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Diffstat (limited to 'doc/examples/encoding.c')
| -rw-r--r-- | doc/examples/encoding.c | 458 |
1 files changed, 458 insertions, 0 deletions
diff --git a/doc/examples/encoding.c b/doc/examples/encoding.c new file mode 100644 index 0000000000..7efd5facce --- /dev/null +++ b/doc/examples/encoding.c @@ -0,0 +1,458 @@ +/* + * 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, 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; +} |