1 files changed, 456 insertions, 0 deletions
diff --git a/doc/examples/encoding.c b/doc/examples/encoding.c
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+/*
+ * Copyright (c) 2001 Fabrice Bellard
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file
+ * libavcodec API use example.
+ *
+ * Note that libavcodec only handles codecs (mpeg, mpeg4, etc...),
+ * not file formats (avi, vob, etc...). See library 'libavformat' for the
+ * format handling
+ */
+
+#include "libavcodec/avcodec.h"
+#include "libavutil/mathematics.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_open(c, codec) < 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 out_size, len;
+    FILE *f, *outfile;
+    uint8_t *outbuf;
+    uint8_t inbuf[AUDIO_INBUF_SIZE + FF_INPUT_BUFFER_PADDING_SIZE];
+    AVPacket avpkt;
+
+    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_open(c, codec) < 0) {
+        fprintf(stderr, "could not open codec\n");
+        exit(1);
+    }
+
+    outbuf = malloc(AVCODEC_MAX_AUDIO_FRAME_SIZE);
+
+    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) {
+        out_size = AVCODEC_MAX_AUDIO_FRAME_SIZE;
+        len = avcodec_decode_audio3(c, (short *)outbuf, &out_size, &avpkt);
+        if (len < 0) {
+            fprintf(stderr, "Error while decoding\n");
+            exit(1);
+        }
+        if (out_size > 0) {
+            /* if a frame has been decoded, output it */
+            fwrite(outbuf, 1, out_size, outfile);
+        }
+        avpkt.size -= len;
+        avpkt.data += len;
+        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);
+    free(outbuf);
+
+    avcodec_close(c);
+    av_free(c);
+}
+
+/*
+ * Video encoding example
+ */
+static void video_encode_example(const char *filename)
+{
+    AVCodec *codec;
+    AVCodecContext *c= NULL;
+    int i, out_size, size, x, y, outbuf_size;
+    FILE *f;
+    AVFrame *picture;
+    uint8_t *outbuf;
+
+    printf("Video encoding\n");
+
+    /* find the mpeg1 video encoder */
+    codec = avcodec_find_encoder(CODEC_ID_MPEG1VIDEO);
+    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;
+
+    /* open it */
+    if (avcodec_open(c, codec) < 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;
+    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);
+        printf("encoding frame %3d (size=%5d)\n", i, out_size);
+        fwrite(outbuf, 1, out_size, f);
+    }
+
+    /* get the delayed frames */
+    for(; out_size; i++) {
+        fflush(stdout);
+
+        out_size = avcodec_encode_video(c, outbuf, outbuf_size, NULL);
+        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_open(c, codec) < 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;
+
+    /* must be called before using avcodec lib */
+    avcodec_init();
+
+    /* 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.mpg");
+        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;
+}