FFMpeg官网源代码中的示例代码(编码和解码示例)（精华）

转:http://blog.csdn.net/cosmoslife/article/details/7583275

//FFMpeg学习官网地址：http://www.ffmpeg.org/developer.html

 

/*
 * Copyright (c) 2001 Fabrice Bellard
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

/**
 * @file
 * libavcodec API use example.
 *
 * Note that libavcodec only handles codecs (mpeg, mpeg4, etc...),
 * not file formats (avi, vob, mp4, mov, mkv, mxf, flv, mpegts, mpegps, etc...). See library 'libavformat' for the
 * format handling
 */

#include "libavutil/imgutils.h"
#include "libavutil/opt.h"
#include "libavcodec/avcodec.h"
#include "libavutil/mathematics.h"
#include "libavutil/samplefmt.h"

#define INBUF_SIZE 4096
#define AUDIO_INBUF_SIZE 20480
#define AUDIO_REFILL_THRESH 4096

/*
 * Audio encoding example
 */
static void audio_encode_example(const char *filename)
{
    AVCodec *codec;
    AVCodecContext *c= NULL;
    int frame_size, i, j, out_size, outbuf_size;
    FILE *f;
    short *samples;
    float t, tincr;
    uint8_t *outbuf;

    printf("Audio encoding\n");

    /* find the MP2 encoder */
    codec = avcodec_find_encoder(CODEC_ID_MP2);
    if (!codec) {
        fprintf(stderr, "codec not found\n");
        exit(1);
    }

    c = avcodec_alloc_context3(codec);

    /* put sample parameters */
    c->bit_rate = 64000;
    c->sample_rate = 44100;
    c->channels = 2;
    c->sample_fmt = AV_SAMPLE_FMT_S16;

    /* open it */
    if (avcodec_open2(c, codec, NULL) < 0) {
        fprintf(stderr, "could not open codec\n");
        exit(1);
    }

    /* the codec gives us the frame size, in samples */
    frame_size = c->frame_size;
    samples = malloc(frame_size * 2 * c->channels);
    outbuf_size = 10000;
    outbuf = malloc(outbuf_size);

    f = fopen(filename, "wb");
    if (!f) {
        fprintf(stderr, "could not open %s\n", filename);
        exit(1);
    }

    /* encode a single tone sound */
    t = 0;
    tincr = 2 * M_PI * 440.0 / c->sample_rate;
    for(i=0;i<200;i++) {
        for(j=0;j<frame_size;j++) {
            samples[2*j] = (int)(sin(t) * 10000);
            samples[2*j+1] = samples[2*j];
            t += tincr;
        }
        /* encode the samples */
        out_size = avcodec_encode_audio(c, outbuf, outbuf_size, samples);
        fwrite(outbuf, 1, out_size, f);
    }
    fclose(f);
    free(outbuf);
    free(samples);

    avcodec_close(c);
    av_free(c);
}

/*
 * Audio decoding.
 */
static void audio_decode_example(const char *outfilename, const char *filename)
{
    AVCodec *codec;
    AVCodecContext *c= NULL;
    int len;
    FILE *f, *outfile;
    uint8_t inbuf[AUDIO_INBUF_SIZE + FF_INPUT_BUFFER_PADDING_SIZE];
    AVPacket avpkt;
    AVFrame *decoded_frame = NULL;

    av_init_packet(&avpkt);

    printf("Audio decoding\n");

    /* find the mpeg audio decoder */
    codec = avcodec_find_decoder(CODEC_ID_MP2);
    if (!codec) {
        fprintf(stderr, "codec not found\n");
        exit(1);
    }

    c = avcodec_alloc_context3(codec);

    /* open it */
    if (avcodec_open2(c, codec, NULL) < 0) {
        fprintf(stderr, "could not open codec\n");
        exit(1);
    }

    f = fopen(filename, "rb");
    if (!f) {
        fprintf(stderr, "could not open %s\n", filename);
        exit(1);
    }
    outfile = fopen(outfilename, "wb");
    if (!outfile) {
        av_free(c);
        exit(1);
    }

