ffmpeg.c

                            goto redo;
                        }
                        if (!got_picture) {
                            /* no picture yet */
                            ptr += ret;
                            len -= ret;
                            continue;
                        }
                    }
                    break;
                default:
                    goto fail_decode;
                }
            } else {
                data_buf = ptr;
                data_size = len;
                ret = len;
            }
            /* update pts */
            switch(ist->st->codec.codec_type) {
            case CODEC_TYPE_AUDIO:
                ist->pts = (INT64)1000000 * ist->sample_index / ist->st->codec.sample_rate;
                ist->sample_index += data_size / (2 * ist->st->codec.channels);
                ist->pts_increment = (INT64) (data_size / (2 * ist->st->codec.channels)) * 1000000 / ist->st->codec.sample_rate;
                break;
            case CODEC_TYPE_VIDEO:
                ist->frame_number++;
                ist->pts = ((INT64)ist->frame_number * 1000000 * FRAME_RATE_BASE) / 
                    ist->st->codec.frame_rate;
                ist->pts_increment = ((INT64) 1000000 * FRAME_RATE_BASE) / 
                    ist->st->codec.frame_rate;
                break;
            default:
                abort();
            }
            ptr += ret;
            len -= ret;

            /* transcode raw format, encode packets and output them */
            
            for(i=0;i<nb_ostreams;i++) {
                int frame_size;
                ost = ost_table[i];
                if (ost->source_index == ist_index) {
                    os = output_files[ost->file_index];

                    if (ost->encoding_needed) {
                        switch(ost->st->codec.codec_type) {
                        case CODEC_TYPE_AUDIO:
                            do_audio_out(os, ost, ist, data_buf, data_size);
                            break;
                        case CODEC_TYPE_VIDEO:
                            do_video_out(os, ost, ist, &picture, &frame_size);
                            if (do_vstats)
                                do_video_stats(ost, ist, frame_size);
                            break;
                        default:
                            abort();
                        }
                    } else {
                        /* no reencoding needed : output the packet directly */
                        /* force the input stream PTS */
                        os->format->write_packet(os, ost->index, data_buf, data_size, pkt.pts);
                    }
                }
            }
        }
        av_free_packet(&pkt);
        
        /* dump report by using the first video and audio streams */
        {
            char buf[1024];
            AVFormatContext *oc;
            INT64 total_size, ti;
            AVCodecContext *enc;
            int frame_number, vid;
            double bitrate, ti1;
            static INT64 last_time;

            if ((min_pts - last_time) >= 500000) {
                last_time = min_pts;
                
                oc = output_files[0];
                
                total_size = url_ftell(&oc->pb);
                
                buf[0] = '\0';
                ti = MAXINT64;
                vid = 0;
                for(i=0;i<nb_ostreams;i++) {
                    ost = ost_table[i];
                    enc = &ost->st->codec;
                    ist = ist_table[ost->source_index];
                    if (!vid && enc->codec_type == CODEC_TYPE_VIDEO) {
                        frame_number = ist->frame_number;
                        sprintf(buf + strlen(buf), "frame=%5d q=%2d ",
                                frame_number, enc->quality);
                        if (do_psnr)
                            sprintf(buf + strlen(buf), "PSNR=%6.2f ", enc->psnr_y);
                        vid = 1;
                    }
                    /* compute min pts value */
                    if (!ist->discard && ist->pts < ti) {
                        ti = ist->pts;
                    }
                }

                ti1 = (double)ti / 1000000.0;
                if (ti1 < 0.01)
                    ti1 = 0.01;
                bitrate = (double)(total_size * 8) / ti1 / 1000.0;

                sprintf(buf + strlen(buf), 
                        "size=%8.0fkB time=%0.1f bitrate=%6.1fkbits/s",
                        (double)total_size / 1024, ti1, bitrate);
                
                fprintf(stderr, "%s   \r", buf);
                fflush(stderr);
            }
        }
    }
    term_exit();

