/*

  * 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
  */
 
 #include "libavutil/buffer.h"
 #include "libavutil/hwcontext.h"
 #include "libavutil/log.h"
 #include "libavutil/mem.h"
 #include "libavutil/opt.h"
 #include "libavutil/pixdesc.h"
 
 #include "avfilter.h"
 #include "formats.h"
 #include "internal.h"
 #include "video.h"
 
 typedef struct HWDownloadContext {
     const AVClass *class;
 
     AVBufferRef       *hwframes_ref;
     AVHWFramesContext *hwframes;
 } HWDownloadContext;
 
 static int hwdownload_query_formats(AVFilterContext *avctx)
 {
     AVFilterFormats  *infmts = NULL;
     AVFilterFormats *outfmts = NULL;
     const AVPixFmtDescriptor *desc;
     int err;
 
     for (desc = av_pix_fmt_desc_next(NULL); desc;
          desc = av_pix_fmt_desc_next(desc)) {
         if (desc->flags & AV_PIX_FMT_FLAG_HWACCEL)
             err = ff_add_format(&infmts,  av_pix_fmt_desc_get_id(desc));
         else
             err = ff_add_format(&outfmts, av_pix_fmt_desc_get_id(desc));
         if (err) {
             ff_formats_unref(&infmts);
             ff_formats_unref(&outfmts);
             return err;
         }
     }
 

     if ((err = ff_formats_ref(infmts,  &avctx->inputs[0]->out_formats)) < 0 ||
         (err = ff_formats_ref(outfmts, &avctx->outputs[0]->in_formats)) < 0)
         return err;
 

     return 0;
 }
 
 static int hwdownload_config_input(AVFilterLink *inlink)
 {
     AVFilterContext *avctx = inlink->dst;
     HWDownloadContext *ctx = avctx->priv;
 
     av_buffer_unref(&ctx->hwframes_ref);
 
     if (!inlink->hw_frames_ctx) {
         av_log(ctx, AV_LOG_ERROR, "The input must have a hardware frame "
                "reference.\n");
         return AVERROR(EINVAL);
     }
 
     ctx->hwframes_ref = av_buffer_ref(inlink->hw_frames_ctx);
     if (!ctx->hwframes_ref)
         return AVERROR(ENOMEM);
 
     ctx->hwframes = (AVHWFramesContext*)ctx->hwframes_ref->data;
 
     return 0;
 }
 
 static int hwdownload_config_output(AVFilterLink *outlink)
 {
     AVFilterContext *avctx = outlink->src;
     AVFilterLink *inlink   = avctx->inputs[0];
     HWDownloadContext *ctx = avctx->priv;
     enum AVPixelFormat *formats;
     int err, i, found;
 
     if (!ctx->hwframes_ref)
         return AVERROR(EINVAL);
 
     err = av_hwframe_transfer_get_formats(ctx->hwframes_ref,
                                           AV_HWFRAME_TRANSFER_DIRECTION_FROM,
                                           &formats, 0);
     if (err < 0)
         return err;
 
     found = 0;
     for (i = 0; formats[i] != AV_PIX_FMT_NONE; i++) {
         if (formats[i] == outlink->format) {
             found = 1;
             break;
         }
     }
     av_freep(&formats);
 
     if (!found) {
         av_log(ctx, AV_LOG_ERROR, "Invalid output format %s for hwframe "
                "download.\n", av_get_pix_fmt_name(outlink->format));
         return AVERROR(EINVAL);
     }
 
     outlink->w = inlink->w;
     outlink->h = inlink->h;
 
     return 0;
 }
 
 static int hwdownload_filter_frame(AVFilterLink *link, AVFrame *input)
 {
     AVFilterContext *avctx = link->dst;
     AVFilterLink  *outlink = avctx->outputs[0];
     HWDownloadContext *ctx = avctx->priv;
     AVFrame *output = NULL;
     int err;
 
     if (!ctx->hwframes_ref || !input->hw_frames_ctx) {
         av_log(ctx, AV_LOG_ERROR, "Input frames must have hardware context.\n");
         err = AVERROR(EINVAL);
         goto fail;
     }
     if ((void*)ctx->hwframes != input->hw_frames_ctx->data) {
         av_log(ctx, AV_LOG_ERROR, "Input frame is not the in the configured "
                "hwframe context.\n");
         err = AVERROR(EINVAL);
         goto fail;
     }
 

     output = ff_get_video_buffer(outlink, ctx->hwframes->width,
                                  ctx->hwframes->height);

     if (!output) {
         err = AVERROR(ENOMEM);
         goto fail;
     }
 
     err = av_hwframe_transfer_data(output, input, 0);
     if (err < 0) {
         av_log(ctx, AV_LOG_ERROR, "Failed to download frame: %d.\n", err);
         goto fail;
     }
 

     output->width  = outlink->w;
     output->height = outlink->h;
 

     err = av_frame_copy_props(output, input);
     if (err < 0)
         goto fail;
 
     av_frame_free(&input);
 
     return ff_filter_frame(avctx->outputs[0], output);
 
 fail:
     av_frame_free(&input);
     av_frame_free(&output);
     return err;
 }
 
 static av_cold void hwdownload_uninit(AVFilterContext *avctx)
 {
     HWDownloadContext *ctx = avctx->priv;
 
     av_buffer_unref(&ctx->hwframes_ref);
 }
 
 static const AVClass hwdownload_class = {
     .class_name = "hwdownload",
     .item_name  = av_default_item_name,
     .option     = NULL,
     .version    = LIBAVUTIL_VERSION_INT,
 };
 
 static const AVFilterPad hwdownload_inputs[] = {
     {
         .name         = "default",
         .type         = AVMEDIA_TYPE_VIDEO,
         .config_props = hwdownload_config_input,
         .filter_frame = hwdownload_filter_frame,
     },
     { NULL }
 };
 
 static const AVFilterPad hwdownload_outputs[] = {
     {
         .name         = "default",
         .type         = AVMEDIA_TYPE_VIDEO,
         .config_props = hwdownload_config_output,
     },
     { NULL }
 };
 
 AVFilter ff_vf_hwdownload = {
     .name          = "hwdownload",
     .description   = NULL_IF_CONFIG_SMALL("Download a hardware frame to a normal frame"),
     .uninit        = hwdownload_uninit,
     .query_formats = hwdownload_query_formats,
     .priv_size     = sizeof(HWDownloadContext),
     .priv_class    = &hwdownload_class,
     .inputs        = hwdownload_inputs,
     .outputs       = hwdownload_outputs,

     .flags_internal = FF_FILTER_FLAG_HWFRAME_AWARE,

 };