ivfdec.c

   1 /*
   2  *  Copyright (c) 2013 The WebM project authors. All Rights Reserved.
   3  *
   4  *  Use of this source code is governed by a BSD-style license
   5  *  that can be found in the LICENSE file in the root of the source
   6  *  tree. An additional intellectual property rights grant can be found
   7  *  in the file PATENTS.  All contributing project authors may
   8  *  be found in the AUTHORS file in the root of the source tree.
   9  */
  10
  11 #include <stdio.h>
  12 #include <stdlib.h>
  13 #include <string.h>
  14
  15 #include "vpx_ports/mem_ops.h"
  16
  17 #include "./ivfdec.h"
  18
  19 static const char *IVF_SIGNATURE = "DKIF";
  20
  21 static void fix_framerate(int *num, int *den) {
  22   // Some versions of vpxenc used 1/(2*fps) for the timebase, so
  23   // we can guess the framerate using only the timebase in this
  24   // case. Other files would require reading ahead to guess the
  25   // timebase, like we do for webm.
  26   if (*num < 1000) {
  27     // Correct for the factor of 2 applied to the timebase in the encoder.
  28     if (*num & 1)
  29       *den *= 2;
  30     else
  31       *num /= 2;
  32   } else {
  33     // Don't know FPS for sure, and don't have readahead code
  34     // (yet?), so just default to 30fps.
  35     *num = 30;
  36     *den = 1;
  37   }
  38 }
  39
  40 int file_is_ivf(struct VpxInputContext *input_ctx) {
  41   char raw_hdr[32];
  42   int is_ivf = 0;
  43
  44   if (fread(raw_hdr, 1, 32, input_ctx->file) == 32) {
  45     if (memcmp(IVF_SIGNATURE, raw_hdr, 4) == 0) {
  46       is_ivf = 1;
  47
  48       if (mem_get_le16(raw_hdr + 4) != 0) {
  49         fprintf(stderr, "Error: Unrecognized IVF version! This file may not"
  50                 " decode properly.");
  51       }
  52
  53       input_ctx->fourcc = mem_get_le32(raw_hdr + 8);
  54       input_ctx->width = mem_get_le16(raw_hdr + 12);
  55       input_ctx->height = mem_get_le16(raw_hdr + 14);
  56       input_ctx->framerate.numerator = mem_get_le32(raw_hdr + 16);
  57       input_ctx->framerate.denominator = mem_get_le32(raw_hdr + 20);
  58       fix_framerate(&input_ctx->framerate.numerator,
  59                     &input_ctx->framerate.denominator);
  60     }
  61   }
  62
  63   if (!is_ivf) {
  64     rewind(input_ctx->file);
  65     input_ctx->detect.buf_read = 0;
  66   } else {
  67     input_ctx->detect.position = 4;
  68   }
  69   return is_ivf;
  70 }
  71
  72 int ivf_read_frame(FILE *infile, uint8_t **buffer,
  73                    size_t *bytes_read, size_t *buffer_size) {
  74   char raw_header[IVF_FRAME_HDR_SZ] = {0};
  75   size_t frame_size = 0;
  76
  77   if (fread(raw_header, IVF_FRAME_HDR_SZ, 1, infile) != 1) {
  78     if (!feof(infile))
  79       warn("Failed to read frame size\n");
  80   } else {
  81     frame_size = mem_get_le32(raw_header);
  82
  83     if (frame_size > 256 * 1024 * 1024) {
  84       warn("Read invalid frame size (%u)\n", (unsigned int)frame_size);
  85       frame_size = 0;
  86     }
  87
  88     if (frame_size > *buffer_size) {
  89       uint8_t *new_buffer = realloc(*buffer, 2 * frame_size);
  90
  91       if (new_buffer) {
  92         *buffer = new_buffer;
  93         *buffer_size = 2 * frame_size;
  94       } else {
  95         warn("Failed to allocate compressed data buffer\n");
  96         frame_size = 0;
  97       }
  98     }
  99   }
 100
 101   if (!feof(infile)) {
 102     if (fread(*buffer, 1, frame_size, infile) != frame_size) {
 103       warn("Failed to read full frame\n");
 104       return 1;
 105     }
 106
 107     *bytes_read = frame_size;
 108     return 0;
 109   }
 110
 111   return 1;
 112 }