    /* dump report by using the first video and audio streams */
    {
        char buf[1024];
        AVFormatContext *oc;
        INT64 total_size, ti;
        AVCodecContext *enc;
        int frame_number, vid;
        double bitrate, ti1;

        oc = output_files[0];
        
        total_size = url_ftell(&oc->pb);
        
        buf[0] = '\0';
        ti = MAXINT64;
        vid = 0;
        for(i=0;i<nb_ostreams;i++) {
            ost = ost_table[i];
            enc = &ost->st->codec;
            ist = ist_table[ost->source_index];
            if (!vid && enc->codec_type == CODEC_TYPE_VIDEO) {
                frame_number = ist->frame_number;
                sprintf(buf + strlen(buf), "frame=%5d q=%2d ",
                        frame_number, enc->quality);
                if (do_psnr)
                    sprintf(buf + strlen(buf), "PSNR=%6.2f ", enc->psnr_y);
                vid = 1;
            }
            /* compute min pts value */
            if (!ist->discard && ist->pts < ti) {
                ti = ist->pts;
            }
        }
        
        ti1 = ti / 1000000.0;
        if (ti1 < 0.01)
            ti1 = 0.01;
        bitrate = (double)(total_size * 8) / ti1 / 1000.0;
        
        sprintf(buf + strlen(buf), 
                "size=%8.0fkB time=%0.1f bitrate=%6.1fkbits/s",
                (double)total_size / 1024, ti1, bitrate);
        
        fprintf(stderr, "%s   \n", buf);
    }
    /* close each encoder */
    for(i=0;i<nb_ostreams;i++) {
        ost = ost_table[i];
        if (ost->encoding_needed) {
            avcodec_close(&ost->st->codec);
        }
    }
    
    /* close each decoder */
    for(i=0;i<nb_istreams;i++) {
        ist = ist_table[i];
        if (ist->decoding_needed) {
            avcodec_close(&ist->st->codec);
        }
    }
    

    /* write the trailer if needed and close file */
    for(i=0;i<nb_output_files;i++) {
        os = output_files[i];
        os->format->write_trailer(os);
    }
    /* finished ! */
    
    ret = 0;
 fail1:
    free(file_table);

    if (ist_table) {
        for(i=0;i<nb_istreams;i++) {
            ist = ist_table[i];
            if (ist) {
                free(ist);
            }
        }
        free(ist_table);
    }
    if (ost_table) {
        for(i=0;i<nb_ostreams;i++) {
            ost = ost_table[i];
            if (ost) {
                if (ost->pict_tmp.data[0])
                    free(ost->pict_tmp.data[0]);
                if (ost->video_resample)
                    img_resample_close(ost->img_resample_ctx);
                if (ost->audio_resample)
                    audio_resample_close(ost->resample);
                free(ost);
            }
        }
        free(ost_table);
    }
    return ret;
 fail:
    ret = -ENOMEM;
    goto fail1;
}

#if 0
int file_read(const char *filename)
{
    URLContext *h;
    unsigned char buffer[1024];
    int len, i;

    if (url_open(&h, filename, O_RDONLY) < 0) {
        printf("could not open '%s'\n", filename);
        return -1;
    }
    for(;;) {
        len = url_read(h, buffer, sizeof(buffer));
        if (len <= 0)
            break;
        for(i=0;i<len;i++) putchar(buffer[i]);
    }
    url_close(h);
    return 0;
}
#endif

void show_licence(void)
{
    printf(
    "ffmpeg version " FFMPEG_VERSION "\n"
    "Copyright (c) 2000,2001 Gerard Lantau\n"
    "This program is free software; you can redistribute it and/or modify\n"
    "it under the terms of the GNU General Public License as published by\n"
    "the Free Software Foundation; either version 2 of the License, or\n"
    "(at your option) any later version.\n"
    "\n"
    "This program is distributed in the hope that it will be useful,\n"
    "but WITHOUT ANY WARRANTY; without even the implied warranty of\n"
    "MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the\n"
    "GNU General Public License for more details.\n"
    "\n"
    "You should have received a copy of the GNU General Public License\n"
    "along with this program; if not, write to the Free Software\n"
    "Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.\n"
    );
    exit(1);
}