    /* decode until eof */
    avpkt.data = inbuf;
    avpkt.size = fread(inbuf, 1, AUDIO_INBUF_SIZE, f);

    while (avpkt.size > 0) {
        int got_frame = 0;

        if (!decoded_frame) {
            if (!(decoded_frame = avcodec_alloc_frame())) {
                fprintf(stderr, "out of memory\n");
                exit(1);
            }
        } else
            avcodec_get_frame_defaults(decoded_frame);

        len = avcodec_decode_audio4(c, decoded_frame, &got_frame, &avpkt);
        if (len < 0) {
            fprintf(stderr, "Error while decoding\n");
            exit(1);
        }
        if (got_frame) {
            /* if a frame has been decoded, output it */
            int data_size = av_samples_get_buffer_size(NULL, c->channels,
                                                       decoded_frame->nb_samples,
                                                       c->sample_fmt, 1);
            fwrite(decoded_frame->data[0], 1, data_size, outfile);
        }
        avpkt.size -= len;
        avpkt.data += len;
        avpkt.dts =
        avpkt.pts = AV_NOPTS_VALUE;
        if (avpkt.size < AUDIO_REFILL_THRESH) {
            /* Refill the input buffer, to avoid trying to decode
             * incomplete frames. Instead of this, one could also use
             * a parser, or use a proper container format through
             * libavformat. */
            memmove(inbuf, avpkt.data, avpkt.size);
            avpkt.data = inbuf;
            len = fread(avpkt.data + avpkt.size, 1,
                        AUDIO_INBUF_SIZE - avpkt.size, f);
            if (len > 0)
                avpkt.size += len;
        }
    }

    fclose(outfile);
    fclose(f);

    avcodec_close(c);
    av_free(c);
    av_free(decoded_frame);
}

/*
 * Video encoding example
 */
static void video_encode_example(const char *filename, int codec_id)
{
    AVCodec *codec;
    AVCodecContext *c= NULL;
    int i, out_size, x, y, outbuf_size;
    FILE *f;
    AVFrame *picture;
    uint8_t *outbuf;
    int had_output=0;

    printf("Video encoding\n");

    /* find the mpeg1 video encoder */
    codec = avcodec_find_encoder(codec_id);
    if (!codec) {
        fprintf(stderr, "codec not found\n");
        exit(1);
    }

    c = avcodec_alloc_context3(codec);
    picture= avcodec_alloc_frame();

    /* put sample parameters */
    c->bit_rate = 400000;
    /* resolution must be a multiple of two */
    c->width = 352;
    c->height = 288;
    /* frames per second */
    c->time_base= (AVRational){1,25};
    c->gop_size = 10; /* emit one intra frame every ten frames */
    c->max_b_frames=1;
    c->pix_fmt = PIX_FMT_YUV420P;

    if(codec_id == CODEC_ID_H264)
        av_opt_set(c->priv_data, "preset", "slow", 0);

    /* open it */
    if (avcodec_open2(c, codec, NULL) < 0) {
        fprintf(stderr, "could not open codec\n");
        exit(1);
    }

    f = fopen(filename, "wb");
    if (!f) {
        fprintf(stderr, "could not open %s\n", filename);
        exit(1);
    }

    /* alloc image and output buffer */
    outbuf_size = 100000 + 12*c->width*c->height;
    outbuf = malloc(outbuf_size);

    /* the image can be allocated by any means and av_image_alloc() is
     * just the most convenient way if av_malloc() is to be used */
    av_image_alloc(picture->data, picture->linesize,
                   c->width, c->height, c->pix_fmt, 1);

    /* encode 1 second of video */
    for(i=0;i<25;i++) {
        fflush(stdout);
        /* prepare a dummy image */
        /* Y */
        for(y=0;y<c->height;y++) {
            for(x=0;x<c->width;x++) {
                picture->data[0][y * picture->linesize[0] + x] = x + y + i * 3;
            }
        }

        /* Cb and Cr */
        for(y=0;y<c->height/2;y++) {
            for(x=0;x<c->width/2;x++) {
                picture->data[1][y * picture->linesize[1] + x] = 128 + y + i * 2;
                picture->data[2][y * picture->linesize[2] + x] = 64 + x + i * 5;
            }
        }

        /* encode the image */
        out_size = avcodec_encode_video(c, outbuf, outbuf_size, picture);
        had_output |= out_size;
        printf("encoding frame %3d (size=%5d)\n", i, out_size);
        fwrite(outbuf, 1, out_size, f);
    }

    /* get the delayed frames */
    for(; out_size || !had_output; i++) {
        fflush(stdout);

        out_size = avcodec_encode_video(c, outbuf, outbuf_size, NULL);
        had_output |= out_size;
        printf("write frame %3d (size=%5d)\n", i, out_size);
        fwrite(outbuf, 1, out_size, f);
    }

    /* add sequence end code to have a real mpeg file */
    outbuf[0] = 0x00;
    outbuf[1] = 0x00;
    outbuf[2] = 0x01;
    outbuf[3] = 0xb7;
    fwrite(outbuf, 1, 4, f);
    fclose(f);
    free(outbuf);

    avcodec_close(c);
    av_free(c);
    av_free(picture->data[0]);
    av_free(picture);
    printf("\n");
}

