +            } else {
> +                ff_proc_from_dnn_to_frame(task->out_frame, &outputs, 
> &th_model->ctx);
> +            }
> +        } else {
> +            task->out_frame->width = 
> outputs.dims[dnn_get_width_idx_by_layout(outputs.layout)];
> +            task->out_frame->height = 
> outputs.dims[dnn_get_height_idx_by_layout(outputs.layout)];
> +        }
> +        break;
> +    default:
> +        avpriv_report_missing_feature(&th_model->ctx, "model function 
> type %d", th_model->model->func_type);
> +        goto err;
> +    }
> +    task->inference_done++;
> +    av_freep(&request->lltask);
> +err:
> +    th_free_request(infer_request);
> +
> +    if (ff_safe_queue_push_back(th_model->request_queue, request) < 0) 
> {
> +        destroy_request_item(&request);
> +        av_log(&th_model->ctx, AV_LOG_ERROR, "Unable to push back 
> request_queue when failed to start inference.\n");
> +    }
> +}
> +
> +static int execute_model_th(THRequestItem *request, Queue 
> *lltask_queue)
> +{
> +    THModel *th_model = NULL;
> +    LastLevelTaskItem *lltask;
> +    TaskItem *task = NULL;
> +    int ret = 0;
> +
> +    if (ff_queue_size(lltask_queue) == 0) {
> +        destroy_request_item(&request);
> +        return 0;
> +    }
> +
> +    lltask = (LastLevelTaskItem *)ff_queue_peek_front(lltask_queue);
> +    if (lltask == NULL) {
> +        av_log(NULL, AV_LOG_ERROR, "Failed to get 
> LastLevelTaskItem\n");
> +        ret = AVERROR(EINVAL);
> +        goto err;
> +    }
> +    task = lltask->task;
> +    th_model = (THModel *)task->model;
> +
> +    ret = fill_model_input_th(th_model, request);
> +    if ( ret != 0) {
> +        goto err;
> +    }
> +    if (task->async) {
> +        avpriv_report_missing_feature(&th_model->ctx, "LibTorch 
> async");
> +    } else {
> +        ret = th_start_inference((void *)(request));
> +        if (ret != 0) {
> +            goto err;
> +        }
> +        infer_completion_callback(request);
> +        return (task->inference_done == task->inference_todo) ? 0 : 
> DNN_GENERIC_ERROR;
> +    }
> +
> +err:
> +    th_free_request(request->infer_request);
> +    if (ff_safe_queue_push_back(th_model->request_queue, request) < 0) 
> {
> +        destroy_request_item(&request);
> +    }
> +    return ret;
> +}
> +
> +static int get_output_th(void *model, const char *input_name, int 
> input_width, int input_height,
> +                                   const char *output_name, int 
> *output_width, int *output_height)
> +{
> +    int ret = 0;
> +    THModel *th_model = (THModel*) model;
> +    THContext *ctx = &th_model->ctx;
> +    TaskItem task = { 0 };
> +    THRequestItem *request = NULL;
> +    DNNExecBaseParams exec_params = {
> +        .input_name     = input_name,
> +        .output_names   = &output_name,
> +        .nb_output      = 1,
> +        .in_frame       = NULL,
> +        .out_frame      = NULL,
> +    };
> +    ret = ff_dnn_fill_gettingoutput_task(&task, &exec_params, 
> th_model, input_height, input_width, ctx);
> +    if ( ret != 0) {
> +        goto err;
> +    }
> +
> +    ret = extract_lltask_from_task(&task, th_model->lltask_queue);
> +    if ( ret != 0) {
> +        av_log(ctx, AV_LOG_ERROR, "unable to extract last level task 
> from task.\n");
> +        goto err;
> +    }
> +
> +    request = (THRequestItem*) 
> ff_safe_queue_pop_front(th_model->request_queue);
> +    if (!request) {
> +        av_log(ctx, AV_LOG_ERROR, "unable to get infer request.\n");
> +        ret = AVERROR(EINVAL);
> +        goto err;
> +    }
> +
