summaryrefslogtreecommitdiff
path: root/doc/examples/encoding.c
diff options
context:
space:
mode:
Diffstat (limited to 'doc/examples/encoding.c')
-rw-r--r--doc/examples/encoding.c456
1 files changed, 456 insertions, 0 deletions
diff --git a/doc/examples/encoding.c b/doc/examples/encoding.c
new file mode 100644
index 0000000000..042947a060
--- /dev/null
+++ b/doc/examples/encoding.c
@@ -0,0 +1,456 @@
+/*
+ * 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;
+}