examples/simple_decoder.c

   1 /*
   2  *  Copyright (c) 2010 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
  12 // Simple Decoder
  13 // ==============
  14 //
  15 // This is an example of a simple decoder loop. It takes an input file
  16 // containing the compressed data (in IVF format), passes it through the
  17 // decoder, and writes the decompressed frames to disk. Other decoder
  18 // examples build upon this one.
  19 //
  20 // The details of the IVF format have been elided from this example for
  21 // simplicity of presentation, as IVF files will not generally be used by
  22 // your application. In general, an IVF file consists of a file header,
  23 // followed by a variable number of frames. Each frame consists of a frame
  24 // header followed by a variable length payload. The length of the payload
  25 // is specified in the first four bytes of the frame header. The payload is
  26 // the raw compressed data.
  27 //
  28 // Standard Includes
  29 // -----------------
  30 // For decoders, you only have to include `vpx_decoder.h` and then any
  31 // header files for the specific codecs you use. In this case, we're using
  32 // vp8. The `VPX_CODEC_DISABLE_COMPAT` macro can be defined to ensure
  33 // strict compliance with the latest SDK by disabling some backwards
  34 // compatibility features. Defining this macro is encouraged.
  35 //
  36 // Initializing The Codec
  37 // ----------------------
  38 // The decoder is initialized by the following code. This is an example for
  39 // the VP8 decoder, but the code is analogous for all algorithms. Replace
  40 // `vpx_codec_vp8_dx()` with a pointer to the interface exposed by the
  41 // algorithm you want to use. The `cfg` argument is left as NULL in this
  42 // example, because we want the algorithm to determine the stream
  43 // configuration (width/height) and allocate memory automatically. This
  44 // parameter is generally only used if you need to preallocate memory,
  45 // particularly in External Memory Allocation mode.
  46 //
  47 // Decoding A Frame
  48 // ----------------
  49 // Once the frame has been read into memory, it is decoded using the
  50 // `vpx_codec_decode` function. The call takes a pointer to the data
  51 // (`frame`) and the length of the data (`frame_sz`). No application data
  52 // is associated with the frame in this example, so the `user_priv`
  53 // parameter is NULL. The `deadline` parameter is left at zero for this
  54 // example. This parameter is generally only used when doing adaptive
  55 // postprocessing.
  56 //
  57 // Codecs may produce a variable number of output frames for every call to
  58 // `vpx_codec_decode`. These frames are retrieved by the
  59 // `vpx_codec_get_frame` iterator function. The iterator variable `iter` is
  60 // initialized to NULL each time `vpx_codec_decode` is called.
  61 // `vpx_codec_get_frame` is called in a loop, returning a pointer to a
  62 // decoded image or NULL to indicate the end of list.
  63 //
  64 // Processing The Decoded Data
  65 // ---------------------------
  66 // In this example, we simply write the encoded data to disk. It is
  67 // important to honor the image's `stride` values.
  68 //
  69 // Cleanup
  70 // -------
  71 // The `vpx_codec_destroy` call frees any memory allocated by the codec.
  72 //
  73 // Error Handling
  74 // --------------
  75 // This example does not special case any error return codes. If there was
  76 // an error, a descriptive message is printed and the program exits. With
  77 // few exeptions, vpx_codec functions return an enumerated error status,
  78 // with the value `0` indicating success.
  79
  80 #include <stdio.h>
  81 #include <stdlib.h>
  82 #include <string.h>
  83
  84 #define VPX_CODEC_DISABLE_COMPAT 1
  85
  86 #include "vpx/vp8dx.h"
  87 #include "vpx/vpx_decoder.h"
  88
  89 #include "./tools_common.h"
  90 #include "./video_reader.h"
  91 #include "./vpx_config.h"
  92
  93 static const char *exec_name;
  94
  95 void usage_exit() {
  96   fprintf(stderr, "Usage: %s <infile> <outfile>\n", exec_name);
  97   exit(EXIT_FAILURE);
  98 }
  99
 100 int main(int argc, char **argv) {
 101   int frame_cnt = 0;
 102   FILE *outfile = NULL;
 103   vpx_codec_ctx_t codec;
 104   VpxVideoReader *reader = NULL;
 105   const VpxInterface *decoder = NULL;
 106   const VpxVideoInfo *info = NULL;
 107
 108   exec_name = argv[0];
 109
 110   if (argc != 3)
 111     die("Invalid number of arguments.");
 112
 113   reader = vpx_video_reader_open(argv[1]);
 114   if (!reader)
 115     die("Failed to open %s for reading.", argv[1]);
 116
 117   if (!(outfile = fopen(argv[2], "wb")))
 118     die("Failed to open %s for writing.", argv[2]);
 119
 120   info = vpx_video_reader_get_info(reader);
 121
 122   decoder = get_vpx_decoder_by_fourcc(info->codec_fourcc);
 123   if (!decoder)
 124     die("Unknown input codec.");
 125
 126   printf("Using %s\n", vpx_codec_iface_name(decoder->codec_interface()));
 127
 128   if (vpx_codec_dec_init(&codec, decoder->codec_interface(), NULL, 0))
 129     die_codec(&codec, "Failed to initialize decoder.");
 130
 131   while (vpx_video_reader_read_frame(reader)) {
 132     vpx_codec_iter_t iter = NULL;
 133     vpx_image_t *img = NULL;
 134     size_t frame_size = 0;
 135     const unsigned char *frame = vpx_video_reader_get_frame(reader,
 136                                                             &frame_size);
 137     if (vpx_codec_decode(&codec, frame, (unsigned int)frame_size, NULL, 0))
 138       die_codec(&codec, "Failed to decode frame.");
 139
 140     while ((img = vpx_codec_get_frame(&codec, &iter)) != NULL) {
 141       vpx_img_write(img, outfile);
 142       ++frame_cnt;
 143     }
 144   }
 145
 146   printf("Processed %d frames.\n", frame_cnt);
 147   if (vpx_codec_destroy(&codec))
 148     die_codec(&codec, "Failed to destroy codec");
 149
 150   printf("Play: ffplay -f rawvideo -pix_fmt yuv420p -s %dx%d %s\n",
 151          info->frame_width, info->frame_height, argv[2]);
 152
 153   vpx_video_reader_close(reader);
 154
 155   fclose(outfile);
 156
 157   return EXIT_SUCCESS;
 158 }