> +    ret = execute_model_th(request, th_model->lltask_queue);
> +    *output_width = task.out_frame->width;
> +    *output_height = task.out_frame->height;
> +
> +err:
> +    av_frame_free(&task.out_frame);
> +    av_frame_free(&task.in_frame);
> +    return ret;
> +}
> +
> +static THInferRequest *th_create_inference_request(void)
> +{
> +    THInferRequest *request = (THInferRequest 
> *)av_malloc(sizeof(THInferRequest));
> +    if (!request) {
> +        return NULL;
> +    }
> +    request->input_tensor = NULL;
> +    request->output = NULL;
> +    return request;
> +}
> +
> +static DNNModel *dnn_load_model_th(const char *model_filename, 
> DNNFunctionType func_type, const char *options, AVFilterContext 
> *filter_ctx)
> +{
> +    DNNModel *model = NULL;
> +    THModel *th_model = NULL;
> +    THRequestItem *item = NULL;
> +    THContext *ctx;
> +
> +    model = (DNNModel *)av_mallocz(sizeof(DNNModel));
> +    if (!model) {
> +        return NULL;
> +    }
> +
> +    th_model = (THModel *)av_mallocz(sizeof(THModel));
> +    if (!th_model) {
> +        av_freep(&model);
> +        return NULL;
> +    }
> +    th_model->model = model;
> +    model->model = th_model;
> +    th_model->ctx.c_class = &dnn_th_class;
> +    ctx = &th_model->ctx;
> +    //parse options
> +    av_opt_set_defaults(ctx);
> +    if (av_opt_set_from_string(ctx, options, NULL, "=", "&") < 0) {
> +        av_log(ctx, AV_LOG_ERROR, "Failed to parse options \"%s\"\n", 
> options);
> +        return NULL;
> +    }
> +
> +    c10::Device device = c10::Device(ctx->options.device_name);
> +    if (!device.is_cpu()) {
> +        av_log(ctx, AV_LOG_ERROR, "Not supported device:\"%s\"\n", 
> ctx->options.device_name);
> +        goto fail;
> +    }
> +
> +    try {
> +        th_model->jit_model = new torch::jit::Module;
> +        (*th_model->jit_model) = torch::jit::load(model_filename);
> +    } catch (const c10::Error& e) {
> +        av_log(ctx, AV_LOG_ERROR, "Failed to load torch model\n");
> +        goto fail;
> +    }
> +
> +    th_model->request_queue = ff_safe_queue_create();
> +    if (!th_model->request_queue) {
> +        goto fail;
> +    }
> +
> +    item = (THRequestItem *)av_mallocz(sizeof(THRequestItem));
> +    if (!item) {
> +        goto fail;
> +    }
> +    item->lltask = NULL;
> +    item->infer_request = th_create_inference_request();
> +    if (!item->infer_request) {
> +        av_log(NULL, AV_LOG_ERROR, "Failed to allocate memory for 
> Torch inference request\n");
> +        goto fail;
> +    }
> +    item->exec_module.start_inference = &th_start_inference;
> +    item->exec_module.callback = &infer_completion_callback;
> +    item->exec_module.args = item;
> +
> +    if (ff_safe_queue_push_back(th_model->request_queue, item) < 0) {
> +        goto fail;
> +    }
> +    item = NULL;
> +
> +    th_model->task_queue = ff_queue_create();
> +    if (!th_model->task_queue) {
> +        goto fail;
> +    }
> +
> +    th_model->lltask_queue = ff_queue_create();
> +    if (!th_model->lltask_queue) {
> +        goto fail;
> +    }
> +
> +    model->get_input = &get_input_th;
> +    model->get_output = &get_output_th;
> +    model->options = NULL;
> +    model->filter_ctx = filter_ctx;
> +    model->func_type = func_type;
> +    return model;
> +
> +fail:
> +    if (item) {
> +        destroy_request_item(&item);
> +        av_freep(&item);
> +    }
> +    dnn_free_model_th(&model);
> +    return NULL;
> +}
> +
> +static int dnn_execute_model_th(const DNNModel *model, 
> DNNExecBaseParams *exec_params)
> +{
> +    THModel *th_model = (THModel *)model->model;
