resize-libav.c

/**
 *
 * resize-libav
 * 
 * Use libav to resize an image using its swscale functions, sample code
 * 
 * Copyright 2018 - Nicolas Mora <mail@babelouest.org>
 * Copyright (c) 2013-2017 Andreas Unterweger
 * 
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU GENERAL PUBLIC LICENSE
 * License as published by the Free Software Foundation;
 * version 3 of the License.
 *
 * This program 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 GENERAL PUBLIC LICENSE for more details.
 *
 * You should have received a copy of the GNU General Public
 * License along with this program.  If not, see <http://www.gnu.org/licenses/>.
 * 
 * Use the following commang to compile with gcc:
 * gcc -o resize-libav resize-libav.c -O3 -lavcodec -lavformat -lswscale -lavutil
 */
#include <libavutil/imgutils.h>
#include <libswscale/swscale.h>
#include <libavformat/avformat.h>
#include <libavutil/frame.h>

#include <stdio.h>

#define THUMB_WIDTH 150
#define THUMB_HEIGHT 150

static char * get_error_text(const int error) {
  static char error_buffer[255];
  av_strerror(error, error_buffer, sizeof(error_buffer));
  return error_buffer;
}

static int my_decode(AVCodecContext *input_codec_context, AVFrame *frame, int *data_present, AVPacket *input_packet) {
  int ret = avcodec_send_packet(input_codec_context, input_packet);
  if (ret < 0) {
    return ret;
  }
  *data_present = 0;
  do {
    ret = avcodec_receive_frame(input_codec_context, frame);
    if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF) {
      break;
    } else if (ret < 0) {
      fprintf(stderr, "Error during decode (%s)\n", get_error_text(ret));
      break;
    } else {
      *data_present += frame->nb_samples > 0;
    }
  } while (ret > 0);
  return 0;
}

static int my_encode(AVCodecContext *output_codec_context, AVPacket *output_packet, AVFrame *frame, int * data_present) {
  int ret;

  ret = avcodec_send_frame(output_codec_context, frame);
  if (ret < 0) {
    return ret;
  }
  *data_present = 0;
  do {
    ret = avcodec_receive_packet(output_codec_context, output_packet);
    if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF) {
      break;
    } else if (ret < 0) {
      fprintf(stderr, "Error during encode: '%s'\n", get_error_text(ret));
      return ret;
    } else {
      *data_present = 1;
    }
  } while (ret > 0);
  return 0;
}

static int resize_image(AVCodecContext * original_image_codec_context, AVCodecContext * resized_image_codec_context, AVPacket * original_image_cover_packet, AVPacket * resized_image_cover_packet, int resized_width, int resized_height) {
  int ret = -1, data_present, err;
  AVFrame * input_frame = av_frame_alloc(), * output_frame = av_frame_alloc();
  struct SwsContext * sws_c;
  
  if (input_frame != NULL && output_frame != NULL) {
    if (!my_decode(original_image_codec_context, input_frame, &data_present, original_image_cover_packet)) {
      if (!resized_width) {
        resized_width = input_frame->width;
      }
      if (!resized_height) {
        resized_height = input_frame->height;
      }
      sws_c = sws_getContext(input_frame->width, input_frame->height, original_image_codec_context->pix_fmt, resized_width, resized_height, AV_PIX_FMT_YUV420P, SWS_BICUBIC, NULL, NULL, NULL);
      if (sws_c != NULL) {
        av_image_alloc(output_frame->data, output_frame->linesize, resized_width, resized_height, original_image_codec_context->pix_fmt, 32);
        output_frame->width = resized_width;
        output_frame->height = resized_height;
        output_frame->format = AV_PIX_FMT_YUV420P;
        if ((err = sws_scale(sws_c, (const uint8_t * const*)input_frame->data, input_frame->linesize, 0, input_frame->height, output_frame->data, output_frame->linesize)) < 0) {
          fprintf(stderr, "Error sws_scale: %d\n", err);
          ret = -1;
        } else if (err > 0) {
          ret = my_encode(resized_image_codec_context, resized_image_cover_packet, output_frame, &data_present);
        }
        sws_freeContext(sws_c);
      } else {
        fprintf(stderr, "Error sws_getContext\n");
      }
    }
    av_freep(&output_frame->data[0]);
    av_frame_free(&output_frame);
    av_frame_free(&input_frame);
  } else {
    fprintf(stderr, "Error allocating resources for input_frame or output_frame\n");
    ret = -1;
  }
  return ret;
}

static int get_media_cover(AVFormatContext * full_size_cover_format_context, AVCodecContext ** full_size_cover_codec_context, AVPacket * full_size_cover_packet) {
  int i, ret = 1;
  AVCodec * cover_codec = NULL;
  int video_stream;
  