void opt_format(const char *arg)
{
    AVFormat *f;
    f = first_format;
    while (f != NULL && strcmp(f->name, arg) != 0) f = f->next;
    if (f == NULL) {
        fprintf(stderr, "Invalid format: %s\n", arg);
        exit(1);
    }
    file_format = f;
}

void opt_video_bitrate(const char *arg)
{
    video_bit_rate = atoi(arg) * 1000;
}

void opt_video_bitrate_tolerance(const char *arg)
{
    video_bit_rate_tolerance = atoi(arg) * 1000;
}

void opt_frame_rate(const char *arg)
{
    frame_rate = (int)(strtod(arg, 0) * FRAME_RATE_BASE);
}

void opt_frame_size(const char *arg)
{
    parse_image_size(&frame_width, &frame_height, arg);
    if (frame_width <= 0 || frame_height <= 0) {
        fprintf(stderr, "Incorrect frame size\n");
        exit(1);
    }
    if ((frame_width % 2) != 0 || (frame_height % 2) != 0) {
        fprintf(stderr, "Frame size must be a multiple of 2\n");
        exit(1);
    }
}

void opt_gop_size(const char *arg)
{
    gop_size = atoi(arg);
}

void opt_b_frames(const char *arg)
{
    b_frames = atoi(arg);
    if (b_frames > FF_MAX_B_FRAMES) {
        fprintf(stderr, "\nCannot have more than %d B frames, increase FF_MAX_B_FRAMES.\n", FF_MAX_B_FRAMES);
        exit(1);
    } else if (b_frames < 1) {
        fprintf(stderr, "\nNumber of B frames must be higher than 0\n");
        exit(1);
    }
}

void opt_qscale(const char *arg)
{
    video_qscale = atoi(arg);
    if (video_qscale < 0 ||
        video_qscale > 31) {
        fprintf(stderr, "qscale must be >= 1 and <= 31\n");
        exit(1);
    }
}

void opt_qmin(const char *arg)
{
    video_qmin = atoi(arg);
    if (video_qmin < 0 ||
        video_qmin > 31) {
        fprintf(stderr, "qmin must be >= 1 and <= 31\n");
        exit(1);
    }
}

void opt_qmax(const char *arg)
{
    video_qmax = atoi(arg);
    if (video_qmax < 0 ||
        video_qmax > 31) {
        fprintf(stderr, "qmax must be >= 1 and <= 31\n");
        exit(1);
    }
}

void opt_qdiff(const char *arg)
{
    video_qdiff = atoi(arg);
    if (video_qdiff < 0 ||
        video_qdiff > 31) {
        fprintf(stderr, "qdiff must be >= 1 and <= 31\n");
        exit(1);
    }
}

void opt_qblur(const char *arg)
{
    video_qblur = atof(arg);
}

void opt_qcomp(const char *arg)
{
    video_qcomp = atof(arg);
}

void opt_audio_bitrate(const char *arg)
{
    audio_bit_rate = atoi(arg) * 1000;
}

void opt_audio_rate(const char *arg)
{
    audio_sample_rate = atoi(arg);
}

void opt_audio_channels(const char *arg)
{
    audio_channels = atoi(arg);
}

#ifdef CONFIG_GRAB
void opt_video_device(const char *arg)
{
    v4l_device = strdup(arg);
}

void opt_audio_device(const char *arg)
{
    audio_device = strdup(arg);
}
#endif

void opt_audio_codec(const char *arg)
{
    AVCodec *p;

    p = first_avcodec;
    while (p) {
        if (!strcmp(p->name, arg) && p->type == CODEC_TYPE_AUDIO)
            break;
        p = p->next;
    }
    if (p == NULL) {
        fprintf(stderr, "Unknown audio codec '%s'\n", arg);
        exit(1);
    } else {
        audio_codec_id = p->id;
    }
}

const char *motion_str[] = {
    "zero",
    "full",
    "log",
    "phods",
    "epzs",
    "x1",
    NULL,
};

void opt_motion_estimation(const char *arg)
{
    const char **p;
    p = motion_str;
    for(;;) {
        if (!*p) {
            fprintf(stderr, "Unknown motion estimation method '%s'\n", arg);
            exit(1);
        }
        if (!strcmp(*p, arg))
            break;
        p++;
    }
    me_method = (p - motion_str) + 1;
}

