Modification of FFMeg's doc/examples/scaling_video.c that scales a YUV image

Makefile

OS := $(shell uname -s)
ifeq ($(OS),Linux)
        LIBTOOL = libtool
endif
ifeq ($(OS),Darwin)
        LIBTOOL = glibtool
endif

FILENAME = scale_image

# use pkg-config for getting CFLAGS and LDLIBS
FFMPEG_LIBS=    libavformat                        \
                libavcodec                         \
                libswscale                         \
                libavutil                          \

CFLAGS += -Wall -g
CFLAGS := $(shell pkg-config --cflags $(FFMPEG_LIBS)) $(CFLAGS)
LDLIBS := $(shell pkg-config --libs $(FFMPEG_LIBS)) $(LDLIBS)

compile: fresh $(FILENAME).o $(FILENAME)

fresh:
	$(LIBTOOL) --mode=compile --tag=CC gcc -g -O -c $(FILENAME).c

.phony: fresh all clean

all: $(OBJS) $(EXAMPLES)

clean:
	rm $(FILENAME) $(FILENAME).{lo,o}

scale_image.c

/*
 * Copyright (c) 2012 Stefano Sabatini
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

/**
 * @file
 * libswscale API use example.
 * @example scaling_image.c
 */



/**

 Dependencies: FFMpeg libraries must be installed on your system.

 To build:

     make

 To run filled demo: 

     ./doc/examples/scaling_video output.yuv 128x128

 To run scaled input file:

     ./doc/examples/scaling_video input.yuv 128x128 output.yuv 2048x256

 To check results:

     ffplay -f rawvideo -pix_finput.yuv 128x128 mt yuv420p -video_size 128x128 output.yuv

*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <libavutil/imgutils.h>
#include <libavutil/parseutils.h>
#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libswscale/swscale.h>

static void fill_yuv_image(uint8_t *data[4], int linesize[4],
                           int width, int height) {
    int x, y;
    /* Y */
    for (y = 0; y < height; y++)
        for (x = 0; x < width; x++)
            data[0][y * linesize[0] + x] = x + y;

    /* Cb and Cr */
    for (y = 0; y < height / 2; y++) {
        for (x = 0; x < width / 2; x++) {
            data[1][y * linesize[1] + x] = 128 + y;
            data[2][y * linesize[2] + x] = 64 + x;
        }
    }
}

static void read_yuv_image(FILE *file, uint8_t *src_data[4], uint8_t *dst_data[4], int width, int height) {
  if (file != NULL) {
    fread(src_data[0], sizeof(char), width * height, file);
    fread(src_data[1], sizeof(char), width/2 * height/2, file);
    fread(src_data[2], sizeof(char), width/2 * height/2, file);
    dst_data = src_data;
  }
}

static void write_yuv_image(FILE *file, uint8_t *data[4], int bufsize) {
  fwrite(data[0], 1, bufsize, file);
  fwrite(data[1], 1, bufsize/4, file);
  fwrite(data[2], 1, bufsize/4, file);
}

static void write_filled_yuv_image(FILE *file, uint8_t *data[4], int bufsize) {
  fwrite(data[0], 1, bufsize, file);
}

static int scale_fill (int argc, char **argv) {
  enum AVPixelFormat src_pix_fmt = AV_PIX_FMT_YUV420P, dst_pix_fmt = AV_PIX_FMT_YUV420P;
  uint8_t *src_data[4], *dst_data[4];
  int src_linesize[4], dst_linesize[4];
  int src_w = 320, src_h = 240, dst_w, dst_h;
  const char *dst_size = NULL;
  const char *dst_filename = NULL;
  FILE *dst_file;
  int dst_bufsize;
  struct SwsContext *sws_ctx;
  int ret;

  dst_filename = argv[1];
  dst_size = argv[2];
 
  if (av_parse_video_size(&dst_w, &dst_h, dst_size) < 0) {
    fprintf(stderr,
            "Invalid destination size '%s', must be in the form WxH or a valid size abbreviation\n",
            dst_size);
    exit(1);
  }
    
  dst_file = fopen(dst_filename, "wb");
  if (!dst_file) {
    fprintf(stderr, "Could not open destination file %s\n", dst_filename);
    exit(1);
  }

  /* create scaling context */
  sws_ctx = sws_getContext(src_w, src_h, src_pix_fmt,
                           dst_w, dst_h, dst_pix_fmt,
                           SWS_BILINEAR | SWS_ACCURATE_RND, NULL, NULL, NULL);
  if (!sws_ctx) {
    fprintf(stderr,
            "Impossible to create scale context for the conversion "
            "fmt:%s s:%dx%d -> fmt:%s s:%dx%d\n",
            av_get_pix_fmt_name(src_pix_fmt), src_w, src_h,
            av_get_pix_fmt_name(dst_pix_fmt), dst_w, dst_h);
    ret = AVERROR(EINVAL);
    goto end;
  }

  /* allocate source and destination image buffers */
  if ((ret = av_image_alloc(src_data, src_linesize,
                            src_w, src_h, src_pix_fmt, 16)) < 0) {
    fprintf(stderr, "Could not allocate source image\n");
    goto end;
  }