  video_stream = -1;
  *full_size_cover_codec_context = NULL;
  for (i=0; i<full_size_cover_format_context->nb_streams; i++) {
    cover_codec = avcodec_find_decoder(full_size_cover_format_context->streams[i]->codecpar->codec_id);
    if (cover_codec->type == AVMEDIA_TYPE_VIDEO) {
      if (cover_codec->id == AV_CODEC_ID_MJPEG) { // TODO See if we can't convert gif or png to jpeg
        video_stream = i;
        *full_size_cover_codec_context = avcodec_alloc_context3(cover_codec);
        avcodec_parameters_to_context(*full_size_cover_codec_context, full_size_cover_format_context->streams[i]->codecpar);
        avcodec_open2(*full_size_cover_codec_context, cover_codec, NULL);
        break;
      }
    }
  }
  
  if (video_stream != -1) {
    while (av_read_frame(full_size_cover_format_context, full_size_cover_packet) >= 0) {
      if (full_size_cover_packet->stream_index == video_stream) {
        ret = 0;
        break;
      }
      av_packet_unref(full_size_cover_packet);
    }
  } else {
    ret = 1;
  }
  
  return ret;
}

static int init_output_jpeg_image(AVCodecContext ** image_codec_context, int dst_width, int dst_height) {
  AVCodec * output_codec = NULL;
  int ret = 1;
  
  if ((output_codec = avcodec_find_encoder(AV_CODEC_ID_MJPEG)) == NULL) {
    fprintf(stderr, "init_output_jpeg_image - error avcodec_find_encoder\n");
  } else if (((*image_codec_context) = avcodec_alloc_context3(output_codec)) == NULL) {
    fprintf(stderr, "init_output_jpeg_image - error avcodec_alloc_context3\n");
  } else {
    (*image_codec_context)->bit_rate = 0;
    (*image_codec_context)->width = dst_width;
    (*image_codec_context)->height = dst_height;
    (*image_codec_context)->time_base.num = 1;
    (*image_codec_context)->time_base.den = 30;
    (*image_codec_context)->pix_fmt = AV_PIX_FMT_YUVJ420P;
    if ((ret = avcodec_open2((*image_codec_context), output_codec, NULL)) < 0) {
      fprintf(stderr, "init_output_jpeg_image - error avcodec_open2 (%s)\n", get_error_text(ret));
      ret = 1;
    } else {
      ret = 0;
    }
  }
  return ret;
}

static int resize_image_from_path(const char * path) {
  AVFormatContext * full_size_cover_format_context = NULL;
  AVCodecContext  * full_size_cover_codec_context  = NULL;
  AVPacket          full_size_cover_packet, thumbnail_cover_packet;
  AVCodecContext  * thumbnail_cover_codec_context = NULL;
  int ret, err;
	FILE * file;
  
	if (!(err = avformat_open_input(&full_size_cover_format_context, path, NULL, NULL))) {
		/* Get information on the input file (number of streams etc.). */
		if (!avformat_find_stream_info(full_size_cover_format_context, NULL)) {
			av_init_packet(&full_size_cover_packet);
			av_init_packet(&thumbnail_cover_packet);
			if (!init_output_jpeg_image(&thumbnail_cover_codec_context, THUMB_WIDTH, THUMB_HEIGHT)) {
				if (!(ret = get_media_cover(full_size_cover_format_context, &full_size_cover_codec_context, &full_size_cover_packet))) {
					if (resize_image(full_size_cover_codec_context, thumbnail_cover_codec_context, &full_size_cover_packet, &thumbnail_cover_packet, THUMB_WIDTH, THUMB_HEIGHT) >= 0) {
						fprintf(stdout, "result size: %zu\n", thumbnail_cover_packet.size);
						file = fopen("out-libav.jpg", "wb");
						fwrite(thumbnail_cover_packet.data, 1, thumbnail_cover_packet.size, file);
						fclose(file);
					} else {
						fprintf(stderr, "media_get_metadata - Error resize_image for %s\n", path);
					}
				}
			} else {
				fprintf(stderr, "Error init_output_jpeg_image\n");
			}
			av_packet_unref(&full_size_cover_packet);
			av_packet_unref(&thumbnail_cover_packet);
			avcodec_free_context(&full_size_cover_codec_context);
			avformat_close_input(&full_size_cover_format_context);
			full_size_cover_format_context = NULL;
		} else {
			fprintf(stderr, "media_get_metadata - Error avformat_open_input for %s\n", path);
		}
	} else {
		fprintf(stderr, "media_get_metadata - Error avformat_find_stream_info: '%s'\n", get_error_text(err));
	}
}

int main(int argc, char ** argv) {
	av_register_all();
  
	if (argc > 1) {
		resize_image_from_path(argv[1]);
	} else {
		fprintf(stderr, "Usage: %s <path_to_image>\n", argv[0]);
	}
	return 0;
}