/* *  Copyright (c) 2010 The WebM project authors. All Rights Reserved. * *  Use of this source code is governed by a BSD-style license *  that can be found in the LICENSE file in the root of the source *  tree. An additional intellectual property rights grant can be found *  in the file PATENTS.  All contributing project authors may *  be found in the AUTHORS file in the root of the source tree. */  // Simple Decoder// ==============//// This is an example of a simple decoder loop. It takes an input file// containing the compressed data (in IVF format), passes it through the// decoder, and writes the decompressed frames to disk. Other decoder// examples build upon this one.//// The details of the IVF format have been elided from this example for// simplicity of presentation, as IVF files will not generally be used by// your application. In general, an IVF file consists of a file header,// followed by a variable number of frames. Each frame consists of a frame// header followed by a variable length payload. The length of the payload// is specified in the first four bytes of the frame header. The payload is// the raw compressed data.//// Standard Includes// -----------------// For decoders, you only have to include `vpx_decoder.h` and then any// header files for the specific codecs you use. In this case, we're using// vp8.//// Initializing The Codec// ----------------------// The libvpx decoder is initialized by the call to vpx_codec_dec_init().// Determining the codec interface to use is handled by VpxVideoReader and the// functions prefixed with vpx_video_reader_. Discussion of those functions is// beyond the scope of this example, but the main gist is to open the input file// and parse just enough of it to determine if it's a VPx file and which VPx// codec is contained within the file.// Note the NULL pointer passed to vpx_codec_dec_init(). We do that in this// example because we want the algorithm to determine the stream configuration// (width/height) and allocate memory automatically.//// Decoding A Frame// ----------------// Once the frame has been read into memory, it is decoded using the// `vpx_codec_decode` function. The call takes a pointer to the data// (`frame`) and the length of the data (`frame_size`). No application data// is associated with the frame in this example, so the `user_priv`// parameter is NULL. The `deadline` parameter is left at zero for this// example. This parameter is generally only used when doing adaptive post// processing.//// Codecs may produce a variable number of output frames for every call to// `vpx_codec_decode`. These frames are retrieved by the// `vpx_codec_get_frame` iterator function. The iterator variable `iter` is// initialized to NULL each time `vpx_codec_decode` is called.// `vpx_codec_get_frame` is called in a loop, returning a pointer to a// decoded image or NULL to indicate the end of list.//// Processing The Decoded Data// ---------------------------// In this example, we simply write the encoded data to disk. It is// important to honor the image's `stride` values.//// Cleanup// -------// The `vpx_codec_destroy` call frees any memory allocated by the codec.//// Error Handling// --------------// This example does not special case any error return codes. If there was// an error, a descriptive message is printed and the program exits. With// few exceptions, vpx_codec functions return an enumerated error status,// with the value `0` indicating success. #include <stdio.h>#include <stdlib.h>#include <string.h> #include "vpx/vpx_decoder.h" #include "../tools_common.h"#include "../video_reader.h"#include "./vpx_config.h" static const char *exec_name; void usage_exit() {  fprintf(stderr, "Usage: %s <infile> <outfile>\n", exec_name);  exit(EXIT_FAILURE);} int main(int argc, char **argv) {  int frame_cnt = 0;  FILE *outfile = NULL;  vpx_codec_ctx_t codec;  VpxVideoReader *reader = NULL;  const VpxInterface *decoder = NULL;  const VpxVideoInfo *info = NULL;   exec_name = argv[0];   if (argc != 3)    die("Invalid number of arguments.");   reader = vpx_video_reader_open(argv[1]);  if (!reader)    die("Failed to open %s for reading.", argv[1]);   if (!(outfile = fopen(argv[2], "wb")))    die("Failed to open %s for writing.", argv[2]);   info = vpx_video_reader_get_info(reader);   decoder = get_vpx_decoder_by_fourcc(info->codec_fourcc);  if (!decoder)    die("Unknown input codec.");   printf("Using %s\n", vpx_codec_iface_name(decoder->codec_interface()));   if (vpx_codec_dec_init(&codec, decoder->codec_interface(), NULL, 0))    die_codec(&codec, "Failed to initialize decoder.");   while (vpx_video_reader_read_frame(reader)) {    vpx_codec_iter_t iter = NULL;    vpx_image_t *img = NULL;    size_t frame_size = 0;    const unsigned char *frame = vpx_video_reader_get_frame(reader,                                                            &frame_size);    if (vpx_codec_decode(&codec, frame, (unsigned int)frame_size, NULL, 0))      die_codec(&codec, "Failed to decode frame.");     while ((img = vpx_codec_get_frame(&codec, &iter)) != NULL) {      vpx_img_write(img, outfile);      ++frame_cnt;    }  }   printf("Processed %d frames.\n", frame_cnt);  if (vpx_codec_destroy(&codec))    die_codec(&codec, "Failed to destroy codec");   printf("Play: ffplay -f rawvideo -pix_fmt yuv420p -s %dx%d %s\n",         info->frame_width, info->frame_height, argv[2]);   vpx_video_reader_close(reader);   fclose(outfile);   return EXIT_SUCCESS;}