void opt_video_codec(const char *arg)
{
    AVCodec *p;

    p = first_avcodec;
    while (p) {
        if (!strcmp(p->name, arg) && p->type == CODEC_TYPE_VIDEO)
            break;
        p = p->next;
    }
    if (p == NULL) {
        fprintf(stderr, "Unknown video codec '%s'\n", arg);
        exit(1);
    } else {
        video_codec_id = p->id;
    }
}

void opt_map(const char *arg)
{
    AVStreamMap *m;
    const char *p;

    p = arg;
    m = &stream_maps[nb_stream_maps++];

    m->file_index = strtol(arg, (char **)&p, 0);
    if (*p)
        p++;

    m->stream_index = strtol(p, (char **)&p, 0);
}

void opt_recording_time(const char *arg)
{
    recording_time = parse_date(arg, 1);
}

/* return the number of packet read to find the codec parameters */
int find_codec_parameters(AVFormatContext *ic)
{
    int val, i, count, ret, got_picture, size;
    AVCodec *codec;
    AVCodecContext *enc;
    AVStream *st;
    AVPacket *pkt;
    AVPicture picture;
    AVPacketList *pktl, **ppktl;
    short samples[AVCODEC_MAX_AUDIO_FRAME_SIZE / 2];
    UINT8 *ptr;

    count = 0;
    ppktl = &ic->packet_buffer;
    for(;;) {
        for(i=0;i<ic->nb_streams;i++) {
            enc = &ic->streams[i]->codec;
            
            switch(enc->codec_type) {
            case CODEC_TYPE_AUDIO:
                val = enc->sample_rate;
                break;
            case CODEC_TYPE_VIDEO:
                val = enc->width;
                break;
            default:
                val = 1;
                break;
            }
            /* if no parameters supplied, then we should read it from
               the stream */
            if (val == 0)
                break;
        }
        if (i == ic->nb_streams) {
            ret = count;
            break;
        }

        if (count == 0) {
            /* open each codec */
            for(i=0;i<ic->nb_streams;i++) {
                st = ic->streams[i];
                codec = avcodec_find_decoder(st->codec.codec_id);
                if (codec == NULL) {
                    ret = -1;
                    goto the_end;
                }
                ret = avcodec_open(&st->codec, codec);
                if (ret < 0)
                    goto the_end;
            }
        }
        pktl = av_mallocz(sizeof(AVPacketList));
        if (!pktl) {
            ret = -1;
            break;
        }

        /* add the packet in the buffered packet list */
        *ppktl = pktl;
        ppktl = &pktl->next;

        pkt = &pktl->pkt;
        if (ic->format->read_packet(ic, pkt) < 0) {
            ret = -1;
            break;
        }
        st = ic->streams[pkt->stream_index];

        /* decode the data and update codec parameters */
        ptr = pkt->data;
        size = pkt->size;
        while (size > 0) {
            switch(st->codec.codec_type) {
            case CODEC_TYPE_VIDEO:
                ret = avcodec_decode_video(&st->codec, &picture, &got_picture, ptr, size);
                break;
            case CODEC_TYPE_AUDIO:
                ret = avcodec_decode_audio(&st->codec, samples, &got_picture, ptr, size);
                break;
            default:
                ret = -1;
                break;
            }
            if (ret < 0) {
                ret = -1;
                goto the_end;
            }
            if (got_picture)
                break;
            ptr += ret;
            size -= ret;
        }

        count++;
    }
 the_end:
    if (count > 0) {
        /* close each codec */
        for(i=0;i<ic->nb_streams;i++) {
            st = ic->streams[i];
            avcodec_close(&st->codec);
        }
    }
    return ret;
}

int filename_number_test(const char *filename)
{
    char buf[1024];

    if (get_frame_filename(buf, sizeof(buf), filename, 1) < 0) {
        fprintf(stderr, "%s: Incorrect image filename syntax.\n"
                "Use '%%d' to specify the image number:\n"
                "  for img1.jpg, img2.jpg, ..., use 'img%%d.jpg';\n"
                "  for img001.jpg, img002.jpg, ..., use 'img%%03d.jpg'.\n", 
                filename);
        return -1;
    } else {
        return 0;
    }
}