> +    THContext *ctx = &th_model->ctx;
> +    TaskItem *task;
> +    THRequestItem *request;
> +    int ret = 0;
> +
> +    ret = ff_check_exec_params(ctx, DNN_TH, model->func_type, 
> exec_params);
> +    if (ret != 0) {
> +        av_log(ctx, AV_LOG_ERROR, "exec parameter checking fail.\n");
> +        return ret;
> +    }
> +
> +    task = (TaskItem *)av_malloc(sizeof(TaskItem));
> +    if (!task) {
> +        av_log(ctx, AV_LOG_ERROR, "unable to alloc memory for task 
> item.\n");
> +        return AVERROR(ENOMEM);
> +    }
> +
> +    ret = ff_dnn_fill_task(task, exec_params, th_model, 0, 1);
> +    if (ret != 0) {
> +        av_freep(&task);
> +        av_log(ctx, AV_LOG_ERROR, "unable to fill task.\n");
> +        return ret;
> +    }
> +
> +    ret = ff_queue_push_back(th_model->task_queue, task);
> +    if (ret < 0) {
> +        av_freep(&task);
> +        av_log(ctx, AV_LOG_ERROR, "unable to push back task_queue.\n");
> +        return ret;
> +    }
> +
> +    ret = extract_lltask_from_task(task, th_model->lltask_queue);
> +    if (ret != 0) {
> +        av_log(ctx, AV_LOG_ERROR, "unable to extract last level task 
> from task.\n");
> +        return ret;
> +    }
> +
> +    request = (THRequestItem 
> *)ff_safe_queue_pop_front(th_model->request_queue);
> +    if (!request) {
> +        av_log(ctx, AV_LOG_ERROR, "unable to get infer request.\n");
> +        return AVERROR(EINVAL);
> +    }
> +
> +    return execute_model_th(request, th_model->lltask_queue);
> +}
> +
> +static DNNAsyncStatusType dnn_get_result_th(const DNNModel *model, 
> AVFrame **in, AVFrame **out)
> +{
> +    THModel *th_model = (THModel *)model->model;
> +    return ff_dnn_get_result_common(th_model->task_queue, in, out);
> +}
> +
> +static int dnn_flush_th(const DNNModel *model)
> +{
> +    THModel *th_model = (THModel *)model->model;
> +    THRequestItem *request;
> +
> +    if (ff_queue_size(th_model->lltask_queue) == 0)
> +        // no pending task need to flush
> +        return 0;
> +
> +    request = (THRequestItem 
> *)ff_safe_queue_pop_front(th_model->request_queue);
> +    if (!request) {
> +        av_log(&th_model->ctx, AV_LOG_ERROR, "unable to get infer 
> request.\n");
> +        return AVERROR(EINVAL);
> +    }
> +
> +    return execute_model_th(request, th_model->lltask_queue);
> +}
> +
> +extern const DNNModule ff_dnn_backend_torch = {
> +    .load_model     = dnn_load_model_th,
> +    .execute_model  = dnn_execute_model_th,
> +    .get_result     = dnn_get_result_th,
> +    .flush          = dnn_flush_th,
> +    .free_model     = dnn_free_model_th,
> +};
> diff --git a/libavfilter/dnn/dnn_interface.c 
> b/libavfilter/dnn/dnn_interface.c
> index e843826aa6..b9f71aea53 100644
> --- a/libavfilter/dnn/dnn_interface.c
> +++ b/libavfilter/dnn/dnn_interface.c
> @@ -28,6 +28,7 @@
> 
>  extern const DNNModule ff_dnn_backend_openvino;
>  extern const DNNModule ff_dnn_backend_tf;
> +extern const DNNModule ff_dnn_backend_torch;
> 
>  const DNNModule *ff_get_dnn_module(DNNBackendType backend_type, void 
> *log_ctx)
>  {
> @@ -40,6 +41,10 @@ const DNNModule *ff_get_dnn_module(DNNBackendType 
> backend_type, void *log_ctx)
>      case DNN_OV:
>          return &ff_dnn_backend_openvino;
>      #endif
> +    #if (CONFIG_LIBTORCH == 1)
> +    case DNN_TH:
> +        return &ff_dnn_backend_torch;
> +    #endif
>      default:
>          av_log(log_ctx, AV_LOG_ERROR,
>                  "Module backend_type %d is not supported or 
> enabled.\n",
> diff --git a/libavfilter/dnn_filter_common.c 
> b/libavfilter/dnn_filter_common.c
> index f012d450a2..7d194c9ade 100644
