vpx/examples/simple_decoder.c

/*
 *  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. The `VPX_CODEC_DISABLE_COMPAT` macro can be defined to ensure
// strict compliance with the latest SDK by disabling some backwards
// compatibility features. Defining this macro is encouraged.
//
// Initializing The Codec
// ----------------------
// The decoder is initialized by the following code. This is an example for
// the VP8 decoder, but the code is analogous for all algorithms. Replace
// `vpx_codec_vp8_dx()` with a pointer to the interface exposed by the
// algorithm you want to use. The `cfg` argument is left as NULL in this
// example, because we want the algorithm to determine the stream
// configuration (width/height) and allocate memory automatically. This
// parameter is generally only used if you need to preallocate memory,
// particularly in External Memory Allocation mode.
//
// 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_sz`). 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
// postprocessing.
//
// 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 exeptions, vpx_codec functions return an enumerated error status,
// with the value `0` indicating success.

#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define VPX_CODEC_DISABLE_COMPAT 1
#include "./vpx_config.h"
#include "vpx/vp8dx.h"
#include "vpx/vpx_decoder.h"
#define interface (vpx_codec_vp8_dx())


#define IVF_FILE_HDR_SZ  (32)
#define IVF_FRAME_HDR_SZ (12)

static unsigned int mem_get_le32(const unsigned char *mem) {
    return (mem[3] << 24)|(mem[2] << 16)|(mem[1] << 8)|(mem[0]);
}

static void die(const char *fmt, ...) {
    va_list ap;

    va_start(ap, fmt);
    vprintf(fmt, ap);
    if(fmt[strlen(fmt)-1] != '\n')
        printf("\n");
    exit(EXIT_FAILURE);
}

static void die_codec(vpx_codec_ctx_t *ctx, const char *s) {
    const char *detail = vpx_codec_error_detail(ctx);

    printf("%s: %s\n", s, vpx_codec_error(ctx));
    if(detail)
        printf("    %s\n",detail);
    exit(EXIT_FAILURE);
}


int main(int argc, char **argv) {
    FILE            *infile, *outfile;
    vpx_codec_ctx_t  codec;
    int              flags = 0, frame_cnt = 0;
    unsigned char    file_hdr[IVF_FILE_HDR_SZ];
    unsigned char    frame_hdr[IVF_FRAME_HDR_SZ];
    unsigned char    frame[256*1024];
    vpx_codec_err_t  res;

    (void)res;
    /* Open files */
    if(argc!=3)
        die("Usage: %s <infile> <outfile>\n", argv[0]);
    if(!(infile = fopen(argv[1], "rb")))
        die("Failed to open %s for reading", argv[1]);
    if(!(outfile = fopen(argv[2], "wb")))
        die("Failed to open %s for writing", argv[2]);

    /* Read file header */
    if(!(fread(file_hdr, 1, IVF_FILE_HDR_SZ, infile) == IVF_FILE_HDR_SZ
         && file_hdr[0]=='D' && file_hdr[1]=='K' && file_hdr[2]=='I'
         && file_hdr[3]=='F'))
        die("%s is not an IVF file.", argv[1]);

    printf("Using %s\n",vpx_codec_iface_name(interface));
    /* Initialize codec */
    if(vpx_codec_dec_init(&codec, interface, NULL, flags))
        die_codec(&codec, "Failed to initialize decoder");

    /* Read each frame */
    while(fread(frame_hdr, 1, IVF_FRAME_HDR_SZ, infile) == IVF_FRAME_HDR_SZ) {
        int               frame_sz = mem_get_le32(frame_hdr);
        vpx_codec_iter_t  iter = NULL;
        vpx_image_t      *img;


        frame_cnt++;
        if(frame_sz > sizeof(frame))
            die("Frame %d data too big for example code buffer", frame_sz);
        if(fread(frame, 1, frame_sz, infile) != frame_sz)
            die("Frame %d failed to read complete frame", frame_cnt);

        /* Decode the frame */
        if(vpx_codec_decode(&codec, frame, frame_sz, NULL, 0))
            die_codec(&codec, "Failed to decode frame");

        /* Write decoded data to disk */
        while((img = vpx_codec_get_frame(&codec, &iter))) {
            unsigned int plane, y;

            for(plane=0; plane < 3; plane++) {
                unsigned char *buf =img->planes[plane];

                for(y=0; y < (plane ? (img->d_h + 1) >> 1 : img->d_h); y++) {
                    (void) fwrite(buf, 1, (plane ? (img->d_w + 1) >> 1 : img->d_w),
                                  outfile);
                    buf += img->stride[plane];
                }
            }
        }
    }
    printf("Processed %d frames.\n",frame_cnt);
    if(vpx_codec_destroy(&codec))
        die_codec(&codec, "Failed to destroy codec");

    fclose(outfile);
    fclose(infile);
    return EXIT_SUCCESS;
}