void opt_input_file(const char *filename)
{
    AVFormatContext *ic;
    AVFormatParameters params, *ap = &params;
    URLFormat url_format;
    AVFormat *fmt;
    int err, i, ret;

    ic = av_mallocz(sizeof(AVFormatContext));
    strcpy(ic->filename, filename);
    /* first format guess to know if we must open file */
    fmt = file_format;
    if (!fmt) 
        fmt = guess_format(NULL, filename, NULL);
    
    if (fmt == NULL || !(fmt->flags & AVFMT_NOFILE)) {
        /* open file */
        if (url_fopen(&ic->pb, filename, URL_RDONLY) < 0) {
            fprintf(stderr, "Could not open '%s'\n", filename);
            exit(1);
        }
    
        /* find format and set default parameters */
        fmt = file_format;
        err = url_getformat(url_fileno(&ic->pb), &url_format);
        if (err >= 0) {
            if (!fmt)
                fmt = guess_format(url_format.format_name, NULL, NULL);
            ap->sample_rate = url_format.sample_rate;
            ap->frame_rate = url_format.frame_rate;
            ap->channels = url_format.channels;
            ap->width = url_format.width;
            ap->height = url_format.height;
            ap->pix_fmt = url_format.pix_fmt;
        } else {
            if (!fmt)
                fmt = guess_format(NULL, filename, NULL);
            memset(ap, 0, sizeof(*ap));
        }
    } else {
        memset(ap, 0, sizeof(*ap));
    }

    if (!fmt || !fmt->read_header) {
        fprintf(stderr, "%s: Unknown file format\n", filename);
        exit(1);
    }
    ic->format = fmt;

    /* get default parameters from command line */
    if (!ap->sample_rate)
        ap->sample_rate = audio_sample_rate;
    if (!ap->channels)
        ap->channels = audio_channels;

    if (!ap->frame_rate)
        ap->frame_rate = frame_rate;
    if (!ap->width)
        ap->width = frame_width;
    if (!ap->height)
        ap->height = frame_height;

    /* check filename in case of an image number is expected */
    if (ic->format->flags & AVFMT_NEEDNUMBER) {
        if (filename_number_test(ic->filename) < 0)
            exit(1);
    }
    
    err = ic->format->read_header(ic, ap);
    if (err < 0) {
        fprintf(stderr, "%s: Error while parsing header\n", filename);
        exit(1);
    }
    
    /* If not enough info for the codecs, we decode the first frames
       to get it. (used in mpeg case for example) */
    ret = find_codec_parameters(ic);
    if (ret < 0) {
        fprintf(stderr, "%s: could not find codec parameters\n", filename);
        exit(1);
    }

    /* update the current parameters so that they match the one of the input stream */
    for(i=0;i<ic->nb_streams;i++) {
        AVCodecContext *enc = &ic->streams[i]->codec;
        switch(enc->codec_type) {
        case CODEC_TYPE_AUDIO:
            //fprintf(stderr, "\nInput Audio channels: %d", enc->channels);
            audio_channels = enc->channels;
            audio_sample_rate = enc->sample_rate;
            break;
        case CODEC_TYPE_VIDEO:
            frame_height = enc->height;
            frame_width = enc->width;
            frame_rate = enc->frame_rate;
            break;
        default:
            abort();
        }
    }
    
    input_files[nb_input_files] = ic;
    /* dump the file content */
    dump_format(ic, nb_input_files, filename, 0);
    nb_input_files++;
    file_format = NULL;
}

void check_audio_video_inputs(int *has_video_ptr, int *has_audio_ptr)
{
    int has_video, has_audio, i, j;
    AVFormatContext *ic;

    has_video = 0;
    has_audio = 0;
    for(j=0;j<nb_input_files;j++) {
        ic = input_files[j];
        for(i=0;i<ic->nb_streams;i++) {
            AVCodecContext *enc = &ic->streams[i]->codec;
            switch(enc->codec_type) {
            case CODEC_TYPE_AUDIO:
                has_audio = 1;
                break;
            case CODEC_TYPE_VIDEO:
                has_video = 1;
                break;
            default:
                abort();
            }
        }
    }
    *has_video_ptr = has_video;
    *has_audio_ptr = has_audio;
}

