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-rw-r--r-- | media/libvpx/libvpx/examples/simple_decoder.c | 149 |
1 files changed, 149 insertions, 0 deletions
diff --git a/media/libvpx/libvpx/examples/simple_decoder.c b/media/libvpx/libvpx/examples/simple_decoder.c new file mode 100644 index 0000000000..d089e826d5 --- /dev/null +++ b/media/libvpx/libvpx/examples/simple_decoder.c @@ -0,0 +1,149 @@ +/* + * 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(void) { + 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("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; +} |