doc/examples/muxing.c

Go to the documentation of this file.

/*
 * Copyright (c) 2003 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.
 */

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <math.h>

#include <libavutil/mathematics.h>
#include <libavformat/avformat.h>
#include <libswscale/swscale.h>

#undef exit

/* 5 seconds stream duration */
#define STREAM_DURATION   200.0
#define STREAM_FRAME_RATE 25 /* 25 images/s */
#define STREAM_NB_FRAMES  ((int)(STREAM_DURATION * STREAM_FRAME_RATE))
#define STREAM_PIX_FMT    PIX_FMT_YUV420P /* default pix_fmt */

static int sws_flags = SWS_BICUBIC;

/**************************************************************/
/* audio output */

static float t, tincr, tincr2;
static int16_t *samples;
static int audio_input_frame_size;

/*
 * add an audio output stream
 */
static AVStream *add_audio_stream(AVFormatContext *oc, enum CodecID codec_id)
{
    AVCodecContext *c;
    AVStream *st;
    AVCodec *codec;

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

    st = avformat_new_stream(oc, codec);
    if (!st) {
        fprintf(stderr, "Could not alloc stream\n");
        exit(1);
    }
    st->id = 1;

    c = st->codec;

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

    // some formats want stream headers to be separate
    if (oc->oformat->flags & AVFMT_GLOBALHEADER)
        c->flags |= CODEC_FLAG_GLOBAL_HEADER;

    return st;
}

static void open_audio(AVFormatContext *oc, AVStream *st)
{
    AVCodecContext *c;

    c = st->codec;

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

    /* init signal generator */
    t     = 0;
    tincr = 2 * M_PI * 110.0 / c->sample_rate;
    /* increment frequency by 110 Hz per second */
    tincr2 = 2 * M_PI * 110.0 / c->sample_rate / c->sample_rate;

    if (c->codec->capabilities & CODEC_CAP_VARIABLE_FRAME_SIZE)
        audio_input_frame_size = 10000;
    else
        audio_input_frame_size = c->frame_size;
    samples = av_malloc(audio_input_frame_size *
                        av_get_bytes_per_sample(c->sample_fmt) *
                        c->channels);
}

/* Prepare a 16 bit dummy audio frame of 'frame_size' samples and
 * 'nb_channels' channels. */
static void get_audio_frame(int16_t *samples, int frame_size, int nb_channels)
{
    int j, i, v;
    int16_t *q;

    q = samples;
    for (j = 0; j < frame_size; j++) {
        v = (int)(sin(t) * 10000);
        for (i = 0; i < nb_channels; i++)
            *q++ = v;
        t     += tincr;
        tincr += tincr2;
    }
}

static void write_audio_frame(AVFormatContext *oc, AVStream *st)
{
    AVCodecContext *c;
    AVPacket pkt = { 0 }; // data and size must be 0;
    AVFrame *frame = avcodec_alloc_frame();
    int got_packet;

    av_init_packet(&pkt);
    c = st->codec;

    get_audio_frame(samples, audio_input_frame_size, c->channels);
    frame->nb_samples = audio_input_frame_size;
    avcodec_fill_audio_frame(frame, c->channels, c->sample_fmt,
                             (uint8_t *)samples,
                             audio_input_frame_size *
                             av_get_bytes_per_sample(c->sample_fmt) *
                             c->channels, 1);

    avcodec_encode_audio2(c, &pkt, frame, &got_packet);
    if (!got_packet)
        return;

    pkt.stream_index = st->index;

    /* Write the compressed frame to the media file. */
    if (av_interleaved_write_frame(oc, &pkt) != 0) {
        fprintf(stderr, "Error while writing audio frame\n");
        exit(1);
    }
}

static void close_audio(AVFormatContext *oc, AVStream *st)
{
    avcodec_close(st->codec);

    av_free(samples);
}

/**************************************************************/
/* video output */

static AVFrame *picture, *tmp_picture;
static uint8_t *video_outbuf;
static int frame_count, video_outbuf_size;

/* Add a video output stream. */
static AVStream *add_video_stream(AVFormatContext *oc, enum CodecID codec_id)
{
    AVCodecContext *c;
    AVStream *st;
    AVCodec *codec;

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

    st = avformat_new_stream(oc, codec);
    if (!st) {
        fprintf(stderr, "Could not alloc stream\n");
        exit(1);
    }

    c = st->codec;

    /* find the video encoder */
    codec = avcodec_find_encoder(codec_id);
    if (!codec) {
        fprintf(stderr, "codec not found\n");
        exit(1);
    }
    avcodec_get_context_defaults3(c, codec);

    c->codec_id = codec_id;

