text: /*
   * Copyright © 2018, VideoLAN and dav1d authors
   * Copyright © 2018, Two Orioles, LLC
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions are met:
   *
   * 1. Redistributions of source code must retain the above copyright notice, this
   *    list of conditions and the following disclaimer.
   *
   * 2. Redistributions in binary form must reproduce the above copyright notice,
   *    this list of conditions and the following disclaimer in the documentation
   *    and/or other materials provided with the distribution.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
   * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
   * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
   * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
   * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  
  #include "config.h"
  
  #include <errno.h>
  #include <limits.h>
  #include <math.h>
  #include <stdio.h>
  #include <stdint.h>
  #include <stdlib.h>
  #include <string.h>
  
  #include "input/demuxer.h"
  
  typedef struct DemuxerPriv {
      FILE *f;
      int broken;
      double timebase;
      uint64_t last_ts;
      uint64_t step;
  } IvfInputContext;
  
  static const uint8_t probe_data[] = {
      'D', 'K', 'I', 'F',
      0, 0, 0x20, 0,
      'A', 'V', '0', '1',
  };
  
  static int ivf_probe(const uint8_t *const data) {
      return !memcmp(data, probe_data, sizeof(probe_data));
  }
  
  static unsigned rl32(const uint8_t *const p) {
      return ((uint32_t)p[3] << 24U) | (p[2] << 16U) | (p[1] << 8U) | p[0];
  }
  
  static int64_t rl64(const uint8_t *const p) {
      return (((uint64_t) rl32(&p[4])) << 32) | rl32(p);
  }
  
  static int ivf_open(IvfInputContext *const c, const char *const file,
                      unsigned fps[2], unsigned *const num_frames, unsigned timebase[2])
  {
      uint8_t hdr[32];
  
      if (!(c->f = fopen(file, "rb"))) {
          fprintf(stderr, "Failed to open %s: %s\n", file, strerror(errno));
          return -1;
      } else if (fread(hdr, 32, 1, c->f) != 1) {
          fprintf(stderr, "Failed to read stream header: %s\n", strerror(errno));
          fclose(c->f);
          return -1;
      } else if (memcmp(hdr, "DKIF", 4)) {
          fprintf(stderr, "%s is not an IVF file [tag=%.4s|0x%02x%02x%02x%02x]\n",
                  file, hdr, hdr[0], hdr[1], hdr[2], hdr[3]);
          fclose(c->f);
          return -1;
      } else if (memcmp(&hdr[8], "AV01", 4)) {
          fprintf(stderr, "%s is not an AV1 file [tag=%.4s|0x%02x%02x%02x%02x]\n",
                  file, &hdr[8], hdr[8], hdr[9], hdr[10], hdr[11]);
          fclose(c->f);
          return -1;
      }
  
      timebase[0] = rl32(&hdr[16]);
      timebase[1] = rl32(&hdr[20]);
      const unsigned duration = rl32(&hdr[24]);
  
      uint8_t data[8];
      c->broken = 0;
      for (*num_frames = 0;; (*num_frames)++) {
          if (fread(data, 4, 1, c->f) != 1) break; // EOF
          size_t sz = rl32(data);
          if (fread(data, 8, 1, c->f) != 1) break; // EOF
          const uint64_t ts = rl64(data);
          if (*num_frames && ts <= c->last_ts)
              c->broken = 1;
          c->last_ts = ts;
          fseeko(c->f, sz, SEEK_CUR);
      }
  
      uint64_t fps_num = (uint64_t) timebase[0] * *num_frames;
      uint64_t fps_den = (uint64_t) timebase[1] * duration;
      if (fps_num && fps_den) { /* Reduce fraction */
          uint64_t gcd = fps_num;
          for (uint64_t a = fps_den, b; (b = a % gcd); a = gcd, gcd = b);
          fps_num /= gcd;
          fps_den /= gcd;
  
          while ((fps_num | fps_den) > UINT_MAX) {
              fps_num >>= 1;
              fps_den >>= 1;
          }
      }
      if (fps_num && fps_den) {
          fps[0] = (unsigned) fps_num;
          fps[1] = (unsigned) fps_den;
      } else {
          fps[0] = fps[1] = 0;
      }
      c->timebase = (double)timebase[0] / timebase[1];
      c->step = duration / *num_frames;
  
      fseeko(c->f, 32, SEEK_SET);
      c->last_ts = 0;
  
      return 0;
  }
  
  static inline int ivf_read_header(IvfInputContext *const c, ptrdiff_t *const sz,
                                    int64_t *const off_, uint64_t *const ts)
  {
      uint8_t data[8];
      int64_t const off = ftello(c->f);
      if (off_) *off_ = off;
      if (fread(data, 4, 1, c->f) != 1) return -1; // EOF
      *sz = rl32(data);
      if (!c->broken) {
          if (fread(data, 8, 1, c->f) != 1) return -1;
          *ts = rl64(data);
      } else {
          if (fseeko(c->f, 8, SEEK_CUR)) return -1;
          *ts = off > 32 ? c->last_ts + c->step : 0;
      }
      return 0;
  }
  
  static int ivf_read(IvfInputContext *const c, Dav1dData *const buf) {
      uint8_t *ptr;
      ptrdiff_t sz;
      int64_t off;
      uint64_t ts;
      if (ivf_read_header(c, &sz, &off, &ts)) return -1;
      if (!(ptr = dav1d_data_create(buf, sz))) return -1;
      if (fread(ptr, sz, 1, c->f) != 1) {
          fprintf(stderr, "Failed to read frame data: %s\n", strerror(errno));
          dav1d_data_unref(buf);
          return -1;
      }
      buf->m.offset = off;
      buf->m.timestamp = ts;
      c->last_ts = ts;
      return 0;
  }
  
  static int ivf_seek(IvfInputContext *const c, const uint64_t pts) {
      uint64_t cur;
      const uint64_t ts = llround((pts * c->timebase) / 1000000000.0);
      if (ts <= c->last_ts)
          if (fseeko(c->f, 32, SEEK_SET)) goto error;
      while (1) {
          ptrdiff_t sz;
          if (ivf_read_header(c, &sz, NULL, &cur)) goto error;
          if (cur >= ts) break;
          if (fseeko(c->f, sz, SEEK_CUR)) goto error;
          c->last_ts = cur;
      }
      if (fseeko(c->f, -12, SEEK_CUR)) goto error;
      return 0;
  error:
      fprintf(stderr, "Failed to seek: %s\n", strerror(errno));
      return -1;
  }
  
  static void ivf_close(IvfInputContext *const c) {
      fclose(c->f);
  }
  
  const Demuxer ivf_demuxer = {
      .priv_data_size = sizeof(IvfInputContext),
      .name = "ivf",
      .probe = ivf_probe,
      .probe_sz = sizeof(probe_data),
      .open = ivf_open,
      .read = ivf_read,
      .seek = ivf_seek,
      .close = ivf_close,
  };
  