WebM Codec SDK: simple_decoder

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simple_decoder
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.
33 //
34 // Initializing The Codec
35 // ----------------------
36 // The libvpx decoder is initialized by the call to vpx_codec_dec_init().
37 // Determining the codec interface to use is handled by VpxVideoReader and the
38 // functions prefixed with vpx_video_reader_. Discussion of those functions is
39 // beyond the scope of this example, but the main gist is to open the input file
40 // and parse just enough of it to determine if it's a VPx file and which VPx
41 // codec is contained within the file.
42 // Note the NULL pointer passed to vpx_codec_dec_init(). We do that in this
43 // example because we want the algorithm to determine the stream configuration
44 // (width/height) and allocate memory automatically.
45 //
46 // Decoding A Frame
47 // ----------------
48 // Once the frame has been read into memory, it is decoded using the
49 // `vpx_codec_decode` function. The call takes a pointer to the data
50 // (`frame`) and the length of the data (`frame_size`). No application data
51 // is associated with the frame in this example, so the `user_priv`
52 // parameter is NULL. The `deadline` parameter is left at zero for this
53 // example. This parameter is generally only used when doing adaptive post
54 // processing.
55 //
56 // Codecs may produce a variable number of output frames for every call to
57 // `vpx_codec_decode`. These frames are retrieved by the
58 // `vpx_codec_get_frame` iterator function. The iterator variable `iter` is
59 // initialized to NULL each time `vpx_codec_decode` is called.
60 // `vpx_codec_get_frame` is called in a loop, returning a pointer to a
61 // decoded image or NULL to indicate the end of list.
62 //
63 // Processing The Decoded Data
64 // ---------------------------
65 // In this example, we simply write the encoded data to disk. It is
66 // important to honor the image's `stride` values.
67 //
68 // Cleanup
69 // -------
70 // The `vpx_codec_destroy` call frees any memory allocated by the codec.
71 //
72 // Error Handling
73 // --------------
74 // This example does not special case any error return codes. If there was
75 // an error, a descriptive message is printed and the program exits. With
76 // few exceptions, vpx_codec functions return an enumerated error status,
77 // with the value `0` indicating success.
78
79 #include <stdio.h>
80 #include <stdlib.h>
81 #include <string.h>
82
83 #include "vpx/vpx_decoder.h"
84
85 #include "../tools_common.h"
86 #include "../video_reader.h"
87 #include "./vpx_config.h"
88
89 static const char *exec_name;
90
91 void usage_exit(void) {
92 fprintf(stderr, "Usage: %s <infile> <outfile>\n", exec_name);
93 exit(EXIT_FAILURE);
94 }
95
96 int main(int argc, char **argv) {
97 int frame_cnt = 0;
98 FILE *outfile = NULL;
99 vpx_codec_ctx_t codec;
100 VpxVideoReader *reader = NULL;
101 const VpxInterface *decoder = NULL;
102 const VpxVideoInfo *info = NULL;
103
104 exec_name = argv[0];
105
106 if (argc != 3)
107 die("Invalid number of arguments.");
108
109 reader = vpx_video_reader_open(argv[1]);
110 if (!reader)
111 die("Failed to open %s for reading.", argv[1]);
112
113 if (!(outfile = fopen(argv[2], "wb")))
114 die("Failed to open %s for writing.", argv[2]);
115
116 info = vpx_video_reader_get_info(reader);
117
118 decoder = get_vpx_decoder_by_fourcc(info->codec_fourcc);
119 if (!decoder)
120 die("Unknown input codec.");
121
122 printf("Using %s\n", vpx_codec_iface_name(decoder->codec_interface()));
123
124 if (vpx_codec_dec_init(&codec, decoder->codec_interface(), NULL, 0))
125 die_codec(&codec, "Failed to initialize decoder.");
126
127 while (vpx_video_reader_read_frame(reader)) {
128 vpx_codec_iter_t iter = NULL;
129 vpx_image_t *img = NULL;
130 size_t frame_size = 0;
131 const unsigned char *frame = vpx_video_reader_get_frame(reader,
132 &frame_size);
133 if (vpx_codec_decode(&codec, frame, (unsigned int)frame_size, NULL, 0))
134 die_codec(&codec, "Failed to decode frame.");
135
136 while ((img = vpx_codec_get_frame(&codec, &iter)) != NULL) {
137 vpx_img_write(img, outfile);
138 ++frame_cnt;
139 }
140 }
141
142 printf("Processed %d frames.\n", frame_cnt);
143 if (vpx_codec_destroy(&codec))
144 die_codec(&codec, "Failed to destroy codec");
145
146 printf("Play: ffplay -f rawvideo -pix_fmt yuv420p -s %dx%d %s\n",
147 info->frame_width, info->frame_height, argv[2]);
148
149 vpx_video_reader_close(reader);
150
151 fclose(outfile);
152
153 return EXIT_SUCCESS;
154 }
vpx_image
Image Descriptor.
Definition: vpx_image.h:88
vpx_decoder.h
Describes the decoder algorithm interface to applications.
vpx_codec_iface_name
const char * vpx_codec_iface_name(vpx_codec_iface_t *iface)
Return the name for a given interface.
vpx_codec_dec_init
#define vpx_codec_dec_init(ctx, iface, cfg, flags)
Convenience macro for vpx_codec_dec_init_ver()
Definition: vpx_decoder.h:154
vpx_codec_decode
vpx_codec_err_t vpx_codec_decode(vpx_codec_ctx_t *ctx, const uint8_t *data, unsigned int data_sz, void *user_priv, long deadline)
Decode data.
vpx_codec_destroy
vpx_codec_err_t vpx_codec_destroy(vpx_codec_ctx_t *ctx)
Destroy a codec instance.
vpx_codec_iter_t
const void * vpx_codec_iter_t
Iterator.
Definition: vpx_codec.h:188
vpx_codec_get_frame
vpx_image_t * vpx_codec_get_frame(vpx_codec_ctx_t *ctx, vpx_codec_iter_t *iter)
Decoded frames iterator.
vpx_codec_ctx
Codec context structure.
Definition: vpx_codec.h:199