/*
 * Video decoding example
 */

static void pgm_save(unsigned char *buf, int wrap, int xsize, int ysize,
                     char *filename)
{
    FILE *f;
    int i;

    f=fopen(filename,"w");
    fprintf(f,"P5\n%d %d\n%d\n",xsize,ysize,255);
    for(i=0;i<ysize;i++)
        fwrite(buf + i * wrap,1,xsize,f);
    fclose(f);
}

static void video_decode_example(const char *outfilename, const char *filename)
{
    AVCodec *codec;
    AVCodecContext *c= NULL;
    int frame, got_picture, len;
    FILE *f;
    AVFrame *picture;
    uint8_t inbuf[INBUF_SIZE + FF_INPUT_BUFFER_PADDING_SIZE];
    char buf[1024];
    AVPacket avpkt;

    av_init_packet(&avpkt);

    /* set end of buffer to 0 (this ensures that no overreading happens for damaged mpeg streams) */
    memset(inbuf + INBUF_SIZE, 0, FF_INPUT_BUFFER_PADDING_SIZE);

    printf("Video decoding\n");

    /* find the mpeg1 video decoder */
    codec = avcodec_find_decoder(CODEC_ID_MPEG1VIDEO);
    if (!codec) {
        fprintf(stderr, "codec not found\n");
        exit(1);
    }

    c = avcodec_alloc_context3(codec);
    picture= avcodec_alloc_frame();

    if(codec->capabilities&CODEC_CAP_TRUNCATED)
        c->flags|= CODEC_FLAG_TRUNCATED; /* we do not send complete frames */

    /* For some codecs, such as msmpeg4 and mpeg4, width and height
       MUST be initialized there because this information is not
       available in the bitstream. */

    /* open it */
    if (avcodec_open2(c, codec, NULL) < 0) {
        fprintf(stderr, "could not open codec\n");
        exit(1);
    }

    /* the codec gives us the frame size, in samples */

    f = fopen(filename, "rb");
    if (!f) {
        fprintf(stderr, "could not open %s\n", filename);
        exit(1);
    }

    frame = 0;
    for(;;) {
        avpkt.size = fread(inbuf, 1, INBUF_SIZE, f);
        if (avpkt.size == 0)
            break;

        /* NOTE1: some codecs are stream based (mpegvideo, mpegaudio)
           and this is the only method to use them because you cannot
           know the compressed data size before analysing it.

           BUT some other codecs (msmpeg4, mpeg4) are inherently frame
           based, so you must call them with all the data for one
           frame exactly. You must also initialize 'width' and
           'height' before initializing them. */

        /* NOTE2: some codecs allow the raw parameters (frame size,
           sample rate) to be changed at any frame. We handle this, so
           you should also take care of it */

        /* here, we use a stream based decoder (mpeg1video), so we
           feed decoder and see if it could decode a frame */
        avpkt.data = inbuf;
        while (avpkt.size > 0) {
            len = avcodec_decode_video2(c, picture, &got_picture, &avpkt);
            if (len < 0) {
                fprintf(stderr, "Error while decoding frame %d\n", frame);
                exit(1);
            }
            if (got_picture) {
                printf("saving frame %3d\n", frame);
                fflush(stdout);

                /* the picture is allocated by the decoder. no need to
                   free it */
                snprintf(buf, sizeof(buf), outfilename, frame);
                pgm_save(picture->data[0], picture->linesize[0],
                         c->width, c->height, buf);
                frame++;
            }
            avpkt.size -= len;
            avpkt.data += len;
        }
    }

    /* some codecs, such as MPEG, transmit the I and P frame with a
       latency of one frame. You must do the following to have a
       chance to get the last frame of the video */
    avpkt.data = NULL;
    avpkt.size = 0;
    len = avcodec_decode_video2(c, picture, &got_picture, &avpkt);
    if (got_picture) {
        printf("saving last frame %3d\n", frame);
        fflush(stdout);

        /* the picture is allocated by the decoder. no need to
           free it */
        snprintf(buf, sizeof(buf), outfilename, frame);
        pgm_save(picture->data[0], picture->linesize[0],
                 c->width, c->height, buf);
        frame++;
    }

    fclose(f);

    avcodec_close(c);
    av_free(c);
    av_free(picture);
    printf("\n");
}

int main(int argc, char **argv)
{
    const char *filename;

    /* register all the codecs */
    avcodec_register_all();

    if (argc <= 1) {
        audio_encode_example("/tmp/test.mp2");
        audio_decode_example("/tmp/test.sw", "/tmp/test.mp2");

        video_encode_example("/tmp/test.h264", CODEC_ID_H264);
        video_encode_example("/tmp/test.mpg", CODEC_ID_MPEG1VIDEO);
        filename = "/tmp/test.mpg";
    } else {
        filename = argv[1];
    }

    //    audio_decode_example("/tmp/test.sw", filename);
    video_decode_example("/tmp/test%d.pgm", filename);

    return 0;
}