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