    /* Put sample parameters. */
    c->bit_rate = 400000;
    /* Resolution must be a multiple of two. */
    c->width    = 352;
    c->height   = 288;
    /* timebase: This is the fundamental unit of time (in seconds) in terms
     * of which frame timestamps are represented. For fixed-fps content,
     * timebase should be 1/framerate and timestamp increments should be
     * identical to 1. */
    c->time_base.den = STREAM_FRAME_RATE;
    c->time_base.num = 1;
    c->gop_size      = 12; /* emit one intra frame every twelve frames at most */
    c->pix_fmt       = STREAM_PIX_FMT;
    if (c->codec_id == CODEC_ID_MPEG2VIDEO) {
        /* just for testing, we also add B frames */
        c->max_b_frames = 2;
    }
    if (c->codec_id == CODEC_ID_MPEG1VIDEO) {
        /* Needed to avoid using macroblocks in which some coeffs overflow.
         * This does not happen with normal video, it just happens here as
         * the motion of the chroma plane does not match the luma plane. */
        c->mb_decision = 2;
    }
    /* Some formats want stream headers to be separate. */
    if (oc->oformat->flags & AVFMT_GLOBALHEADER)
        c->flags |= CODEC_FLAG_GLOBAL_HEADER;

    return st;
}

static AVFrame *alloc_picture(enum PixelFormat pix_fmt, int width, int height)
{
    AVFrame *picture;
    uint8_t *picture_buf;
    int size;

    picture = avcodec_alloc_frame();
    if (!picture)
        return NULL;
    size        = avpicture_get_size(pix_fmt, width, height);
    picture_buf = av_malloc(size);
    if (!picture_buf) {
        av_free(picture);
        return NULL;
    }
    avpicture_fill((AVPicture *)picture, picture_buf,
                   pix_fmt, width, height);
    return picture;
}

static void open_video(AVFormatContext *oc, AVStream *st)
{
    AVCodecContext *c;

    c = st->codec;

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

    video_outbuf = NULL;
    if (!(oc->oformat->flags & AVFMT_RAWPICTURE)) {
        /* Allocate output buffer. */
        /* XXX: API change will be done. */
        /* Buffers passed into lav* can be allocated any way you prefer,
         * as long as they're aligned enough for the architecture, and
         * they're freed appropriately (such as using av_free for buffers
         * allocated with av_malloc). */
        video_outbuf_size = 200000;
        video_outbuf      = av_malloc(video_outbuf_size);
    }

    /* Allocate the encoded raw picture. */
    picture = alloc_picture(c->pix_fmt, c->width, c->height);
    if (!picture) {
        fprintf(stderr, "Could not allocate picture\n");
        exit(1);
    }

    /* If the output format is not YUV420P, then a temporary YUV420P
     * picture is needed too. It is then converted to the required
     * output format. */
    tmp_picture = NULL;
    if (c->pix_fmt != PIX_FMT_YUV420P) {
        tmp_picture = alloc_picture(PIX_FMT_YUV420P, c->width, c->height);
        if (!tmp_picture) {
            fprintf(stderr, "Could not allocate temporary picture\n");
            exit(1);
        }
    }
}

/* Prepare a dummy image. */
static void fill_yuv_image(AVFrame *pict, int frame_index,
                           int width, int height)
{
    int x, y, i;

    i = frame_index;

    /* Y */
    for (y = 0; y < height; y++)
        for (x = 0; x < width; x++)
            pict->data[0][y * pict->linesize[0] + x] = x + y + i * 3;

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

static void write_video_frame(AVFormatContext *oc, AVStream *st)
{
    int out_size, ret;
    AVCodecContext *c;
    static struct SwsContext *img_convert_ctx;

    c = st->codec;

    if (frame_count >= STREAM_NB_FRAMES) {
        /* No more frames to compress. The codec has a latency of a few
         * frames if using B-frames, so we get the last frames by
         * passing the same picture again. */
    } else {
        if (c->pix_fmt != PIX_FMT_YUV420P) {
            /* as we only generate a YUV420P picture, we must convert it
             * to the codec pixel format if needed */
            if (img_convert_ctx == NULL) {
                img_convert_ctx = sws_getContext(c->width, c->height,
                                                 PIX_FMT_YUV420P,
                                                 c->width, c->height,
                                                 c->pix_fmt,
                                                 sws_flags, NULL, NULL, NULL);
                if (img_convert_ctx == NULL) {
                    fprintf(stderr,
                            "Cannot initialize the conversion context\n");
                    exit(1);
                }
            }
            fill_yuv_image(tmp_picture, frame_count, c->width, c->height);
            sws_scale(img_convert_ctx, tmp_picture->data, tmp_picture->linesize,
                      0, c->height, picture->data, picture->linesize);
        } else {
            fill_yuv_image(picture, frame_count, c->width, c->height);
        }
    }

    if (oc->oformat->flags & AVFMT_RAWPICTURE) {
        /* Raw video case - the API will change slightly in the near
         * future for that. */
        AVPacket pkt;
        av_init_packet(&pkt);

        pkt.flags        |= AV_PKT_FLAG_KEY;
        pkt.stream_index  = st->index;
        pkt.data          = (uint8_t *)picture;
        pkt.size          = sizeof(AVPicture);

        ret = av_interleaved_write_frame(oc, &pkt);
    } else {
        /* encode the image */
        out_size = avcodec_encode_video(c, video_outbuf,
                                        video_outbuf_size, picture);
        /* If size is zero, it means the image was buffered. */
        if (out_size > 0) {
            AVPacket pkt;
            av_init_packet(&pkt);

            if (c->coded_frame->pts != AV_NOPTS_VALUE)
                pkt.pts = av_rescale_q(c->coded_frame->pts,
                                       c->time_base, st->time_base);
            if (c->coded_frame->key_frame)
                pkt.flags |= AV_PKT_FLAG_KEY;

            pkt.stream_index = st->index;
            pkt.data         = video_outbuf;
            pkt.size         = out_size;