void opt_output_file(const char *filename)
{
    AVStream *st;
    AVFormatContext *oc;
    int use_video, use_audio, nb_streams, input_has_video, input_has_audio;
    int codec_id;

    if (!strcmp(filename, "-"))
        filename = "pipe:";

    oc = av_mallocz(sizeof(AVFormatContext));

    if (!file_format) {
        file_format = guess_format(NULL, filename, NULL);
        if (!file_format)
            file_format = &mpeg_mux_format;
    }
    
    oc->format = file_format;

    if (!strcmp(file_format->name, "ffm") && 
        strstart(filename, "http:", NULL)) {
        /* special case for files sent to ffserver: we get the stream
           parameters from ffserver */
        if (read_ffserver_streams(oc, filename) < 0) {
            fprintf(stderr, "Could not read stream parameters from '%s'\n", filename);
            exit(1);
        }
    } else {
        use_video = file_format->video_codec != CODEC_ID_NONE;
        use_audio = file_format->audio_codec != CODEC_ID_NONE;

        /* disable if no corresponding type found and at least one
           input file */
        if (nb_input_files > 0) {
            check_audio_video_inputs(&input_has_video, &input_has_audio);
            if (!input_has_video)
                use_video = 0;
            if (!input_has_audio)
                use_audio = 0;
        }

        /* manual disable */
        if (audio_disable) {
            use_audio = 0;
        }
        if (video_disable) {
            use_video = 0;
        }
        
        nb_streams = 0;
        if (use_video) {
            AVCodecContext *video_enc;
            
            st = av_mallocz(sizeof(AVStream));
            if (!st) {
                fprintf(stderr, "Could not alloc stream\n");
                exit(1);
            }
            video_enc = &st->codec;

            codec_id = file_format->video_codec;
            if (video_codec_id != CODEC_ID_NONE)
                codec_id = video_codec_id;

            video_enc->codec_id = codec_id;
            video_enc->codec_type = CODEC_TYPE_VIDEO;
            
            video_enc->bit_rate = video_bit_rate;
            video_enc->bit_rate_tolerance = video_bit_rate_tolerance;
            video_enc->frame_rate = frame_rate; 
            
            video_enc->width = frame_width;
            video_enc->height = frame_height;
            if (!intra_only)
                video_enc->gop_size = gop_size;
            else
                video_enc->gop_size = 0;
            if (video_qscale || same_quality) {
                video_enc->flags |= CODEC_FLAG_QSCALE;
                video_enc->quality = video_qscale;
            }
            
            if (use_hq) {
                video_enc->flags |= CODEC_FLAG_HQ;
            }
            
            if (use_4mv) {
                video_enc->flags |= CODEC_FLAG_HQ;
                video_enc->flags |= CODEC_FLAG_4MV;
            }
            
            if (b_frames) {
                if (codec_id != CODEC_ID_MPEG4) {
                    fprintf(stderr, "\nB frames encoding only supported by MPEG-4.\n");
                    exit(1);
                }
                video_enc->max_b_frames = b_frames;
                video_enc->b_frame_strategy = 0;
                video_enc->b_quant_factor = 2.0;
            }
            
            video_enc->qmin = video_qmin;
            video_enc->qmax = video_qmax;
            video_enc->max_qdiff = video_qdiff;
            video_enc->qblur = video_qblur;
            video_enc->qcompress = video_qcomp;
            
            if (do_psnr)
                video_enc->get_psnr = 1;
            else
                video_enc->get_psnr = 0;
            
            video_enc->me_method = me_method;
            