> --- a/libavfilter/dnn_filter_common.c
> +++ b/libavfilter/dnn_filter_common.c
> @@ -53,12 +53,22 @@ static char **separate_output_names(const char 
> *expr, const char *val_sep, int *
> 
>  int ff_dnn_init(DnnContext *ctx, DNNFunctionType func_type, 
> AVFilterContext *filter_ctx)
>  {
> +    DNNBackendType backend = ctx->backend_type;
> +
>      if (!ctx->model_filename) {
>          av_log(filter_ctx, AV_LOG_ERROR, "model file for network is 
> not specified\n");
>          return AVERROR(EINVAL);
>      }
> 
> -    if (ctx->backend_type == DNN_TF) {
> +    if (backend == DNN_TH) {
> +        if (ctx->model_inputname)
> +            av_log(filter_ctx, AV_LOG_WARNING, "LibTorch backend do 
> not require inputname, "\
> +                                               "inputname will be 
> ignored.\n");
> +        if (ctx->model_outputnames)
> +            av_log(filter_ctx, AV_LOG_WARNING, "LibTorch backend do 
> not require outputname(s), "\
> +                                               "all outputname(s) will 
> be ignored.\n");
> +        ctx->nb_outputs = 1;
> +    } else if (backend == DNN_TF) {
>          if (!ctx->model_inputname) {
>              av_log(filter_ctx, AV_LOG_ERROR, "input name of the model 
> network is not specified\n");
>              return AVERROR(EINVAL);
> @@ -115,7 +125,8 @@ int ff_dnn_get_input(DnnContext *ctx, DNNData 
> *input)
> 
>  int ff_dnn_get_output(DnnContext *ctx, int input_width, int 
> input_height, int *output_width, int *output_height)
>  {
> -    char * output_name = ctx->model_outputnames ? 
> ctx->model_outputnames[0] : NULL;
> +    char * output_name = ctx->model_outputnames && ctx->backend_type 
> != DNN_TH ?
> +                         ctx->model_outputnames[0] : NULL;
>      return ctx->model->get_output(ctx->model->model, 
> ctx->model_inputname, input_width, input_height,
>                                      (const char *)output_name, 
> output_width, output_height);
>  }
> diff --git a/libavfilter/dnn_interface.h b/libavfilter/dnn_interface.h
> index 852d88baa8..63f492e690 100644
> --- a/libavfilter/dnn_interface.h
> +++ b/libavfilter/dnn_interface.h
> @@ -32,7 +32,7 @@
> 
>  #define DNN_GENERIC_ERROR FFERRTAG('D','N','N','!')
> 
> -typedef enum {DNN_TF = 1, DNN_OV} DNNBackendType;
> +typedef enum {DNN_TF = 1, DNN_OV, DNN_TH} DNNBackendType;
> 
>  typedef enum {DNN_FLOAT = 1, DNN_UINT8 = 4} DNNDataType;
> 
> diff --git a/libavfilter/vf_dnn_processing.c 
> b/libavfilter/vf_dnn_processing.c
> index e7d21eef32..fdac31665e 100644
> --- a/libavfilter/vf_dnn_processing.c
> +++ b/libavfilter/vf_dnn_processing.c
> @@ -50,6 +50,9 @@ static const AVOption dnn_processing_options[] = {
>  #endif
>  #if (CONFIG_LIBOPENVINO == 1)
>      { "openvino",    "openvino backend flag",      0,                  
>       AV_OPT_TYPE_CONST,     { .i64 = DNN_OV },    0, 0, FLAGS, .unit = 
> "backend" },
> +#endif
> +#if (CONFIG_LIBTORCH == 1)
> +    { "torch",       "torch backend flag",         0,                  
>       AV_OPT_TYPE_CONST,     { .i64 = DNN_TH },    0, 0, FLAGS, 
> "backend" },
>  #endif
>      DNN_COMMON_OPTIONS
>      { NULL }
> -- 
> 2.34.1
>
> _______________________________________________
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> ffmpeg-devel@ffmpeg.org
> https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>
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> ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".

-- 
Jean-Baptiste Kempf -  President
+33 672 704 734
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