            /* Write the compressed frame to the media file. */
            ret = av_interleaved_write_frame(oc, &pkt);
        } else {
            ret = 0;
        }
    }
    if (ret != 0) {
        fprintf(stderr, "Error while writing video frame\n");
        exit(1);
    }
    frame_count++;
}

static void close_video(AVFormatContext *oc, AVStream *st)
{
    avcodec_close(st->codec);
    av_free(picture->data[0]);
    av_free(picture);
    if (tmp_picture) {
        av_free(tmp_picture->data[0]);
        av_free(tmp_picture);
    }
    av_free(video_outbuf);
}

/**************************************************************/
/* media file output */

int main(int argc, char **argv)
{
    const char *filename;
    AVOutputFormat *fmt;
    AVFormatContext *oc;
    AVStream *audio_st, *video_st;
    double audio_pts, video_pts;
    int i;

    /* Initialize libavcodec, and register all codecs and formats. */
    av_register_all();

    if (argc != 2) {
        printf("usage: %s output_file\n"
               "API example program to output a media file with libavformat.\n"
               "The output format is automatically guessed according to the file extension.\n"
               "Raw images can also be output by using '%%d' in the filename\n"
               "\n", argv[0]);
        return 1;
    }

    filename = argv[1];

    /* allocate the output media context */
    avformat_alloc_output_context2(&oc, NULL, NULL, filename);
    if (!oc) {
        printf("Could not deduce output format from file extension: using MPEG.\n");
        avformat_alloc_output_context2(&oc, NULL, "mpeg", filename);
    }
    if (!oc) {
        return 1;
    }
    fmt = oc->oformat;

    /* Add the audio and video streams using the default format codecs
     * and initialize the codecs. */
    video_st = NULL;
    audio_st = NULL;
    if (fmt->video_codec != CODEC_ID_NONE) {
        video_st = add_video_stream(oc, fmt->video_codec);
    }
    if (fmt->audio_codec != CODEC_ID_NONE) {
        audio_st = add_audio_stream(oc, fmt->audio_codec);
    }

    /* Now that all the parameters are set, we can open the audio and
     * video codecs and allocate the necessary encode buffers. */
    if (video_st)
        open_video(oc, video_st);
    if (audio_st)
        open_audio(oc, audio_st);

    av_dump_format(oc, 0, filename, 1);

    /* open the output file, if needed */
    if (!(fmt->flags & AVFMT_NOFILE)) {
        if (avio_open(&oc->pb, filename, AVIO_FLAG_WRITE) < 0) {
            fprintf(stderr, "Could not open '%s'\n", filename);
            return 1;
        }
    }

    /* Write the stream header, if any. */
    avformat_write_header(oc, NULL);

    picture->pts = 0;
    for (;;) {
        /* Compute current audio and video time. */
        if (audio_st)
            audio_pts = (double)audio_st->pts.val * audio_st->time_base.num / audio_st->time_base.den;
        else
            audio_pts = 0.0;

        if (video_st)
            video_pts = (double)video_st->pts.val * video_st->time_base.num /
                        video_st->time_base.den;
        else
            video_pts = 0.0;

        if ((!audio_st || audio_pts >= STREAM_DURATION) &&
            (!video_st || video_pts >= STREAM_DURATION))
            break;

        /* write interleaved audio and video frames */
        if (!video_st || (video_st && audio_st && audio_pts < video_pts)) {
            write_audio_frame(oc, audio_st);
        } else {
            write_video_frame(oc, video_st);
            picture->pts++;
        }
    }

    /* Write the trailer, if any. The trailer must be written before you
     * close the CodecContexts open when you wrote the header; otherwise
     * av_write_trailer() may try to use memory that was freed on
     * av_codec_close(). */
    av_write_trailer(oc);

    /* Close each codec. */
    if (video_st)
        close_video(oc, video_st);
    if (audio_st)
        close_audio(oc, audio_st);

    /* Free the streams. */
    for (i = 0; i < oc->nb_streams; i++) {
        av_freep(&oc->streams[i]->codec);
        av_freep(&oc->streams[i]);
    }

    if (!(fmt->flags & AVFMT_NOFILE))
        /* Close the output file. */
        avio_close(oc->pb);

    /* free the stream */
    av_free(oc);

    return 0;
}

---