fprintf(stderr, "Must supply at least one input file\n"); exit(1);
int has_video, has_audio, i, j; AVFormatContext *oc; AVFormatContext *ic; AVFormatParameters ap1, *ap = &ap1;   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(); } } }  if (has_video == 0 && has_audio == 0) { fprintf(stderr, "Output file must have at least one audio or video stream\n"); exit(1); }  if (has_video) { AVInputFormat *fmt1; fmt1 = av_find_input_format("video_grab_device"); if (av_open_input_file(&ic, "", fmt1, 0, ap) < 0) { fprintf(stderr, "Could not find video grab device\n"); exit(1); }  ic->streams[0]->r_frame_rate = ap->frame_rate; input_files[nb_input_files] = ic; dump_format(ic, nb_input_files, v4l_device, 0); nb_input_files++; } if (has_audio) { AVInputFormat *fmt1; fmt1 = av_find_input_format("audio_device"); if (av_open_input_file(&ic, "", fmt1, 0, ap) < 0) { fprintf(stderr, "Could not find audio grab device\n"); exit(1); } input_files[nb_input_files] = ic; dump_format(ic, nb_input_files, audio_device, 0); nb_input_files++; }
void prepare_grab(void){    fprintf(stderr, "Must supply at least one input file\n");    exit(1);}