  /* buffer is going to be written to rawvideo file, no alignment */
  if ((ret = av_image_alloc(dst_data, dst_linesize,
                            dst_w, dst_h, dst_pix_fmt, 1)) < 0) {
    fprintf(stderr, "Could not allocate destination image\n");
    goto end;
  }

  dst_bufsize = ret;
    
  fill_yuv_image(src_data, src_linesize, src_w, src_h);
  /* convert to destination format */
  sws_scale(sws_ctx, (const uint8_t * const*)src_data,
            src_linesize, 0, src_h, dst_data, dst_linesize);
  write_filled_yuv_image(dst_file, dst_data, dst_bufsize);
  fprintf(stderr, "Scaling succeeded. Play the output file with the command:\n"
          "~/Downloads/ffplay -f rawvideo -pix_fmt %s -video_size %dx%d %s\n",
          av_get_pix_fmt_name(dst_pix_fmt), dst_w, dst_h, dst_filename);

 end:
  fclose(dst_file);
  av_freep(&src_data[0]);
  av_freep(&dst_data[0]);
  sws_freeContext(sws_ctx);
  return ret < 0;
}

static int scale_file (int argc, char **argv) {
  const char *dst_size = NULL;
  const char *src_size = NULL;
  const char *dst_filename = NULL;
  const char *src_filename = NULL;
  FILE *dst_file;
  FILE *src_file;
  int dst_bufsize;
  struct SwsContext *sws_ctx;
  int ret;
  AVFrame* src_frame = av_frame_alloc();
  AVFrame* dst_frame = av_frame_alloc();
  
  src_filename = argv[1];
  src_size = argv[2];
  dst_filename = argv[3];
  dst_size = argv[4];

  src_frame->format = AV_PIX_FMT_YUV420P;
  if (av_parse_video_size(&src_frame->width, &src_frame->height, src_size) < 0) {
    fprintf(stderr,
            "Invalid source size '%s', must be in the form WxH or a valid size abbreviation\n",
            src_size);
    exit(1);
  }

  avpicture_fill((AVPicture*)src_frame, NULL, src_frame->format, src_frame->width, src_frame->height);

  dst_frame->format = AV_PIX_FMT_YUV420P;
  if (av_parse_video_size(&dst_frame->width, &dst_frame->height, dst_size) < 0) {
    fprintf(stderr,
            "Invalid destination size '%s', must be in the form WxH or a valid size abbreviation\n",
            dst_size);
    exit(1);
  }
  avpicture_fill((AVPicture*)dst_frame, NULL, dst_frame->format, dst_frame->width, dst_frame->height);

    
  src_file = fopen(src_filename, "rb");
  if (!src_file) {
      fprintf(stderr, "Could not open source file %s\n", src_filename);
      exit(1);
  }
  dst_file = fopen(dst_filename, "wb");
  if (!dst_file) {
    fprintf(stderr, "Could not open destination file %s\n", dst_filename);
    exit(1);
  }

  /* create scaling context */
  sws_ctx = sws_getContext(src_frame->width, src_frame->height, src_frame->format,
                           dst_frame->width, dst_frame->height, dst_frame->format,
                           SWS_BILINEAR, NULL, NULL, NULL);
  if (!sws_ctx) {
    fprintf(stderr,
            "Impossible to create scale context for the conversion "
            "fmt:%s s:%dx%d -> fmt:%s s:%dx%d\n",
            av_get_pix_fmt_name(src_frame->format), src_frame->width, src_frame->height,
            av_get_pix_fmt_name(dst_frame->format), dst_frame->width, dst_frame->height);
    ret = AVERROR(EINVAL);
    goto end;
  }

  /* allocate source and destination image buffers */
  if ((ret = av_image_alloc(src_frame->data, src_frame->linesize,
                            src_frame->width, src_frame->height,
                            src_frame->format, 16)) < 0) {
    fprintf(stderr, "Could not allocate source image\n");
    goto end;
  }

  /* buffer is going to be written to rawvideo file, no alignment */
  if ((ret = av_image_alloc(dst_frame->data, dst_frame->linesize,
                            dst_frame->width, dst_frame->height,
                            dst_frame->format, 1)) < 0) {
    fprintf(stderr, "Could not allocate destination image\n");
    goto end;
  }
  dst_bufsize = dst_frame->width * dst_frame->height;
  read_yuv_image(src_file, src_frame->data, dst_frame->data, src_frame->width, src_frame->height);
  /* convert to destination format */
  sws_scale(sws_ctx,
            (const uint8_t * const*)src_frame->data, src_frame->linesize,
            0, src_frame->height,
            dst_frame->data, dst_frame->linesize);
  write_yuv_image(dst_file, dst_frame->data, dst_bufsize);

  fprintf(stderr, "Scaling succeeded. Play the output file with the command:\n"
          "~/Downloads/ffplay -f rawvideo -pix_fmt %s -video_size %dx%d %s\n",
          av_get_pix_fmt_name(dst_frame->format), dst_frame->width, dst_frame->height, dst_filename);

 end:
  fclose(src_file);
  fclose(dst_file);
  av_frame_unref(src_frame);
  av_frame_unref(dst_frame);
  sws_freeContext(sws_ctx);
  return ret < 0;
}

int main(int argc, char **argv) {
  av_register_all();
  int ret;
  if (argc == 3) {
    ret = scale_fill(argc, argv);
  } else if (argc == 5) {
    ret = scale_file(argc, argv);
  } else {
    fprintf(stderr, "Usage: %s intput_file input_size output_file output_size\n"
            "API example program to show how to scale an image with libswscale.\n"
            "This program generates a series of pictures, rescales them to the given "
            "output_size and saves them to an output file named output_file\n."
            "\n", argv[0]);
    exit(1);
  }
  return ret < 0;
}