            /* XXX: need to find a way to set codec parameters */
            if (oc->format == &ppm_format ||
                oc->format == &ppmpipe_format) {
                video_enc->pix_fmt = PIX_FMT_RGB24;
            }

            oc->streams[nb_streams] = st;
            nb_streams++;
        }
    
        if (use_audio) {
            AVCodecContext *audio_enc;

            st = av_mallocz(sizeof(AVStream));
            if (!st) {
                fprintf(stderr, "Could not alloc stream\n");
                exit(1);
            }
            audio_enc = &st->codec;
            codec_id = file_format->audio_codec;
            if (audio_codec_id != CODEC_ID_NONE)
                codec_id = audio_codec_id;
            audio_enc->codec_id = codec_id;
            audio_enc->codec_type = CODEC_TYPE_AUDIO;
            
            audio_enc->bit_rate = audio_bit_rate;
            audio_enc->sample_rate = audio_sample_rate;
            /* For audio codecs other than AC3 we limit */
            /* the number of coded channels to stereo   */
            if (audio_channels > 2 && codec_id != CODEC_ID_AC3) {
                audio_enc->channels = 2;
            } else
                audio_enc->channels = audio_channels;
            oc->streams[nb_streams] = st;
            nb_streams++;
        }

        oc->nb_streams = nb_streams;

        if (!nb_streams) {
            fprintf(stderr, "No audio or video streams available\n");
            exit(1);
        }

        if (str_title)
            nstrcpy(oc->title, sizeof(oc->title), str_title);
        if (str_author)
            nstrcpy(oc->author, sizeof(oc->author), str_author);
        if (str_copyright)
            nstrcpy(oc->copyright, sizeof(oc->copyright), str_copyright);
        if (str_comment)
            nstrcpy(oc->comment, sizeof(oc->comment), str_comment);
    }

    output_files[nb_output_files] = oc;
    /* dump the file content */
    dump_format(oc, nb_output_files, filename, 1);
    nb_output_files++;

    strcpy(oc->filename, filename);

    /* check filename in case of an image number is expected */
    if (oc->format->flags & AVFMT_NEEDNUMBER) {
        if (filename_number_test(oc->filename) < 0)
            exit(1);
    }

    if (!(oc->format->flags & AVFMT_NOFILE)) {
        /* test if it already exists to avoid loosing precious files */
        if (!file_overwrite && 
            (strchr(filename, ':') == NULL ||
             strstart(filename, "file:", NULL))) {
            if (url_exist(filename)) {
                int c;
                
                printf("File '%s' already exists. Overwrite ? [y/N] ", filename);
                fflush(stdout);
                c = getchar();
                if (toupper(c) != 'Y') {
                    fprintf(stderr, "Not overwriting - exiting\n");
                    exit(1);
                }
            }
        }
        
        /* open the file */
        if (url_fopen(&oc->pb, filename, URL_WRONLY) < 0) {
            fprintf(stderr, "Could not open '%s'\n", filename);
            exit(1);
        }
    }

    /* reset some options */
    file_format = NULL;
    audio_disable = 0;
    video_disable = 0;
    audio_codec_id = CODEC_ID_NONE;
    video_codec_id = CODEC_ID_NONE;
}

#ifdef CONFIG_GRAB

/* prepare dummy protocols for grab */
void prepare_grab(void)
{
    int has_video, has_audio, i, j;
    AVFormatContext *oc;
    AVFormatContext *ic;
    AVFormatParameters ap1, *ap = &ap1;

    /* see if audio/video inputs are needed */
    has_video = 0;
    has_audio = 0;
    memset(ap, 0, sizeof(*ap));
    for(j=0;j<nb_output_files;j++) {
        oc = output_files[j];
        for(i=0;i<oc->nb_streams;i++) {
            AVCodecContext *enc = &oc->streams[i]->codec;
            switch(enc->codec_type) {
            case CODEC_TYPE_AUDIO:
                if (enc->sample_rate > ap->sample_rate)
                    ap->sample_rate = enc->sample_rate;
                if (enc->channels > ap->channels)
                    ap->channels = enc->channels;
                has_audio = 1;
                break;
            case CODEC_TYPE_VIDEO:
                if (enc->width > ap->width)
                    ap->width = enc->width;
                if (enc->height > ap->height)
                    ap->height = enc->height;
                if (enc->frame_rate > ap->frame_rate)
                    ap->frame_rate = enc->frame_rate;
                has_video = 1;
                break;
            default:
                abort();
            }
        }